New to KubeVault? Please start here.

Manage MongoDB credentials using the KubeVault operator

MongoDB is one of the supported plugins for the database secrets engine. This plugin generates database credentials dynamically based on configured roles for the MongoDB database. You can easily manage MongoDB secret engine using the KubeVault operator.

Elasticsearch secret engine

You need to be familiar with the following CRDs:

Before you begin

  • Install KubeVault operator in your cluster from here.

To keep things isolated, we are going to use a separate namespace called demo throughout this tutorial.

$ kubectl create ns demo
namespace/demo created

In this tutorial, we are going to create a role using MongoDB and issue credential using SecretAccessRequest.

Vault Server

If you don’t have a Vault Server, you can deploy it by using the KubeVault operator.

The KubeVault operator can manage policies and secret engines of Vault servers which are not provisioned by the KubeVault operator. You need to configure both the Vault server and the cluster so that the KubeVault operator can communicate with your Vault server.

Now, we have the AppBinding that contains connection and authentication information about the Vault server.

$ kubectl get appbinding -n demo
NAME    AGE
vault   50m

$ kubectl get appbinding -n demo vault -o yaml
apiVersion: appcatalog.appscode.com/v1alpha1
kind: AppBinding
metadata:
  creationTimestamp: "2021-08-16T08:23:38Z"
  generation: 1
  labels:
    app.kubernetes.io/instance: vault
    app.kubernetes.io/managed-by: kubevault.com
    app.kubernetes.io/name: vaultservers.kubevault.com
  name: vault
  namespace: demo
  ownerReferences:
  - apiVersion: kubevault.com/v1alpha1
    blockOwnerDeletion: true
    controller: true
    kind: VaultServer
    name: vault
    uid: 6b405147-93da-41ff-aad3-29ae9f415d0a
  resourceVersion: "602898"
  uid: b54873fd-0f34-42f7-bdf3-4e667edb4659
spec:
  clientConfig:
    service:
      name: vault
      port: 8200
      scheme: http
  parameters:
    apiVersion: config.kubevault.com/v1alpha1
    kind: VaultServerConfiguration
    kubernetes:
      serviceAccountName: vault
      tokenReviewerServiceAccountName: vault-k8s-token-reviewer
      usePodServiceAccountForCSIDriver: true
    path: kubernetes
    vaultRole: vault-policy-controller

Enable and Configure Elasticsearch Secret Engine

When a SecretEngine crd object is created, the KubeVault operator will enable a secret engine on specified path and configure the secret engine with given configurations.

A sample SecretEngine object for the Elasticsearch secret engine:

apiVersion: engine.kubevault.com/v1alpha1
kind: SecretEngine
metadata:
  name: mongo-engine
  namespace: demo
spec:
  vaultRef:
    name: vault
  mongodb:
    databaseRef:
      name: mongodb
      namespace: demo
    pluginName: "mongodb-database-plugin"

Let’s deploy SecretEngine:

$ kubectl apply -f docs/examples/guides/secret-engines/mongodb/secretengine.yaml
secretengine.engine.kubevault.com/mongo-engine created

Wait till the status become Success:

$ kubectl get secretengines -n demo
NAME        STATUS    AGE
mongo-engine   Success   10s

Since the status is Success, the Elasticsearch secret engine is enabled and successfully configured. You can use kubectl describe secretengine -n <namepsace> <name> to check for error events, if any.

Create MongoDB Role

By using MongoDBRole, you can create a role on the Vault server in Kubernetes native way.

A sample MongoDBRole object is given below:

apiVersion: engine.kubevault.com/v1alpha1
kind: MongoDBRole
metadata:
  name: mongo-superuser-role
  namespace: demo
spec:
  secretEngineRef:
    name: mongo-secret-engine
  creationStatements:
    - "{ \"db\": \"admin\", \"roles\": [{ \"role\": \"readWrite\" }, {\"role\": \"read\", \"db\": \"foo\"}] }"
  defaultTTL: 1h
  maxTTL: 24h

Let’s deploy MongoDBRole:

$ kubectl apply -f docs/examples/guides/secret-engines/mongodb/secretenginerole.yaml
mongodbrole.engine.kubevault.com/mongo-superuser-role created

$ kubectl get mongodbrole -n demo
NAME                STATUS    AGE
mongo-superuser-role   Success   34m

You can also check from Vault that the role is created. To resolve the naming conflict, name of the role in Vault will follow this format: k8s.{clusterName}.{metadata.namespace}.{metadata.name}.

Don’t have Vault CLI? Download and configure it as described here

$ vault list your-database-path/roles
Keys
----
k8s.-.demo.mongo-superuser-role

$ vault read your-database-path/roles/k8s.-.demo.mongo-superuser-role
Key                      Value
---                      -----
creation_statements      [{ "db": "admin", "roles": [{ "role": "readWrite" }, {"role": "read", "db": "foo"}] }]
db_name                  k8s.-.db.mongodb
default_ttl              1h
max_ttl                  24h
renew_statements         []
revocation_statements    []
rollback_statements      []

If we delete the MongoDBRole, then the respective role will be deleted from the Vault.

