Installing MongoDB on IBM Cloud

This document will describe how to install MongoDB on IBM Cloud using Kubernetes services.

Step 1 — Provision Kubernetes Cluster

• Click the Catalog button on the top
• Select Service from the Catalog
• Search for Kubernetes Service and click on it

• You are now at the Kubernetes deployment page. You need to specify some information about the cluster.
• Choose either of the following plans; standard or free. The free plan only has one worker node and no subnet. To provision a standard cluster. You will need to upgrade your account to Pay-As-You-Go
• To upgrade to a Pay-As-You-Go account, complete the following steps:
• In the console, go to Manage > Account.
• Select Account settings and click Add credit card.
• Enter your payment information, click Next, and submit your information
• Choose classic or VPC. Read the docs and choose the most suitable type for yourself

• Now choose your location settings,
• Choose Geography (continent)

• Choose Single or Multizone.

In single zone, your data is only kept on the datacenter while on the other hand with Multizone, it is distributed to multiple zones, thus safer in an unforeseen zone failure

If you wish to use Multizone, please set up your account with VRF

• If at your current location selection, there is no available Virtual LAN, a new VLAN will be created for you
• Choose a Worker node setup or use the preselected one. Set Worker node amount per zone
• Choose Master Service Endpoint.

In VRF-enabled accounts, you can choose private-only to make your master accessible on the private network or via VPN tunnel. Choose public-only to make your master publicly accessible. When you have a VRF-enabled account, your cluster is set up by default to use both private and public endpoints.

• Give desired tags to your cluster, click create
• Wait for your cluster to be provisioned
• Your cluster is ready for usage

Step 2 — Deploy IBM Cloud Block Storage plug-in

The Block Storage plug-in is a persistent, high-performance iSCSI storage that you can add to your apps by using Kubernetes Persistent Volumes (PVs).

• Click the Catalog button on the top
• Select Software from the catalog
• Search for IBM Cloud Block Storage plug-in and click on it

• On the application page Click on the dot next to the cluster, you wish to use

• Click on Enter or Select Namespace and choose the default Namespace or use a custom one (if you get an error please wait 30 minutes for the cluster to finalize)

• Give a name to this workspace
• Click install and wait for the deployment

Step 3 — Installing MongoDB

Prerequisites

• IBM Cloud Block Storage plug-in
• Kubernetes 1.12+
• Helm 3.1.0
• PV provisioner support in the underlying infrastructure

Installation

To install the chart with the release name my-release:

$ helm install my-release bitnami/mongodb

The command deploys MongoDB on the Kubernetes cluster in the default configuration. The Parameters section lists the parameters that can be configured during installation.

Initialize a fresh instance

The Bitnami MongoDB image allows you to use your custom scripts to initialize a fresh instance. In order to execute the scripts, you can specify them using the initdbScripts parameter as dict.

You can also set an external ConfigMap with all the initialization scripts. This is done by setting the initdbScriptsConfigMap parameter. Note that this will override the previous option.

The allowed extensions are .sh, and .js.

Accessing MongoDB nodes from outside the cluster

In order to access MongoDB nodes from outside the cluster when using a replica set architecture, a specific service per MongoDB pod will be created.

There are two ways of configuring external access:

• Using LoadBalancer services
• Using NodePort services

Using loadbalancer services

There are two alternatives to use LoadBalancer services:

1. Use random load balancer IPs using an initContainer that waits for the IPs to be ready and discover them automatically

architecture=replicaset
replicaCount=2
externalAccess.enabled=true
externalAccess.service.type=LoadBalancer
externalAccess.service.port=27017
externalAccess.autoDiscovery.enabled=true
serviceAccount.create=true
rbac.create=true

Note: This option requires creating RBAC rules on clusters, where RBAC policies are enabled.

1. Manually specify the load balancer IPs:

architecture=replicaset
replicaCount=2
externalAccess.enabled=true
externalAccess.service.type=LoadBalancer
externalAccess.service.port=27017
externalAccess.service.loadBalancerIPs[0]='external-ip-1'
externalAccess.service.loadBalancerIPs[1]='external-ip-2'}

Note: You should know the load balancer IP’s in advance so that each MongoDB node advertised hostname is configured with it.

Using nodeport services

Manually specify the node ports to use:

architecture=replicaset
replicaCount=2
externalAccess.enabled=true
externalAccess.service.type=NodePort
externalAccess.service.nodePorts[0]='node-port-1'
externalAccess.service.nodePorts[1]='node-port-2'

Note: You need to know in advance the node ports that will be exposed so each MongoDB node advertised hostname is configured with it.

Persistence

The Bitnami MongoDB image stores the MongoDB data and configurations at the /bitnami/mongodb path of the container.

The chart mounts a Persistent Volume at this location. The volume is created using dynamic volume provisioning.

Adjust permissions of persistent volume mountpoint

As the image runs as non-root by default, it is necessary to adjust the ownership of the persistent volume so that the container can write data into it. By default, the chart is configured to use Kubernetes Security Context to automatically change the ownership of the volume. However, this feature does not work in all Kubernetes distributions.

As an alternative, this chart supports using an initContainer to change the ownership of the volume before mounting it in the final destination. You can enable this initContainer by setting volumePermissions.enabled to true.

Using Prometheus rules

You can use custom Prometheus rules for Prometheus operator by using the prometheusRule parameter, see below a basic configuration example:

metrics:

enabled: true
prometheusRule:
  enabled: true
  rules:
  - name: rule1
  rules:
  alert: HighRequestLatency
  expr: job:request_latency_seconds:mean5m{job="myjob"} > 0.5
  for: 10m
  labels:
  severity: page
  annotations:
  summary: High request latency

Enabling SSL/TLS

This container supports enabling SSL/TLS between nodes in the cluster, as well as between mongo clients and nodes, by setting the MONGODB_EXTRA_FLAGS and MONGODB_CLIENT_EXTRA_FLAGS environment variables, together with the correct MONGODB_ADVERTISED_HOSTNAME. To enable full TLS encryption set tls.enabled to true.

Using your own CA

To use your own CA, set tls.caCert and tls.caKey with appropriate base64 encoded data. The secrets-ca.yaml will utilize this data to create a secret.

Accessing the cluster

To access the cluster you will need to enable the initContainer, which generates the MongoDB server/client pem needed to access the cluster. Please ensure that you include the $my_hostname section with your actual hostname and the alternative hostnames section should contain the hostnames you want to allow access to the MongoDB replica set.

Starting the cluster

After the certs have been generated and made available to the containers at the correct mount points, the MongoDB server will be started with TLS enabled. The options for the TLS mode will be (disabled|allowTLS|preferTLS|requireTLS). This value can be changed via the MONGODB_EXTRA_FLAGS field using the tlsMode. The client should now be able to connect to the TLS enabled cluster with the provided certs.

Setting Pod’s affinity

This chart allows you to set your custom affinity using the XXX.affinity parameter(s). Find more information about Pod’s affinity in the kubernetes documentation.

As an alternative, you can use the preset configurations for pod affinity, pod anti-affinity, and node affinity available at the bitnami/common chart. To do so, set the XXX.podAffinityPreset, XXX.podAntiAffinityPreset, or XXX.nodeAffinityPreset parameters.

The installation is done. Enjoy!