Updating tokenless authentication to use GitHub OIDC

Tokenless authentication is Launchable's specialized authentication method for public repositories that use GitHub Actions for CI.

We are updating this method to use OpenID Connect (OIDC) to make it more scalable and secure. This change requires action on your part.

OIDC implementation overview

GitHub now provides a short-lived signed token for each GitHub Actions run (About security hardening with OpenID Connect). This token is signed by GitHub's private key, and we can verify its validity via its public key. This makes the token a security credential that major Cloud providers such as AWS, Azure, and Google Cloud can use as an authentication token. Launchable implemented the same mechanism as these Cloud providers, so now we can accept it as a credential.

The new implementation of tokenless authentication provides the same benefit as the previous one: no API key is needed.

However, on top of that, the new implementation provides more security as it uses a verifiable short-lived token. Because the previous implementation involved calling GitHub APIs, the authentication process occasionally hit its API limit, resulting in request failures. With the new implementation, we no longer need to hit the GitHub API, which makes the service more stable.

Migration process

Steps

To migrate to the new implementation, follow these steps:

1. The new OIDC-based authentication is supported by CLI v1.52.0. If you typically install the latest CLI using pip3 install --upgrade, you will get the necessary version automatically. Otherwise, you need to upgrade to the latest version.

2. Add/update the permissions section of your GitHub Actions YAML file. (See #github-actions-permissions below).

3. Add a new EXPERIMENTAL_GITHUB_OIDC_TOKEN_AUTH environment variable. Set this to 1 to enable the new auth implementation.

4. Remove the GITHUB_PR_HEAD_SHA environment variable. It is no longer needed.

5. Keep the LAUNCHABLE_ORGANIZATION and LAUNCHABLE_WORKSPACE environment variables that were already set.

Environment variables summary

GitHub Actions Permissions

To use the OIDC token in GitHub Actions, you need to configure permissions to retrieve it. As described in the GitHub Help Article, id-token: write permission needs to be added.

This permission can be added per job or to the entire workflow.

Examples

1name: Verify Launchable tokenless authentication
2
3on:
4  pull_request:
5    paths:
6      - gradle/**
7
8env:
9  LAUNCHABLE_ORGANIZATION: "examples"
10  LAUNCHABLE_WORKSPACE: "gradle"
11  EXPERIMENTAL_GITHUB_OIDC_TOKEN_AUTH: 1
12
13permissions:
14  id-token: write
15  contents: read
16
17jobs:
18  build:
19    runs-on: ubuntu-latest
20
21    steps:
22      - uses: actions/checkout@v2
23        with:
24          fetch-depth: 0
25      - uses: actions/setup-python@v2
26      - name: Set up JDK 1.8
27        uses: actions/setup-java@v1
28        with:
29          java-version: 1.8
30
31      - name: Launchable
32        run: |
33          pip3 install --user launchable~=1.0
34          export PATH=~/.local/bin:$PATH
35          launchable verify
36        working-directory: ./gradle

Frequently Asked Questions

What is included in the OIDC token?

GitHub provides a detailed explanation and example of the OIDC token. See Understanding the OIDC token.

How does Launchable verify the OIDC token?

When you apply for tokenless authentication, we associate your GitHub repository with your Launchable workspace in our internal database.

When you run the CLI, the Launchable API server verifies the OIDC token and checks that the repository claim in it matches the stored association.

Can I see how the CLI handles the OIDC token?

Sure! Check out these commits in the public CLI repository:

1. https://github.com/launchableinc/cli/commit/945597f3fffeb49cd5968ba29054de78505aab61

2. https://github.com/launchableinc/cli/commit/68b06c01607b43bed33b2f774f424f7a8c220af6