6. Set up mutual TLS

This section details setting up mTLS communication between the backends and the orchestrator.

In this scenario, the orchestrator acts as the certificate authority checking the certificates. These instructions have to be repeated for each backend.

This guide assumes that you already have followed the instructions to Setup TLS.

6.1. Generate backend Certificate Signing Request and signing key

The first step is to generate the Certificate Signing Request and a signing key for the organization.

openssl req -newkey rsa:2048 -nodes -keyout ORGNAME.key -subj "/O=ORGNAME/CN=HOSTNAME" -out ORGNAME.csr

Replace ORGNAME with your organization name. It should be the same as the value you put in your values.yaml file for the key orchestrator.mspID.

Replace HOSTNAME with the hostname of your substra backend.

Then send the file named ORGNAME.csr to the organization managing the orchestrator for them to sign your certificate.

6.2. Sign the Substra backend certificate

Now that you have the Certificate Signing Request from your backend in your orchestrator, you can sign it with the orchestrator certificate authority.

Navigate to the directory where the files orchestrator-ca.crt and orchestrator-ca.key are located (created during Setup TLS), and sign the certificates:

openssl x509 -req -days 365 -in ORGNAME.csr -CA orchestrator-ca.crt -CAkey orchestrator-ca.key -CAcreateserial -out ORGNAME.crt -sha256

Replace ORGNAME with the organization name.

Caution

We don’t recommend having your certificate valid for a year (365 days in the previous command), you should change this value based on your company policy.

Then send the file named ORGNAME.crt back to the organization managing the Substra backend. You don’t need to keep a copy of this certificate.

6.3. Update backend configuration

Once you received the certificate (named ORGNAME.crt), you can create a secret in the Kubernetes cluster containing this file and the file ORGNAME.key:

kubectl create secret tls orchestrator-client-cert --cert=ORGNAME.crt --key=ORGNAME.key

To use this certificate, update or create the backend backend-values.yaml config file and add the following lines:

orchestrator:
  tls:
     enabled: true
     cacert: orchestrator-cacert
     mtls:
         enabled: true
         clientCertificate: orchestrator-client-cert

Note that you need to have the orchestrator TLS enabled for this to work.

If your backend is already running, apply the changes (this will restart it):

helm upgrade RELEASE-NAME substra/substra-backend --version VERSION --values backend-values.yaml

Replace RELEASE-NAME with the name of your substra backend release. You can retrieve it with helm list.

Replace VERSION with the version of the substra backend helm chart you want to deploy. If you don’t want to change version you can retrieve your currently deployed version with helm list.

6.4. Update orchestrator configuration

Finally, create or update the orchestrator values orchestrator-values.yaml config file with the following values:

orchestrator:
    tls:
      enabled: true
      mtls:
        enabled: true
        clientCACerts:
          orchestrator:
            - orchestrator-tls-cacert

Here we just put the orchestrator CA cert as a validation certificate.

If your client certs were signed by another authority that you trust you would need to add them as configmaps to your cluster and reference them here. With the key orchestrator in our example being the name of the organization that depend on this CA (it can be any arbitrary name). The items represent the names of the configmaps you wish to load, note that the object in the configmap shoud be named ca.crt.

If your orchestrator is already running, apply the changes (this will restart it):

helm upgrade RELEASE-NAME substra/orchestrator --version VERSION --values orchestrator-values.yaml

Replace RELEASE-NAME with the name of your orchestrator release. You can retrieve it with helm list.

Replace VERSION with the version of your orchestrator. You can retrieve the currently deployed version with helm list.