OpenID Connect in Shell Scripting: Automating Secure Authentication

The terminal waits for your command, and the API will not yield without a valid token.

OpenID Connect (OIDC) in shell scripting is the key to automating secure authentication with minimal friction. When you integrate OIDC into your scripts, you control access without hardcoding secrets, issuing CLI calls that conform to modern identity standards. This is faster, safer, and portable across environments.

What is OpenID Connect in Shell Scripting?

OpenID Connect is an identity layer built on top of OAuth 2.0. It verifies the identity of the caller and provides user profile data in a secure, standardized way. In shell scripts, OIDC lets you request, store, and refresh tokens directly from the terminal using tools like curl or wget. It replaces weak patterns like embedding static credentials or relying on insecure session hacks.

Why use OIDC in automation?

Shell scripts often run in CI/CD pipelines, maintenance jobs, or provisioning tools. Without OIDC, you risk exposing credentials or creating brittle authentication flows. With OIDC, the script negotiates tokens with the identity provider, receives signed JWTs, and calls APIs using short-lived credentials. This limits damage if compromised and aligns with zero-trust principles.

Core steps to implement OIDC in a shell script:

1. Register your client in the identity provider with a redirect URI.
2. Obtain the authorization URL and open it for the user or service flow.
3. Handle the authorization code sent to your redirect listener.
4. Exchange the code for an ID token and access token using curl POST requests.
5. Store tokens securely in memory or temporary files with proper permissions.
6. Refresh tokens automatically before expiry using the provider’s /token endpoint.

Sample token request using curl:

curl -X POST https://idp.example.com/token \
 -d grant_type=authorization_code \
 -d code="$AUTH_CODE"\
 -d redirect_uri="$REDIRECT_URI"\
 -d client_id="$CLIENT_ID"\
 -d client_secret="$CLIENT_SECRET"

Best practices:

• Use environment variables for secrets in shell scripts.
• Validate ID tokens with jq or OpenSSL to confirm signature and claims.
• Limit scopes to the minimum needed for the API calls.
• Log only what is necessary and avoid printing tokens in stdout.

Testing the OIDC flow:

Test against a staging identity provider with test accounts. Use verbose curl mode to see HTTP headers and confirm TLS connections are enforced. Check expiration timestamps and refresh logic under varied network conditions.

If your scripts need real security and modern identity compliance, OIDC is the way forward. Cut the static secrets. Work with short-lived, verifiable tokens that expire cleanly.

See how it works in minutes with a live OIDC shell scripting example at hoop.dev.