SingleTenantMongoDB Controller

A simple Kubernetes Operator for managing single-tenant MongoDB replica sets.

It allows applications to consume MongoDB through a declarative Custom Resource rather than manually managing StatefulSets, Secrets, and replica set administration.

Getting started

1. Install Helm chart (controller and CRD)

   helm install mongodb-operator oci://ghcr.io/mrhachi/charts/mongodb-operator --namespace mongodb-system

2. Deploy user secrets

   kubectl -n sample-app create secret generic singletenantmongodb-sample-admin-pass \
       --from-literal=password=Ar34l5ecureP@ssw0rd?
   kubectl -n sample-app create secret generic singletenantmongodb-sample-app-user-pass \
       --from-literal=password=An0th3r1.
   kubectl -n sample-app create secret generic singletenantmongodb-sample-operation-user-pass \
       --from-literal=password=4N0THER0N3.

3. Install MongoDB custom resource

   kubectl -n sample-app apply -f singletenantmongodb.yml

   singletenantmongodb.yml

   apiVersion: db.mrhachi.dev/v1alphav1
   kind: SingleTenantMongoDB
   metadata:
     labels:
       app.kubernetes.io/name: controller
       app.kubernetes.io/managed-by: kustomize
     name: singletenantmongodb-sample
   spec:
     databaseName: sample
     replicas: 2
   
     admin:
       username: admin
       secretRef:
         name: singletenantmongodb-sample-admin-pass
   
     users:
       - username: app
         secretRef:
           name: singletenantmongodb-sample-app-user-pass
         roles:
           - role: readWrite
             database: sample
   
       - username: operation
         secretRef:
           name: singletenantmongodb-sample-operation-user-pass
         roles:
           - role: read
             database: sample
   
     storage:
       size: "2Gi"
   
     resources:
       requests:
         cpu: "500m"
         memory: "256Mi"
       limits:
         cpu: "1"
         memory: "512Mi"
   

SingleTenantMongoDB Custom Resource API

Represents a single MongoDB replica set managed by the operator.

Creating a SingleTenantMongoDB causes the operator to create and reconcile the following:

• MongoDB StatefulSets
• MongoDB Services
• Connection information ConfigMap
• Replica set topology
• Application user roles and passwords
• MongoDB replica set keyfile secrets

spec.databaseName

The default MongoDB database used.

spec.replicas

Number of MongoDB replica set members.

spec.admin

Defines the MongoDB administrator account.

username

MongoDB administrator username

secretRef.name

Kubernetes Secret containing the administrator password

The referenced Secret must contain the secret under the password key.

spec.users

Defines MongoDB application users managed by the operator.

[].username

MongoDB administrator username

[].secretRef.name

Kubernetes Secret containing the administrator password

The referenced Secret must contain the secret under the password key.

[].roles

[].role: MongoDB user role [].database: Database against which the role applies

spec.storage

Defines persistent storage allocated to each MongoDB replica.

Example:

storage:
  size: "10Gi"

The value is applied to the StatefulSet volume claims.

spec.resources

Defines Kubernetes resource requests and limits for MongoDB containers.

Managed resources

A SingleTenantMongoDB resource creates:

• StatefulSet
• Headless Service
• PersistentVolumeClaims
• Connection ConfigMap
• MongoDB authentication Secrets

Resources are owned by the Custom Resource and are garbage collected when the resource is deleted.