I have tried to take into account all of the corrections and suggestions people have made. If you want to see exactly what has changed since the last post, look at https://github.com/brettcannon/github-transition-pep/blob/master/pep-0512.rst and its commit history. In the last round of discussions, the most divisive thing was the switch to a cherry-picking workflow over the current merge-up one. I tried to flesh out the explanation for the planned change, but if people still want to discuss it then someone who wants to see it kept to a merge-up workflow needs to start a separate thread on that topic. Otherwise my hope is we can agree that the PEP covers what needs to be done soon so that we can start prioritizing work and then finding people to work on various things. And if you do reply to this email, please trim out what you don't comment on as the length of this PEP is such that after one reply the emails start getting held for moderation due to email size. ---------- PEP: 512 Title: Migrating from hg.python.org to GitHub Version: $Revision$ Last-Modified: $Date$ Author: Brett Cannon <brett@python.org> Status: Active Type: Process Content-Type: text/x-rst Created: Post-History: 17-Jan-2015, 19-Jan-2015 Abstract ======== This PEP outlines the steps required to migrate Python's development process from Mercurial [#hg]_ as hosted at hg.python.org [#h.p.o]_ to Git [#git]_ on GitHub [#GitHub]_. Meeting the minimum goals of this PEP should allow for the development process of Python to be as productive as it currently is, and meeting its extended goals should improve it. Rationale ========= In 2014, it became obvious that Python's custom development process was becoming a hindrance. As an example, for an external contributor to submit a fix for a bug that eventually was committed, the basic steps were: 1. Open an issue for the bug at bugs.python.org [#b.p.o]_. 2. Checkout out the CPython source code from hg.python.org [#h.p.o]_. 3. Make the fix. 4. Upload a patch. 5. Have a core developer review the patch using our fork of the Rietveld code review tool [#rietveld]_. 6. Download the patch to make sure it still applies cleanly. 7. Run the test suite manually. 8. Commit the change manually. 9. If the change was for a bugfix release, merge into the in-development branch. 10. Run the test suite manually again. 11. Commit the merge. 12. Push the changes. This is a very heavy, manual process for core developers. Even in the simple case, you could only possibly skip the code review step, as you would still need to build the documentation. This led to patches languishing on the issue tracker due to core developers not being able to work through the backlog fast enough to keep up with submissions. In turn, that led to a side-effect issue of discouraging outside contribution due to frustration from lack of attention, which is dangerous problem for an open source project as it runs counter to having a viable future for the project. Simply accepting patches uploaded to bugs.python.org [#b.p.o]_ is potentially simple for an external contributor, it is as slow and burdensome as it gets for a core developer to work with. Hence the decision was made in late 2014 that a move to a new development process was needed. A request for PEPs proposing new workflows was made, in the end leading to two: PEP 481 and PEP 507 proposing GitHub [#github]_ and GitLab [#gitlab]_, respectively. The year 2015 was spent off-and-on working on those proposals and trying to tease out details of what made them different from each other on the core-workflow mailing list [#core-workflow]_. PyCon US 2015 also showed that the community was a bit frustrated with our process due to both cognitive overhead for new contributors and how long it was taking for core developers to look at a patch (see the end of Guido van Rossum's keynote at PyCon US 2015 [#guido-keynote]_ as an example of the frustration). On January 1, 2016, the decision was made by Brett Cannon to move the development process to GitHub. The key reasons for choosing GitHub were [#reasons]_: * Maintaining custom infrastructure has been a burden on volunteers (e.g., a custom fork of Rietveld [#rietveld]_ that is not being maintained is currently being used). * The custom workflow is very time-consuming for core developers (not enough automated tooling built to help support it). * The custom workflow is a hindrance to external contributors (acts as a barrier of entry due to time required to ramp up on development process). * There is no feature differentiating GitLab from GitHub beyond GitLab being open source. * Familiarity with GitHub is far higher amongst core developers and external contributors than with GitLab. * Our BDFL prefers GitHub (who would be the first person to tell you that his opinion shouldn't matter, but the person making the decision felt it was important that the BDFL feel comfortable with the workflow of his own programming language to encourage his continued participation). There's even already an unofficial image to use to represent the migration to GitHub [#pythocat]_. The overarching goal of this migration is to improve the development process to the extent that a core developer can go from external contribution submission through all the steps leading to committing said contribution all from within a browser on a tablet with WiFi using *some* development process (this does not inherently mean GitHub's default workflow). All of this will be done in such a way that if an external contributor chooses not to use GitHub then they will continue to have that option. Repositories to Migrate ======================= While hg.python.org [#h.p.o]_ hosts many repositories, there are only five key repositories that should move: 1. devinabox [#devinabox-repo]_ 2. benchmarks [#benchmarks-repo]_ 4. peps [#peps-repo]_ 5. devguide [#devguide-repo]_ 6. cpython [#cpython-repo]_ The devinabox and benchmarks repositories are code-only. The peps and devguide repositories involve the generation of webpages. And the cpython repository has special requirements for integration with bugs.python.org [#b.p.o]_. Migration Plan ============== The migration plan is separated into sections based on what is required to migrate the repositories listed in the `Repositories to Migrate`_ section. Completion of requirements outlined in each section should unblock the migration of the related repositories. The sections are expected to be completed in order, but not necessarily the requirements within a section. Requirements