Add changed_charts and chart_version outputs (#130)

* Add `changed_charts` and `chart_version` outputs

This should let downstream steps make conditional decisions
based on what we found.

Also: fix a confusing double-negative test in main().

Signed-off-by: Nathan J. Mehl <n@oden.io>

---------

Signed-off-by: Nathan J. Mehl <n@oden.io>

action.yml

@@ -32,11 +32,19 @@ inputs:
     description: Mark the created GitHub release as 'latest'
     required: false
     default: true
+outputs:
+  changed_charts:
+    description: "A comma-separated list of charts that were released on this run. Will be an empty string if no updates were detected, will be unset if `--skip_packaging` is used: in the latter case your custom packaging step is responsible for setting its own outputs if you need them."
+    value: ${{ steps.release.outputs.changed_charts }}
+  chart_version:
+    description: "The version of the most recently generated charts; will be set even if no charts have been updated since the last run."
+    value: ${{ steps.release.outputs.chart_version }}
 
 runs:
   using: composite
   steps:
-    - run: |
+    - id: release
+      run: |
         owner=$(cut -d '/' -f 1 <<< "$GITHUB_REPOSITORY")
         repo=$(cut -d '/' -f 2 <<< "$GITHUB_REPOSITORY")
 
@@ -77,4 +85,12 @@ runs:
         fi
 
         "$GITHUB_ACTION_PATH/cr.sh" "${args[@]}"
+
+        if [[ -f changed_charts.txt ]]; then
+            cat changed_charts.txt >> "$GITHUB_OUTPUT"
+        fi
+        if [[ -f chart_version.txt ]]; then
+            cat chart_version.txt >> "$GITHUB_OUTPUT"
+        fi
+        rm -f changed_charts.txt chart_version.txt
       shell: bash