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135 lines
5.5 KiB
Markdown
135 lines
5.5 KiB
Markdown
## Java EE Application using WildFly and MySQL
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The following document describes the deployment of a Java EE application using [WildFly](http://wildfly.org) application server and MySQL database server on Kubernetes. The sample application source code is at: https://github.com/javaee-samples/javaee7-simple-sample.
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### Prerequisites
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https://github.com/kubernetes/kubernetes/blob/master/docs/user-guide/prereqs.md
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### Start MySQL Pod
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In Kubernetes a [_Pod_](../../docs/user-guide/pods.md) is the smallest deployable unit that can be created, scheduled, and managed. It's a collocated group of containers that share an IP and storage volume.
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Here is the config for MySQL pod: [mysql-pod.yaml](mysql-pod.yaml)
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<!-- BEGIN MUNGE: mysql-pod.yaml -->
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<!-- END MUNGE: EXAMPLE -->
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Create the MySQL pod:
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```sh
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kubectl create -f examples/javaee/mysql-pod.yaml
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```
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Check status of the pod:
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```sh
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kubectl get -w po
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NAME READY STATUS RESTARTS AGE
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mysql-pod 0/1 Pending 0 4s
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NAME READY STATUS RESTARTS AGE
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mysql-pod 0/1 Running 0 44s
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mysql-pod 1/1 Running 0 44s
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```
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Wait for the status to `1/1` and `Running`.
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### Start MySQL Service
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We are creating a [_Service_](../../docs/user-guide/services.md) to expose the TCP port of the MySQL server. A Service distributes traffic across a set of Pods. The order of Service and the targeted Pods does not matter. However Service needs to be started before any other Pods consuming the Service are started.
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In this application, we will use a Kubernetes Service to provide a discoverable endpoints for the MySQL endpoint in the cluster. MySQL service target pods with the labels `name: mysql-pod` and `context: docker-k8s-lab`.
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Here is definition of the MySQL service: [mysql-service.yaml](mysql-service.yaml)
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<!-- BEGIN MUNGE: mysql-service.yaml -->
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<!-- END MUNGE: EXAMPLE -->
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Create this service:
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```sh
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kubectl create -f examples/javaee/mysql-service.yaml
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```
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Get status of the service:
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```sh
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kubectl get -w svc
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NAME LABELS SELECTOR IP(S) PORT(S)
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kubernetes component=apiserver,provider=kubernetes <none> 10.247.0.1 443/TCP
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mysql-service context=docker-k8s-lab,name=mysql-pod context=docker-k8s-lab,name=mysql-pod 10.247.63.43 3306/TCP
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```
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If multiple services are running, then it can be narrowed by specifying labels:
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```sh
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kubectl get -w po -l context=docker-k8s-lab,name=mysql-pod
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NAME READY STATUS RESTARTS AGE
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mysql-pod 1/1 Running 0 4m
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```
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This is also the selector label used by service to target pods.
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When a Service is run on a node, the kubelet adds a set of environment variables for each active Service. It supports both Docker links compatible variables and simpler `{SVCNAME}_SERVICE_HOST` and `{SVCNAME}_SERVICE_PORT` variables, where the Service name is upper-cased and dashes are converted to underscores.
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Our service name is ``mysql-service'' and so ``MYSQL_SERVICE_SERVICE_HOST'' and ``MYSQL_SERVICE_SERVICE_PORT'' variables are available to other pods. This host and port variables are then used to create the JDBC resource in WildFly.
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### Start WildFly Replication Controller
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WildFly is a lightweight Java EE 7 compliant application server. It is wrapped in a Replication Controller and used as the Java EE runtime.
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In Kubernetes a [_Replication Controller_](../../docs/user-guide/replication-controller.md) is responsible for replicating sets of identical pods. Like a _Service_ it has a selector query which identifies the members of it's set. Unlike a service it also has a desired number of replicas, and it will create or delete pods to ensure that the number of pods matches up with it's desired state.
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Here is definition of the MySQL service: [wildfly-rc.yaml](wildfly-rc.yaml).
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<!-- BEGIN MUNGE: wildfly-rc.yaml -->
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<!-- END MUNGE: EXAMPLE -->
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Create this controller:
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```sh
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kubectl create -f examples/javaee/wildfly-rc.yaml
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```
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Check status of the pod inside replication controller:
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```sh
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kubectl get po
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NAME READY STATUS RESTARTS AGE
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mysql-pod 1/1 Running 0 1h
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wildfly-rc-w2kk5 1/1 Running 0 6m
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```
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### Access the application
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Get IP address of the pod:
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```sh
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kubectl get -o template po wildfly-rc-w2kk5 --template={{.status.podIP}}
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10.246.1.23
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```
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Log in to node and access the application:
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```sh
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vagrant ssh node-1
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Last login: Thu Jul 16 00:24:36 2015 from 10.0.2.2
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[vagrant@kubernetes-node-1 ~]$ curl http://10.246.1.23:8080/employees/resources/employees/
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<?xml version="1.0" encoding="UTF-8" standalone="yes"?><collection><employee><id>1</id><name>Penny</name></employee><employee><id>2</id><name>Sheldon</name></employee><employee><id>3</id><name>Amy</name></employee><employee><id>4</id><name>Leonard</name></employee><employee><id>5</id><name>Bernadette</name></employee><employee><id>6</id><name>Raj</name></employee><employee><id>7</id><name>Howard</name></employee><employee><id>8</id><name>Priya</name></employee></collection>
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```
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### Delete resources
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All resources created in this application can be deleted:
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```sh
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kubectl delete -f examples/javaee/mysql-pod.yaml
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kubectl delete -f examples/javaee/mysql-service.yaml
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kubectl delete -f examples/javaee/wildfly-rc.yaml
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```
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<!-- BEGIN MUNGE: GENERATED_ANALYTICS -->
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[]()
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<!-- END MUNGE: GENERATED_ANALYTICS -->
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