chore: Added Init Container example

INSTALL.adoc

@@ -124,6 +124,11 @@ function pod {
   kubectl get pod -o name | grep -v "Terminating" | grep $1 | sed -e "s/^pods\///"
 }
 
+# Get the nodePort of first port mapping of a service
+function svc_node_port {
+  kubectl get svc $1 -o jsonpath={.spec.ports[0].nodePort}
+}
+
 # Change the current context (e.g. 'k8s_context minikube')
 function k8s_context {
    kubectl config use-context $1

README.adoc

@@ -46,23 +46,23 @@ link:behavorial/SelfAwareness/README.adoc[Self Awareness]::
 
 === Structural Patterns
 
+link:structural/InitContainer/README.adoc[Init Container]::
+  Initialize a HTTP server's HTML source from a remote git repository [*]
 link:structural/Sidecar/README.adoc[Sidecar]::
   Git polling example for a sidecar
-link:structural/InitContainer/README.adoc[Init Container]::
-  _TBD_
 link:structural/Ambassador/README.adoc[Ambassador]::
   _TBD_
 link:structural/Adapter/README.adoc[Adapter]::
   Adapter for exporting timing information from the sample random-generator application in a Prometheus format [*]
 
 === Configuration Patterns
 
-link:configuration/EnvvarConfiguration/README.adoc[Envvar Configuration]::
+link:configuration/EnvvarConfiguration/README.adoc[EnvVar Configuration]::
   _TBD_
 link:configuration/ConfigurationResource/README.adoc[Configuration Resource]::
   _TBD_
 link:configuration/ConfigurationTemplate/README.adoc[Configuration Template]::
-  Example how to use a template configuration `standalone.xml` which is processed with a template processed and filled with data from `ConfigMap` before a Wildfly server is started.
+  Example how to use a template configuration `standalone.xml` which is processed with a template processed and filled with data from ConfigMap before a Wildfly server is started.
 link:configuration/ImmutableConfiguration/README.adoc[Immutable Configuration]::
   Several examples how to use immutable configuration containers for application configuration. This includes examples for the plain Docker case and for Kubernetes.
 
@@ -71,9 +71,9 @@ link:configuration/ImmutableConfiguration/README.adoc[Immutable Configuration]::
 link:advanced/StatefulService/README.adoc[Stateful Service]::
   _TBD_
 link:advanced/Controller/README.adoc[Controller]::
-  Simple, pure shell based controller which watches `ConfigMap` resources for changes and restarts `Pods` by using a label selector provided as annotation. An additional link:advanced/Controller/expose-controller/README.adoc[example controller] exposes an `Ingress` route when it detects an `exposeService` label attached to the service.
+  Simple, pure shell based controller which watches ConfigMap resources for changes and restarts `Pods` by using a label selector provided as annotation. An additional link:advanced/Controller/expose-controller/README.adoc[example controller] exposes an Ingress route when it detects an `exposeService` label attached to the service.
 link:advanced/Operator/README.adoc[Operator]::
-  Operator based on the `ConfigMap` watch link:advanced/Controller/README.adoc[controller] and introduces a CRD `ConfigWatcher` which connects a `ConfigMap` with a set of `Pods` to restart in case of a config change.
+  Operator based on the ConfigMap watch link:advanced/Controller/README.adoc[controller] and introduces a CRD ConfigWatcher which connects a ConfigMap with a set of Pods to restart in case of a config change.
 link:advanced/ImageBuilder/README.adoc[Image Builder]::
   Setup a link:advanced/ImageBuilder/openshift/README.adoc[chained build] on OpenShift and use link:advanced/ImageBuilder/knative/README.adoc[Knative build] for doing builds within the cluster.
 link:advanced/ElasticScale/README.adoc[ElasticScale]::

behavorial/BatchJob/README.adoc

@@ -26,14 +26,13 @@ kubectl create -f pv-and-pvc.yml
 
 The job can be started with
 
-
 [source, bash]
 ----
 kubectl create -f job.yml
 ----
 
 This Job will create multiple Pods to create the number.
-Each Pod will run for creating 10000 entries into `logs/random-generator.log`.
+Each Pod will run for creating 10000 entries into `logs/random.log`.
 The Job is confiured to run the Pod 5 times, with 3 max running in parallel.
 That will take some minutes, but at the end you should have 50000 entries in the log file.
 

