Deploy Microservices

Service Mesh OpenShift

- Thomas Jungbauer Thomas Jungbauer ( Lastmod: 2024-05-05 ) - 3 min read

The second tutorials explains how to install an example application containing thee microservices. All operations have been successfully tested on OpenShift 4.3.

Introduction

As quickly explained at Issue #1, OpenShift 4.3 and the Service Mesh shall be installed already. At this point you should have all 4 operators installed and ready. The test application used in this scenario is based on Java and contains 3 microservices in the following traffic flow:

Customer ⇒ Preference ⇒ Recomandation

The microservices are the same as used at the Interactive Learning Portal.

Deploy microservices

  1. First lets create a new project for our tests

    oc new-project tutorial

  2. EITHER: Add tutorial to ServiceMeshMemberRoll

Service Mesh 1.1 now supports the object ServiceMember which can created under the application namespace and which automatically configures the ServiceMemberRoll. However, below description still works.

+ OpenShift will auto-inject the sidecar proxy to pods of a namespace, if the namespace is configured in the ServiceMeshMemberRoll object which was created for the operator.

  1. Create the file memberroll.yaml:

    cat <<'EOF' > memberroll.yaml
apiVersion: maistra.io/v1
kind: ServiceMeshMemberRoll
metadata:
  name: default
spec:
  members:
    - tutorial
EOF

  2. Add the namespace to the member roll:

    oc apply -f memberroll.yaml -n istio-system
If you already have namespaces configured for ServiceMeshMemberRoll, better modify the object manually. Custom Resource Definitions (CRD) do not like to be modified on the fly (currently?)

  1. OR: Create ServiceMeshMember object: Available since ServiceMesh 1.1

    apiVersion: maistra.io/v1
kind: ServiceMeshMember
metadata:
  name: default
  namespace: tutorial
spec:
  controlPlaneRef:
    name: basic-install
    namespace: istio-system

  2. Download the tutorial application locally

    git clone https://github.com/redhat-developer-demos/istio-tutorial/

Deploy microservice: customer

To deploy the first microservice 2 objects (Deployment and Service) must be created. Moreover, the service will be exposed, since the service customer is our entry point.
Verify ~/istio-tutorial/customer/kubernetes/Deployment.yml to check where the actual image is coming from: quay.io/rhdevelopers/istio-tutorial-customer:v1.1

cd ~/istio-tutorial/customer
oc apply -f kubernetes/Deployment.yml -n tutorial
oc apply -f kubernetes/Service.yml -n tutorial
oc expose service customer

Check if pods are running with two containers:

oc get pods -w

The result should look somehow like this:

NAME                             READY   STATUS    RESTARTS   AGE
customer-6948b8b959-g77bs        2/2     Running   0          52m
If there is only 1 container running, indicated by READY = 1/1, then most likely the ServiceMeshMemberRoll was not updated with the name tutorial or contains a wrong project name.

Deploy microservice: preference

The deployment of the microservice preference is exactly like it is done for customer, except that no service must be exposed:

cd ~/istio-tutorial/preference/
oc apply -f kubernetes/Deployment.yml -n tutorial
oc apply -f kubernetes/Service.yml -n tutorial

Check if pods are running with two containers:

oc get pods -w

The result should look somehow like this:

NAME                                 READY   STATUS    RESTARTS   AGE
customer-6948b8b959-g77bs            2/2     Running   0          4d15h
preference-v1-7fdb89c86b-gkk5g       2/2     Running   0          4d14h

Deploy microservice: recommendation

The deployment of the microservice recommendation is exactly like it is done for preference:

cd ~/istio-tutorial/recommendation/
oc apply -f kubernetes/Deployment.yml -n tutorial
oc apply -f kubernetes/Service.yml -n tutorial

Check if pods are running with two containers:

oc get pods -w

The result should look somehow like this:

NAME                                 READY   STATUS    RESTARTS   AGE
customer-6948b8b959-g77bs            2/2     Running   0          4d15h
preference-v1-7fdb89c86b-gkk5g       2/2     Running   0          4d14h
recommendation-v1-69db8d6c48-p9w2b   2/2     Running   0          4d14h

Optional: build the images

It is possible (and probably a good training) to build the microservices locally to understand how this works. In order to achieve this the packages maven and podman must be installed.

