Support downloading artifacts with common prefix

This commit adds the `name-prefix` input parameter to allow downloading
multiple artifacts of which the names share a common prefix.

This is useful for aggregating artifacts produced by matrix runs (e.g.
reports from matrixed test jobs).

Provides a smoother migration path for the use cases in #248.

README.md

@@ -46,9 +46,15 @@ For more information, see the [`@actions/artifact`](https://github.com/actions/t
 - uses: actions/download-artifact@v4
   with:
     # Name of the artifact to download.
-    # Optional. If unspecified, all artifacts for the run are downloaded.
+    # Optional. If unspecified, all artifacts for the run are downloaded, unless restricted by `name-prefix`.
     name:
 
+    # Name prefix of artifacts to download.
+    # If specified, download all artifacts of which the name starts with the given prefix.
+    # This is useful for aggregating artifacts produced by matrix jobs, for example.
+    # Optional; only meaningful if `name` is unspecified. 
+    name-prefix:
+
     # Destination path. Supports basic tilde expansion.
     # Optional. Defaults is $GITHUB_WORKSPACE
     path:

action.yml

@@ -3,7 +3,11 @@ description: 'Download a build artifact that was previously uploaded in the work
 author: 'GitHub'
 inputs:
   name:
-    description: 'Name of the artifact to download. If unspecified, all artifacts for the run are downloaded'
+    description: 'Name of the artifact to download. If unspecified, all artifacts for the run are downloaded, 
+      unless filtered out by name-prefix.'
+    required: false
+  name-prefix:
+    description: 'Download all artifacts starting with this prefix.'
     required: false
   path:
     description: 'Destination path. Supports basic tilde expansion. Defaults to $GITHUB_WORKSPACE'

src/constants.ts

@@ -1,5 +1,6 @@
 export enum Inputs {
   Name = 'name',
+  NamePrefix = 'name-prefix',
   Path = 'path',
   GitHubToken = 'github-token',
   Repository = 'repository',

src/download-artifact.ts

@@ -17,6 +17,7 @@ export const chunk = <T>(arr: T[], n: number): T[][] =>
 async function run(): Promise<void> {
   const inputs = {
     name: core.getInput(Inputs.Name, {required: false}),
+    namePrefix: core.getInput(Inputs.NamePrefix, {required: false}),
     path: core.getInput(Inputs.Path, {required: false}),
     token: core.getInput(Inputs.GitHubToken, {required: false}),
     repository: core.getInput(Inputs.Repository, {required: false}),
@@ -73,7 +74,10 @@ async function run(): Promise<void> {
     artifacts = [targetArtifact]
   } else {
     core.info(
-      `No input name specified, downloading all artifacts. Extra directory with the artifact name will be created for each download`
+      `No input name specified, downloading all artifacts ${
+        inputs.namePrefix ? `starting with '${inputs.namePrefix}'` : ''
+      }.
+      Extra directory with the artifact name will be created for each download`
     )
 
     const listArtifactResponse = await artifactClient.listArtifacts({
@@ -87,9 +91,21 @@ async function run(): Promise<void> {
       )
     }
 
-    core.debug(`Found ${listArtifactResponse.artifacts.length} artifacts`)
+    if (inputs.namePrefix) {
+      artifacts = listArtifactResponse.artifacts.filter(art =>
+        art.name.startsWith(inputs.namePrefix)
+      )
+
+      if (artifacts.length === 0) {
+        throw new Error(
+          `No artifacts found starting with prefix ${inputs.namePrefix} for run '${inputs.runID}' in '${inputs.repository}'`
+        )
+      }
+    } else {
       artifacts = listArtifactResponse.artifacts
     }
+    core.debug(`Found ${artifacts.length} artifacts`)
+  }
 
   const downloadPromises = artifacts.map(artifact =>
     artifactClient.downloadArtifact(artifact.id, {