for Code-Only Repositories --------------------------------------- Completion of the requirements in this section will allow the devinabox and benchmarks repositories to move to GitHub. While devinabox has a sufficiently descriptive name, the benchmarks repository does not; therefore, it will be named "python-benchmark-suite". Create a 'python-dev' team '''''''''''''''''''''''''' To manage permissions, a 'python-dev' team will be created as part of the python organization [#github-python-org]_. Any repository that is moved will have the 'python-dev' team added to it with write permissions [#github-org-perms]_. Anyone who previously had rights to manage SSH keys on hg.python.org will become a team maintainer for the 'python-dev' team. Define commands to move a Mercurial repository to Git ''''''''''''''''''''''''''''''''''''''''''''''''''''' Since moving to GitHub also entails moving to Git [#git]_, we must decide what tools and commands we will run to translate a Mercurial repository to Git. The exact tools and steps to use are an open issue; see `Tools and commands to move from Mercurial to Git`_. CLA enforcement ''''''''''''''' A key part of any open source project is making sure that its source code can be properly licensed. This requires making sure all people making contributions have signed a contributor license agreement (CLA) [#cla]_. Up until now, enforcement of CLA signing of contributed code has been enforced by core developers checking whether someone had an ``*`` by their username on bugs.python.org [#b.p.o]_. With this migration, the plan is to start off with automated checking and enforcement of contributors signing the CLA. Adding GitHub username support to bugs.python.org +++++++++++++++++++++++++++++++++++++++++++++++++ To keep tracking of CLA signing under the direct control of the PSF, tracking who has signed the PSF CLA will be continued by marking that fact as part of someone's bugs.python.org user profile. What this means is that an association will be needed between a person's bugs.python.org [#b.p.o]_ account and their GitHub account, which will be done through a new field in a user's profile. This does implicitly require that contributors will need both a GitHub [#github]_ and bugs.python.org account in order to sign the CLA and contribute through GitHub. A bot to enforce CLA signing ++++++++++++++++++++++++++++ With an association between someone's GitHub account and their bugs.python.org [#b.p.o]_ account, which has the data as to whether someone has signed the CLA, a bot can monitor pull requests on GitHub and denote whether the contributor has signed the CLA. If the user has signed the CLA, the bot will add a positive label to the issue to denote the pull request has no CLA issues (e.g., a green label stating, "CLA: ✓"). If the contributor has not signed a CLA, a negative label will be added to the pull request will be blocked using GitHub's status API (e.g., a red label stating, "CLA: ✗"). If a contributor lacks a bugs.python.org account, that will lead to another label (e.g., "CLA: ✗ (no account)"). Using a label for both positive and negative cases provides a fallback notification if the bot happens to fail, preventing potential false-positives or false-negatives. It also allows for an easy way to trigger the bot again by simply removing a CLA-related label. Requirements for Web-Related Repositories ----------------------------------------- Due to their use for generating webpages, the devguide [#devguide-repo]_ and peps [#peps-repo]_ repositories need their respective processes updated to pull from their new Git repositories. The devguide repository might also need to be named ``python-devguide`` to make sure the repository is not ambiguous when viewed in isolation from the python organization [#github-python-org]_. Requirements for the cpython Repository --------------------------------------- Obviously the most active and important repository currently hosted at hg.python.org [#h.p.o]_ is the cpython repository [#cpython-repo]_. Because of its importance and high- frequency use, it requires more tooling before being moved to GitHub compared to the other repositories mentioned in this PEP. Document steps to commit a pull request ''''''''''''''''''''''''''''''''''''''' During the process of choosing a new development workflow, it was decided that a linear history is desired. People preferred having a single commit representing a single change instead of having a set of unrelated commits lead to a merge commit that represented a single change. This means that the convenient "Merge" button in GitHub pull requests is undesirable, as it creates a merge commit along with all of the contributor's individual commits (this does not affect the other repositories where the desire for a linear history doesn't exist). Luckily, Git [#git]_ does not require GitHub's workflow and so one can be chosen which gives us a linear history by using Git's CLI. The expectation is that all pull requests will be fast-forwarded and rebased before being pushed to the master repository. This should give proper attribution to the pull request author in the Git history. This does have the consequence of losing some GitHub features such as automatic closing of pull requests, link generation, etc. A second set of recommended commands will also be written for committing a contribution from a patch file uploaded to bugs.python.org [#b.p.o]_. This will obviously help keep the linear history, but it will need to be made to have attribution to the patch author. The exact sequence of commands that will be given as guidelines to core developers is an open issue: `Git CLI commands for committing a pull request to cpython`_. Handling Misc/NEWS '''''''''''''''''' Traditionally the ``Misc/NEWS`` file [#news-file]_ has been problematic for changes which spanned Python releases. Often times there will be merge conflicts when committing a change between e.g., 3.5 and 3.6 only in the ``Misc/NEWS`` file. It's so common, in fact, that the example instructions in the devguide explicitly mention how to resolve conflicts in the ``Misc/NEWS`` file [#devguide-merge-across-branches]_. As part of our tool modernization, working with the ``Misc/NEWS`` file will be simplified. There are currently two competing approaches to solving the ``Misc/NEWS`` problem which are discussed in an open issue: `How to handle the Misc/NEWS file`_. Handling Misc/ACKS '''''''''''''''''' Traditionally the ``Misc/ACKS`` file [#acks-file]_ has been managed by