download-artifact/docs/MIGRATION.md

Migration

• Migration
  • Multiple uploads to the same named Artifact

Several behavioral differences exist between Artifact actions v3 and below vs v4. This document outlines common scenarios in v3, and how they would be handled in v4.

Multiple uploads to the same named Artifact

In v3, Artifacts are mutable so it's possible to write workflow scenarios where multiple jobs upload to the same Artifact like so:

jobs:
  upload:
    strategy:
      matrix:
        runs-on: [ubuntu-latest, macos-latest, windows-latest]
    runs-on: ${{ matrix.runs-on }}
    steps:
      - name: Create a File
        run: echo "hello from ${{ matrix.runs-on }}" > file-${{ matrix.runs-on }}.txt
      - name: Upload Artifact
        uses: actions/upload-artifact@v3
        with:
          name: my-artifact # NOTE: same artifact name
          path: file-${{ matrix.runs-on }}.txt
  download:
    needs: upload
    runs-on: ubuntu-latest
    steps:
      - name: Download All Artifacts
        uses: actions/download-artifact@v3
        with:
          path: my-artifact
      - run: ls -R my-artifact

This results in a directory like so:

my-artifact/
  file-macos-latest.txt
  file-ubuntu-latest.txt
  file-windows-latest.txt

In v4, Artifacts are immutable (unless deleted). So you must change each of the uploaded Artifacts to have a different name and filter the downloads by name to achieve the same effect:

jobs:
  upload:
    strategy:
      matrix:
        runs-on: [ubuntu-latest, macos-latest, windows-latest]
    runs-on: ${{ matrix.runs-on }}
    steps:
    - name: Create a File
      run: echo "hello from ${{ matrix.runs-on }}" > file-${{ matrix.runs-on }}.txt
    - name: Upload Artifact
-     uses: actions/upload-artifact@v3
+     uses: actions/upload-artifact@v4
      with:
-       name: my-artifact
+       name: my-artifact-${{ matrix.runs-on }}
        path: file-${{ matrix.runs-on }}.txt
  download:
    needs: upload
    runs-on: ubuntu-latest
    steps:
    - name: Download All Artifacts
-     uses: actions/download-artifact@v3
+     uses: actions/download-artifact@v4
      with:
        path: my-artifact
+       pattern: my-artifact-*
+       merge-multiple: true
    - run: ls -R my-artifact

In v4, the new pattern: input will filter the downloaded Artifacts to match the name specified. The new merge-multiple: input will support downloading multiple Artifacts to the same directory. If the files within the Artifacts have the same name, the last writer wins.