Samples

Samples

SlimCluster.Samples.Service

This sample showcases a simple .NET Service (exposing a distributed counter API) that can be built into a docker image and then deployed to Kubernetes (minikube or docker desktop). The app is running in 3 instances (pods) on Kubernetes. The instances are forming a cluster.

The node name is assigned from the machine name (Environment.MachineName), this is to have the node name align with pod names in Kubernetes.

The scripts were tested on Docker Desktop with Minikube

To run the sample:

1. Navigate to SlimCluster.Samples.Service folder.

2. Build docker & publish image locally:

./Docker-BuildSample.ps1

3. Deploy to Kubernetes:

./Kube-ApplySample.ps1

4. Check if the pods are running:

kubectl get pods

As per the deployment.yml file, there should be 3 pods running:

PS D:\dev\mygithub\SlimCluster\src\Samples\SlimCluster.Samples.Service> kubectl get pods
NAME                          READY   STATUS    RESTARTS   AGE
sc-service-69bfd7f7b7-f428h   1/1     Running   0          2s
sc-service-69bfd7f7b7-gw6pp   1/1     Running   0          2s
sc-service-69bfd7f7b7-rmxbr   1/1     Running   0          2s

5. When checking the logs for the first pod:

kubectl logs -f sc-service-69bfd7f7b7-f428h

The result could look like this:

PS D:\dev\mygithub\SlimCluster\src\Samples\SlimCluster.Samples.Service> kubectl logs -f sc-service-69bfd7f7b7-f428h
info: SlimCluster.Consensus.Raft.RaftNode[0]
      Becoming a follower for term 0
info: SlimCluster.Samples.ConsoleApp.MainApp[0]
      Starting service...
info: SlimCluster.Host.ClusterControl[0]
      Node is starting...
info: SlimCluster.Transport.Ip.IPMessageEndpoint[0]
      Joining multicast group 239.1.1.1
info: SlimCluster.Membership.Swim.SwimClusterMembership[0]
      Cluster membership protocol (SWIM) starting for sc-service-69bfd7f7b7-f428h ...
info: SlimCluster.Membership.Swim.SwimClusterMembership[0]
      Sending NodeJoinedMessage for node sc-service-69bfd7f7b7-f428h to the multicast group 239.1.1.1:60001
info: SlimCluster.Host.ClusterControl[0]
      Node started
info: Microsoft.Hosting.Lifetime[14]
      Now listening on: http://[::]:5000
info: Microsoft.Hosting.Lifetime[0]
      Application started. Press Ctrl+C to shut down.
info: Microsoft.Hosting.Lifetime[0]
      Hosting environment: Production
info: Microsoft.Hosting.Lifetime[0]
      Content root path: /app
info: SlimCluster.Samples.ConsoleApp.MainApp[0]
      The member sc-service-69bfd7f7b7-gw6pp joined
info: SlimCluster.Samples.ConsoleApp.MainApp[0]
      This node is aware of [email protected]:60001, sc-service-69bfd7f7b7-f428h@Unknown
info: SlimCluster.Membership.Swim.SwimClusterMembership[0]
      Node sc-service-69bfd7f7b7-gw6pp joined at 10.1.0.177:60001
info: SlimCluster.Membership.Swim.SwimMember[0]
      Updated member sc-service-69bfd7f7b7-f428h observed address to 10.1.0.176:60001
info: SlimCluster.Samples.ConsoleApp.MainApp[0]
      The member sc-service-69bfd7f7b7-rmxbr joined
info: SlimCluster.Samples.ConsoleApp.MainApp[0]
      This node is aware of [email protected]:60001, [email protected]:60001, [email protected]:60001
info: SlimCluster.Membership.Swim.SwimClusterMembership[0]
      Node sc-service-69bfd7f7b7-rmxbr joined at 10.1.0.178:60001
info: SlimCluster.Consensus.Raft.RaftNode[0]
      [email protected]:60001: Node indicated there is a higher term 1
info: SlimCluster.Consensus.Raft.RaftNode[0]
      Becoming a follower for term 1
info: SlimCluster.Consensus.Raft.RaftNode[0]
      Sending RequestVoteResponse(Term=1,VoteGranted=True) to node [email protected]:60001
info: SlimCluster.Consensus.Raft.RaftFollowerState[0]
      New leader is [email protected]:60001 for term 1

The second node sc-service-69bfd7f7b7-gw6pp (Kubernetes pod) has been elected the leader for term 1.

6. If the 2nd pod where to be deleted, the other nodes should detect this failure:

kubectl delete pod sc-service-69bfd7f7b7-gw6pp

Then checking logs on first pod again (kubectl logs -f sc-service-69bfd7f7b7-gw6pp):

info: SlimCluster.Consensus.Raft.RaftFollowerState[0]
      New leader is [email protected]:60001 for term 1
info: SlimCluster.Membership.Swim.SwimClusterMembership[0]
      Node sc-service-69bfd7f7b7-gw6pp left at 10.1.0.177:60001
info: SlimCluster.Samples.ConsoleApp.MainApp[0]
      The member sc-service-69bfd7f7b7-gw6pp left/faulted
info: SlimCluster.Samples.ConsoleApp.MainApp[0]
      This node is aware of [email protected]:60001, [email protected]:60001
info: SlimCluster.Samples.ConsoleApp.MainApp[0]
      The member sc-service-69bfd7f7b7-qps5s joined
info: SlimCluster.Samples.ConsoleApp.MainApp[0]
      This node is aware of [email protected]:60001, [email protected]:60001, [email protected]:60001
info: SlimCluster.Membership.Swim.SwimClusterMembership[0]
      Node sc-service-69bfd7f7b7-qps5s joined at 10.1.0.179:60001
info: SlimCluster.Consensus.Raft.RaftNode[0]
      [email protected]:60001: Node indicated there is a higher term 2
info: SlimCluster.Consensus.Raft.RaftNode[0]
      Becoming a follower for term 2
info: SlimCluster.Consensus.Raft.RaftNode[0]
      Sending RequestVoteResponse(Term=2,VoteGranted=True) to node [email protected]:60001
info: SlimCluster.Consensus.Raft.RaftFollowerState[0]
      New leader is [email protected]:60001 for term 2
info: SlimCluster.Consensus.Raft.RaftNode[0]
      Sending RequestVoteResponse(Term=2,VoteGranted=False) to node [email protected]:60001
info: SlimCluster.Consensus.Raft.RaftNode[0]
      [email protected]:60001: Node indicated there is a higher term 3
info: SlimCluster.Consensus.Raft.RaftNode[0]
      Becoming a follower for term 3
info: SlimCluster.Consensus.Raft.RaftNode[0]
      Sending RequestVoteResponse(Term=3,VoteGranted=True) to node [email protected]:60001
info: SlimCluster.Consensus.Raft.RaftFollowerState[0]
      New leader is [email protected]:60001 for term 3

The sample uses Docker and Kubernetes, but this is matter of convenience (docker desktop with minikube). The sample app will also work if it were to be started directly on some host machines that are on the same network.