hand. But thanks to Git supporting an ``author`` value as well as a ``committer`` value per commit, authorship of a commit can be part of the history of the code itself. As such, manual management of ``Misc/ACKS`` will become optional. A script will be written that will collect all author and committer names and merge them into ``Misc/ACKS`` with all of the names listed prior to the move to Git. Running this script will become part of the release process. Linking pull requests to issues ''''''''''''''''''''''''''''''' Historically, external contributions were attached to an issue on bugs.python.org [#b.p.o]_ thanks to the fact that all external contributions were uploaded as a file. For changes committed by a core developer who committed a change directly, the specifying of an issue number in the commit message of the format ``Issue #`` at the start of the message led to a comment being posted to the issue linking to the commit. Linking a pull request to an issue ++++++++++++++++++++++++++++++++++ An association between a pull request and an issue is needed to track when a fix has been proposed. The association needs to be many-to-one as there can take multiple pull requests to solve a single issue (technically it should be a many-to-many association for when a single fix solves multiple issues, but this is fairly rare and issues can be merged into one using the ``Superseder`` field on the issue tracker). Association between a pull request and an issue will be done based on detecting the regular expression``[Ii]ssue #(?P<bpo_id>\d+)``. If this is specified in either the title or in the body of a message on a pull request then connection will be made on bugs.python.org [#b.p.o]_. A label will also be added to the pull request to signify that the connection was made successfully. This could lead to incorrect associations if the wrong issue or referencing another issue was done, but these are rare occasions. Notify the issue if the pull request is committed +++++++++++++++++++++++++++++++++++++++++++++++++ Once a pull request is closed (merged or not), the issue should be updated to reflect this fact. Update linking service for mapping commit IDs to URLs ''''''''''''''''''''''''''''''''''''''''''''''''''''' Currently you can use https://hg.python.org/lookup/ with a revision ID from either the Subversion or Mercurial copies of the cpython repo [#cpython-repo]_ to get redirected to the URL for that revision in the Mercurial repository. The URL rewriter will need to be updated to redirect to the Git repository and to support the new revision IDs created for the Git repository. Create https://git.python.org ''''''''''''''''''''''''''''' Just as hg.python.org [#h.p.o]_ currently points to the Mercurial repository for Python, git.python.org should do the equivalent for the Git repository. Backup of pull request data ''''''''''''''''''''''''''' Since GitHub [#github]_ is going to be used for code hosting and code review, those two things need to be backed up. In the case of code hosting, the backup is implicit as all non-shallow Git [#git]_ clones contain the full history of the repository, hence there will be many backups of the repository. The code review history does not have the same implicit backup mechanism as the repository itself. That means a daily backup of code review history should be done so that it is not lost in case of any issues with GitHub. It also helps guarantee that a migration from GitHub to some other code review system is feasible were GitHub to disappear overnight. Change sys._mercurial ''''''''''''''''''''' Once Python is no longer kept in Mercurial, the ``sys._mercurial`` attribute will need to be removed. An equivalent ``sys._git`` attribute will be needed to take its place. Update the devguide ''''''''''''''''''' The devguide will need to be updated with details of the new workflow. Mostly likely work will take place in a separate branch until the migration actually occurs. Update PEP 101 '''''''''''''' The release process will need to be updated as necessary. Optional, Planned Features -------------------------- Once the cpython repository [#cpython-repo]_ is migrated, all repositories will have been moved to GitHub [#github]_ and the development process should be on equal footing as before. But a key reason for this migration is to improve the development process, making it better than it has ever been. This section outlines some plans on how to improve things. It should be mentioned that overall feature planning for bugs.python.org [#b.p.o]_ -- which includes plans independent of this migration -- are tracked on their own wiki page [#tracker-plans]_. Bot to handle pull request merging '''''''''''''''''''''''''''''''''' As stated in the section entitled "`Document steps to commit a pull request`_", the desire is to maintain a linear history for cpython. Unfortunately, Github's [#github]_ web-based workflow does not support a linear history. Because of this, a bot should be written to substitute for GitHub's in-browser commit abilities. To start, the bot should accept commands to commit a pull request against a list of branches. This allows for committing a pull request that fixes a bug in multiple versions of Python. More advanced features such as a commit queue can come later. This would linearly apply accepted pull requests and verify that the commits did not interfere with each other by running the test suite and backing out commits if the test run failed. To help facilitate the speed of testing, all patches committed since the last test run can be applied and run in a single test run as the optimistic assumption is that the patches will work in tandem. Inspiration or basis of the bot could be taken from pre-existig bots such as Homu [#homu]_ or Zuul [#zuul]_. The name given to this bot in order to give it commands is an open issue: `Naming the commit bot`_. Continuous integration per pull request ''''''''''''''''''''''''''''''''''''''' To help speed up pull request approvals, continuous integration testing should be used. This helps mitigate the need for a core developer to download a patch simply to run the test suite against the patch. Which free CI service to use is an open issue: `Choosing a CI service`_. Test coverage report '''''''''''''''''''' Getting an up-to-date test coverage report for Python's standard library would be extremely beneficial as generating such a report can take quite a while to produce. There are a couple pre-existing services that provide free test coverage for