Build customer

Go to the source folder of customer application and build it:

cd ~/projects/istio-tutorial/customer/java/springboot
mvn package

It will take a few seconds, but it should give "BUILD SUCCESS" as output, if everything worked.

Now the image will be built using podman

podman build -t example/customer .

Build preference

The image build process of the second microservice follows the same flow as customer:

cd ~/istio-tutorial/preference/java/springboot
mvn package
podman build -t example/preference:v1 .
the "v1" tag at the image name is important and must be used.

Build recommendation

The image build process of the third microservice follows the same flow as preference:

cd ~/projects/istio-tutorial/recommendation/java/vertx
mvn package
podman build -t example/recommendation:v1 .
the "v1" tag at the image name is important and must be used. Later other versions will be deployed.

See Also:

  • Introducing AdminNetworkPolicies –

    Classic Kubernetes/OpenShift offer a feature called NetworkPolicy that allows users to control the traffic to and from their assigned Namespace. NetworkPolicies are designed to give project owners or tenants the ability to protect their own namespace. Sometimes, however, I worked with customers where the cluster administrators or a dedicated (network) team need to enforce these policies. Since the NetworkPolicy API is namespace-scoped, it is not possible to enforce policies across namespaces. The only solution was to create custom (project) admin and edit roles, and remove the ability of creating, modifying or deleting NetworkPolicy objects. Technically, this is possible and easily done. But shifts the whole network security to cluster administrators. Luckily, this is where AdminNetworkPolicy (ANP) and BaselineAdminNetworkPolicy (BANP) comes into play.

  • Using Kustomize to post render a Helm Chart –

    Lately I came across several issues where a given Helm Chart must be modified after it has been rendered by Argo CD. Argo CD does a helm template to render a Chart. Sometimes, especially when you work with Subcharts or when a specific setting is not yet supported by the Chart, you need to modify it later …​ you need to post-render the Chart. In this very short article, I would like to demonstrate this on a real-live example I had to do. I would like to inject annotations to a Route objects, so that the certificate can be injected. This is done by the cert-utils operator. For the post-rendering the Argo CD repo pod will be extended with a sidecar container, that is watching for the repos and patches them if required.

  • Managing Certificates using GitOps approach –

    The article SSL Certificate Management for OpenShift on AWS explains how to use the Cert-Manager Operator to request and install a new SSL Certificate. This time, I would like to leverage the GitOps approach using the Helm Chart cert-manager I have prepared to deploy the Operator and order new Certificates. I will use an ACME Letsencrypt issuer with a DNS challenge. My domain is hosted at AWS Route 53. However, any other integration can be easily used.

  • Update Cluster Version using GitOps approach –

    During a GitOps journey at one point, the question arises, how to update a cluster? Nowadays it is very easy to update a cluster using CLI or WebUI, so why bother with GitOps in that case? The reason is simple: Using GitOps you can be sure that all clusters are updated to the correct, required version and the version of each cluster is also managed in Git. All you need is the channel you want to use and the desired cluster version. Optionally, you can define the exact image SHA. This might be required when you are operating in a restricted environment.

  • Multiple Sources for Applications in Argo CD –

    Argo CD or OpenShift GitOps uses Applications or ApplicationSets to define the relationship between a source (Git) and a cluster. Typically, this is a 1:1 link, which means one Application is using one source to compare the cluster status. This can be a limitation. For example, if you are working with Helm Charts and a Helm repository, you do not want to re-build (or re-release) the whole chart just because you made a small change in the values file that is packaged into the repository. You want to separate the configuration of the chart with the Helm package. The most common scenarios for multiple sources are (see: Argo CD documentation): Your organization wants to use an external/public Helm chart You want to override the Helm values with your own local values You don’t want to clone the Helm chart locally as well because that would lead to duplication and you would need to monitor it manually for upstream changes. This small article describes three different ways with a working example and tries to cover the advantages and disadvantages of each of them. They might be opinionated but some of them proved to be easier to use and manage.

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