Optionally override the "strip prefix"

Typically, build artifacts are downloaded in the form of a `.zip` file
that contains the files, where the original path is prefixed by the
artifact name. For example, an artifact name "heya" will be reflected in
the downloaded `.zip` file by having all files inside the `heya/`
subdirectory. For that reason, this Action strips that prefix from the
extracted files.

Under certain circumstances, it may be desirable to strip an even longer
prefix, e.g. when downloading Git's `vcpkg` artifact. The corresponding
files are all inside the `compat/vcbuild/vcpkg/` subdirectory, and if we
want to cache the artifact files, we can only download them to an empty
(or non-existing) directory, and `compat/` is definitely not empty once
Git's source code is checked out.

So let's offer the option to override the strip prefix.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>

Author: dscho

.github/workflows/test.yml

@@ -38,3 +38,17 @@ jobs:
       - name: Verify that the package was downloaded
         shell: bash
         run: test -f sparse/sparse_*.deb
+  test-strip-prefix: # make sure the action works on a clean machine without building
+    runs-on: windows-latest
+    steps:
+      - uses: actions/checkout@v2
+      - name: Run this Action in-place
+        uses: ./
+        with:
+          repository: git/git
+          definitionId: 9
+          path: compat/vcbuild/vcpkg
+          stripPrefix: compat/vcbuild/vcpkg/
+      - name: Verify that the artifact files were downloaded
+        shell: bash
+        run: compat/vcbuild/vcpkg/vcpkg.exe version

README.md

@@ -46,6 +46,10 @@ Every Azure Pipeline has a numerical identifier that is part of the URL. For exa
 
 Pipelines can have an arbitrary number of artifacts, which are identified by a name. The `artifact` parameter specifies which one to download. It can be omitted if the given Pipeline run has only one artifact attached to it.
 
+### Strip prefix
+
+Pipeline artifacts can contain entire directory structures. The `stripPrefix` parameter allows filtering by a given path prefix; Any files matching that prefix will be written (after stripping the prefix), all other files will be skipped.
+
 ### Output location
 
 By default, the artifact files will be stored in the current directory. The `path` parameter can be used to override that.

__tests__/downloader.test.ts

@@ -49,7 +49,12 @@ test('can obtain build ID', async () => {
   mocked(fetch).mockReturnValue(
     Promise.resolve(new Response(JSON.stringify(buildIdResponse)))
   )
-  const {cacheId} = await get('git-for-windows/git', '22', 'git-sdk-64-minimal')
+  const {cacheId} = await get(
+    'git-for-windows/git',
+    '22',
+    'git-sdk-64-minimal',
+    undefined
+  )
   expect(fetch).toHaveBeenCalledTimes(1)
   expect(cacheId).toEqual('git-for-windows/git-22-git-sdk-64-minimal-71000')
 })

action.yml

@@ -14,6 +14,9 @@ inputs:
   artifact:
     required: false
     description: 'The name of the Azure Pipeline artifact'
+  stripPrefix:
+    required: false
+    description: "Strip this prefix from the artifact files' paths; Defaults to '<artifact>/'"
   path:
     required: false
     description: 'Where to write the artifact file(s)'

main.ts

@@ -8,7 +8,8 @@ async function run(): Promise<void> {
     const {artifactName, download, cacheId} = await get(
       core.getInput('repository'),
       core.getInput('definitionId'),
-      core.getInput('artifact')
+      core.getInput('artifact'),
+      core.getInput('stripPrefix')
     )
     const outputDirectory = core.getInput('path') || artifactName
     let useCache = core.getInput('cache') === 'true'

src/downloader.ts

@@ -96,7 +96,8 @@ async function unzip(
 export async function get(
   repository: string,
   definitionId: string,
-  artifactName: string
+  artifactName: string,
+  stripPrefix?: string
 ): Promise<{
   artifactName: string
   cacheId: string
@@ -161,7 +162,12 @@ export async function get(
     let delayInSeconds = 1
     for (;;) {
       try {
-        return await unzip(url, `${artifactName}/`, outputDirectory, verbose)
+        return await unzip(
+          url,
+          stripPrefix || `${artifactName}/`,
+          outputDirectory,
+          verbose
+        )
       } catch (e) {
         delayInSeconds *= 2
         if (delayInSeconds >= 60) {