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Load balancing with the Apache HTTP Server

This document describes how to set up and start an Apache HTTP Server for load balancing inside a Kubernetes cluster. The configuration and startup can be either automatic, when you create a domain using the WebLogic Operator's create-weblogic-domain.sh script, or manual, if you have an existing WebLogic domain configuration.

Build the Docker image for the Apache HTTP Server

You need to build the Docker image for the Apache HTTP Server that embeds the Oracle WebLogic Server Proxy Plugin.

  1. Download and build the Docker image for the Apache HTTP Server with the 12.2.1.3.0 Oracle WebLogic Server Proxy Plugin. See the instructions in Apache HTTP Server with Oracle WebLogic Server Proxy Plugin on Docker.

  2. Tag your Docker image, store/oracle/apache:12.2.1.3, using the docker tag command.


     $ docker tag 12213-apache:latest store/oracle/apache:12.2.1.3

For more information about the Apache plugin, see Configuring the Plug-In for Apache HTTP Server.

After you have access to the Docker image of the Apache HTTP Server, you can follow the instructions below to set up and start the Kubernetes resources for the Apache HTTP Server.

Use the Apache load balancer with a WebLogic domain created with the WebLogic Operator

For how to create a domain with the WebLogic Operator, please refer to Creating a domain using the WebLogic Operator.

You need to configure the Apache HTTP Server as your load balancer for a WebLogic domain by setting the loadBalancer option to APACHE in the create-weblogic-domain-inputs.yaml (as shown below) when running the create-weblogic-domain.sh script to create a domain.


# Load balancer to deploy.  Supported values are: VOYAGER, TRAEFIK, APACHE, NONE

loadBalancer: APACHE

The create-weblogic-domain.sh script installs the Apache HTTP Server with the Oracle WebLogic Server Proxy Plugin into the Kubernetes cluster in the same namespace as the domain.

The Apache HTTP Server will expose a NodePort that allows access to the load balancer from outside of the Kubernetes cluster. The port is configured by setting loadBalancerWebPort in the create-weblogic-domain-inputs.yaml file.


# Load balancer web port

loadBalancerWebPort: 30305

Users can access an application from outside of the Kubernetes cluster by using http://<host>:30305/<application-url>.

Use the default plugin WL module configuration

By default, the Apache Docker image supports a simple WebLogic Server proxy plugin configuration for a single WebLogic domain with an Administration Server and a cluster. The create-weblogic-domain.sh script automatically customizes the default behavior based on your domain configuration by generating a customized Kubernetes resources YAML file for Apache named weblogic-domain-apache.yaml. The default setting supports only the type of load balancing that uses the root path ("/"). You can further customize the root path of the load balancer with the loadBalancerAppPrepath property in the create-weblogic-domain-inputs.yaml file.


# Load balancer app prepath

loadBalancerAppPrepath: /weblogic

Users can then access an application from outside of the Kubernetes cluster by using http://<host>:30305/weblogic/<application-url>.

The generated Kubernetes YAML files look like the following, given the domainUID, "domain1".

Sample weblogic-domain-apache.yaml file for Apache HTTP Server deployment.


--

apiVersion: v1

kind: ServiceAccount

metadata:

  name: domain1-apache-webtier

  namespace: default

  labels:

    weblogic.domainUID: domain1

    weblogic.domainName: base_domain

    app: apache-webtier

---

kind: Deployment

apiVersion: extensions/v1beta1

metadata:

  name: domain1-apache-webtier

  namespace: default

  labels:

    weblogic.domainUID: domain1

    weblogic.domainName: base_domain

    app: apache-webtier

spec:

  replicas: 1

  selector:

    matchLabels:

      weblogic.domainUID: domain1

      weblogic.domainName: base_domain

      app: apache-webtier

  template:

    metadata:

      labels:

        weblogic.domainUID: domain1

        weblogic.domainName: base_domain

        app: apache-webtier

    spec:

      serviceAccountName: domain1-apache-webtier

      terminationGracePeriodSeconds: 60

      # volumes:

      # - name: "domain1-apache-webtier"

      #   hostPath:

      #     path: %LOAD_BALANCER_VOLUME_PATH%

      containers:

      - name: domain1-apache-webtier

        image: store/oracle/apache:12.2.1.3

        imagePullPolicy: Never

        # volumeMounts:

        # - name: "domain1-apache-webtier"

        #   mountPath: "/config"

        env:

          - name: WEBLOGIC_CLUSTER

            value: 'domain1-cluster-cluster-1:8001'

          - name: LOCATION

            value: '/weblogic'

        # - name: WEBLOGIC_HOST

        #   value: 'domain1-admin-server'

        # - name: WEBLOGIC_PORT

        #   value: '7001'

        readinessProbe:

          tcpSocket:

            port: 80

          failureThreshold: 1

          initialDelaySeconds: 10

          periodSeconds: 10

          successThreshold: 1

          timeoutSeconds: 2

        livenessProbe:

          tcpSocket:

            port: 80

          failureThreshold: 3

          initialDelaySeconds: 10

          periodSeconds: 10

          successThreshold: 1

          timeoutSeconds: 2

---

apiVersion: v1

kind: Service

metadata:

  name: domain1-apache-webtier

  namespace: default

  labels:

    weblogic.domainUID: domain1

    weblogic.domainName: base_domain

spec:

  type: NodePort

  selector:

    weblogic.domainUID: domain1

    weblogic.domainName: base_domain

    app: apache-webtier

  ports:

    - port: 80

      nodePort: 30305

      name: rest-https

Sample weblogic-domain-apache-security.yaml file for associated RBAC roles and role bindings.


