Preserve readonly flag when converting mounts to -v for WSLc - #1314
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Akio Takahashi (akiotakahashi)
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The WSLc code path converts --mount strings to -v syntax but dropped the readonly/ro option, so every mount declared readonly in devcontainer.json was mounted writable. wslc supports the "-v source:target:ro" suffix (verified with wslc 3.0.1), so append ":ro" when the mount string carries readonly/ro unless its value is explicitly false. Co-Authored-By: Claude Fable 5 <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_018psPhUnN32LKjqd4ZkATtP
Keep consistency=cached in the example so it still illustrates that options other than source/target/readonly are dropped. Co-Authored-By: Claude Fable 5 <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_018psPhUnN32LKjqd4ZkATtP
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Problem
When the CLI drives WSL containers (
--docker-path wslc,CLIVariant.Wslcadded in #1249),--mountstrings are converted to-vsyntax byconvertMountToVolumeinsrc/spec-node/singleContainer.ts. The conversion only readssourceandtarget, so thereadonly/rooption is silently dropped for theworkspaceMountand for every entry ofmounts. Mounts that a devcontainer.json declares readonly end up writable inside the container.Observed with @devcontainers/cli 0.89.0 and wslc 3.0.1 (GA) on Windows 11: a config with 15
readonlymounts produced awslc runcommand line containing no:roat all, and a file behind a readonly mount could be modified from inside the container.wslc itself supports the readonly suffix —
wslc run -v C:/path:/mnt:ro ...correctly yields a read-only mount (verified with wslc 3.0.1, including drive-letter source paths) — so this is purely a conversion issue.Fix
convertMountToVolumenow appends:rowhen the mount string carriesreadonlyorro(bare, or with a value other thanfalse/0), matching Docker's--mountsemantics. Other options (type,consistency) are dropped as before.The function is exported for testing and unit tests are added in
src/test/singleContainer.test.tscovering the bare/valuedreadonly/roforms,readonly=false, named volumes, Windows source paths, and the target-only and fallback paths.Notes
generateMountCommandnever emitsreadonlyfor them, and theMountinterface has no such field.🤖 Generated with Claude Code
https://claude.ai/code/session_018psPhUnN32LKjqd4ZkATtP