$ kubectl delete mongodbrole -n demo mongo-superuser-role
mongodbrole.engine.kubevault.com "mongo-superuser-role" deleted

Check from Vault whether the role exists:

$ vault read your-database-path/roles/k8s.-.demo.mongo-superuser-role
No value found at your-database-path/roles/k8s.-.demo.mongo-superuser-role

$ vault list your-database-path/roles
No value found at your-database-path/roles/

Generate MongoDB credentials

Here, we are going to make a request to Vault for Elasticsearch credentials by creating mongo-cred-rqst SecretAccessRequest in demo namespace.

apiVersion: engine.kubevault.com/v1alpha1
kind: SecretAccessRequest
metadata:
  name: mongo-cred-rqst
  namespace: demo
spec:
  roleRef:
    kind: MongoDBRole
    name: mongo-superuser-role
  subjects:
    - kind: ServiceAccount
      name: demo-sa
      namespace: demo

Here, spec.roleRef is the reference of MongoDB against which credentials will be issued. spec.subjects is the reference to the object or user identities a role binding applies to it will have read access of the credential secret.

Now, we are going to create SecretAccessRequest.

$ kubectl apply -f docs/examples/guides/secret-engines/mongodb/mongodbaccessrequest.yaml
secretaccessrequest.engine.kubevault.com/mongo-cred-rqst created

$ kubectl get secretaccessrequest -n demo
NAME              AGE
mongo-cred-rqst   72m

Database credentials will not be issued until it is approved. The KubeVault operator will watch for the approval in the status.conditions[].type field of the request object. You can use KubeVault CLI, a kubectl plugin, to approve or deny SecretAccessRequest.

# using KubeVault CLI as kubectl plugin to approve request
$ kubectl vault approve secretaccessrequest mongo-cred-rqst -n demo
approved

$ kubectl get secretaccessrequest -n demo mongo-cred-rqst -o yaml
apiVersion: engine.kubevault.com/v1alpha1
kind: SecretAccessRequest
metadata:
  name: mongo-cred-rqst
  namespace: demo
spec:
  roleRef:
    kind: MongoDBRole
    name: mongo-superuser-role
    namespace: demo
  subjects:
  - kind: ServiceAccount
    name: demo-sa
    namespace: demo
status:
  conditions:
  - lastUpdateTime: "2020-11-18T06:41:57Z"
    message: This was approved by kubectl vault approve secretaccessrequest
    reason: KubectlApprove
    type: Approved
  lease:
    duration: 1h0m0s
    id: your-database-path/creds/k8s.-.demo.mongo-superuser-role/ni3TCo2HkSwCUb8kmQuvIDdx
    renewable: true
  secret:
    name: mongo-cred-rqst-gy66wq

Once SecretAccessRequest is approved, the KubeVault operator will issue credentials from Vault and create a secret containing the credential. It will also create a role and rolebinding so that spec.subjects can access secret. You can view the information in the status field.

$ kubectl get secretaccessrequest mongo-cred-rqst -n demo -o json | jq '.status'
{
  "conditions": [
    {
      "lastUpdateTime": "2019-11-18T06:41:57Z",
      "message": "This was approved by kubectl vault approve secretaccessrequest",
      "reason": "KubectlApprove",
      "type": "Approved"
    }
  ],
  "lease": {
    "duration": "1h0m0s",
    "id": "your-database-path/creds/k8s.-.demo.mongo-superuser-role/ni3TCo2HkSwCUb8kmQuvIDdx",
    "renewable": true
  },
  "secret": {
    "name": "mongo-cred-rqst-gy66wq"
  }
}

$ kubectl get secret -n demo mongo-cred-rqst-gy66wq -o yaml
apiVersion: v1
data:
  password: QTFhLVBkZGlsZFFxa0o1cnlvR20=
  username: di1rdWJlcm5ldGVzLWRlbW8TE1NzQwNTkzMTc=
kind: Secret
metadata:
  name: mongo-cred-rqst-gy66wq
  namespace: demo
  ownerReferences:
  - apiVersion: engine.kubevault.com/v1alpha1
    controller: true
    kind: SecretAccessRequest
    name: mongo-cred-rqst
    uid: 54ce63ca-d0e7-4b97-9085-b52eb3cb334f
type: Opaque

If SecretAccessRequest is deleted, then credential lease (if any) will be revoked.

$ kubectl delete secretaccessrequest -n demo mongo-cred-rqst
secretaccessrequest.engine.kubevault.com "mongo-cred-rqst" deleted

If SecretAccessRequest is Denied, then the KubeVault operator will not issue any credential.

$ kubectl vault deny secretaccessrequest mongo-cred-rqst -n demo
  Denied

Note: Once SecretAccessRequest is Approved, you cannot change spec.roleRef and spec.subjects field.