feat: add ability to output candidate releases

In order to enable this new feature, I've added a new input called `only` that allows running only the desired functionality (`'create-github-releases' | 'list-candidate-releases' | 'update-pull-requests'`). It is backwards compatible with the `skipGitHubRelease` and `skipGitHubPullRequest` inputs.

Author: niieani

README.md

@@ -81,8 +81,7 @@ steps:
 | `fork`                     | If `true`, send the PR from a fork. This requires the `token` to be a user that can create forks (e.g. not the default `GITHUB_TOKEN`) |
 | `include-component-in-tag` | If true, add prefix to tags and branches, allowing multiple libraries to be released from the same repository                          |
 | `proxy-server`             | Configure a proxy servier in the form of `<host>:<port>` e.g. `proxy-host.com:8080`                                                    |
-| `skip-github-release`      | If `true`, do not attempt to create releases. This is useful if splitting release tagging from PR creation.                            |
-| `skip-github-pull-request` | If `true`, do not attempt to create release pull requests. This is useful if splitting release tagging from PR creation.               |
+| `only`                     | If `create-github-releases`, only attempt to create releases. This is useful if splitting release tagging from PR creation. If `update-pull-requests` only attempt to create release pull requests. If `list-candidate-releases`, only output information about which packages would be released.               |
 
 ## GitHub Credentials
 
@@ -167,6 +166,13 @@ New types of releases can be [added here](https://github.com/googleapis/release-
 | `pr`               | A JSON string of the [PullRequest object](https://github.com/googleapis/release-please/blob/main/src/pull-request.ts#L15) (unset if no release created)           |
 | `prs`              | A JSON string of the array of [PullRequest objects](https://github.com/googleapis/release-please/blob/main/src/pull-request.ts#L15) (unset if no release created) |
 
+> When used with `only: 'list-candidate-releases'`, the following properties are available.
+
+| output             | description                                                                                                                                                       |
+| ------------------ | ----------------------------------------------------------------------------------------------------------------------------------------------------------------- |
+| `releases_pending` | `true` if any release is pending, `false` otherwise                                                                                                              |
+| `paths_to_release` | A JSON string of the array of paths that have releases pending (`[]` if )                                                                                          |
+
 ### Root component outputs
 
 If you have a root component (path is `.` or unset), then the action will also output:
@@ -381,10 +387,10 @@ If you were setting the `command` option, you will likely need to modify your co
 
 | Command          | New Configuration                                                | Description                                                                                                                                  |
 | ---------------- | ---------------------------------------------------------------- | -------------------------------------------------------------------------------------------------------------------------------------------- |
-| `github-release` | `skip-github-pull-request: true`                                 | This command was used for only tagging releases. Now we tell release-please to skip opening release PRs.                                      |
-| `release-pr`     | `skip-github-release: true`                                      | This command was used for only opening release PRs. Now we tell release-please to skip tagging releases.                                     |
-| `manifest`       | do not set `release-type` option                                 | This command told release-please to use a manifest config file. This is now the default behavior unless you explicitly set a `release-type`. |
-| `manifest-pr`    | `skip-github-release: true` and do not set `release-type` option | This command told release-please to use a manifest config file and only open the pull reuqest.                                               |
+| `github-release` | `only: 'create-github-releases'`                                    | This command was used for only tagging releases. Now we tell release-please to skip opening release PRs.                                      |
+| `release-pr`     | `only: 'update-pull-requests'`                                      | This command was used for only opening release PRs. Now we tell release-please to skip tagging releases.                                     |
+| `manifest`       | do not set `release-type` option                                    | This command told release-please to use a manifest config file. This is now the default behavior unless you explicitly set a `release-type`. |
+| `manifest-pr`    | `only: 'update-pull-requests'` and do not set `release-type` option | This command told release-please to use a manifest config file and only open the pull reuqest.                                               |
 
 ### Package options
 

action.yml

@@ -54,10 +54,15 @@ inputs:
     description: 'if set to true, then do not try to tag releases'
     required: false
     default: false
+    deprecationMessage: 'Use only=update-pull-requests instead.'
   skip-github-pull-request:
     description: 'if set to true, then do not try to open pull requests'
     required: false
     default: false
+    deprecationMessage: 'Use only=create-github-releases instead.'
+  only:
+    description: "one of 'create-github-releases' | 'list-candidate-releases' | 'update-pull-requests' or empty to run all"
+    required: false
   changelog-host:
     description: 'The proto://host where commits live. Default `https://github.com`'
     required: false

src/index.ts

@@ -13,7 +13,7 @@
 // limitations under the License.
 
