[CERTTF-344] Return job ID as output from submit composite action (#…

…309)

* feat(actions): return job ID as output from the `submit` action
* refactor(actions): Use `id` output from submission step in polling step
* docs(actions): Document the output of the `submit` action in README.md

.github/actions/submit/action.yaml

@@ -19,6 +19,10 @@ inputs:
     description: The Testflinger server to use
     required: false
     default: testflinger.canonical.com
+outputs:
+  id:
+    description: 'The ID of the submitted job'
+    value: ${{ steps.submit.outputs.id }}
 runs:
   using: composite
   steps:
@@ -79,13 +83,14 @@ runs:
       run: |
         JOB_ID=$(testflinger --server $SERVER submit --quiet "$JOB")
         echo "job id: $JOB_ID"
-        echo "JOB_ID=$JOB_ID" >> $GITHUB_ENV
+        echo "id=$JOB_ID" >> $GITHUB_OUTPUT
 
     - name: Track the status of the job and mirror its exit status
       if: inputs.poll == 'true' && inputs.dry-run != 'true'
       shell: bash
       env:
         SERVER: https://${{ inputs.server }}
+        JOB_ID: ${{ steps.submit.outputs.id }}
       run: |
         # poll
         PYTHONUNBUFFERED=1 testflinger --server $SERVER poll $JOB_ID

README.md

@@ -44,6 +44,7 @@ If you need to submit a job to a testflinger server through a Github action (ins
 The corresponding step in the workflow would look like this:
 ```
     - name: Submit job
+      id: submit-job
       uses: canonical/testflinger/.github/actions/submit@v1
       with:
         poll: true
@@ -54,10 +55,21 @@ This assumes that there is a previous `create-job` step in the workflow that cre
 Alternatively, you can use the `job` argument (instead of `job-path`) to provide the contents of the job inline:
 ```
     - name: Submit job
+      id: submit-job
       uses: canonical/testflinger/.github/actions/submit@v1
       with:
         poll: true
         job: |
             ...  # inline YAML for Testflinger job
 ```
-In the latter case, do remember to use escapes for environment variables in the inline text, e.g. `\$DEVICE_IP`.
+In the latter case, do remember to use escapes for environment variables in the inline text, e.g. `\$DEVICE_IP`.
+
+The `id` of the submitted job is returned as an output of the `submit` action, so you can use it (if you need it)
+in any of the subsequent steps of the workflow:
+
+```
+    - name: Display results
+      run: |
+        testflinger results ${{ steps.submit-job.outputs.id }}"
+```
+In this example, `submit-job` is the step where the `submit` action is used.