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MongoDB TLS/SSL Encryption

Prerequisite : To configure TLS/SSL in MongoDB, KubeDB uses cert-manager to issue certificates. So first you have to make sure that the cluster has cert-manager installed. To install cert-manager in your cluster following steps here.

To issue a certificate, the following crd of cert-manager is used:

  • Issuer/ClusterIssuer: Issuers, and ClusterIssuers represent certificate authorities (CAs) that are able to generate signed certificates by honoring certificate signing requests. All cert-manager certificates require a referenced issuer that is in a ready condition to attempt to honor the request. You can learn more details here.

  • Certificate: cert-manager has the concept of Certificates that define a desired x509 certificate which will be renewed and kept up to date. You can learn more details here.

MongoDB CRD Specification :

KubeDB uses following crd fields to enable SSL/TLS encryption in MongoDB.

  • spec:
    • sslMode
    • tls:
      • issuerRef
      • certificates
    • clusterAuthMode Read about the fields in details from mongodb concept,

When, sslMode is set to requireSSL, the users must specify the tls.issuerRef field. KubeDB uses the issuer or clusterIssuer referenced in the tls.issuerRef field, and the certificate specs provided in tls.certificate to generate certificate secrets using Issuer/ClusterIssuers specification. These certificates secrets including ca.crt, tls.crt and tls.key etc. are used to configure MongoDB server, exporter etc. respectively.

How TLS/SSL configures in MongoDB

The following figure shows how KubeDB enterprise used to configure TLS/SSL in MongoDB. Open the image in a new tab to see the enlarged version.

Deploy MongoDB with TLS/SSL
Fig: Deploy MongoDB with TLS/SSL

Deploying MongoDB with TLS/SSL configuration process consists of the following steps:

  1. At first, a user creates a Issuer/ClusterIssuer cr.

  2. Then the user creates a MongoDB cr which refers to the Issuer/ClusterIssuer cr that the user created in the previous step.

  3. KubeDB Community operator watches for the MongoDB cr.

  4. When it finds one, it creates Secret, Service, etc. for the MongoDB database.

  5. KubeDB Enterprise operator watches for MongoDB(5c), Issuer/ClusterIssuer(5b), Secret and Service(5a).

  6. When it finds all the resources(MongoDB, Issuer/ClusterIssuer, Secret, Service), it creates Certificates by using tls.issuerRef and tls.certificates field specification from MongoDB cr.

  7. cert-manager watches for certificates.

  8. When it finds one, it creates certificate secrets tls-secrets(server, client, exporter secrets etc.) that holds the actual certificate signed by the CA.

  9. KubeDB Community operator watches for the Certificate secrets tls-secrets.

  10. When it finds all the tls-secret, it creates the related StatefulSets so that MongoDB database can be configured with TLS/SSL.

In the next doc, we are going to show a step by step guide on how to configure a MongoDB database with TLS/SSL.