Update minimum supported Python to 3.9. #232
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gsnedders
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gsnedders
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This clearly needs review from someone at Chromium more than anyone else, but:
| Historically, continued Python 3.8 support was required due to downstream CI | ||
| integrations with Apple’s and Google’s infrastructure. These systems have since |
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WebKit hasn't had any need for Python 3.8 since we dropped support for Xcode 12 several years ago. Our own tooling hasn't support it in a while.
It's not clear to me from #200 when Mozilla stopped needing Python 3.8 support? After upgrading systems after Ubuntu 20.04 LTS reached extended security maintenance?
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I think we still have some older Ubuntu versions, but we've updated all the Python to at least 3.9, and that's what the build system requires. In practice I think all the CI machines might have at least 3.10, but I'm not sure about that.
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This was done with https://bugzilla.mozilla.org/show_bug.cgi?id=1958321.
| - Refresh vendored dependencies that were previously constrained by | ||
| Python 3.8 compatibility. |
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Note with web-platform-tests/wpt#49752 unlanded we don't have a particularly easy way to do this. :'(
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I assume that this was just a comment from your side and nothing specific to update this content with?
| - Re-run CI for Dependabot pull requests to allow dependency updates to proceed. | ||
| Some dependencies may now require Python 3.10 or newer; in those cases, we | ||
| should manually update to the latest release that remains compatible with | ||
| Python 3.9. |
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I did question in web-platform-tests/wpt#55608 whether we should just outright disable dependabot; it's unclear to me we're gaining much except noise with our minimum version?
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I think that would require a new RFC, but I'd be opposed; at least some dependencies do usefully get updates.
| Python 3.9 itself reached end of life in October 2025, which means we | ||
| will encounter similar pressure to raise the minimum version again as | ||
| dependencies may already require Python 3.10 or newer. Any further |
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We could also change policy about how we lock dependency versions.
We've typically gone for something approximating the fewest versions (along the lines of uv pip compile's --fork-strategy fewest); we could also use split it by the required Python version (along the lines of its --fork-strategy requires-python).
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I assume this is as well something not blocking this RFC?
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@jonathan-j-lee Could you take a look? |
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From @jonathan-j-lee:
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jonathan-j-lee
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LGTM from Chromium CI
| Historically, continued Python 3.8 support was required due to downstream CI | ||
| integrations with Apple’s and Google’s infrastructure. These systems have since |
There was a problem hiding this comment.
I think we still have some older Ubuntu versions, but we've updated all the Python to at least 3.9, and that's what the build system requires. In practice I think all the CI machines might have at least 3.10, but I'm not sure about that.
| - Re-run CI for Dependabot pull requests to allow dependency updates to proceed. | ||
| Some dependencies may now require Python 3.10 or newer; in those cases, we | ||
| should manually update to the latest release that remains compatible with | ||
| Python 3.9. |
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I think that would require a new RFC, but I'd be opposed; at least some dependencies do usefully get updates.
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web-platform-tests/wpt#57379 for the implementation. |
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@gsnedders mind checking again now that Google approved this RFC? Thanks. |
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Fixes #200.
@jgraham, @gsnedders and @WeizhongX please review. Thanks