Consider changing the installation location

[kkebo]

Currently, a swift toolchain is installed under /usr/bin.

https://github.com/apple/swift-docker/blob/88941f87eaded894699adae832cd0a820ee544ae/nightly-6.0/ubuntu/22.04/Dockerfile#L62

This is a problem because apt packages overwrites them. For example, apt-get install llvm overwrites Swift's builtin LLVM tools by themselves so that LLVM tools is downgraded from 17 to 14.

[finagolfin]

This is a known issue with the Swift toolchain, which is why Fedora installs it in /usr/libexec/swift/5.8.1/ instead.

[kkebo]

Thank you for the information.

However, when it comes to swift-docker, I think this problem can be solved with small modifications like this:

diff --git a/nightly-main/ubuntu/22.04/Dockerfile b/nightly-main/ubuntu/22.04/Dockerfile
index 31496b5..1088ee2 100644
--- a/nightly-main/ubuntu/22.04/Dockerfile
+++ b/nightly-main/ubuntu/22.04/Dockerfile
@@ -59,8 +59,8 @@ RUN set -e; \
     && curl -fSsL https://swift.org/keys/all-keys.asc | gpg --import -  \
     && gpg --batch --verify latest_toolchain.tar.gz.sig latest_toolchain.tar.gz \
     # - Unpack the toolchain, set libs permissions, and clean up.
-    && tar -xzf latest_toolchain.tar.gz --directory / --strip-components=1 \
-    && chmod -R o+r /usr/lib/swift \
+    && tar -xzf latest_toolchain.tar.gz --directory /usr/local --strip-components=2 \
+    && chmod -R o+r /usr/local/lib/swift \
     && rm -rf "$GNUPGHOME" latest_toolchain.tar.gz.sig latest_toolchain.tar.gz \
     && apt-get purge --auto-remove -y curl

[finagolfin]

Feel free to submit a pull, and someone may review it.

[kkebo]

I was wrong. My suggestion will be a breaking change if there's a user who expects swift to be in /usr/bin/swift.

[finagolfin]

That's why Fedora adds symlinks into /usr/bin/.

[kkebo]

I don't think so. Fedora's package manager always needs to install packages under /usr, but docker images don't have such restrictions. The whole problem with swift-docker is just a compatibility issue.

[finagolfin]

Right, Fedora worked around this issue already by installing the Swift toolchain into /usr/libexec/swift/5.8.1/ instead and symlinking Swift executables into /usr/bin/. These docker images could do the same.

[FranzBusch]

It might be worth considering if we could do a one-time change of install locations for Swift 6 cc @shahmishal

[kkebo]

Right, Fedora worked around this issue already by installing the Swift toolchain into /usr/libexec/swift/5.8.1/ instead and symlinking Swift executables into /usr/bin/. These docker images could do the same.

Like swift-ci images, if Swift executables are installed into $SWIFT_PREFIX/ and $SWIFT_PREFIX/usr/bin has a higher priority position than /usr/bin in $PATH, it may be acceptable to copy the executable to /usr/bin for compatibility.

However, we may not be able to use symbolic links for that purpose. Because symlinking Swift executables does not work in Swift 6.0 due to swiftlang/swift#70932 at least for now. It has been fixed on the main branch, but not on the release/6.0 branch.