ウェビナーシリーズ：Kubernetesでのステートフルサービスの展開

brew install kubernetes-helm

Output==> Downloading https://homebrew.bintray.com/bottles/kubernetes-helm-2.8.2.high_sierra.bottle.tar.gz
...
==> Summary
🍺  /usr/local/Cellar/kubernetes-helm/2.8.2: 50 files, 121.7MB

helm version

OutputClient: &version.Version{SemVer:"v2.7.2", GitCommit:"8478fb4fc723885b155c924d1c8c410b7a9444e6", GitTreeState:"clean"}
Server: &version.Version{SemVer:"v2.8.2", GitCommit:"a80231648a1473929271764b920a8e346f6de844", GitTreeState:"clean"}

kubectl get storageclass

[secondary_label Output
NAME                     PROVISIONER                            AGE
digitalocean (default)   digitalocean/flex-volume-provisioner   1d

mkdir ~/mongo-rs
cd ~/mongo-rs

git clone https://github.com/kubernetes/charts.git

cd charts/stable/mongodb-replicaset/
ls values.yaml

Outputvalues.yaml

nano values.yaml

...
# storageClass: "-"
...

...
storageClass:
...

cd ~/mongo-rs

helm install --name= -f charts/stable/mongodb-replicaset/values.yaml stable/mongodb-replicaset

OutputNAME:   todo
LAST DEPLOYED: Sat Mar 31 10:37:06 2018
NAMESPACE: default
STATUS:

RESOURCES:
==> v1/Service
NAME                     TYPE       CLUSTER-IP  EXTERNAL-IP  PORT(S)    AGE
 ClusterIP  None        <none>       27017/TCP  1s

==> v1beta1/StatefulSet
NAME                     DESIRED  CURRENT  AGE
 3        1        0s

==> v1/Pod(related)
NAME                       READY  STATUS    RESTARTS  AGE
 0/1    Init:0/2  0         0s

==> v1/ConfigMap
NAME                           DATA  AGE
       1     1s
 1     1s


NOTES:
1. After the statefulset is created completely, one can check which instance is primary by running:

   $ for ((i = 0; i < 3; ++i)); do kubectl exec --namespace default todo-mongodb-replicaset-$i -- sh -c 'mongo --eval="printjson(rs.isMaster())"'; done

2. One can insert a key into the primary instance of the mongodb replica set by running the following:
   MASTER_POD_NAME must be replaced with the name of the master found from the previous step.

   $ kubectl exec --namespace default MASTER_POD_NAME -- mongo --eval="printjson(db.test.insert({key1: 'value1'}))"

3. One can fetch the keys stored in the primary or any of the slave nodes in the following manner.
   POD_NAME must be replaced by the name of the pod being queried.

   $ kubectl exec --namespace default POD_NAME -- mongo --eval="rs.slaveOk(); db.test.find().forEach(printjson)"

kubectl get statefulset

OutputNAME                      DESIRED   CURRENT   AGE
  3         2         2m

kubectl get pods

OutputNAME                        READY     STATUS        RESTARTS   AGE
  1/1       Running       0          3m
  1/1       Running       0          1m
  1/1       Running       0          54s

kubectl exec -it  mongo

OutputMongoDB shell version v3.6.3
connecting to: mongodb://127.0.0.1:27017
MongoDB server version: 3.6.3
Welcome to the MongoDB shell.
For interactive help, type "help".
...

2018-03-31T05:08:20.239+0000 I CONTROL  [initandlisten]

rs.conf()

Output{
   "_id" : "rs0",
   "version" : 3,
   "protocolVersion" : NumberLong(1),
   "members" : [
       {
           "_id" : 0,
           "host" : ",
           "arbiterOnly" : false,
           "buildIndexes" : true,
           "hidden" : false,
           "priority" : 1,
           "tags" : {

           },
           "slaveDelay" : NumberLong(0),
           "votes" : 1
       },
       {
           "_id" : 1,
           "host" : "",
           "arbiterOnly" : false,
           "buildIndexes" : true,
           "hidden" : false,
           "priority" : 1,
           "tags" : {

           },
           "slaveDelay" : NumberLong(0),
           "votes" : 1
       },
       {
           "_id" : 2,
           "host" : "",
           "arbiterOnly" : false,
           "buildIndexes" : true,
           "hidden" : false,
           "priority" : 1,
           "tags" : {

           },
           "slaveDelay" : NumberLong(0),
           "votes" : 1
       }
   ],
   "settings" : {
       "chainingAllowed" : true,
       "heartbeatIntervalMillis" : 2000,
       "heartbeatTimeoutSecs" : 10,
       "electionTimeoutMillis" : 10000,
       "catchUpTimeoutMillis" : -1,
       "catchUpTakeoverDelayMillis" : 30000,
       "getLastErrorModes" : {

       },
       "getLastErrorDefaults" : {
           "w" : 1,
           "wtimeout" : 0
       },
       "replicaSetId" : ObjectId("5abdb4f61d952afc4b0b8218")
   }
}

exit

persistentVolume:
 enabled: true
 ## mongodb-replicaset data Persistent Volume Storage Class
 ## If defined, storageClassName: <storageClass>
 ## If set to "-", storageClassName: "", which disables dynamic provisioning
 ## If undefined (the default) or set to null, no storageClassName spec is
 ##   set, choosing the default provisioner.  (gp2 on AWS, standard on
 ##   GKE, AWS & OpenStack)
 ##
 storageClass: digitalocean
 accessModes:
   - ReadWriteOnce

 annotations: {}

mkdir ~/web-app
cd ~/web-app

git clone https://github.com/janakiramm/todo.git

cd todo-app/kubernetes

nano web-rs-ss.yaml

     containers:
     - name: web
       image: janakiramm/todo



       ports:
       - containerPort: 3000

kubectl create -f web-rs-ss.yaml -f web-service.yaml

Outputreplicaset "web" created
service "web" created

kubectl get pods

OutputNAME                        READY     STATUS    RESTARTS   AGE
todo-mongodb-replicaset-0   1/1       Running   0          26m
todo-mongodb-replicaset-1   1/1       Running   0          24m
todo-mongodb-replicaset-2   1/1       Running   0          23m



Let’s check out the Kubernetes services

​```command
kubectl get svc

OutputNAME                      TYPE        CLUSTER-IP   EXTERNAL-IP   PORT(S)          AGE
kubernetes                ClusterIP   10.3.0.1     <none>        443/TCP          1d
todo-mongodb-replicaset   ClusterIP   None         <none>        27017/TCP        27m

kubectl scale rs/web --replicas=10

Outputreplicaset "web" scaled

kubectl scale rs/web --replicas=2

Outputreplicaset "web" scaled

kubectl delete pod todo-mongodb-replicaset-2

Outputpod "todo-mongodb-replicaset-2" deleted

kubectl get pods

OutputNAME                        READY     STATUS        RESTARTS   AGE
todo-mongodb-replicaset-0   1/1       Running       0          33m
todo-mongodb-replicaset-1   1/1       Running       0          32m

web-t5zzk                   1/1       Running       0          8m
web-x6dh8                   1/1       Running       0          8m

kubectl get pods

NAME                        READY     STATUS     RESTARTS   AGE
todo-mongodb-replicaset-0   1/1       Running    0          34m
todo-mongodb-replicaset-1   1/1       Running    0          33m

web-t5zzk                   1/1       Running    0          8m
web-x6dh8                   1/1       Running    0          8m

helm delete --purge todo

kubectl delete -f web-rs-ss.yaml -f web-service.yaml

Outputreplicaset "web" deleted
service "web" deleted