behavorial/BatchJob/job.yml

@@ -28,7 +28,7 @@ spec:
         # Class running batch job
         - RandomRunner
         # 1. Arg: File to store data (on a PV)
-        - /logs/random-generator.log
+        - /logs/random.log
         # 2. How many iterations
         - "10000"
         volumeMounts:

behavorial/ScheduledJob/README.adoc

@@ -13,7 +13,7 @@ Then create the PersistenVolume and PersistenVolumeClaim with
 kubectl create -f pv-and-pvc.yml
 ----
 
-but you don't have to do it, if you already have your Minikube still running from the _Batch Job_example footnote:[If you reuse the Batch Job example, don't forget that the `random-generator.log` is generated in the `logs/` directory over there.]
+but you don't have to do it, if you already have your Minikube still running from the _Batch Job_example footnote:[If you reuse the Batch Job example, don't forget that the `random.log` is generated in the `logs/` directory over there.]
 
 Now create the CronJob which fires every three minutes:
 
@@ -24,7 +24,7 @@ kubectl create -f cron-jobs.yml
 
 In this example we only use only one completion per Job (i.e. the default for a Job).
 
-You can check the `logs/random-generator.log` for the numbers generated, and also of course the Pods that are run on behalf of the job.
+You can check the `logs/random.log` for the numbers generated, and also of course the Pods that are run on behalf of the job.
 
 === More Information
 

behavorial/ScheduledJob/cron-job.yml

@@ -21,7 +21,7 @@ spec:
             # Class running batch job
             - RandomRunner
             # 1. Arg: File to store data (on a PV)
-            - /logs/random-generator.log
+            - /logs/random.log
             # 2. How many iterations
             - "10000"
             volumeMounts:

structural/Adapter/README.adoc

@@ -1,3 +1,8 @@
 == Adapter
 
-* Prometheus adapter with `nc` for the random-generator service, transforming the log to a Prometheus related format
+IMPORTANT: The instructions have not been written/finished, but the resource file has been verified. Instructions will be added soon.
+
+
+=== More Information
+
+* https://www.youtube.com/watch?v=Ph3t8jIt894[Container patterns for modular distributed system design]

structural/Adapter/deployment.yml

@@ -28,7 +28,7 @@ spec:
           protocol: TCP
         volumeMounts:
         - mountPath: /logs
-          name: logs
+          name: log-volume
       # ------------------------------------------------
       # Prometheus adapter
       - image: k8spatterns/random-generator-exporter
@@ -44,8 +44,8 @@ spec:
         # Mount shared volume for accessing the logs
         volumeMounts:
         - mountPath: /logs
-          name: logs
+          name: log-volume
       volumes:
       # New empty directory volume for sharing the log file between container
-      - name: logs
+      - name: log-volume
         emptyDir: {}

structural/InitContainer/README.adoc

@@ -1 +1,27 @@
-## Init Container
+== Init Container
+
+IMPORTANT: The instructions have not been written/finished, but the resource file has been verified. Instructions will be added soon.
+
+[source, bash]
+----
+kubctl create -f pod.yml
+
+kubectl get pods -w
+NAME   READY   STATUS            RESTARTS   AGE
+www    0/1     Init:0/1          0          8s
+www    0/1     PodInitializing   0          10s
+www    1/1     Running           0          12s
+
+kubectl create -f service.yml
+
+port=$(kubectl get svc www -o jsonpath={.spec.ports[0].nodePort})
+curl -s http://$(minikube ip):$port
+----
+
+=== More Information
+
+* https://github.com/k8spatterns/examples/tree/master/structural/InitContainer[Init Container example]
+* https://kubernetes.io/docs/concepts/workloads/pods/init-containers/[Init Containers]
+* https://kubernetes.io/docs/tasks/configure-pod-container/configure-pod-initialization/#creating-a-pod-that-has-an-init-container[Configuring Pod Initialization]
+* http://blog.javascriptroom.com/2013/01/21/the-initializer-pattern/[The Initializer Pattern in JavaScript]
+* https://developer.apple.com/library/content/documentation/General/Conceptual/CocoaEncyclopedia/Initialization/Initialization.html[Object Initialization in Swift]

