feat: gh-actions/build-debian: Add extra-apt-repositories input

gh-actions/common/build-debian/action.yaml

@@ -21,6 +21,11 @@ inputs:
     # FIXME: this should default to '', but we don't want to break job depending on us for now
     default: 'ca-certificates'
 
+  extra-apt-repositories:
+    description: |
+      A list of extra APT repositories to add.
+      The entries are passed to add-apt-repository, one per line.
+
   extra-source-build-script:
     description: |
       A script to run to prepare the source build machine.
@@ -210,6 +215,20 @@ runs:
           "${{ env.GITHUB_ACTION_PATH }}"/prepare-container.sh
           echo "::endgroup::"
 
+          if [ -n "${{ inputs.extra-apt-repositories != '' && 'true' || '' }}" ]; then
+            echo "::group::Add extra APT repositories"
+            (
+              set -eux
+              apt-get install -y software-properties-common
+              echo "${{ inputs.extra-apt-repositories }}" | while read -r repo; do
+                if [ -n "$repo" ]; then
+                  add-apt-repository -y "$repo"
+                fi
+              done
+            )
+            echo "::endgroup::"
+          fi
+
           echo "::group::Install build dependencies"
           apt build-dep .
 
@@ -374,6 +393,20 @@ runs:
           apt install fakeroot
           echo "::endgroup::"
 
+          if [ -n "${{ inputs.extra-apt-repositories != '' && 'true' || '' }}" ]; then
+            echo "::group::Add extra APT repositories"
+            (
+              set -eux
+              apt-get install -y software-properties-common
+              echo "${{ inputs.extra-apt-repositories }}" | while read -r repo; do
+                if [ -n "$repo" ]; then
+                  add-apt-repository -y "$repo"
+                fi
+              done
+            )
+            echo "::endgroup::"
+          fi
+
           echo "::group::Install build dependencies"
           apt build-dep .
           echo "::endgroup::"