Discover the agent address from BLACKSMITH_AGENT_ADDR

.github/workflows/test.yml

@@ -17,3 +17,14 @@ jobs:
 
       - name: Lint action.yml
         run: yamllint -d relaxed action.yml
+
+  smoke:
+    runs-on: blacksmith
+    steps:
+      - uses: actions/checkout@v4
+
+      - name: Assert BLACKSMITH_AGENT_ADDR is advertised
+        run: test -n "$BLACKSMITH_AGENT_ADDR"
+
+      - name: Run begin-testbox in validation mode
+        uses: ./

action.yml

@@ -1,13 +1,13 @@
 name: 'Begin Testbox'
 description: 'Initialize a Blacksmith Testbox session. Phones home to receive config, installs SSH key and rsync.'
 
 inputs:
   testbox_id:
     description: 'Testbox session ID (from workflow_dispatch input). Leave empty for validation mode.'
     required: false
     default: ''
   api_url:
     description: 'Override the backend API URL (default: discovered from VM metadata)'
     required: false
 
 runs:
@@ -17,25 +17,30 @@
       shell: bash
       run: |
         if [ -z "${{ inputs.testbox_id }}" ]; then
           echo "::notice::Running in validation mode — setup steps will be validated without starting a testbox session."
         fi
 
     - name: Discover metadata service
       id: metadata
       shell: bash
       run: |
+        if [ -z "${BLACKSMITH_AGENT_ADDR:-}" ]; then
+          echo "::warning::BLACKSMITH_AGENT_ADDR is not set; testbox is only supported on Blacksmith runners. Skipping testbox setup."
+          echo "available=false" >> "$GITHUB_OUTPUT"
+          exit 0
+        fi
         METADATA_PORT="${METADATA_PORT:-}"
         if [ -z "$METADATA_PORT" ]; then
-          METADATA_PORT=$(cat /proc/cmdline | tr ' ' '\n' | grep '^metadata_port=' | cut -d'=' -f2)
+          METADATA_PORT=$(tr ' ' '\n' < /proc/cmdline | grep '^metadata_port=' | cut -d'=' -f2 || true)
           if [ -z "$METADATA_PORT" ]; then
-            echo "metadata_port not found in kernel cmdline"
+            echo "::warning::metadata_port not found in kernel cmdline; testbox is only supported on Blacksmith runners. Skipping testbox setup."
             echo "available=false" >> "$GITHUB_OUTPUT"
             exit 0
           fi
           export METADATA_PORT
         fi
         echo "available=true" >> "$GITHUB_OUTPUT"
-        echo "metadata_addr=192.168.127.1:${METADATA_PORT}" >> "$GITHUB_OUTPUT"
+        echo "metadata_addr=${BLACKSMITH_AGENT_ADDR}:${METADATA_PORT}" >> "$GITHUB_OUTPUT"
 
     - name: Phone home and configure testbox
       if: steps.metadata.outputs.available == 'true' && inputs.testbox_id
@@ -49,11 +54,11 @@
         mkdir -p "$STATE"
         chmod 700 "$STATE"
 
         INSTALLATION_MODEL_ID=$(curl -s --connect-timeout 2 --max-time 5 "http://${METADATA_ADDR}/installationModelID")
         if [ -n "$API_URL_OVERRIDE" ]; then
           API_URL="$API_URL_OVERRIDE"
         else
           API_URL=$(curl -s --connect-timeout 2 --max-time 5 "http://${METADATA_ADDR}/backendURL")
         fi
 
         # Piggyback on the VM's stickyDiskToken for phone-home authentication.