open source projects. Which option is best is an open issue: `Choosing a test coverage service`_. Notifying issues of pull request comments ''''''''''''''''''''''''''''''''''''''''' The current development process does not include notifying an issue on bugs.python.org [#b.p.o]_ when a review comment is left on Rietveld [#rietveld]_. It would be nice to fix this so that people can subscribe only to comments at bugs.python.org and not GitHub [#github]_ and yet still know when something occurs on GitHub in terms of review comments on relevant pull requests. Current thinking is to post a comment to bugs.python.org to the relevant issue when at least one review comment has been made over a certain period of time (e.g., 15 or 30 minutes). This keeps the email volume down for those that receive both GitHub and bugs.python.org email notifications while still making sure that those only following bugs.python.org know when there might be a review comment to address. Allow bugs.python.org to use GitHub as a login provider ''''''''''''''''''''''''''''''''''''''''''''''''''''''' As of right now, bugs.python.org [#b.p.o]_ allows people to log in using Google, Launchpad, or OpenID credentials. It would be good to expand this to GitHub credentials. Web hooks for re-generating web content ''''''''''''''''''''''''''''''''''''''' The content at https://docs.python.org/, https://docs.python.org/devguide, and https://www.python.org/dev/peps/ are all derived from files kept in one of the repositories to be moved as part of this migration. As such, it would be nice to set up appropriate webhooks to trigger rebuilding the appropriate web content when the files they are based on change instead of having to wait for, e.g., a cronjob to trigger. Link web content back to files that it is generated from '''''''''''''''''''''''''''''''''''''''''''''''''''''''' It would be helpful for people who find issues with any of the documentation that is generated from a file to have a link on each page which points back to the file on GitHub [#github]_ that stores the content of the page. That would allow for quick pull requests to fix simple things such as spelling mistakes. Splitting out parts of the documentation into their own repositories '''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''' While certain parts of the documentation at https://docs.python.org change with the code, other parts are fairly static and are not tightly bound to the CPython code itself. The following sections of the documentation fit this category of slow-changing, loosely-coupled: * `Tutorial <https://docs.python.org/3/tutorial/index.html>`__ * `Python Setup and Usage <https://docs.python.org/3/using/index.html>`__ * `HOWTOs <https://docs.python.org/3/howto/index.html>`__ * `Installing Python Modules < https://docs.python.org/3/installing/index.html>`__ * `Distributing Python Modules < https://docs.python.org/3/distributing/index.html>`__ * `Extending and Embedding <https://docs.python.org/3/extending/index.html >`__ * `FAQs <https://docs.python.org/3/faq/index.html>`__ These parts of the documentation could be broken out into their own repositories to simplify their maintenance and to expand who has commit rights to them to ease in their maintenance. It has also been suggested to split out the `What's New <https://docs.python.org/3/whatsnew/index.html>`__ documents. That would require deciding whether a workflow could be developed where it would be difficult to forget to update What's New (potentially through a label added to PRs, like "What's New needed"). Backup of Git repositories '''''''''''''''''''''''''' While not necessary, it would be good to have official backups of the various Git repositories for disaster protection. It will be up to the PSF infrastructure committee to decide if this is worthwhile or unnecessary. Status ====== Requirements for migrating the devinabox [#devinabox-repo]_ and benchmarks [#benchmarks-repo]_ repositories: * Not started - `Create a 'python-dev' team`_ - `Define commands to move a Mercurial repository to Git`_ - `Adding GitHub username support to bugs.python.org`_ - `A bot to enforce CLA signing`_ * In progress - None * Completed - None Repositories whose build steps need updating: * Not started - peps [#peps-repo]_ - devguide [#devguide-repo]_ * In progress - None * Completed - None Requirements to move over the cpython repo [#cpython-repo]_: * Not started - `Document steps to commit a pull request`_ - `Handling Misc/NEWS`_ - `Handling Misc/ACKS`_ - `Linking a pull request to an issue`_ - `Notify the issue if the pull request is committed`_ - `Update linking service for mapping commit IDs to URLs`_ - `Create https://git.python.org`_ - `Backup of pull request data`_ - `Change sys._mercurial`_ - `Update the devguide`_ - `Update PEP 101`_ * In progress - None * Completed - None Optional features: * Not started - `Bot to handle pull request merging`_ - `Continuous integration per pull request`_ - `Test coverage report`_ - `Notifying issues of pull request comments`_ - `Allow bugs.python.org to use GitHub as a login provider`_ - `Web hooks for re-generating web content`_ - `Link web content back to files that it is generated from`_ - `Splitting out parts of the documentation into their own repositories`_ - `Backup of Git repositories`_ * In progress - None * Completed - None Open Issues =========== For this PEP, open issues are ones where a decision needs to be made to how to approach or solve a problem. Open issues do not entail coordination issues such as who is going to write a certain bit of code. The fate of hg.python.org ------------------------- With the code repositories moving over to Git [#git]_, there is no technical need to keep hg.python.org [#h.p.o]_ running. Having said that, some in the community would like to have it stay functioning as a Mercurial [#hg]_ mirror of the Git repositories. Others have said that they still want a mirror, but one using Git. As maintaining hg.python.org is not necessary, it will be up to the PSF infrastructure committee to decide if they want to spend the time and resources to keep it running. They may also choose whether they want to host a Git mirror on PSF infrastructure. Depending on the decision reached, other ancillary repositories will either be forced to migration or they can choose to simply stay on hg.python.org. Tools and commands to move from Mercurial to Git ------------------------------------------------ A decision needs to be made on exactly what tooling and what commands