is_default_branch global expression

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

README.md

@@ -32,6 +32,12 @@ ___
 * [Notes](#notes)
   * [Latest tag](#latest-tag)
   * [Global expressions](#global-expressions)
+    * [`{{branch}}`](#branch)
+    * [`{{tag}}`](#tag)
+    * [`{{sha}}`](#sha)
+    * [`{{base_ref}}`](#base_ref)
+    * [`{{is_default_branch}}`](#is_default_branch)
+    * [`{{date '<format>'}}`](#date-format)
   * [Major version zero](#major-version-zero)
   * [JSON output object](#json-output-object)
   * [Overwrite labels](#overwrite-labels)
@@ -232,7 +238,7 @@ Content of `${{ steps.meta.outputs.bake-file }}` file will look like this with `
         "org.opencontainers.image.source": "https://github.com/octocat/Hello-World",
         "org.opencontainers.image.version": "1.2.3",
         "org.opencontainers.image.created": "2020-01-10T00:30:00.000Z",
-        "org.opencontainers.image.revision": "90dd6032fac8bda1b6c4436a2e65de27961ed071",
+        "org.opencontainers.image.revision": "860c1904a1ce19322e91ac35af1ab07466440c37",
         "org.opencontainers.image.licenses": "MIT"
       },
       "args": {
@@ -605,26 +611,28 @@ tags: |
 * [`type=semver,pattern=...`](#typesemver)
 * [`type=match,pattern=...`](#typematch)
 
-For conditionally tagging with latest for a specific branch name, e.g. if your default branch name
+For conditionally tagging with latest for a specific branch name, e.g. if your
-is not `master`, use `type=raw` with a boolean expression:
+default branch name is not `master`, use `type=raw` with a boolean expression:
 
 ```yaml
 tags: |
-  type=raw,value=latest,enable=${{ github.ref == format('refs/heads/{0}', github.event.repository.default_branch) }}
+  # set latest tag for master branch
+  type=raw,value=latest,enable=${{ github.ref == format('refs/heads/{0}', 'master') }}
+```
+
+You can also use the [`{{is_default_branch}}` global expression](#is_default_branch)
+to conditionally tag with latest for the default branch:
+
+```yaml
+tags: |
+  # set latest tag for default branch
+  type=raw,value=latest,enable={{is_default_branch}}
 ```
 
 ### Global expressions
 
-The following [Handlebars' template](https://handlebarsjs.com/guide/) expressions for `prefix`, `suffix` and `value`
+The following [Handlebars' template](https://handlebarsjs.com/guide/) expressions
-attributes are available:
+for `prefix`, `suffix`, `value` and `enable` attributes are available:
-
-| Expression               | Output               |
-|--------------------------|----------------------|
-| `{{branch}}`             | `master`             |
-| `{{tag}}`                | `v1.2.3`             |
-| `{{sha}}`                | `90dd603`            |
-| `{{base_ref}}`           | `master`             |
-| `{{date 'YYYYMMDD'}}`    | `20210326`           |
 
 ```yaml
 tags: |
@@ -634,6 +642,63 @@ tags: |
   type=raw,value=mytag-{{branch}}-{{sha}}
 ```
 
+#### `{{branch}}`
+
+Returns the branch name that triggered the workflow run. Will be empty if not 
+a branch reference:
+
+| Event           | Ref                           | Output              |
+|-----------------|-------------------------------|---------------------|
+| `pull_request`  | `refs/pull/2/merge`           |                     |
+| `push`          | `refs/heads/master`           | `master`            |
+| `push`          | `refs/heads/my/branch`        | `my-branch`         |
+| `push tag`      | `refs/tags/v1.2.3`            |                     |
+
+#### `{{tag}}`
+
+Returns the tag name that triggered the workflow run. Will be empty if not a
+tag reference:
+
+| Event           | Ref                           | Output             |
+|-----------------|-------------------------------|--------------------|
+| `pull_request`  | `refs/pull/2/merge`           |                    |
+| `push`          | `refs/heads/master`           |                    |
+| `push`          | `refs/heads/my/branch`        |                    |
+| `push tag`      | `refs/tags/v1.2.3`            | `v1.2.3`           |
+
+#### `{{sha}}`
+
+Returns the short commit SHA that triggered the workflow run (e.g., `90dd603`).
+
+#### `{{base_ref}}`
+
+Returns the base ref or target branch of the pull request that triggered the
+workflow run. Will be empty for a branch reference:
+
+| Event           | Ref                           | Output             |
+|-----------------|-------------------------------|--------------------|
+| `pull_request`  | `refs/pull/2/merge`           | `master`           |
+| `push`          | `refs/heads/master`           |                    |
+| `push`          | `refs/heads/my/branch`        |                    |
+| `push tag`      | `refs/tags/v1.2.3`            | `master`           |
+
+#### `{{is_default_branch}}`
+
+Returns `true` if the branch that triggered the workflow run is the default
+one, otherwise `false`.
+
+Will compare against the branch name that triggered the workflow run or the 
+base ref or target branch for a pull request or a tag.
+
+#### `{{date '<format>'}}`
+
+Returns the current date rendered by its [moment format](https://momentjs.com/docs/#/displaying/format/).
+
+| Expression                                 | Output example                          |
+|--------------------------------------------|-----------------------------------------|
+| `{{date 'YYYYMMDD'}}`                      | `20200110`                              |
+| `{{date 'dddd, MMMM Do YYYY, h:mm:ss a'}}` | `Friday, January 10th 2020, 3:25:50 pm` |
+
 ### Major version zero
 
