docs(federation): M2 Step-CA setup guide + admin CLI reference (FED-M2-12) (#502)

2026-04-22 06:06:45 +00:00
parent fc1600b738
commit 194c3b603e
2 changed files with 196 additions and 0 deletions
--- a/docs/federation/SETUP.md
+++ b/docs/federation/SETUP.md
@@ -70,6 +70,96 @@ For JSON output (useful in CI/automation):
 mosaic gateway doctor --json
 ```

+## Step 2: Step-CA Bootstrap
+
+Step-CA is a certificate authority that issues X.509 certificates for federation peers. In Mosaic federation, it signs peer certificates with custom OIDs that embed grant and user identities, enforcing authorization at the certificate level.
+
+### Prerequisites for Step-CA
+
+Before starting the CA, you must set up the dev password:
+
+```bash
+cp infra/step-ca/dev-password.example infra/step-ca/dev-password
+# Edit dev-password and set your CA password (minimum 16 characters)
+```
+
+The password is required for the CA to boot and derive the provisioner key used by the gateway.
+
+### Start the Step-CA service
+
+Add the step-ca service to your federated stack:
+
+```bash
+docker compose -f docker-compose.federated.yml --profile federated up -d step-ca
+```
+
+On first boot, the init script (`infra/step-ca/init.sh`) runs automatically. It:
+
+- Generates the CA root key and certificate in the Docker volume
+- Creates the `mosaic-fed` JWK provisioner
+- Applies the X.509 template from `infra/step-ca/templates/federation.tpl`
+
+The volume is persistent, so subsequent boots reuse the existing CA keys.
+
+Verify the CA is healthy:
+
+```bash
+curl https://localhost:9000/health --cacert /tmp/step-ca-root.crt
+```
+
+(If the root cert file doesn't exist yet, see the extraction steps below.)
+
+### Extract credentials for the gateway
+
+The gateway requires two credentials from the running CA:
+
+**1. Provisioner key (for `STEP_CA_PROVISIONER_KEY_JSON`)**
+
+```bash
+docker exec $(docker ps -qf name=step-ca) cat /home/step/secrets/mosaic-fed.json > /tmp/step-ca-provisioner.json
+```
+
+This JSON file contains the JWK public and private keys for the `mosaic-fed` provisioner. Store it securely and pass its contents to the gateway via the `STEP_CA_PROVISIONER_KEY_JSON` environment variable.
+
+**2. Root certificate (for `STEP_CA_ROOT_CERT_PATH`)**
+
+```bash
+docker cp $(docker ps -qf name=step-ca):/home/step/certs/root_ca.crt /tmp/step-ca-root.crt
+```
+
+This PEM file is the CA's root certificate, used to verify peer certificates issued by step-ca. Pass its path to the gateway via `STEP_CA_ROOT_CERT_PATH`.
+
+### Custom OID Registry
+
+Federation certificates include custom OIDs in the certificate extension. These encode authorization metadata:
+
+| OID                 | Name                   | Description           |
+| ------------------- | ---------------------- | --------------------- |
+| 1.3.6.1.4.1.99999.1 | mosaic_grant_id        | Federation grant UUID |
+| 1.3.6.1.4.1.99999.2 | mosaic_subject_user_id | Subject user UUID     |
+
+These OIDs are verified by the gateway after the CSR is signed, ensuring the certificate was issued with the correct grant and user context.
+
+### Environment Variables
+
+Configure the gateway with the following environment variables before startup:
+
+| Variable                       | Required | Description                                                                                               |
+| ------------------------------ | -------- | --------------------------------------------------------------------------------------------------------- |
+| `STEP_CA_URL`                  | Yes      | Base URL of the step-ca instance, e.g. `https://step-ca:9000` (use `https://localhost:9000` in local dev) |
+| `STEP_CA_PROVISIONER_KEY_JSON` | Yes      | JSON-encoded JWK from `/home/step/secrets/mosaic-fed.json`                                                |
+| `STEP_CA_ROOT_CERT_PATH`       | Yes      | Absolute path to the root CA certificate (e.g. `/tmp/step-ca-root.crt`)                                   |
+| `BETTER_AUTH_SECRET`           | Yes      | Secret used to seal peer private keys at rest; already required for M1                                    |
+
+Example environment setup:
+
+```bash
+export STEP_CA_URL="https://localhost:9000"
+export STEP_CA_PROVISIONER_KEY_JSON="$(cat /tmp/step-ca-provisioner.json)"
+export STEP_CA_ROOT_CERT_PATH="/tmp/step-ca-root.crt"
+export BETTER_AUTH_SECRET="<your-secret>"
+```
+
 ## Troubleshooting

 ### Port conflicts