feat: add support for npm Trusted Publishers with NPM_ID_TOKEN

.changeset/yummy-hairs-enjoy.md

@@ -0,0 +1,5 @@
+---
+"changesets-gitlab": minor
+---
+
+Add support for Trusted Publishers

README.md

@@ -89,7 +89,12 @@ release:
 
 #### With Publishing
 
-Before you can setup this action with publishing, you'll need to have an [npm token](https://docs.npmjs.com/creating-and-viewing-authentication-tokens) that can publish the packages in the repo you're setting up the action for and doesn't have 2FA on publish enabled ([2FA on auth can be enabled](https://docs.npmjs.com/about-two-factor-authentication)). You'll also need to [add it as a custom environment variable on your GitLab repo](https://docs.gitlab.com/ee/ci/variables/#custom-cicd-variables) with the name `NPM_TOKEN`. Once you've done that, you can create a file at `.gitlab-ci.yml` with the following content.
+There are two ways to authenticate with npm when publishing:
+
+1. Trusted Publishers (recommended): Configure npm Trusted Publishers for your GitLab pipeline (see the npm docs: <https://docs.npmjs.com/trusted-publishers#supported-cicd-providers>). When the pipeline runs, npm will inject an `NPM_ID_TOKEN`, which this tool detects. In this mode you do NOT need to set `NPM_TOKEN`, and no `.npmrc` file is required—the npm CLI exchanges the identity token automatically.
+2. Classic Automation Token: Create an [npm automation token](https://docs.npmjs.com/creating-and-viewing-authentication-tokens) (without 2FA on publish) and add it as a [custom environment variable in GitLab](https://docs.gitlab.com/ee/ci/variables/#custom-cicd-variables) named `NPM_TOKEN`.
+
+For any of the methods, create a file at `.gitlab-ci.yml` with the following content:
 
 ```yml
 stages:
@@ -114,13 +119,14 @@ release:
     INPUT_PUBLISH: yarn release
 ```
 
-By default the GitLab CI cli creates a `.npmrc` file with the following content:
+By default the GitLab CI cli creates a `.npmrc` file with the following content when `NPM_TOKEN` is present and no `.npmrc` exists (classic token mode):
 
 ```sh
 //registry.npmjs.org/:_authToken=${process.env.NPM_TOKEN}
 ```
 
 However, if a `.npmrc` file is found, the GitLab CI cli does not recreate the file. This is useful if you need to configure the `.npmrc` file on your own.
+If `NPM_ID_TOKEN` is detected (Trusted Publishers), no `.npmrc` file is created or required.
 For example, you can add a step before running the Changesets GitLab CI cli:
 
 ```yml

src/main.ts

@@ -21,8 +21,8 @@
 export const main = async ({
   published,
   onlyChangesets,
 }: MainCommandOptions = {}) => {
-  const { GITLAB_TOKEN, NPM_TOKEN } = env
+  const { GITLAB_TOKEN, NPM_TOKEN, NPM_ID_TOKEN } = env
 
   setOutput('published', false)
   setOutput('publishedPackages', [])
@@ -69,15 +69,20 @@
       const npmrcPath = `${env.HOME}/.npmrc`
       if (fs.existsSync(npmrcPath)) {
         console.log('Found existing .npmrc file')
+      } else if (NPM_ID_TOKEN) {
+        // Using npm Trusted Publishers: npm will exchange the OIDC token for a publish token internally.
+        console.log(
+          'Detected `NPM_ID_TOKEN`; skipping `.npmrc` creation (Trusted Publishers mode).',
+        )
       } else if (NPM_TOKEN) {
-        console.log('No .npmrc file found, creating one')
+        console.log('No .npmrc file found, creating one with `NPM_TOKEN`')
         await fs.promises.writeFile(
           npmrcPath,
           `//registry.npmjs.org/:_authToken=${NPM_TOKEN}`,
         )
       } else {
         setFailed(
-          'No `.npmrc` found nor `NPM_TOKEN` provided, unable to publish packages',
+          'No `.npmrc` found and neither `NPM_TOKEN` nor `NPM_ID_TOKEN` provided, unable to publish packages',
         )
         return
       }

src/types.ts

@@ -27,6 +27,9 @@ export type Env = GitLabCIPredefinedVariables &
 
     HOME: string
     NPM_TOKEN?: string
+    // Presence of NPM_ID_TOKEN indicates usage of npm Trusted Publishers;
+    // when set we don't require nor create an .npmrc with NPM_TOKEN.
+    NPM_ID_TOKEN?: string
   }
 
 type MergeRequestVariables =