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| title | lang | meta | description | |||||
|---|---|---|---|---|---|---|---|---|
| Cloud Run | en-US |
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This guide covers how to deploy Pomerium to Cloud Run and use it to protect other endpoints via Authorization Headers. |
Securing Cloud Run endpoints
This recipe's sources can be found on github
Background
Services on Cloud Run and other Google Cloud serverless products can be restricted to only permit access with a properly signed bearer token. This allows requests from other services running in GCP or elsewhere to be securely authorized despite the endpoints being public.
These bearer tokens are not easily set in a browser session and must be refreshed on a regular basis, preventing them from being useful for end user authorization. Pomerium, however, can generate compatible tokens on behalf of end users and proxy the request to these services.
How it works
- Add an IAM policy delegating
roles/run.invokerpermissions to a service account - Run Pomerium with access to a key for the corresponding service account
- Publish DNS records for each protected application pointing to Pomerium
- Configure Pomerium with appropriate policy and
enable_google_cloud_serverless_authentication
The protected application delegates trust to a GCP service account which Pomerium runs as, and Pomerium performs user based authorization on a per route basis. This turns Pomerium into a bridge between a user-centric and service-centric authorization models.
Pre-requisites
This guide assumes you have Editor access to a Google Cloud project which can be used for isolated testing, and a DNS zone which you are also able to control. DNS does not need to be inside Google Cloud for the example to work.
Set Up
To deploy Pomerium to Cloud Run securely and easily, a special image is available at gcr.io/pomerium-io/pomerium:[version]-cloudrun. It allows sourcing configuration from GCP Secrets Manager, and sets some defaults for Cloud Run to keep configuration minimal. We will be leveraging it in this example to store IdP credentials. Our policy contains no secrets so we can place it directly in an ENV var.
Dockerfile Based on vals-entrypoint
The image expects a config file at /pomerium/config.yaml. Set VALS_FILES=[secretref]:/pomerium/config.yaml and set any other Pomerium Environment Variables directly or with secret refs such as ref+gcpsecrets://PROJECT/SECRET(#/key]).
Config
Set up a config.yaml to contain your IdP credentials and secrets (config.yaml):
<<< @/examples/cloudrun/config.yaml
Substitute cloudrun.pomerium.io for your own subdomain and your e-mail domain if appropriate (policy.template.yaml):
<<< @/examples/cloudrun/policy.template.yaml
DNS
Substitute cloudrun.pomerium.io for your own subdomain (zonefile.txt):
<<< @/examples/cloudrun/zonefile.txt
Or set an equivalent CNAME in your DNS provider.
Deploy
Ensure you have set a default project:
glcoud config set default-project MYTESTPROJECT
<<< @/examples/cloudrun/deploy.sh
Results
Overview
We should see two applications deployed. The hello app is our protected app, and pomerium is...Pomerium!
Notice that Pomerium allows unauthenticated access, but hello does not.
Here are the domain mappings set up:
Direct Access
Let's verify we cannot access the main application directly by visiting https://hello-direct.cloudrun.pomerium.io
You should see a 403 error because you do not have the proper credentials.
Authenticated Access
Now let's access via https://hello.cloudrun.pomerium.io
We should get an auth flow through your IdP:
And a hello page:
Non-GCP Applications
If your target application is not running on GCP, you can also perform your own header validation.
Browse to https://verify.cloudrun.pomerium.io
You should see your identity header set:
See getting user's identity for more details on using this header.