🐥 Avoid tzdata prompts in GitHub Actions

When setting up CI pipelines with GitHub Actions on Ubuntu runners, you might encounter this familiar and frustrating interactive prompt during package installation:

Configuring tzdata
------------------
Please select the geographic area in which you live. Subsequent configuration
questions will narrow this down by presenting a list of cities, representing
the time zones in which they are located.

This happens when installing the tzdata package, which is used to configure timezones. On your local machine, it’s easy to interact with the prompt—but in CI, it causes the workflow to hang or fail.

Luckily, there’s a simple fix.

To prevent the interactive prompt and let the installation proceed automatically, set the DEBIAN_FRONTEND environment variable to noninteractive before calling apt-get. Here's how to do it inside a GitHub Actions workflow:

jobs:
  build:
    runs-on: ubuntu-latest
    steps:
      - name: Checkout code
        uses: actions/checkout@v3

      - name: Set up dependencies
        run: |
          sudo apt-get update
          sudo DEBIAN_FRONTEND=noninteractive apt-get install -y tzdata

That single environment variable tells apt to suppress all interactive questions and use default values, allowing your workflow to continue without interruption.

If you're building Docker images or scripts that will also be used in CI, you might want to include this setting there too:

RUN DEBIAN_FRONTEND=noninteractive apt-get install -y tzdata

This avoids surprises when your Dockerfile is used in different environments.