coherence-operator

Storage-Disabled Client in Cluster via Interceptor

This sample demonstrates deploying 2 tiers, a storage-enabled data tier, and a storage-disabled client tier. The client tier uses an interceptor to start up a Coherence storage-disabled client and perform some processing.

The advantage of using this method is that when you run the DefaultCacheServer process, all Prometheus metrics is collected for the storage-disabled member.

This is achieved by using two helm install commands, both of which include a sidecar container for the data tier, and a client tier cache configuration as well as the interceptor code.

This sample uses only one storage-disabled client. You can change this by setting clusterSize to a value other than one on the client chart install.

Return to Storage-Disabled clients samples / Return to Coherence Deployments samples / Return to samples

Sample files

• src/main/docker/Dockerfile - Dockerfile for creating sidecar image from which the configuration and the server side jar will be read at pod startup

• src/main/resources/conf/storage-cache-config.xml - Cache configuration for storage-enabled tier

• src/main/resources/conf/interceptor-cache-config.xml - Cache configuration for storage-disabled tier

• src/main/java/com/oracle/coherence/examples/DemoInterceptor.java - Interceptor that starts our mock client

Note: If you want to enable Prometheus or log capture, ensure you set the appropriate properties for the Coherence Operator install:

• Prometheus: --set prometheusoperator.enabled=true

• Log capture: --set logCaptureEnabled=true

Prerequisites

Ensure that you have installed the Coherence Operator by following the instructions here.

Installation Steps

1. Change to the samples/coherence-deployments/storage-disabled/interceptor directory. Ensure that you have your maven build environment set for JDK8, and build the project.

   $ mvn clean install -P docker
   

   This builds the Docker image with the cache configuration files and compiled Java classes, with the name in the format, interceptor-sample:${version}. For example,

   interceptor-sample:1.0.0-SNAPSHOT
   

   Note: If you are running against a remote Kubernetes cluster, you must push the above image to your repository accessible to that cluster. You must also prefix the image name in the helm command as shown below.

2. Install the Coherence cluster.

   Set the cluster-name to interceptor-cluster for use in later steps.

   $ helm install \
      --namespace sample-coherence-ns \
      --name storage \
      --set clusterSize=3 \
      --set cluster=interceptor-cluster \
      --set imagePullSecrets=sample-coherence-secret \
      --set store.cacheConfig=storage-cache-config.xml \
      --set logCaptureEnabled=false \
      --set userArtifacts.image=interceptor-sample:1.0.0-SNAPSHOT \
      coherence/coherence
   

   Once the installation is complete, run the following command to retrieve the list of pods:

   $ kubectl get pods -n sample-coherence-ns
   

   All the three storage-coherence pods should be running and ready, as shown in the output:

   NAME                  READY   STATUS    RESTARTS   AGE
   storage-coherence-0   1/1     Running   0          4m
   storage-coherence-1   1/1     Running   0          2m
   storage-coherence-2   1/1     Running   0          1m
   

3. Install the storage-disabled client tier.

   Set the following properties to ensure that this release connects to the Coherence cluster created by the storage release:

   • --set cluster=interceptor-cluster - Uses the same cluster name

   • --set store.wka=storage-coherence-headless - Ensures that it can contact the cluster

   • --set store.storageEnabled=false - Sets storage to false

   • --set store.cacheConfig=interceptor-cache-config.xml - Uses interceptor cache configuration from the sidecar image

   $ helm install \
     --namespace sample-coherence-ns \
     --set cluster=interceptor-cluster \
     --set clusterSize=1 \
     --set store.wka=storage-coherence-headless \
     --name interceptor-client-tier \
     --set imagePullSecrets=sample-coherence-secret \
     --set store.cacheConfig=interceptor-cache-config.xml \
     --set store.storageEnabled=false \
     --set logCaptureEnabled=false \
     --set userArtifacts.image=interceptor-sample:1.0.0-SNAPSHOT \
     coherence/coherence
   

   To confirm that the storage-disabled client has joined the cluster, you can look at the logs using the following kubectl commands:

     $  kubectl logs interceptor-client-tier-coherence-0 -n sample-coherence-ns -f
   

   This continuously follows the log, and you see messages similar to the following indicating that the storage-disabled client is inserting data:

   2019-03-20 08:33:43.138/48.454 Oracle Coherence GE 12.2.1.3.0 <Info> (thread=pool-1-thread-1, member=4): Inserted key=40, value=08:33:43
   2019-03-20 08:33:44.143/49.459 Oracle Coherence GE 12.2.1.3.0 <Info> (thread=pool-1-thread-1, member=4): Inserted key=41, value=08:33:44
   

Uninstall the Charts

Run the following command to delete both the charts installed in this sample.

$ helm delete storage interceptor-client-tier --purge

Before starting another sample, ensure that all pods are removed from the previous sample. To remove coherence-operator, use the helm delete command.

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