Configuring the Master and Nodes on OpenShift 3.11

Preparing the Installation

Before Maistra can be installed into an existing installation it is necessary to make a number of changes to the master configuration and each of the schedulable nodes. These changes will enable features required within Istio and also ensure Elasticsearch will function correctly.

The master/node updates discussed below are not necessary in OCP/OKD 4.1

Updating the Master

If manual sidecar injection (i.e. kube-inject) is used this section may be skipped.

To enable the automatic injection of the Istio sidecar we first need to modify the master configuration on each master to include support for webhooks and signing of Certificate Signing Requests (CSRs). Then each individual Deployment requiring automatic injection needs to be modified.

First, make the following changes on each master within your installation.

  • Change to the directory containing the master configuration file (e.g. /etc/origin/master/master-config.yaml)

  • Create a file named master-config.patch with the following contents

        kubeConfigFile: /dev/null
        kind: WebhookAdmission
        kubeConfigFile: /dev/null
        kind: WebhookAdmission
  • Within the same directory issue the following commands:

cp -p master-config.yaml master-config.yaml.prepatch
oc ex config patch master-config.yaml.prepatch -p "$(cat master-config.patch)" > master-config.yaml
master-restart api
master-restart controllers

Updating the Nodes

In order to run the Elasticsearch application it is necessary to make a change to the kernel configuration on each node, this change will be handled through the sysctl service.

Make the following changes on each node within your installation

  • Create a file named /etc/sysctl.d/99-elasticsearch.conf with the following contents: vm.max_map_count = 262144

  • Execute the following command:

sysctl vm.max_map_count=262144