 Major version zero (`0.y.z`) is for initial development and **may** change at any time. This means the public API

__tests__/meta.test.ts

@@ -598,7 +598,8 @@ describe('push', () => {
           `type=raw,value=mytag-{{branch}}`,
           `type=raw,value=mytag-{{date 'YYYYMMDD'}}`,
           `type=raw,value=mytag-tag-{{tag}}`,
-          `type=raw,value=mytag-baseref-{{base_ref}}`
+          `type=raw,value=mytag-baseref-{{base_ref}}`,
+          `type=raw,value=mytag-defbranch,enable={{is_default_branch}}`
         ],
       } as Inputs,
       {
@@ -606,7 +607,8 @@ describe('push', () => {
         partial: [
           'mytag-20200110',
           'mytag-tag-',
-          'mytag-baseref-'
+          'mytag-baseref-',
+          'mytag-defbranch'
         ],
         latest: false
       } as Version,
@@ -614,7 +616,8 @@ describe('push', () => {
         'user/app:mytag-master',
         'user/app:mytag-20200110',
         'user/app:mytag-tag-',
-        'user/app:mytag-baseref-'
+        'user/app:mytag-baseref-',
+        'user/app:mytag-defbranch'
       ],
       [
         "org.opencontainers.image.title=Hello-World",
@@ -667,7 +670,8 @@ describe('push', () => {
         tags: [
           `type=edge,branch=master`,
           `type=ref,event=branch,enable=false`,
-          `type=sha,format=long`
+          `type=sha,format=long`,
+          `type=raw,value=defbranch,enable={{is_default_branch}}`
         ],
       } as Inputs,
       {
@@ -1321,21 +1325,25 @@ describe('tag', () => {
         images: ['org/app', 'ghcr.io/user/app'],
         tags: [
           `type=raw,{{tag}}-{{sha}}-foo`,
-          `type=raw,{{base_ref}}-foo`
+          `type=raw,{{base_ref}}-foo`,
+          `type=raw,defbranch-foo,enable={{is_default_branch}}`
         ]
       } as Inputs,
       {
         main: 'v1.1.1-860c190-foo',
         partial: [
-          'master-foo'
+          'master-foo',
+          'defbranch-foo'
         ],
         latest: false
       } as Version,
       [
         'org/app:v1.1.1-860c190-foo',
         'org/app:master-foo',
+        'org/app:defbranch-foo',
         'ghcr.io/user/app:v1.1.1-860c190-foo',
-        'ghcr.io/user/app:master-foo'
+        'ghcr.io/user/app:master-foo',
+        'ghcr.io/user/app:defbranch-foo'
       ],
       [
         "org.opencontainers.image.title=Hello-World",
@@ -2317,15 +2325,19 @@ describe('pr', () => {
         images: ['org/app'],
         tags: [
           `type=raw,value=mytag-{{base_ref}}`,
+          `type=raw,mytag-defbranch,enable={{is_default_branch}}`
         ]
       } as Inputs,
       {
         main: 'mytag-master',
-        partial: [],
+        partial: [
+          'mytag-defbranch'
+        ],
         latest: false
       } as Version,
       [
-        'org/app:mytag-master'
+        'org/app:mytag-master',
+        'org/app:mytag-defbranch'
       ],
       [
         "org.opencontainers.image.title=Hello-World",
@@ -2339,21 +2351,25 @@ describe('pr', () => {
       ]
     ],
     [
-      'pr06',
+      'pr11',
       'event_pull_request.env',
       {
         images: ['org/app'],
         tags: [
           `type=raw,value=mytag-{{base_ref}}`,
+          `type=raw,mytag-defbranch,enable={{is_default_branch}}`
         ]
       } as Inputs,
       {
         main: 'mytag-master',
-        partial: [],
+        partial: [
+          'mytag-defbranch'
+        ],
         latest: false
       } as Version,
       [
-        'org/app:mytag-master'
+        'org/app:mytag-master',
+        'org/app:mytag-defbranch'
       ],
       [
         "org.opencontainers.image.title=Hello-World",
@@ -2521,19 +2537,25 @@ describe('schedule', () => {
         images: ['org/app', 'ghcr.io/user/app'],
         tags: [
           `type=schedule`,
-          `type=sha,priority=2000`
+          `type=sha,priority=2000`,
+          `type=raw,value=defbranch,enable={{is_default_branch}}`
         ]
       } as Inputs,
       {
         main: 'sha-860c190',
-        partial: ['nightly'],
+        partial: [
+          'nightly',
+          'defbranch'
+        ],
         latest: false
       } as Version,
       [
         'org/app:sha-860c190',
         'org/app:nightly',
+        'org/app:defbranch',
         'ghcr.io/user/app:sha-860c190',
-        'ghcr.io/user/app:nightly'
+        'ghcr.io/user/app:nightly',
+        'ghcr.io/user/app:defbranch'
       ],
       [
         "org.opencontainers.image.title=Hello-World",
@@ -2611,6 +2633,40 @@ describe('release', () => {
         "org.opencontainers.image.licenses=MIT"
       ]
     ],
+    [
+      'release02',
+      'event_release_created.env',
+      {
+        images: ['user/app'],
+        tags: [
+          `type=ref,event=tag`,
+          `type=raw,value=baseref-{{base_ref}}`,
+          `type=raw,value=defbranch,enable={{is_default_branch}}`
+        ]
+      } as Inputs,
+      {
+        main: 'v1.1.1',
+        partial: [
+          'baseref-'
+        ],
+        latest: true
+      } as Version,
+      [
+        'user/app:v1.1.1',
+        'user/app:baseref-',
+        'user/app:latest'
+      ],
+      [
+        "org.opencontainers.image.title=Hello-World",
+        "org.opencontainers.image.description=This your first repo!",
+        "org.opencontainers.image.url=https://github.com/octocat/Hello-World",
+        "org.opencontainers.image.source=https://github.com/octocat/Hello-World",
+        "org.opencontainers.image.version=v1.1.1",
+        "org.opencontainers.image.created=2020-01-10T00:30:00.000Z",
+        "org.opencontainers.image.revision=860c1904a1ce19322e91ac35af1ab07466440c37",
+        "org.opencontainers.image.licenses=MIT"
+      ]
+    ]
   ])('given %s with %p event', tagsLabelsTest);
 });
 