 import * as core from '@actions/core';
-import {GitHub, Manifest, CreatedRelease, PullRequest, VERSION} from 'release-please';
+import {GitHub, Manifest, CreatedRelease, PullRequest, VERSION, type CandidateRelease} from 'release-please';
 
 const DEFAULT_CONFIG_FILE = 'release-please-config.json';
 const DEFAULT_MANIFEST_FILE = '.release-please-manifest.json';
@@ -39,12 +39,15 @@ interface ActionInputs {
   targetBranch?: string;
   skipGitHubRelease?: boolean;
   skipGitHubPullRequest?: boolean;
+  only?: 'create-github-releases' | 'list-candidate-releases' | 'update-pull-requests';
   fork?: boolean;
   includeComponentInTag?: boolean;
   changelogHost: string;
 }
 
 function parseInputs(): ActionInputs {
+  const skipGitHubRelease = getOptionalBooleanInput('skip-github-release');
+  const skipGitHubPullRequest = getOptionalBooleanInput('skip-github-pull-request');
   const inputs: ActionInputs = {
     token: core.getInput('token', {required: true}),
     releaseType: getOptionalInput('release-type'),
@@ -58,8 +61,15 @@ function parseInputs(): ActionInputs {
       (core.getInput('github-graphql-url') || '').replace(/\/graphql$/, '') ||
       DEFAULT_GITHUB_GRAPHQL_URL,
     proxyServer: getOptionalInput('proxy-server'),
-    skipGitHubRelease: getOptionalBooleanInput('skip-github-release'),
-    skipGitHubPullRequest: getOptionalBooleanInput('skip-github-pull-request'),
+    only:
+      (core.getInput('only') as ActionInputs['only']) ||
+      (skipGitHubRelease && !skipGitHubPullRequest
+        ? 'update-pull-requests'
+        : !skipGitHubRelease && skipGitHubPullRequest
+        ? 'create-github-releases'
+        : skipGitHubRelease && skipGitHubPullRequest
+        ? 'list-candidate-releases'
+        : undefined),
     fork: getOptionalBooleanInput('fork'),
     includeComponentInTag: getOptionalBooleanInput('include-component-in-tag'),
     changelogHost: core.getInput('changelog-host') || DEFAULT_GITHUB_SERVER_URL,
@@ -119,14 +129,19 @@ export async function main() {
   const inputs = parseInputs();
   const github = await getGitHubInstance(inputs);
 
-  if (!inputs.skipGitHubRelease) {
-    const manifest = await loadOrBuildManifest(github, inputs);
-    core.debug('Creating releases');
+  const manifest = await loadOrBuildManifest(github, inputs);
+
+  if (inputs.only === 'list-candidate-releases') {
+    core.debug('Listing pending releases');
+    outputCandidateReleases(await manifest.buildReleases());
+  }
+
+  if (inputs.only === 'create-github-releases' || !inputs.only) {
+    core.debug('Creating github releases');
     outputReleases(await manifest.createReleases());
   }
 
-  if (!inputs.skipGitHubPullRequest) {
-    const manifest = await loadOrBuildManifest(github, inputs);
+  if (inputs.only === 'update-pull-requests' || !inputs.only) {
     core.debug('Creating pull requests');
     outputPRs(await manifest.createPullRequests());
   }
@@ -196,6 +211,35 @@ function outputReleases(releases: (CreatedRelease | undefined)[]) {
   core.setOutput('paths_released', JSON.stringify(pathsReleased));
 }
 
+function outputCandidateReleases(releases: CandidateRelease[]) {
+  releases = releases.filter(release => release !== undefined);
+  const pathsReleased = [];
+  core.setOutput('releases_pending', releases.length > 0);
+  if (releases.length) {
+    for (const release of releases) {
+      if (!release) {
+        continue;
+      }
+      const path = release.path || '.';
+      if (path) {
+        pathsReleased.push(path);
+        // If the special root release is set (representing project root)
+        // and this is explicitly a manifest release, set the release_created boolean.
+        setPathOutput(path, 'release_pending', true);
+      }
+      if (release.tag) {
+        // Historically tagName was output as tag_name, keep this
+        // consistent to avoid breaking change:
+        setPathOutput(path, 'tag_name', release.tag.toString());
+        setPathOutput(path, 'body', release.notes)
+      }
+    }
+  }
+  // Paths of all releases that were created, so that they can be passed
+  // to matrix in next step:
+  core.setOutput('paths_to_release', JSON.stringify(pathsReleased));
+}
+
 function outputPRs(prs: (PullRequest | undefined)[]) {
   prs = prs.filter(pr => pr !== undefined);
   core.setOutput('prs_created', prs.length > 0);