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AWS ALB Proxy Provider

Backstage can de deployed behind AWS Application Load Balancer and get the user seamlessly authenticated.

Configuration​

The provider configuration can be added to your app-config.yaml under the root auth configuration, similar to the following example:

app-config.yaml
auth:
  providers:
    awsalb:
      # this is the URL of the IdP you configured
      issuer: 'https://example.okta.com/oauth2/default'
      # this is the ARN of your ALB instance
      signer: 'arn:aws:elasticloadbalancing:us-east-2:123456789012:loadbalancer/app/my-load-balancer/1234567890123456'
      # this is the region where your ALB instance resides
      region: 'us-west-2'
      signIn:
        resolvers:
          # See https://backstage.io/docs/auth/aws-alb/provider#resolvers for more resolvers
          - resolver: emailMatchingUserEntityProfileEmail

Ensure that you have set the signer correctly. It is also recommended that you restrict your target groups' security policy to only accept connections from that ALB.

Resolvers​

This provider includes several resolvers out of the box that you can use:

  • emailMatchingUserEntityProfileEmail: Matches the email address from the auth provider with the User entity that has a matching spec.profile.email. If no match is found it will throw a NotFoundError.
  • emailLocalPartMatchingUserEntityName: Matches the local part of the email address from the auth provider with the User entity that has a matching name. If no match is found it will throw a NotFoundError.
Note

The resolvers will be tried in order, but will only be skipped if they throw a NotFoundError.

If these resolvers do not fit your needs you can build a custom resolver, this is covered in the Building Custom Resolvers section of the Sign-in Identities and Resolvers documentation.

Backend Installation​

To add the provider to the backend we will first need to install the package by running this command:

from your Backstage root directory
yarn --cwd packages/backend add @backstage/plugin-auth-backend-module-aws-alb-provider

Then we will need to add this line:

in packages/backend/src/index.ts
backend.add(import('@backstage/plugin-auth-backend'));
backend.add(import('@backstage/plugin-auth-backend-module-aws-alb-provider'));

Adding the provider to the Backstage frontend​

See Sign-In with Proxy Providers for pointers on how to set up the sign-in page, and to also make it work smoothly for local development. You'll use awsalb as the provider name.

If you provide a custom sign in resolver, you can skip the signIn block entirely.