Istio Routing Mission for Node.js

Purpose

Showcase Routing in Istio with a Node.js application

Prerequisites

• Openshift 3.10 cluster with Istio. For local development, download the latest release from Maistra and run:

# Set oc to be the Maistra one
oc cluster up --enable="*,istio"
oc login -u system:admin
oc apply -f https://raw.githubusercontent.com/Maistra/openshift-ansible/maistra-0.6/istio/cr-minimal.yaml -n istio-operator
oc get pods -n istio-system -w

Wait until the openshift-ansible-istio-installer-job-xxxx job has completed. It can take several minutes. The OpenShift console is available on https://127.0.0.1:8443.

• Create a new project/namespace on the cluster. This is where your application will be deployed.

oc login -u system:admin
oc adm policy add-cluster-role-to-user admin developer --as=system:admin
oc adm policy add-scc-to-user anyuid -z default -n myproject
oc adm policy add-scc-to-user privileged -z default -n myproject
oc login -u developer -p developer
oc new-project <whatever valid project name you want> # not required

Build and Deploy the Application

Launcher Flow Setup

If the Booster is installed through the Launcher and the Continuous Delivery flow, no additional steps are necessary.

Skip to the Use Cases section.

With Source to Image build (S2I)

Prepare the Namespace

Create a new namespace/project:

oc new-project <whatever valid project name you want>

Build and Deploy the Application

With Source to Image build (S2I)

Run the following commands to apply and execute the OpenShift templates that will configure and deploy the applications:

find . | grep openshiftio | grep application | xargs -n 1 oc apply -f

oc new-app --template=nodejs-istio-routing-client-service -p SOURCE_REPOSITORY_URL=https://github.com/nodeshift-starters/nodejs-istio-routing -p SOURCE_REPOSITORY_REF=master -p SOURCE_REPOSITORY_DIR=routing-client
oc new-app --template=nodejs-istio-routing-service-a-service -p SOURCE_REPOSITORY_URL=https://github.com/nodeshift-starters/nodejs-istio-routing -p SOURCE_REPOSITORY_REF=master -p SOURCE_REPOSITORY_DIR=routing-service-a
oc new-app --template=nodejs-istio-routing-service-b-service -p SOURCE_REPOSITORY_URL=https://github.com/nodeshift-starters/nodejs-istio-routing -p SOURCE_REPOSITORY_REF=master -p SOURCE_REPOSITORY_DIR=routing-service-b

Any steps issuing oc commands require the user to have run oc login first and switched to the appropriate project with oc project <project name>.

Default Service load balancing

1. Create a Gateway and Virtual Service in Istio so that we can access the service within the Mesh:

   oc apply -f istio-config/gateway.yaml
   

2. Retrieve the URL for the Istio Ingress Gateway route, with the below command, and open it in a web browser.

   echo http://$(oc get route istio-ingressgateway -o jsonpath='{.spec.host}{"\n"}' -n istio-system)/nodejs-istio-routing
   

3. The user will be presented with the web page of the Booster
4. Click the "Invoke" button. You should see a message in the result box indicating which service instance was called.
5. Click "Invoke" several more times. Notice that there is an even 50% split between service a and b.

Transfer load between services

1. Modify the load balancing such that all requests go to service a:

   oc apply -f istio-config/load-balancing-rule.yaml
   

2. Clicking on "Invoke" in the UI you will see that all requests are now being sent to service a.