Upload core dump files as test artifacts (#14499)

This PR sets the `core_pattern` such that core dumps from LXD with be
gzipped and placed in `/var/crash`. Then, if any files are present in
`/var/crash` at the end of the run they will be uploaded as artifacts
(regardless of test status).

#14498 should be merged first and I'll remove the cherry-picked commit.

.github/workflows/tests.yml

@@ -264,12 +264,23 @@ jobs:
 
       - name: "Run system tests (${{ matrix.suite }}, ${{ matrix.backend }})"
         run: |
+          echo '|/bin/sh -c $@ -- eval exec gzip --fast > /var/crash/core-%e.%p.gz' | sudo tee /proc/sys/kernel/core_pattern
           set -eux
           chmod +x ~
           echo "root:1000000:1000000000" | sudo tee /etc/subuid /etc/subgid
           cd test
           sudo --preserve-env=PATH,GOPATH,GOCOVERDIR,GITHUB_ACTIONS,LXD_VERBOSE,LXD_BACKEND,LXD_CEPH_CLUSTER,LXD_CEPH_CEPHFS,LXD_CEPH_CEPHOBJECT_RADOSGW,LXD_OFFLINE,LXD_SKIP_TESTS,LXD_REQUIRED_TESTS, LXD_BACKEND=${{ matrix.backend }} ./main.sh ${{ matrix.suite }}
 
+      - name: Upload crash dumps
+        if: always()
+        uses: actions/upload-artifact@b4b15b8c7c6ac21ea08fcf65892d2ee8f75cf882 # v4.4.3
+        with:
+          name: crash-dumps-${{ matrix.suite }}-${{ matrix.backend }}
+          path: |
+            /var/crash/core-*
+          retention-days: 5
+          if-no-files-found: ignore
+
       - name: Upload coverage data
         uses: actions/upload-artifact@b4b15b8c7c6ac21ea08fcf65892d2ee8f75cf882 # v4.4.3
         with:

test/main.sh

@@ -113,13 +113,6 @@ cleanup() {
     if [ "${expandDmesg}" = "no" ]; then
       echo "::endgroup::"
     fi
-
-    if [ "$(ls -A /var/crash)" ]; then
-      echo "::group::crashes"
-      ls -la /var/crash
-      find /var/crash -type f -exec cat {} +
-      echo "::endgroup::"
-    fi
   fi
 
   if [ -n "${GITHUB_ACTIONS:-}" ]; then