ci: Downgrade Docker

Work around incompatibility between old Podman and new Docker.

.github/workflows/build.yml

@@ -40,6 +40,11 @@ jobs:
         with:
           go-version: ${{ matrix.go }}
 
+      - name: Install Kerberos client
+        run: |
+          sudo apt-get update
+          sudo DEBIAN_FRONTEND=noninteractive apt-get install -yq libkrb5-dev krb5-user
+
       - name: golangci-lint (gokrb5)
         uses: golangci/golangci-lint-action@v5
         if: github.event_name == 'pull_request'
@@ -61,10 +66,19 @@ jobs:
         env:
           GOOS: windows
 
-      - name: Install Kerberos client
+      - name: Podman version
+        id: podman
+        shell: bash
         run: |
-          sudo apt-get update
-          sudo DEBIAN_FRONTEND=noninteractive apt-get install -yq libkrb5-dev krb5-user
+          echo "version=$(podman version | grep '^Version:' | tr -s ' ' | cut -d ' ' -f 2)" >>"${GITHUB_OUTPUT}"
+
+      - name: Downgrade Docker
+        if: steps.podman.outputs.version == '3.4.4'
+        shell: bash
+        run: |
+          apt-cache madison docker.io
+          sudo apt-get remove containerd.io
+          sudo apt-get install docker.io=24.0.7-0ubuntu2~22.04.1
 
       - name: Set up Docker Buildx
         uses: docker/setup-buildx-action@v3

testdata/Dockerfile

@@ -1,4 +1,4 @@
-FROM rockylinux/rockylinux:9-ubi-init as kdc
+FROM rockylinux/rockylinux:9-ubi-init AS kdc
 
 EXPOSE 8088
 EXPOSE 8464
@@ -21,7 +21,7 @@ RUN kadmin.local ktadd -norandkey -k /etc/test.keytab test
 RUN kadmin.local addprinc -randkey DNS/ns.example.com
 RUN kadmin.local ktadd -k /etc/dns.keytab DNS/ns.example.com
 
-FROM rockylinux/rockylinux:9-ubi-init as ns
+FROM rockylinux/rockylinux:9-ubi-init AS ns
 
 EXPOSE 8053
 
@@ -40,6 +40,6 @@ RUN chmod 640 /etc/named.conf
 COPY --chown=named:named db.* /var/named/dynamic/
 RUN chmod 644 /var/named/dynamic/db.*
 
-FROM scratch as keytab
+FROM scratch AS keytab
 COPY --from=kdc /etc/test.keytab /test.keytab
 COPY --from=kdc /etc/dns.keytab /dns.keytab