kubernetes-web-mongo-sample

This is a sample project containing a kubernetes setup of a webservice and mongodb database.

Setup your kubernetes cluster

You can set up your cluster on Google container engine using the free trial: https://console.cloud.google.com/freetrial

Instructions on how to setup your cluster:

First steps: https://cloud.google.com/container-engine/docs/before-you-begin
Creating a new Google Container Engine(GKE) cluster: https://cloud.google.com/container-engine/docs/clusters/operations

Inspect your cluster

You have to install kubectl, configure your project and created a new GKE cluster. After you have done that, you can use the k8s(Kubernetes) dashboard or watch your cluster from the command line:

Watch connected cluster: watch 'kubectl config current-context'
Watch your pods: kubectl get pods --namespace=minefield --watch

Prepare your cluster project

The following setup will work within the minefield namespace. Read more about k8s namespaces here.

Create the minefield namespace: kubectl create -f k8s/minefield.namespace.yaml

Setup the MongoDB cluster

Create persistent disks
gcloud compute disks create --size 200GB mongodb-pd-1 --project=<YOUR_PROJECT> --zone=<ZONE>
gcloud compute disks create --size 200GB mongodb-pd-2 --project=<YOUR_PROJECT> --zone=<ZONE>
gcloud compute disks create --size 200GB mongodb-pd-3 --project=<YOUR_PROJECT> --zone=<ZONE>
Create replication controllers
kubectl --namespace=minefield create -f k8s/mongodb-1.rc.yaml
kubectl --namespace=minefield create -f k8s/mongodb-2.rc.yaml
kubectl --namespace=minefield create -f k8s/mongodb-3.rc.yaml
Create services. The service exposes the pod with a stable IP address and DNS name to other pods
kubectl --namespace=minefield create -f k8s/mongodb-1.service.yaml
kubectl --namespace=minefield create -f k8s/mongodb-2.service.yaml
kubectl --namespace=minefield create -f k8s/mongodb-3.service.yaml
kubectl --namespace=minefield create -f k8s/mongodb.service.yaml
Inititate mongoDB replica set
Ensure the mongoDB container is started with --replSet command
Find the name of one of the pods
kubectl --namespace=minefield get pods
Get a shell in the pod and initiate the replica set
kubectl --namespace=minefield exec -ti mongodb-1-$$$$$
mongo
rs.initiate()
rs.status() should report (some fields omitted)

  {
      "set" : "rs-minefield",
      "myState" : 1,
      "term" : NumberLong(1),
      "heartbeatIntervalMillis" : NumberLong(2000),
      "members" : [
              {
                      "_id" : 0,
                      "name" : "mongodb-1-$$$$$:27017",
                      "health" : 1,
                      "state" : 1,
                      "stateStr" : "PRIMARY",
                      "configVersion" : 1,
                      "self" : true
              }
      ],
      "ok" : 1
  }
  ```
- Check whether you can reach mongodb via its public service name
 - 'mongo mongodb-1:27017' (the port number is *required*)
 - `rs.status()` should give the same output as above
- Build the cluster to use public service names
 - `c = rs.conf()`
 - `c.members[0].host = "mongodb-1:27017"`
 - `rs.reconfig(c)` (Overwrites our host name)
 - `rs.status()` should still indicate a healthy state using "mongodb-1" as the hostname
 - `rs.add("mongodb-2:27017")`
 - `rs.add("mongodb-3:27017")`
 - Verify the cluster is healthy. `rs.status()` should print (with some fields omitted)

{ "set" : "rs-minefield", "members" : [ { "_id" : 0, "name" : "mongodb-1:27017", "health" : 1, "state" : 1, "stateStr" : "PRIMARY", "self" : true }, { "_id" : 1, "name" : "mongodb-2:27017", "health" : 1, "state" : 2, "stateStr" : "SECONDARY", "syncingTo" : "mongodb-1:27017", }, { "_id" : 2, "name" : "mongodb-3:27017", "health" : 1, "state" : 2, "stateStr" : "SECONDARY", "syncingTo" : "mongodb-1:27017", } ], "ok" : 1 } ``` - Connect to another replica set member and check this looks good, too - mongo mongodb-2 - `rs.status()` should report same data as above, self being a secondary.

Setup the guestbook

Build the docker image according to guestbook/README.md. Upload the docker image to your docker registry and change k8s/guestbook.rc.yaml accordingly.

Create the replication controller for the guestbook: kubectl create -f k8s/guestbook.rc.yaml --namespace=minefield
Create the service for the guestbook: kubectl create -f k8s/guestbook.service.yaml --namespace=minefield