More network flake improvements (#30)

* Increase docker retries

* Add debug logging for failed docker pull

* Add retryable sccache warm up

internal/docker-run/action.yml

@@ -78,14 +78,20 @@ runs:
 
     - name: Pull fresh docker image
       if: ${{ !inputs.docker-cache }}
+      id: docker-pull
       uses: nick-fields/retry@943e742917ac94714d2f408a0e8320f2d1fcafcd # v2.8.3
       with:
         timeout_minutes: 5
-        retry_wait_seconds: 30
-        max_attempts: 3
+        retry_wait_seconds: 60
+        max_attempts: 5
         shell: bash
         command: time docker pull -q ${{ inputs.image }}
 
+    - name: Report docker pull failures
+      if: ${{ steps.docker-pull.outputs.exit_code }}
+      shell: bash
+      run: echo ${{ steps.docker-pull.exit_error }}
+
     - name: Forward sccache arguments
       shell: bash
       id: sccache

sccache/action.yml

@@ -58,6 +58,7 @@ runs:
         echo "SCCACHE_GCS_KEY_PATH=${{ steps.auth.outputs.credentials-file }}" >> $GITHUB_ENV
         echo "SCCACHE_GCS_BUCKET=protobuf-sccache" >> $GITHUB_ENV
         echo "SCCACHE_GCS_KEY_PREFIX=${{ inputs.cache-prefix }}" >> $GITHUB_ENV
+        echo "SCCACHE_IDLE_TIMEOUT=0" >> $GITHUB_ENV
 
     # Only trusted runs should have write access to our caches.
     - name: Enable sccache cache writing
@@ -72,6 +73,16 @@ runs:
       with:
         version: ${{ inputs.version }}
 
+    - name: Warm-up sccache server (non-docker)
+      if: ${{ runner.os != 'Linux' }}
+      uses: nick-fields/retry@943e742917ac94714d2f408a0e8320f2d1fcafcd # v2.8.3
+      with:
+        timeout_minutes: 5
+        retry_wait_seconds: 60
+        max_attempts: 5
+        shell: bash
+        command: sccache --start-server
+
     - name: Configure sccache cmake arguments
       shell: bash
       run: |