Several tasks in Devstack require pulling fresh copies of Python packages from PyPI. Depending on the application you are working on this can take anywhere from a few seconds to several minutes. Additionally, those tasks could not be done while offline due to not being able to contact PyPI.
To help speed up those tasks and bring us close to being able to use Devstack entirely offline we have introduced a devpi PyPI cache container to Devstack. Currently it is only configured as a package cache for LMS and Studio, but the hope is to expand its use to the other Devstack applications and to move to a state where it comes pre-populated with the requirements of all Devstack applications.
In general the operation of devpi should be transparent. You may notice
some significant speedup in tox testing and paver update_prereqs
operations after the first run. Container storage should persist through
make down and make dev.up operations.
The devpi web interface can be browsed from the host at: http://localhost:3141/
Documentation for devpi is at: https://www.devpi.net/
devpi will cache anything that LMS or Studio pull from PyPI via pip,
including things from the various requirements files. It will not cache
requirements given as URLs (ex. git+https style links) or local
packages (ex. -e common/lib/calc). When these types of packages are
encountered they bypass devpi.
devpi runs in a separate container started via the usual make
operations and controlled through Docker Compose. Devstack components
can use the devpi_consumer role in edx-configuration to add devpi
configuration to their containers, and override configuration
variables as necessary.
devpi_consumer creates a pip.config file in the configured location
that tells pip to use devpi as the primary package repository. If devpi
does not have a requested package it will call through to PyPI and
cache the result if something is found.
To temporarily remove devpi caching from an edxapp container, start a
shell (lms-shell or studio-shell) and move or delete
/root/.pip/pip.conf. This will be undone on the next container
restart unless the container state is persisted.
You can monitor the devpi logs by running this command on the host:
docker logs -f edx.devstack.devpi or looking at the output in
Kitematic. You can also check the devpi server status by visiting:
http://localhost:3141/+status