structural/InitContainer/pod.yml

@@ -0,0 +1,33 @@
+apiVersion: v1
+kind: Pod
+metadata:
+  name: www
+  labels:
+    app: www
+spec:
+  initContainers:
+  - name: download
+    image: axeclbr/git
+    # Clone an HTML page to be served
+    command:
+    - git
+    - clone
+    - https://github.com/mdn/beginner-html-site-scripted
+    - /var/lib/data
+    # Shared volume with main container
+    volumeMounts:
+    - mountPath: /var/lib/data
+      name: source
+  containers:
+  # Simple static HTTP server for serving these pages
+  - name: run
+    image: docker.io/centos/httpd
+    ports:
+    - containerPort: 80
+    # Shared volume with main container
+    volumeMounts:
+    - mountPath: /var/www/html
+      name: source
+  volumes:
+  - emptyDir: {}
+    name: source

structural/InitContainer/random-generator/README.adoc

@@ -0,0 +1,19 @@
+== Init Container (random-genertor example)
+
+[source, bash]
+----
+kubctl create -f deployment.yml
+
+k get pods -w
+NAME                                READY   STATUS     RESTARTS   AGE
+random-generator-6c8f6bb79c-jc6nf   0/1     Init:0/1   0          4s
+random-generator-6c8f6bb79c-jc6nf   0/1     PodInitializing   0   61s
+random-generator-6c8f6bb79c-jc6nf   1/1     Running   0           62s
+
+kubectl create -f service.yml
+
+kubectl get service
+
+port=$(kubectl get svc random-generator -o jsonpath={.spec.ports[0].nodePort})
+curl -s http://$(minikube ip):$port/logs | head -10
+----

structural/InitContainer/random-generator/deployment.yml

@@ -0,0 +1,54 @@
+# DeploymentConfig for starting up the random-generator
+apiVersion: apps/v1
+kind: Deployment
+metadata:
+  name: random-generator
+spec:
+  replicas: 1
+  selector:
+    matchLabels:
+      app: random-generator
+  template:
+    metadata:
+      labels:
+        app: random-generator
+    spec:
+      initContainers:
+      # Same image as main container, but used for calling the batch CLI
+      - image: k8spatterns/random-generator:1.0
+        name: init
+        command:
+        - java
+        # Use / as classpath to pick up the class file
+        - -classpath
+        - /
+        # Class running batch job
+        - RandomRunner
+        # 1. Arg: File to store data (on a PV)
+        - /logs/random.log
+        # 2. How many iterations
+        - "100000"
+        # Shared volume with main container. Use for initializing the batch file
+        volumeMounts:
+        - mountPath: /logs
+          name: log-volume
+      containers:
+      # ------------------------------------------------
+      # Main container sharing the /logs dir with the init container
+      - image: k8spatterns/random-generator:1.0
+        name: random-generator
+        env:
+        # The log file that we want to export
+        - name: LOG_FILE
+          value: /logs/random.log
+        ports:
+        # Application running on port 8080
+        - containerPort: 8080
+          protocol: TCP
+        volumeMounts:
+        - mountPath: /logs
+          name: log-volume
+      volumes:
+      # New empty directory volume for sharing the log file between container
+      - name: log-volume
+        emptyDir: {}

structural/InitContainer/random-generator/service.yml

@@ -0,0 +1,13 @@
+apiVersion: v1
+kind: Service
+metadata:
+  name: random-generator
+spec:
+  selector:
+    app: random-generator
+  ports:
+  - name: random
+    port: 8080
+    protocol: TCP
+    targetPort: 8080
+  type: NodePort

structural/InitContainer/service.yml

@@ -0,0 +1,13 @@
+apiVersion: v1
+kind: Service
+metadata:
+  name: www
+spec:
+  selector:
+    app: www
+  ports:
+  - name: http
+    port: 8080
+    protocol: TCP
+    targetPort: 80
+  type: NodePort