Deploying Applications to specific Nodes

In this video

In his latest demo, Veer Muchandi explains how you can run different parts of your OpenShift projects in different components of your existing infrastructure.

Additional Notes

1. Setting the Default Node Selector for the OpenShift environment

OpenShift Administrator sets the default Node selectors for the entire OpenShift environment by editing

/etc/origin/master/master-config.yaml

Find the projectConfig section and add defaultNodeSelector as follows. This is a yaml file; so make sure that the indentation is right.

projectConfig:

  defaultNodeSelector: "region=primary”

2. Setting the NodeSelector for specific project

OpenShift administrator sets the node selector for a specific project by editing the project namespace. As an example to edit namespace for a project named “new project”

# oc edit namespace newproject

Find the annotations section and add a node selector annotation as under. This is a yaml file; so make sure that the indentation is right.

  annotations:

    openshift.io/node-selector: “region=secondary"

    openshift.io/description: ""

    openshift.io/display-name: ""

    openshift.io/node-selector: “"

To override the default node selectors (that are set for the entire environment in #1 above), the administrator can set the above value as an empty string (“”) for a project namespace. In such projects the defaults won’t apply.

3. Adding NodeSelectors to a DeploymentConfig

A developer or a deployer can make specific components to deploy on specific nodes by adding node selectors to a deployment configuration.

#oc edit dc <deploymentConfigName> -o json

find the section “spec” under “template” and add node selector section

        "template": {

            "metadata": {

                "name": "mysql",

                "creationTimestamp": null,

                "labels": {

                    "name": "mysql"

                }

            },

            "spec": {

         "nodeSelector": {

            "region": “primary"

         },

4. Adding NodeSelectors to a Template

You can copy a template first

#oc get template <templatename> -n openshift > filename.json

Edit the json file and add the nodeselectors like how you did for the deployment configuration in #3 above. Also change the template name and namespace values in the metadata section at the beginning of the template.Save the json file.

Upload the template to your project by using

#oc create -f filename.json

Then you can start using the template.
 

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