Harden E2E tester build against transient MCR DNS failures

.gitea/workflows/cicd.yaml

@@ -831,6 +831,40 @@ jobs:
         run: |
           set -euo pipefail
 
+          PLAYWRIGHT_BASE_IMAGE="mcr.microsoft/playwright:v1.56.1-jammy"
+
+          retry_pull_with_dns_probe() {
+            image_ref="$1"
+            attempts="${2:-6}"
+            backoff="${3:-5}"
+            attempt=1
+
+            while [ "${attempt}" -le "${attempts}" ]; do
+              echo "base pull attempt ${attempt}/${attempts} for ${image_ref}"
+
+              if getent hosts mcr.microsoft >/dev/null 2>&1; then
+                echo "mcr.microsoft DNS resolution: ok"
+              else
+                echo "mcr.microsoft DNS resolution: failed"
+              fi
+
+              timeout 10 curl -fsSIL "https://mcr.microsoft/v2/" >/dev/null || true
+
+              if docker pull "${image_ref}"; then
+                return 0
+              fi
+
+              if [ "${attempt}" -lt "${attempts}" ]; then
+                sleep_seconds=$((backoff * attempt))
+                echo "Retrying base image pull in ${sleep_seconds}s"
+                sleep "${sleep_seconds}"
+              fi
+              attempt=$((attempt + 1))
+            done
+
+            return 1
+          }
+
           retry_registry_op() {
             op_name="$1"
             image_ref="$2"
@@ -865,7 +899,8 @@ jobs:
           E2E_TESTER_REPO="${GITEA_REGISTRY}/darkhelm.org/plex-playlist-e2e"
           E2E_TESTER_TAG_REF="${E2E_TESTER_REPO}:${HEAD_SHA}"
 
-          docker build -f Dockerfile.e2e-tester -t plex-playlist-e2e:"${HEAD_SHA}" .
+          retry_pull_with_dns_probe "${PLAYWRIGHT_BASE_IMAGE}" 6 5
+          DOCKER_BUILDKIT=0 docker build --pull=false -f Dockerfile.e2e-tester -t plex-playlist-e2e:"${HEAD_SHA}" .
           docker tag plex-playlist-e2e:"${HEAD_SHA}" "${E2E_TESTER_TAG_REF}"
 
           retry_registry_op push "${E2E_TESTER_TAG_REF}" 5 4