involving those tools will be used to convert a Mercurial repository to Git. Currently a suggestion has been made to use https://github.com/frej/fast-export. Another suggestion is to use https://github.com/felipec/git-remote-hg. Finally, http://hg-git.github.io/ has been suggested. Git CLI commands for committing a pull request to cpython --------------------------------------------------------- Because Git [#git]_ may be a new version control system for core developers, the commands people are expected to run will need to be written down. These commands also need to keep a linear history while giving proper attribution to the pull request author. Another set of commands will also be necessary for when working with a patch file uploaded to bugs.python.org [#b.p.o]_. Here the linear history will be kept implicitly, but it will need to make sure to keep/add attribution. How to handle the Misc/NEWS file -------------------------------- There are three competing approaches to handling ``Misc/NEWS`` [#news-file]_. One is to add a news entry for issues on bugs.python.org [#b.p.o]_. This would mean an issue that is marked as "resolved" could not be closed until a news entry is added in the "news" field in the issue tracker. The benefit of tying the news entry to the issue is it makes sure that all changes worthy of a news entry have an accompanying issue. It also makes classifying a news entry automatic thanks to the Component field of the issue. The Versions field of the issue also ties the news entry to which Python releases were affected. A script would be written to query bugs.python.org for relevant new entries for a release and to produce the output needed to be checked into the code repository. This approach is agnostic to whether a commit was done by CLI or bot. A competing approach is to use an individual file per news entry, containing the text for the entry. In this scenario each feature release would have its own directory for news entries and a separate file would be created in that directory that was either named after the issue it closed or a timestamp value (which prevents collisions). Merges across branches would have no issue as the news entry file would still be uniquely named and in the directory of the latest version that contained the fix. A script would collect all news entry files no matter what directory they reside in and create an appropriate news file (the release directory can be ignored as the mere fact that the file exists is enough to represent that the entry belongs to the release). Classification can either be done by keyword in the new entry file itself or by using subdirectories representing each news entry classification in each release directory (or classification of news entries could be dropped since critical information is captured by the "What's New" documents which are organized). The benefit of this approach is that it keeps the changes with the code that was actually changed. It also ties the message to being part of the commit which introduced the change. For a commit made through the CLI, a script will be provided to help generate the file. In a bot-driven scenario, the merge bot will have a way to specify a specific news entry and create the file as part of its flattened commit (while most likely also supporting using the first line of the commit message if no specific news entry was specified). Code for this approach has been written previously for the Mercurial workflow at http://bugs.python.org/issue18967. There is also tools from the community like https://pypi.python.org/pypi/towncrier and https://github.com/twisted/newsbuilder . A yet third option is a merge script to handle the conflicts. This approach allows for keeping the NEWS file as a single file. It does run the risk, though, of failure and thus blocking a commit until it can be manually resolved. Naming the commit bot --------------------- As naming things can lead to bikeshedding of epic proportions, Brett Cannon will choose the final name of the commit bot (the name of the project for the bot itself can be anything, this is purely for the name used in giving commands to the bot). The name will come from Monty Python, which is only fitting since Python is named after the comedy troupe. It will most likely come from 'Monty Python and the Holy Grail' [#holy-grail]_ (which happens to be how Brett was introduced to Monty Python). Current ideas on the name include: "Black Knight" sketch [#black-knight-sketch]_: * black-knight * none-shall-pass * just-a-flesh-wound "Bridge of Death" sketch [#bridge-of-death-sketch]_: * bridge-keeper * man-from-scene-24 * five-questions * what-is-your-quest * blue-no-green * air-speed-velocity * your-favourite-colour (and that specific spelling; Monty Python is British, after all) "Killer rabbit" sketch [#killer-rabbit-sketch]_: * killer-rabbit * holy-hand-grenade * 5-is-right-out "Witch Village" sketch [#witch-village-sketch]_: * made-of-wood * burn-her "French Taunter" sketch [#french-taunter-sketch]_: * elderberries * kanigget "Constitutional Peasants" sketch [#constitutional-peasants-sketch]_: * dennis * from-the-masses "Knights Who Say Ni" sketch [#ni-sketch]_: * shubbery * ni >From "Monty Python and the Holy Grail" in general: * brave-sir-robin Choosing a CI service --------------------- There are various CI services that provide free support for open source projects hosted on GitHub [#github]_. Two such examples are Travis [#travis]_ and Codeship [#codeship]_. Whatever solution is chosen will need to not time out in the time it takes to execute Python's test suite. It should optimally provide access to multiple C compilers for more thorough testing. Network access is also beneficial. The current CI service for Python is Pypatcher [#pypatcher]_. A request can be made in IRC to try a patch from bugs.python.org [#b.p.o]_. The results can be viewed at https://ci.centos.org/job/cPython-build-patch/ . Choosing a test coverage service -------------------------------- Getting basic test coverage of Python's standard library can be created simply by using coverage.py [#coverage]_. Getting thorough test coverage is actually quite tricky, with the details outlined in the devinabox's README [#devinabox-repo]_. It would be best if a service could be found that would allow for thorough test coverage, but it might not be feasible. Free test coverage services include Coveralls [#coveralls]_ and Codecov [#codecov]_. Rejected Ideas ============== Separate Python 2 and Python 3 repositories ------------------------------------------- It was discussed whether separate repositories for Python 2 and Python 3 were desired. The thinking was that this would shrink the overall repository size which benefits people with slow Internet connections or small bandwidth caps. In the end it was decided that it was easier logistically to simply keep all of CPython's history in a single repository. Commit multi-release changes in bugfix branch first --------------------------------------------------- As the current development process has changes committed in the oldest branch first and then merged up to the default branch, the question came up as to whether this workflow should be perpetuated. In the end it was decided that committing in the newest branch and then cherry-picking changes into older branches would work best as most people will instinctively work off the newest branch and it is a more common workflow when using Git [#git]_. Cherry-picking is also more bot-friendly for an in-browser workflow. In the merge-up scenario, if you were to request a bot to do a merge and it failed, then you would have to make sure to immediately solve the merge conflicts if you still allowed the main commit, else you would need to postpone the entire commit until all merges could be handled. With a cherry-picking workflow, the main commit could proceed while postponing the merge-failing cherry-picks. This allows for possibly distributing the work of managing conflicting merges. Deriving ``Misc/NEWS`` from the commit logs ------------------------------------------- As part of the discussion surrounding `Handling Misc/NEWS`_, the suggestion has come up of deriving the file from the commit logs itself. In this scenario, the first line of a commit message would be taken to represent the news entry for the change. Some heuristic to tie in whether a change warranted a news entry would be used, e.g., whether an issue number is listed. This idea has been rejected due to some core developers preferring to write a news entry separate from the commit message. The argument is the first line of a commit message compared to that of a news entry have different requirements in terms of brevity, what should be said, etc. References ========== .. [#h.p.o] https://hg.python.org .. [#GitHub] GitHub (https://github.com) .. [#hg] Mercurial (https://www.mercurial-scm.org/) .. [#git] Git (https://git-scm.com/) .. [#b.p.o] https://bugs.python.org .. [#rietveld] Rietveld (https://github.com/rietveld-codereview/rietveld) .. [#gitlab] GitLab (https://about.gitlab.com/) .. [#core-workflow] core-workflow mailing list ( https://mail.python.org/mailman/listinfo/core-workflow) .. [#guido-keynote] Guido van Rossum's keynote at PyCon US ( https://www.youtube.com/watch?v=G-uKNd5TSBw) .. [#reasons] Email to core-workflow outlining reasons why GitHub was selected (https://mail.python.org/pipermail/core-workflow/2016-January/000345.html ) .. [#benchmarks-repo] Mercurial repository for the Unified Benchmark Suite (https://hg.python.org/benchmarks/) .. [#devinabox-repo] Mercurial repository for devinabox ( https://hg.python.org/devinabox/) .. [#peps-repo] Mercurial repository of the Python Enhancement Proposals ( https://hg.python.org/peps/) .. [#devguide-repo] Mercurial repository for the Python Developer's Guide ( https://hg.python.org/devguide/) .. [#cpython-repo] Mercurial repository for CPython ( https://hg.python.org/cpython/) .. [#github-python-org] Python organization on GitHub ( https://github.com/python) .. [#github-org-perms] GitHub repository permission levels ( https://help.github.com/enterprise/2.4/user/articles/repository-permission-levels-for-an-organization/ ) .. [#cla] Python Software Foundation Contributor Agreement ( https://www.python.org/psf/contrib/contrib-form/) .. [#news-file] ``Misc/NEWS`` ( https://hg.python.org/cpython/file/default/Misc/NEWS) .. [#acks-file] ``Misc/ACKS`` ( https://hg.python.org/cpython/file/default/Misc/ACKS) .. [#devguide-merge-across-branches] Devguide instructions on how to merge across branches ( https://docs.python.org/devguide/committing.html#merging-between-different-branches-within-the-same-major-version ) .. [#pythocat] Pythocat (https://octodex.github.com/pythocat/) .. [#tracker-plans] Wiki page for bugs.python.org feature development (https://wiki.python.org/moin/TrackerDevelopmentPlanning) .. [#black-knight-sketch] The "Black Knight" sketch from "Monty Python and the Holy Grail" (https://www.youtube.com/watch?v=dhRUe-gz690) .. [#bridge-of-death-sketch] The "Bridge of Death" sketch from "Monty Python and the Holy Grail" (https://www.youtube.com/watch?v=cV0tCphFMr8) .. [#holy-grail] "Monty Python and the Holy Grail" sketches (https://www.youtube.com/playlist?list=PL-Qryc-SVnnu1MvN3r94Y9atpaRuIoGmp ) .. [#killer-rabbit-sketch] "Killer rabbit" sketch from "Monty Python and the Holy Grail" ( https://www.youtube.com/watch?v=Nvs5pqf-DMA&list=PL-Qryc-SVnnu1MvN3r94Y9atpaRuIoGmp&index=11 ) .. [#witch-village-sketch] "Witch Village" from "Monty Python and the Holy Grail" ( https://www.youtube.com/watch?v=k3jt5ibfRzw&list=PL-Qryc-SVnnu1MvN3r94Y9atpaRuIoGmp&index=12 ) .. [#french-taunter-sketch] "French Taunter" from "Monty Python and the Holy Grail" ( https://www.youtube.com/watch?v=A8yjNbcKkNY&list=PL-Qryc-SVnnu1MvN3r94Y9atpaRuIoGmp&index=13 ) .. [#constitutional-peasants-sketch] "Constitutional Peasants" from "Monty Python and the Holy Grail" ( https://www.youtube.com/watch?v=JvKIWjnEPNY&list=PL-Qryc-SVnnu1MvN3r94Y9atpaRuIoGmp&index=14 ) .. [#ni-sketch] "Knights Who Say Ni" from "Monty Python and the Holy Grail" ( https://www.youtube.com/watch?v=zIV4poUZAQo&list=PL-Qryc-SVnnu1MvN3r94Y9atpaRuIoGmp&index=15 ) .. [#homu] Homu (http://homu.io/) .. [#zuul] Zuul (http://docs.openstack.org/infra/zuul/) .. [#travis] Travis (https://travis-ci.org/) .. [#codeship] Codeship (https://codeship.com/) .. [#coverage] coverage.py (https://pypi.python.org/pypi/coverage) .. [#coveralls] Coveralls (https://coveralls.io/) .. [#codecov] Codecov (https://codecov.io/) .. [#pypatcher] Pypatcher (https://github.com/kushaldas/pypatcher) Copyright ========= This document has been placed in the public domain. .. Local Variables: mode: indented-text indent-tabs-mode: nil sentence-end-double-space: t fill-column: 70 coding: utf-8 End:
Hi Brett,
Change sys._mercurial ''''''''''''''''''''' Once Python is no longer kept in Mercurial, the ``sys._mercurial`` attribute will need to be removed. An equivalent ``sys._git`` attribute will be needed to take its place.
