# Changing MongoDB options

When you deploy a new Percona Server for MongoDB cluster, the Operator spins it up with the set of defaults that ensure its correct operation. However, your application may need additional configuration of MongoDB. You can define this configuration using the `mongod.conf` configuration file options. 
You can configure mongod Pods, mongos Pods and config server replica set Pods separately, based on your requirements.  
Then you pass these options to MongoDB instances in the cluster in one of the following ways:

- [Edit the `deploy/cr.yaml` file](#edit-the-deploycryaml-file)
- [Use a ConfigMap](#use-a-configmap)
- [Use a Secret object](#use-a-secret-object)

Note that you can't change options that may break the behavior of the Operator. For example, TLS/SSL options. If you try changing such options, your changes will be ignored.  

## Edit the `deploy/cr.yaml` file

You can add MongoDB configuration options to the following keys of the `deploy/cr.yaml`: 

* [replsets.configuration](operator.md#replsetsconfiguration)
* [sharding.mongos.configuration](operator.md#shardingmongosconfiguration)
* [sharding.configsvrReplSet.configuration](operator.md#shardingconfigsvrreplsetconfiguration)

### Example

This example shows how to enable [rate limit for database profiler](https://docs.percona.com/percona-server-for-mongodb/rate-limit.html) and define the default verbosity level for system log:

```yaml
spec:
  ...
  replsets:
    - name: rs0
      size: 3
      configuration: |
        operationProfiling:
          mode: slowOp
        systemLog:
          verbosity: 1
      ...
```


Find the complete list of options in the [official manual  :octicons-link-external-16:](https://docs.mongodb.com/manual/reference/configuration-options/). Also refer to these pages in Percona Server for MongoDB documentation:

* [Profiling rate limit :octicons-link-external-16:](https://docs.percona.com/percona-server-for-mongodb/rate-limit.html)
* [Percona memory engine :octicons-link-external-16:](https://docs.percona.com/percona-server-for-mongodb/LATEST/inmemory.html)
* [Data-at-rest encryption  :octicons-link-external-16:](https://docs.percona.com/percona-server-for-mongodb/data-at-rest-encryption.html)
* [Log redaction  :octicons-link-external-16:](https://docs.percona.com/percona-server-for-mongodb/LATEST/log-redaction.html)
* [Audit logging :octicons-link-external-16:](https://docs.percona.com/percona-server-for-mongodb/LATEST/audit-logging.html).

## Use a ConfigMap

You can use a [ConfigMap  :octicons-link-external-16:](https://kubernetes.io/docs/tasks/configure-pod-container/configure-pod-configmap/)
and the cluster restart to reset configuration options. A ConfigMap allows
Kubernetes to pass or update configuration data inside a containerized
application.

You should give the ConfigMap a specific name, which is composed of your cluster
name and a specific suffix:

* `my-cluster-name-rs0-mongod` for the Replica Set (mongod) Pods,
* `my-cluster-name-cfg-mongod` for the Config Server Pods,
* `my-cluster-name-mongos` for the mongos Pods,

!!! note

    To find the cluster name, you can use the following command:

    ```bash
    kubectl get psmdb
    ```

For example, let’s define a `mongod.conf` configuration file and put there
several MongoDB options we used in the previous example:

```yaml
operationProfiling:
  mode: slowOp
systemLog:
  verbosity: 1
```

You can create a ConfigMap from the `mongod.conf` file with the
`kubectl create configmap` command. It has the following syntax:

```bash
kubectl create configmap <configmap-name> <resource-type=resource-name>
```

The following example defines `my-cluster-name-rs0-mongod` as the ConfigMap name
and the `mongod.conf` file as the data source:

```bash
kubectl create configmap my-cluster-name-rs0-mongod --from-file=mongod.conf=mongod.conf
```

To view the created ConfigMap, use the following command:

```bash
kubectl describe configmaps my-cluster-name-rs0-mongod
```

!!! note

    Do not forget to restart Percona Server for MongoDB to ensure the
    cluster has updated the configuration (see details on how to connect in the
    [Install Percona Server for MongoDB on Kubernetes](kubernetes.md)
    page).

## Use a Secret Object

The Operator can also store configuration options in [Kubernetes Secrets  :octicons-link-external-16:](https://kubernetes.io/docs/concepts/configuration/secret/).
This can be useful if you need additional protection for some sensitive data.

You should create a Secret object with a specific name, composed of your cluster
name and a specific suffix:

* `my-cluster-name-rs0-mongod` for the Replica Set Pods,
* `my-cluster-name-cfg-mongod` for the Config Server Pods,
* `my-cluster-name-mongos` for the mongos Pods,

!!! note

    To find the cluster name, you can use the following command:

    ```bash
    kubectl get psmdb
    ```

Configuration options should be put inside a specific key:

* `data.mongod` key for Replica Set (mongod) and Config Server Pods,
* `data.mongos` key for mongos Pods.

Actual options should be encoded with [Base64  :octicons-link-external-16:](https://en.wikipedia.org/wiki/Base64).

For example, let’s define a `mongod.conf` configuration file and put there
several MongoDB options we used in the previous example:

```yaml
operationProfiling:
  mode: slowOp
systemLog:
  verbosity: 1
```

You can get a Base64 encoded string from your options via the command line as
follows:

=== "in Linux"

    ```bash
    cat mongod.conf | base64 --wrap=0
    ```

=== "in macOS"

    ```bash
    cat mongod.conf | base64
    ```

!!! note

    Similarly, you can read the list of options from a Base64 encoded
    string:

    ```bash
    echo "ICAgICAgb3BlcmF0aW9uUHJvZmlsaW5nOgogICAgICAgIG1vZGU6IHNsb3dPc\
    AogICAgICBzeXN0ZW1Mb2c6CiAgICAgICAgdmVyYm9zaXR5OiAxCg==" | base64 --decode
    ```

Finally, use a yaml file to create the Secret object. For example, you can
create a `deploy/my-mongod-secret.yaml` file with the following contents:

```yaml
apiVersion: v1
kind: Secret
metadata:
  name: my-cluster-name-rs0-mongod
data:
  mongod.conf: "ICAgICAgb3BlcmF0aW9uUHJvZmlsaW5nOgogICAgICAgIG1vZGU6IHNsb3dPc\
   AogICAgICBzeXN0ZW1Mb2c6CiAgICAgICAgdmVyYm9zaXR5OiAxCg=="
```

When ready, apply it with the following command:

```bash
kubectl create -f deploy/my-mongod-secret.yaml
```

!!! note

    Do not forget to restart Percona Server for MongoDB to ensure the
    cluster has updated the configuration (see details on how to connect in the
    [Install Percona Server for MongoDB on Kubernetes](kubernetes.md)
    page).