dotcloud/docker-registry — pull request #473 by wking (2014-07-16 18:41:13+00:00)
Title: docker_registry.app: Add a /_versions endpoint

For debugging it's good to know what package versions folks are
running. This endpoint allows folks using floating dependencies (or
just different versions of docker-registry) to figure out the exact
version of all of their Python dependencies.

The only basic dependency that *doesn't* define a __version__ is
itsdangerous (as of v0.24), which doesn't provide a
programmatically-accessible version number. I haven't checked all the
peripheral dependencies outside of what gets pulled in by a stock:

$ pip install depends/docker-registry-core/
$ pip install .

To avoid accidentally leaking implementation details, the /_versions
endpoint is disabled in the common config_sample.yml block, and only
enabled by default in the dev block. In both cases, you can use the
VERSIONS environment variable to enable/disable the endpoint for your
particular instance.

This should make it easier for users to report which versions they're
using. See [here][1] and [here][2].

[1]: https://github.com/dotcloud/docker-registry/issues/466#issuecomment-49063166
[2]: https://github.com/dotcloud/docker-registry/issues/466#issuecomment-49165764