Transport Layer Security (TLS)¶

The Percona Operator for MongoDB uses Transport Layer Security (TLS) cryptographic protocol for the following types of communication:

Internal - communication between Percona Server for MongoDB instances in the cluster
External - communication between the client application and the cluster

The internal certificate is also used as an authorization method.

Certificates for TLS security can be generated in several ways. By default, the Operator generates long-term certificates automatically if there are no certificate secrets available. Other options are the following ones:

the Operator can use a specifically installed cert-manager, which will automatically generate and renew short-term TLS certificates,
certificates can be generated manually.

You can also use pre-generated certificates available in the deploy/ssl-secrets.yaml file for test purposes, but we strongly recommend avoiding their usage on any production system!

The following subsections explain how to configure TLS security with the Operator yourself, as well as how to temporarily disable it if needed.

Install and use the cert-manager¶

About the cert-manager¶

The cert-manager is a Kubernetes certificate management controller which widely used to automate the management and issuance of TLS certificates. It is community-driven, and open source.

When you have already installed cert-manager and deploy the operator, the operator requests a certificate from the cert-manager. The cert-manager acts as a self-signed issuer and generates certificates. The Percona Operator self-signed issuer is local to the operator namespace. This self-signed issuer is created because Percona Server for MongoDB requires all certificates issued by the same CA (Certificate authority).

Self-signed issuer allows you to deploy and use the Percona Operator without creating a cluster issuer separately.

Installation of the cert-manager¶

The steps to install the cert-manager are the following:

create a namespace,
disable resource validations on the cert-manager namespace,
install the cert-manager.

The following commands perform all the needed actions:

$ kubectl apply -f https://github.com/jetstack/cert-manager/releases/download/v1.8.0/cert-manager.yaml --validate=false

After the installation, you can verify the cert-manager by running the following command:

$ kubectl get pods -n cert-manager

The result should display the cert-manager and webhook active and running:

NAME                                       READY   STATUS    RESTARTS   AGE
cert-manager-7d59dd4888-tmjqq              1/1     Running   0          3m8s
cert-manager-cainjector-85899d45d9-8ncw9   1/1     Running   0          3m8s
cert-manager-webhook-84fcdcd5d-697k4       1/1     Running   0          3m8s

Once you create the database with the Operator, it will automatically trigger cert-manager to create certificates. Whenever you check certificates for expiration, you will find that they are valid and short-term.

Generate certificates manually¶

To generate certificates manually, follow these steps:

Provision a Certificate Authority (CA) to generate TLS certificates,
Generate a CA key and certificate file with the server details,
Create the server TLS certificates using the CA keys, certs, and server details.

The set of commands generate certificates with the following attributes:

Server-pem - Certificate
Server-key.pem - the private key
ca.pem - Certificate Authority

You should generate certificates twice: one set is for external communications, and another set is for internal ones. A secret created for the external use must be added to the spec.secrets.ssl key of the deploy/cr.yaml file. A certificate generated for internal communications must be added to the spec.secrets.sslInternal key of the deploy/cr.yaml file.

Supposing that your cluster name is my-cluster-name, the instructions to generate certificates manually are as follows:

$ CLUSTER_NAME=my-cluster-name
$ NAMESPACE=default
$ cat <<EOF | cfssl gencert -initca - | cfssljson -bare ca
  {
    "CN": "Root CA",
    "names": [
      {
        "O": "PSMDB"
      }
    ],
    "key": {
      "algo": "rsa",
      "size": 2048
    }
  }
EOF

$ cat <<EOF > ca-config.json
  {
    "signing": {
      "default": {
        "expiry": "87600h",
        "usages": ["signing", "key encipherment", "server auth", "client auth"]
      }
    }
  }
EOF

