Using Minio in Github actions to mock s3

I recently added Github Actions for simples3. In a recent PR, a contributor added support for custom endpoints. I was currently running go test on the library using a local .env files which contains real AWS keys and an actual s3 bucket. I realized that we can mock this using a minio server as well.

Coming from having used Gitlab pipelines, it seemed to be straightforward to do. I would simply have to run a service and just set the appropriate environment vars. Unfortunately, Github pipelines does not seem to support container args for services. The conventional hack on most repos, is to build a custom Dockerfile with the custom command, but it seemed unnecessary for just mocking minio for tests.

So after reading a bit, I found out that you can actually just run docker run inside the job command as a step. Essentially, it boils down to just adding it to your pipeline and setting up a few env vars. Minio accepts MINIO_ACCESS_KEY and MINIO_SECRET_KEY in the docker env, which it uses to bootstrap the admin credentials for the first time. These can be further used to create a mock bucket using aws s3 mb and provide the custom endpoint as a flag. Finally, simples3 will use its own environment vars to interact with the mock minio, and run the tests on it.

Here is the full workflow for reference:

name: Go Test

on:
  push:
    branches: [master]
  pull_request:
    branches: [master]

jobs:
  test:
    runs-on: ubuntu-latest
    steps:
      - uses: actions/[email protected]

      - name: Set up Go
        uses: actions/[email protected]
        with:
          go-version: 1.15
      - name: Setup minio
        run: |
          docker run -d -p 9000:9000 --name minio \
                     -e "MINIO_ACCESS_KEY=minioadmin" \
                     -e "MINIO_SECRET_KEY=minioadmin" \
                     -v /tmp/data:/data \
                     -v /tmp/config:/root/.minio \
                     minio/minio server /data

          export AWS_ACCESS_KEY_ID=minioadmin
          export AWS_SECRET_ACCESS_KEY=minioadmin
          export AWS_EC2_METADATA_DISABLED=true

          aws --endpoint-url http://127.0.0.1:9000/ s3 mb s3://testbucket

      - name: Run Go Test
        run: go test -v ./...
        env:
          AWS_S3_BUCKET: testbucket
          AWS_S3_ACCESS_KEY: minioadmin
          AWS_S3_SECRET_KEY: minioadmin
          AWS_S3_ENDPOINT: http://127.0.0.1:9000