---

kind: ClusterRole

apiVersion: rbac.authorization.k8s.io/v1beta1

metadata:

  name: domain1-apache-webtier

  labels:

    weblogic.domainUID: domain1

    weblogic.domainName: base_domain

rules:

  - apiGroups:

      - ""

    resources:

      - pods

      - services

      - endpoints

      - secrets

    verbs:

      - get

      - list

      - watch

  - apiGroups:

      - extensions

    resources:

      - ingresses

    verbs:

      - get

      - list

      - watch

---

kind: ClusterRoleBinding

apiVersion: rbac.authorization.k8s.io/v1beta1

metadata:

  name: domain1-apache-webtier

  labels:

    weblogic.domainUID: domain1

    weblogic.domainName: base_domain

roleRef:

  apiGroup: rbac.authorization.k8s.io

  kind: ClusterRole

  name: domain1-apache-webtier

subjects:

- kind: ServiceAccount

  name: domain1-apache-webtier

  namespace: default

Here are examples of the Kubernetes resources created by the WebLogic Operator:


NAME                            DESIRED   CURRENT   UP-TO-DATE   AVAILABLE   AGE

bash-4.2$ kubectl get all |grep apache

deploy/domain1-apache-webtier   1         1         1            1           2h


rs/domain1-apache-webtier-7b8b789797   1         1         1         2h


deploy/domain1-apache-webtier   1         1         1            1           2h


rs/domain1-apache-webtier-7b8b789797   1         1         1         2h



po/domain1-apache-webtier-7b8b789797-lm45z   1/1       Running   0          2h


svc/domain1-apache-webtier                      NodePort    10.111.114.67    <none>        80:30305/TCP      2h



bash-4.2$ kubectl get clusterroles |grep apache

domain1-apache-webtier                                                 2h



bash-4.2$ kubectl get clusterrolebindings |grep apache

domain1-apache-webtier                                    2h

It is sometimes, but rarely, desirable to expose a WebLogic Administration Server host and port through a load balancer to a public network. If this is needed, you can customize the exposure of the WebLogic Administration Server host and port by using the loadBalancerExposeAdminPort property in the create-weblogic-domain-inputs.yaml file.


# Boolean to indicate if the admin port is going to be exposed via APACHE load balancer. By default, it is false.
loadBalancerExposeAdminPort: false

If the domain is created with the loadBalancerExposeAdminPort set to true, an adminstrator can access the Administration Console using http://<host>:30305/console.

Use your own plugin WL module configuration

You can fine tune the behavior of the Apache plugin by providing your own Apache plugin configuration. You put your custom_mod_wl_apache.conf file in a local directory, for example, <host-config-dir> , and specify this location in the create-weblogic-domain-inputs.yaml file as follows:


# Docker volume path for APACHE

# By default, the VolumePath is empty, which will cause the volume mount to be disabled

loadBalancerVolumePath: <host-config-dir>

After the loadBalancerVolumePath property is specified, the create-weblogic-domain.sh script will use the custom_mod_wl_apache.conf file in the <host-config-dir> directory to replace what is in the Docker image.

The generated YAML files will look similar except with un-commented entries like below:


      volumes:

      - name: "domain1-apache-webtier"

        hostPath:

          path: <host-config-dir>

      containers:

      - name: domain1-apache-webtier

        image: store/oracle/apache:12.2.1.3

        imagePullPolicy: Never

        volumeMounts:

        - name: "domain1-apache-webtier"

          mountPath: "/config"

Use the Apache load balancer with a manually created WebLogic domain

If your WebLogic domain is not created by the WebLogic Operator, you need to manually create and start all Kubernetes resources for the Apache HTTP Server.

  1. Create your own custom_mod_wl_apache.conf file, and put it in a local directory, for example, <host-conf-dir>. See the instructions in [Apache Web Server with Oracle WebLogic Server Proxy Plugin on Docker]](https://github.com/oracle/docker-images/tree/master/OracleWebLogic/samples/12213-webtier-apache).

  2. Create the Apache deployment YAML file. See the example above. Note that you need to use the volumes and volumeMounts to mount <host-config-dir> into the /config directory inside the pod that runs the Apache web tier. Note that the Apache HTTP Server needs to be in the same Kubernetes namespace as the WebLogic domain that it needs to access.

  3. Create a RBAC YAML file. See the example above.

Note that you can choose to run one Apache HTTP Server to balance the loads from multiple domains/clusters inside the same Kubernetes cluster, as long as the Apache HTTP Server and the domains are all in the same namespace.