Would it make sense to change it to something more general like: sys._version_control_system or sys._vcs with maybe a new field for the type of vcs: 'mercurial', 'git' or 'the next one' :-) Regards, francis
For backwards compatibility sys._mercurial must probably stay. Maybe it could be None, so we could write if sys._mercurial: ... elif sys._git: ... else: # unknown VCS ... On Wed, Jan 20, 2016 at 12:39 PM, francismb <francismb@email.de> wrote:
Hi Brett,
Change sys._mercurial ''''''''''''''''''''' Once Python is no longer kept in Mercurial, the ``sys._mercurial`` attribute will need to be removed. An equivalent ``sys._git`` attribute will be needed to take its place.
Would it make sense to change it to something more general like:
sys._version_control_system or sys._vcs with maybe a new field for the type of vcs: 'mercurial', 'git' or 'the next one' :-)
Regards, francis _______________________________________________ core-workflow mailing list core-workflow@python.org https://mail.python.org/mailman/listinfo/core-workflow This list is governed by the PSF Code of Conduct: https://www.python.org/psf/codeofconduct
-- --Guido van Rossum (python.org/~guido)
FWIW sys.subversion has been deprecated in 3.2.1 and removed in 3.3 [0]. In 3.2.1+ and 2.7 it returns ('CPython', '', ''). In theory sys._mercurial is private, so technically we don't have to go through the same deprecation process, but I see no harm in deprecating it in 3.6 and then removing it in 3.7+ (assuming we are going to remove it). Best Regards, Ezio Melotti [0]: https://docs.python.org/3.2/library/sys.html#sys.subversion On Thu, Jan 21, 2016 at 12:34 AM, Guido van Rossum <guido@python.org> wrote:
For backwards compatibility sys._mercurial must probably stay. Maybe it could be None, so we could write
if sys._mercurial: ... elif sys._git: ... else: # unknown VCS ...
On Wed, Jan 20, 2016 at 12:39 PM, francismb <francismb@email.de> wrote:
Hi Brett,
Change sys._mercurial ''''''''''''''''''''' Once Python is no longer kept in Mercurial, the ``sys._mercurial`` attribute will need to be removed. An equivalent ``sys._git`` attribute will be needed to take its place.
Would it make sense to change it to something more general like:
sys._version_control_system or sys._vcs with maybe a new field for the type of vcs: 'mercurial', 'git' or 'the next one' :-)
Regards, francis _______________________________________________ core-workflow mailing list core-workflow@python.org https://mail.python.org/mailman/listinfo/core-workflow This list is governed by the PSF Code of Conduct: https://www.python.org/psf/codeofconduct
-- --Guido van Rossum (python.org/~guido)
_______________________________________________ core-workflow mailing list core-workflow@python.org https://mail.python.org/mailman/listinfo/core-workflow This list is governed by the PSF Code of Conduct: https://www.python.org/psf/codeofconduct
On Wed, 20 Jan 2016 at 12:40 francismb <francismb@email.de> wrote:
Hi Brett,
Change sys._mercurial ''''''''''''''''''''' Once Python is no longer kept in Mercurial, the ``sys._mercurial`` attribute will need to be removed. An equivalent ``sys._git`` attribute will be needed to take its place.
Would it make sense to change it to something more general like:
sys._version_control_system or sys._vcs with maybe a new field for the type of vcs: 'mercurial', 'git' or 'the next one' :-)
This is brought up every time we change the VCS. I'm not pushing one way or the other so I leave it up to others to argue whether we should change the approach taken by starting a new thread (but unless a consensus is reached I'm sticking with what we have done in the past). If I remember correctly, the original argument for not going generic is there is no guarantee future VCSs will have similar semantics that will fit into whatever tuple or dict structure we chose.
On 22 January 2016 at 03:21, Brett Cannon <brett@python.org> wrote:
If I remember correctly, the original argument for not going generic is there is no guarantee future VCSs will have similar semantics that will fit into whatever tuple or dict structure we chose.
