global expressions support for labels and annotations

Signed-off-by: CrazyMax <1951866+crazy-max@users.noreply.github.com>

.github/workflows/ci.yml

@@ -269,6 +269,8 @@ jobs:
           images: |
             ${{ env.DOCKER_IMAGE }}
             ghcr.io/name/app
+          labels: |
+            org.opencontainers.image.created={{commit_date 'YYYY-MM-DDTHH:mm:ss.SSS[Z]'}}
           tags: |
             type=sha
             type=raw,value=gexp-branch-{{branch}}

README.md

@@ -818,7 +818,8 @@ Each tags `type` attribute has a default priority:
 ### Global expressions
 
 The following [Handlebars' template](https://handlebarsjs.com/guide/) expressions
-for `prefix`, `suffix`, `value` and `enable` attributes are available:
+for `prefix`, `suffix`, `value` and `enable` attributes of `tags` input are
+available:
 
 ```yaml
 tags: |
@@ -828,6 +829,13 @@ tags: |
   type=raw,value=mytag-{{branch}}-{{sha}}
 ```
 
+They can also be applied to `labels` and `annotations` inputs:
+
+```yaml
+labels: |
+  org.opencontainers.image.created={{commit_date 'YYYY-MM-DDTHH:mm:ss.SSS[Z]'}}
+```
+
 #### `{{branch}}`
 
 Returns the branch name that triggered the workflow run. Will be empty if not 

__tests__/meta.test.ts

@@ -785,6 +785,9 @@ describe('push', () => {
           `type=raw,value=mytag-baseref-{{base_ref}}`,
           `type=raw,value=mytag-defbranch,enable={{is_default_branch}}`
         ],
+        labels: [
+          "org.opencontainers.image.created={{commit_date 'YYYY-MM-DDTHH:mm:ss.SSS[Z]'}}"
+        ]
       } as Inputs,
       {
         main: 'mytag-master',

src/meta.ts

@@ -372,7 +372,7 @@ export class Meta {
     return val;
   }
 
-  private setGlobalExp(val): string {
+  private setGlobalExp(val: string): string {
     const context = this.context;
     const currentDate = this.date;
     const commitDate = this.context.commitDate;
@@ -517,7 +517,9 @@ export class Meta {
       `org.opencontainers.image.revision=${this.context.sha || ''}`,
       `org.opencontainers.image.licenses=${this.repo.license?.spdx_id || ''}`
     ];
-    res.push(...extra);
+    extra.forEach(label => {
+      res.push(this.setGlobalExp(label));
+    });
 
     return Array.from(
       new Map<string, string>(