__tests__/tag.test.ts

@@ -417,11 +417,6 @@ describe('parse', () => {
       {} as Tag,
       true
     ],
-    [
-      `type=sha,enable=foo`,
-      {} as Tag,
-      true
-    ],
     [
       `type=sha,format=foo`,
       {} as Tag,

src/meta.ts

@@ -30,6 +30,7 @@ export class Meta {
   constructor(inputs: Inputs, context: Context, repo: ReposGetResponseData) {
     // Needs to override Git reference with pr ref instead of upstream branch ref
     // for pull_request_target event
+    // https://docs.github.com/en/actions/using-workflows/events-that-trigger-workflows#pull_request_target
     if (/pull_request_target/.test(context.eventName)) {
       context.ref = `refs/pull/${context.payload.number}/merge`;
     }
@@ -51,7 +52,11 @@ export class Meta {
     };
 
     for (const tag of this.tags) {
-      if (!/true/i.test(tag.attrs['enable'])) {
+      const enabled = this.setGlobalExp(tag.attrs['enable']);
+      if (!['true', 'false'].includes(enabled)) {
+        throw new Error(`Invalid value for enable attribute: ${enabled}`);
+      }
+      if (!/true/i.test(enabled)) {
         continue;
       }
       switch (tag.type) {
@@ -369,6 +374,27 @@ export class Meta {
         }
         return '';
       },
+      is_default_branch: function () {
+        let branch = ctx.ref.replace(/^refs\/heads\//g, '');
+        if (/^refs\/tags\//.test(ctx.ref) && ctx.payload?.base_ref != undefined) {
+          branch = ctx.payload.base_ref.replace(/^refs\/heads\//g, '');
+        }
+        if (/^refs\/pull\//.test(ctx.ref) && ctx.payload?.pull_request?.base?.ref != undefined) {
+          branch = ctx.payload.pull_request.base.ref;
+        }
+        if (branch == undefined || branch.length == 0) {
+          return 'false';
+        }
+        if (ctx.payload?.repository?.default_branch == branch) {
+          return 'true';
+        }
+        // following events always trigger for last commit on default branch
+        // https://docs.github.com/en/actions/using-workflows/events-that-trigger-workflows
+        if (/create/.test(ctx.eventName) || /discussion/.test(ctx.eventName) || /issues/.test(ctx.eventName) || /schedule/.test(ctx.eventName)) {
+          return 'true';
+        }
+        return 'false';
+      },
       date: function (format) {
         return moment(currentDate).utc().format(format);
       }

src/tag.ts

@@ -206,9 +206,6 @@ export function Parse(s: string): Tag {
   if (!Object.prototype.hasOwnProperty.call(tag.attrs, 'priority')) {
     tag.attrs['priority'] = DefaultPriorities[tag.type];
   }
-  if (!['true', 'false'].includes(tag.attrs['enable'])) {
-    throw new Error(`Invalid value for enable attribute: ${tag.attrs['enable']}`);
-  }
 
   return tag;
 }