On Aug 28, 2014, at 6:09 PM, Donald Stufft <donald@stufft.io> wrote:

On Aug 28, 2014, at 2:58 PM, Donald Stufft <donald@stufft.io> wrote:

Right now the “canonical” page for a particular project on PyPI is whatever the

author happened to name their package (e.g. Django). This requires PyPI to have

some "smarts" so that it can redirect things like /simple/django/ to

/simple/Django/ otherwise someone doing ``pip install django`` would fall back

to a much worse behavior.

If this redirect doesn't happen, then pip will issue a request for just

/simple/ and look for a link that, when both sides are normalized, compares

equal to the name it's looking for. It will then follow the link, get

/simple/Django/ and everything works... Except it doesn't. The problem here

comes from the external link classification that we have now. Pip sees the

link to /simple/Django/ as an external link (because it lacks the required

rels) and the installation finally fails.

The /simple/ case rarely happens when installing from PyPI itself because of

the redirect, however it happens quite often when someone is attempting to

instal from a mirror instead. Even when everything works correctly the penality

for not knowing exactly what name to type in results in at least 1 extra http

request, one of which (/simple/) requires pulling down a 2.1MB file.

To fix this I'm going to modify PyPI so that it uses the normalized name in

the /simple/ URL and redirects everything else to the non-normalized name. I'm

also going to submit a PR to bandersnatch so that it will use normalized names

for it's directories and such as well. These two changes will make it so that

the client side will know ahead of time exactly what form the server expects

any given name to be in. This will allow a change in pip to happen which

will pre-normalize all names which will make the interaction with mirrors better

and will reduce the number of HTTP requests that a single ``pip install`` needs

to make.

---

Donald Stufft

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Hm, so here’s the problem.

I have this implemented and deployed to TestPyPI, it works great!

However, the next step is to make the change to bandersnatch so that it saves

things using their normalized name instead of using their "proper" name. Doing

this will trigger it so that everyone using pip 1.5 won't be able to install

anything from that mirror unless it's name is specified as the normalized name

(e.g. ``pip install Django`` will fail without --allow-unverified but

``pip install django`` will work). This would be fixed with pip 1.6 (since

it would know to "normalize" the name before fetching the URL).

The same thing will occur if we make the change in pip first, it would

normalize names so you'd need to use --allow-unverified for everything because

it would act as if you typed ``pip install django`` instead of ``pip install

Django``.

To my knowledge, this *only* will affect pip 1.5.x.

So the only way forward I can see to make this change, which I think is a good

change and will remove a big "gotcha" from using a mirror, is to coordinate

a release of bandersnatch that coincides with pip 1.6, and tell people they

need to upgrade in lockstep.

Does anyone have any other ideas?

---

Donald Stufft

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