ci: pin Docker to v28 to avoid v29 breaking changes

Docker 29 (shipped with runner-images 20260209.23.1) breaks docker
build via Go client libraries (broken pipe writing build context)
and docker load/save with certain tarball formats. Add Docker's
official apt repository and install docker-ce 28.5.x in all CI
jobs that interact with Docker.

See https://github.com/actions/runner-images/issues/13474

Updates #3058

.github/workflows/integration-test-template.yml

@@ -67,6 +67,24 @@ jobs:
         with:
           name: postgres-image
           path: /tmp/artifacts
+      - name: Pin Docker to v28 (avoid v29 breaking changes)
+        run: |
+          # Docker 29 breaks docker build via Go client libraries and
+          # docker load/save with certain tarball formats.
+          # Pin to Docker 28.x until our tooling is updated.
+          # https://github.com/actions/runner-images/issues/13474
+          sudo install -m 0755 -d /etc/apt/keyrings
+          curl -fsSL https://download.docker.com/linux/ubuntu/gpg \
+            | sudo gpg --dearmor -o /etc/apt/keyrings/docker.gpg
+          echo "deb [arch=$(dpkg --print-architecture) signed-by=/etc/apt/keyrings/docker.gpg] \
+            https://download.docker.com/linux/ubuntu $(. /etc/os-release && echo "$VERSION_CODENAME") stable" \
+            | sudo tee /etc/apt/sources.list.d/docker.list > /dev/null
+          sudo apt-get update -qq
+          VERSION=$(apt-cache madison docker-ce | grep '28\.5' | head -1 | awk '{print $3}')
+          sudo apt-get install -y --allow-downgrades \
+            "docker-ce=${VERSION}" "docker-ce-cli=${VERSION}"
+          sudo systemctl restart docker
+          docker version
       - name: Load Docker images, Go cache, and prepare binary
         run: |
           gunzip -c /tmp/artifacts/headscale-image.tar.gz | docker load

.github/workflows/release.yml

@@ -17,6 +17,25 @@ jobs:
         with:
           fetch-depth: 0
 
+      - name: Pin Docker to v28 (avoid v29 breaking changes)
+        run: |
+          # Docker 29 breaks docker build via Go client libraries and
+          # docker load/save with certain tarball formats.
+          # Pin to Docker 28.x until our tooling is updated.
+          # https://github.com/actions/runner-images/issues/13474
+          sudo install -m 0755 -d /etc/apt/keyrings
+          curl -fsSL https://download.docker.com/linux/ubuntu/gpg \
+            | sudo gpg --dearmor -o /etc/apt/keyrings/docker.gpg
+          echo "deb [arch=$(dpkg --print-architecture) signed-by=/etc/apt/keyrings/docker.gpg] \
+            https://download.docker.com/linux/ubuntu $(. /etc/os-release && echo "$VERSION_CODENAME") stable" \
+            | sudo tee /etc/apt/sources.list.d/docker.list > /dev/null
+          sudo apt-get update -qq
+          VERSION=$(apt-cache madison docker-ce | grep '28\.5' | head -1 | awk '{print $3}')
+          sudo apt-get install -y --allow-downgrades \
+            "docker-ce=${VERSION}" "docker-ce-cli=${VERSION}"
+          sudo systemctl restart docker
+          docker version
+
       - name: Login to DockerHub
         uses: docker/login-action@5e57cd118135c172c3672efd75eb46360885c0ef # v3.6.0
         with:

.github/workflows/test-integration.yaml

@@ -69,6 +69,25 @@ jobs:
           name: go-cache
           path: go-cache.tar.gz
           retention-days: 10
+      - name: Pin Docker to v28 (avoid v29 breaking changes)
+        if: steps.changed-files.outputs.files == 'true'
+        run: |
+          # Docker 29 breaks docker build via Go client libraries and
+          # docker load/save with certain tarball formats.
+          # Pin to Docker 28.x until our tooling is updated.
+          # https://github.com/actions/runner-images/issues/13474
+          sudo install -m 0755 -d /etc/apt/keyrings
+          curl -fsSL https://download.docker.com/linux/ubuntu/gpg \
+            | sudo gpg --dearmor -o /etc/apt/keyrings/docker.gpg
+          echo "deb [arch=$(dpkg --print-architecture) signed-by=/etc/apt/keyrings/docker.gpg] \
+            https://download.docker.com/linux/ubuntu $(. /etc/os-release && echo "$VERSION_CODENAME") stable" \
+            | sudo tee /etc/apt/sources.list.d/docker.list > /dev/null
+          sudo apt-get update -qq
+          VERSION=$(apt-cache madison docker-ce | grep '28\.5' | head -1 | awk '{print $3}')
+          sudo apt-get install -y --allow-downgrades \
+            "docker-ce=${VERSION}" "docker-ce-cli=${VERSION}"
+          sudo systemctl restart docker
+          docker version
       - name: Build headscale image
         if: steps.changed-files.outputs.files == 'true'
         run: |
@@ -104,6 +123,24 @@ jobs:
     needs: build
     if: needs.build.outputs.files-changed == 'true'
     steps:
+      - name: Pin Docker to v28 (avoid v29 breaking changes)
+        run: |
+          # Docker 29 breaks docker build via Go client libraries and
+          # docker load/save with certain tarball formats.
+          # Pin to Docker 28.x until our tooling is updated.
+          # https://github.com/actions/runner-images/issues/13474
+          sudo install -m 0755 -d /etc/apt/keyrings
+          curl -fsSL https://download.docker.com/linux/ubuntu/gpg \
+            | sudo gpg --dearmor -o /etc/apt/keyrings/docker.gpg
+          echo "deb [arch=$(dpkg --print-architecture) signed-by=/etc/apt/keyrings/docker.gpg] \
+            https://download.docker.com/linux/ubuntu $(. /etc/os-release && echo "$VERSION_CODENAME") stable" \
+            | sudo tee /etc/apt/sources.list.d/docker.list > /dev/null
+          sudo apt-get update -qq
+          VERSION=$(apt-cache madison docker-ce | grep '28\.5' | head -1 | awk '{print $3}')
+          sudo apt-get install -y --allow-downgrades \
+            "docker-ce=${VERSION}" "docker-ce-cli=${VERSION}"
+          sudo systemctl restart docker
+          docker version
       - name: Pull and save postgres image
         run: |
           docker pull postgres:latest