reimplement entrypoint in Python #1014
Conversation
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Didn't work :/ |
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Do you think it's worth converting the entrypoint to Python and using |
Maybe. I'll give it a go and see if that changes anything. |
- make sure to set PYTHONUNBUFFERED - implement tee with subprocess readlines - forward all relevant signals from entrypoint to 'true' command - add monitor process to ensure child shuts down if parent does (maybe not useful in docker?)
minrk
changed the title
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| # Docker exports all passed env variables, so we can | ||
| # just look at exported variables. | ||
| "export; sleep 1", |
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Removing this sleep is what verifies that this is (probably) actually fixing the problem.
- remove redundant monitor sibling process - use python3-login executable instead of login shell subprocess (same effect, but in more natural order) - use non-blocking binary IO in tee instead of readline (switch to binary mode, as text wrappers don't support non-blocking mode see https://bugs.python.org/issue13322)
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This does seem to work. I'm not sure how folks feel about doing things this way - it is basically a Python reimplementation of a subset of tini with the I do feel a lot more comfortable with parsing out the logic of the pipes, processes, and flushing in Python than named fds in a shell, though the signals and reaping I am a bit less confident about. |
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I haven't had time to test this yet, but I'm in favour of switching to Python. |
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Let's see what this does :D It feels like some comment from Inception is appropriate as we add another layer of Python :D |
Per @manics idea, this reimplements the entrypoint in Python, mainly so we can better apply our expertise and understanding to it.
python3-loginto preserve login-shell behavior (source profiles, etc.) because we can't nest interpreters in a single shebang line. First attempt extracted login env from a subprocess, but I think this is a little more natural, maybe, as it matches the usual process hierarchy (bash -l > Python > 'real' entrypoint.It seems to work! Honestly, I cannot say if this fixes the issue because I know how to do unbuffered output in Python and couldn't figure it out with other tools, or if it's because Python is just enough slower that the previously lost output always loses the race 🤷 .
Original description: use stdbuf to make sure everything is unbuffered
stdbufto everything in repo2docker-entrypointA bit of a shot in the dark at #1008