Yep, the name of the attribute conveys how to interpret it, while a generic name means you need some *other* data source to tell you "OK, up to version X.Y it's a subversion version, up to 3.5 it's a Mercurial hash, in 3.6+ it's a git hash..." With the attribute changing names, folks trying to use the VCS info at least get a really clear indicator when we change version control systems, even if they're not closely following upstream process changes. Cheers, Nick. -- Nick Coghlan | ncoghlan@gmail.com | Brisbane, Australia
On Thu, 21 Jan 2016 at 20:24 Nick Coghlan <ncoghlan@gmail.com> wrote:
On 22 January 2016 at 03:21, Brett Cannon <brett@python.org> wrote:
If I remember correctly, the original argument for not going generic is there is no guarantee future VCSs will have similar semantics that will fit into whatever tuple or dict structure we chose.
Yep, the name of the attribute conveys how to interpret it, while a generic name means you need some *other* data source to tell you "OK, up to version X.Y it's a subversion version, up to 3.5 it's a Mercurial hash, in 3.6+ it's a git hash..."
With the attribute changing names, folks trying to use the VCS info at least get a really clear indicator when we change version control systems, even if they're not closely following upstream process changes.
Actually, do people find the sys._mercurial attribute useful? I just want to double-check that this is worth continually going through this every few years when we change VCSs to swap in a new attribute. I will definitely update the PEP to set sys._mercurial to `('CPython', '', '')` (the attribute isn't even documented so there's no real deprecation to do).
Hi,
Repositories to Migrate ======================= While hg.python.org [#h.p.o]_ hosts many repositories, there are only five key repositories that should move:
1. devinabox [#devinabox-repo]_ 2. benchmarks [#benchmarks-repo]_ 4. peps [#peps-repo]_ 5. devguide [#devguide-repo]_ 6. cpython [#cpython-repo]_
On the web site I'm getting: """ While hg.python.org [1] hosts many repositories, there are only five key repositories that should move: devinabox [12] System Message: WARNING/2 ( pep-0512.txt , line 112) Enumerated list ends without a blank line; unexpected unindent. 2. benchmarks [11] 4. peps [13] 5. devguide [14] 6. cpython [15] """ Regards, francis
Bot to handle pull request merging '''''''''''''''''''''''''''''''''' As stated in the section entitled "`Document steps to commit a pull request`_", the desire is to maintain a linear history for cpython. Unfortunately, Github's [#github]_ web-based workflow does not support a linear history. Because of this, a bot should be written to substitute for GitHub's in-browser commit abilities.
To start, the bot should accept commands to commit a pull request against a list of branches. This allows for committing a pull request that fixes a bug in multiple versions of Python.
More advanced features such as a commit queue can come later. This would linearly apply accepted pull requests and verify that the commits did not interfere with each other by running the test suite and backing out commits if the test run failed. To help facilitate the speed of testing, all patches committed since the last test run can be applied and run in a single test run as the optimistic assumption is that the patches will work in tandem.
Inspiration or basis of the bot could be taken from pre-existig bots such as Homu [#homu]_ or Zuul [#zuul]_.
From the experience on both OpenShift [1] and Kubernetes [2] I know there's a need to rerun tests quite frequently (flakes, errors, etc). One option is to close and re-open the issue to
On Wed, Jan 20, 2016 at 1:51 AM, Brett Cannon <brett@python.org> wrote: trigger the integrated CI services to re-run, which is cumbersome imho. Both of the aforementioned projects have testing bots. The one in orgin [1] is more sophisticated in that it allows core-devs running finer grained tests before actually merging the PR. The merge bot runs quite bit of the tests, but not all, possible examples include benchmarks. Just a food for thought ;) Maciej [1] https://github.com/openshift/origin/ [2] https://github.com/kubernetes/kubernetes
On Fri, 22 Jan 2016 at 14:44 Maciej Szulik <soltysh@gmail.com> wrote:
On Wed, Jan 20, 2016 at 1:51 AM, Brett Cannon <brett@python.org> wrote:
Bot to handle pull request merging '''''''''''''''''''''''''''''''''' As stated in the section entitled "`Document steps to commit a pull request`_", the desire is to maintain a linear history for cpython. Unfortunately, Github's [#github]_ web-based workflow does not support a linear history. Because of this, a bot should be written to substitute for GitHub's in-browser commit abilities.
To start, the bot should accept commands to commit a pull request against a list of branches. This allows for committing a pull request that fixes a bug in multiple versions of Python.
More advanced features such as a commit queue can come later. This would linearly apply accepted pull requests and verify that the commits did not interfere with each other by running the test suite and backing out commits if the test run failed. To help facilitate the speed of testing, all patches committed since the last test run can be applied and run in a single test run as the optimistic assumption is that the patches will work in tandem.
Inspiration or basis of the bot could be taken from pre-existig bots such as Homu [#homu]_ or Zuul [#zuul]_.
From the experience on both OpenShift [1] and Kubernetes [2] I know there's a need to rerun tests quite frequently (flakes, errors, etc). One option is to close and re-open the issue to trigger the integrated CI services to re-run, which is cumbersome imho. Both of the aforementioned projects have testing bots. The one in orgin [1] is more sophisticated in that it allows core-devs running finer grained tests before actually merging the PR. The merge bot runs quite bit of the tests, but not all, possible examples include benchmarks. Just a food for thought ;)
Thanks for the warning, Maciej. I have added a note that test re-runs should be considered in its design. Will go out with the next set of updates (hopefully tomorrow once I find out if anyone actually uses the sys._mercurial attribute).
participants (6)
-
Brett Cannon -
Ezio Melotti -
francismb -
Guido van Rossum -
Maciej Szulik -
Nick Coghlan