$ cat <<EOF | cfssl gencert -ca=ca.pem  -ca-key=ca-key.pem -config=./ca-config.json - | cfssljson -bare server
  {
    "hosts": [
      "localhost",
      "${CLUSTER_NAME}-rs0",
      "${CLUSTER_NAME}-rs0.${NAMESPACE}",
      "${CLUSTER_NAME}-rs0.${NAMESPACE}.svc.cluster.local",
      "*.${CLUSTER_NAME}-rs0",
      "*.${CLUSTER_NAME}-rs0.${NAMESPACE}",
      "*.${CLUSTER_NAME}-rs0.${NAMESPACE}.svc.cluster.local"
    ],
    "names": [
      {
        "O": "PSMDB"
      }
    ],
    "CN": "${CLUSTER_NAME/-rs0}",
    "key": {
      "algo": "rsa",
      "size": 2048
    }
  }
EOF
$ cfssl bundle -ca-bundle=ca.pem -cert=server.pem | cfssljson -bare server

$ kubectl create secret generic my-cluster-name-ssl-internal --from-file=tls.crt=server.pem --from-file=tls.key=server-key.pem --from-file=ca.crt=ca.pem --type=kubernetes.io/tls

$ cat <<EOF | cfssl gencert -ca=ca.pem  -ca-key=ca-key.pem -config=./ca-config.json - | cfssljson -bare client
  {
    "hosts": [
      "${CLUSTER_NAME}-rs0",
      "${CLUSTER_NAME}-rs0.${NAMESPACE}",
      "${CLUSTER_NAME}-rs0.${NAMESPACE}.svc.cluster.local",
      "*.${CLUSTER_NAME}-rs0",
      "*.${CLUSTER_NAME}-rs0.${NAMESPACE}",
      "*.${CLUSTER_NAME}-rs0.${NAMESPACE}.svc.cluster.local"
    ],
    "names": [
      {
        "O": "PSMDB"
      }
    ],
    "CN": "${CLUSTER_NAME/-rs0}",
    "key": {
      "algo": "rsa",
      "size": 2048
    }
  }
EOF

$ kubectl create secret generic my-cluster-name-ssl --from-file=tls.crt=client.pem --from-file=tls.key=client-key.pem --from-file=ca.crt=ca.pem --type=kubernetes.io/tls

Check your certificates for expiration¶

First, check the necessary secrets names (my-cluster-name-ssl and my-cluster-name-ssl-internal by default):

$ kubectl get certificate

You will have the following response:

NAME                           READY   SECRET                         AGE
my-cluster-name-ssl            True    my-cluster-name-ssl            49m
my-cluster-name-ssl-internal   True    my-cluster-name-ssl-internal   49m

Optionally you can also check that the certificates issuer is up and running:
```
$ kubectl get issuer
```
The response should be as follows:
```
NAME                       READY   AGE
my-cluster-name-psmdb-ca   True    61s
```

Now use the following command to find out the certificates validity dates, substituting Secrets names if necessary:

$ {
  kubectl get secret/my-cluster-name-ssl-internal -o jsonpath='{.data.tls\.crt}' | base64 --decode | openssl x509 -noout -dates
  kubectl get secret/my-cluster-name-ssl -o jsonpath='{.data.ca\.crt}' | base64 --decode | openssl x509 -noout -dates
  }

The resulting output will be self-explanatory:

notBefore=Apr 25 12:09:38 2022 GMT notAfter=Jul 24 12:09:38 2022 GMT
notBefore=Apr 25 12:09:38 2022 GMT notAfter=Jul 24 12:09:38 2022 GMT

Run Percona Server for MongoDB without TLS¶

Omitting TLS is also possible, but we recommend that you run your cluster with the TLS protocol enabled.

To disable TLS protocol (e.g. for demonstration purposes) set the spec.allowUnsafeConfigurations key to true in the deploy/cr.yaml file and and make sure that there are no certificate secrets available.

Warning

Normally, the Operator prevents users from configuring a cluster with unsafe parameters (starting it with less than 3 replica set instances or without TLS, etc.), automatically changing such unsafe parameters to safe defaults. If you switch the cluster to the unsafe configurations permissive mode, you will not be able to switch it back by setting spec.allowUnsafeConfigurations key to false, the flag will be ignored.

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Last update: 2023-09-11