From f7c51606f0eae56f0cf52c54713f7816d8e9f97c Mon Sep 17 00:00:00 2001 From: Mike Frysinger Date: Tue, 18 Jun 2019 17:23:39 -0400 Subject: hooks: support external hooks running different Python version As we convert repo to support Python 3, the version of Python that we use might not be the version that repo hooks users have written for. Since repo upgrades are not immediate, and not easily under direct control of end users (relative to the projects maintaining the hook code), allow hook authors to declare the version of Python that they want to use. Now repo will read the shebang from the hook script and compare it against the version of Python repo itself is running under. If they differ, we'll try to execute a separate instance of Python and have it load & execute the hook. If things are compatible, then we still use the inprocess execution logic that we have today. This allows repo hook users to upgrade on their own schedule (they could even upgrade to Python 3 ahead of us) without having to worry about their supported version being exactly in sync with repo's. Bug: https://crbug.com/gerrit/10418 Change-Id: I97c7c96b64fb2ee465c39b90e9bdcc76394a146a Reviewed-on: https://gerrit-review.googlesource.com/c/git-repo/+/228432 Reviewed-by: David Pursehouse Tested-by: Mike Frysinger --- docs/python-support.md | 15 +++++++++++++++ docs/repo-hooks.md | 25 +++++++++++++++++++++++++ 2 files changed, 40 insertions(+) (limited to 'docs') diff --git a/docs/python-support.md b/docs/python-support.md index af19cd05..35806de7 100644 --- a/docs/python-support.md +++ b/docs/python-support.md @@ -28,5 +28,20 @@ The master branch will require Python 3.6 at a minimum. If the system has an older version of Python 3, then users will have to select the legacy Python 2 branch instead. +### repo hooks +Projects that use [repo hooks] run on independent schedules. +They might migrate to Python 3 earlier or later than us. +To support them, we'll probe the shebang of the hook script and if we find an +interpreter in there that indicates a different version than repo is currently +running under, we'll attempt to reexec ourselves under that. + +For example, a hook with a header like `#!/usr/bin/python2` will have repo +execute `/usr/bin/python2` to execute the hook code specifically if repo is +currently running Python 3. + +For more details, consult the [repo hooks] documentation. + + +[repo hooks]: ./repo-hooks.md [repo launcher]: ../repo diff --git a/docs/repo-hooks.md b/docs/repo-hooks.md index e198b390..7c37c30e 100644 --- a/docs/repo-hooks.md +++ b/docs/repo-hooks.md @@ -83,6 +83,31 @@ then check it directly. Hooks should not normally modify the active git repo the user. Although user interaction is discouraged in the common case, it can be useful when deploying automatic fixes. +### Shebang Handling + +*** note +This is intended as a transitional feature. Hooks are expected to eventually +migrate to Python 3 only as Python 2 is EOL & deprecated. +*** + +If the hook is written against a specific version of Python (either 2 or 3), +the script can declare that explicitly. Repo will then attempt to execute it +under the right version of Python regardless of the version repo itself might +be executing under. + +Here are the shebangs that are recognized. + +* `#!/usr/bin/env python` & `#!/usr/bin/python`: The hook is compatible with + Python 2 & Python 3. For maximum compatibility, these are recommended. +* `#!/usr/bin/env python2` & `#!/usr/bin/python2`: The hook requires Python 2. + Version specific names like `python2.7` are also recognized. +* `#!/usr/bin/env python3` & `#!/usr/bin/python3`: The hook requires Python 3. + Version specific names like `python3.6` are also recognized. + +If no shebang is detected, or does not match the forms above, we assume that the +hook is compatible with both Python 2 & Python 3 as if `#!/usr/bin/python` was +used. + ## Hooks Here are all the points available for hooking. -- cgit v1.2.3-54-g00ecf