Update readme, switch to ImagePullStrategy: IfNotPresent

PullPolicy: Always will not work when testing locally

docker-plain/files/README.md

@@ -1,5 +1,46 @@
 # Plain Docker image (docker-plain)
 
+## Purpose
+
+This Quickstarter serves as a minimal starting point for building your own components that don't fit any of the other Quickstarters.
+For demonstration purposes, a nginx webserver provides a simple 'Hello World' message.
+
+## Folder structure and important files
+
+- docker: All files inside this folder are available for use in building the docker container
+  - [docker/Dockerfile](docker/Dockerfile): Defines the container to be built.
+- chart: The Helm chart used for deploying the component.
+  - [chart/Chart.yaml](chart/Chart.yaml): Metadata for your Helm chart.
+    - [chart/values.yaml](chart/values.yaml): Default values used when templating the Helm chart.
+    - [chart/values.dev.yaml](chart/values.dev.yaml): Values used for deployment in the 'dev' environment. Values specified in this file are overriding default values from [chart/values.yaml](chart/values.yaml).
+    - chart/templates:
+      - [chart/templates/deployment.yaml](chart/templates/deployment.yaml): Template for the [deployment](https://kubernetes.io/docs/concepts/workloads/controllers/deployment/) resource. This is where you add additional configuration like environment variables.
+        - [chart/templates/service.yaml](chart/templates/service.yaml): Template for the [service](https://kubernetes.io/docs/concepts/services-networking/service/) resource.
+        - [chart/templates/ingress.yaml](chart/templates/ingress.yaml): Template for the [ingress](https://kubernetes.io/docs/concepts/services-networking/ingress/) resource.
+
+## Testing locally
+
+If you want to run this component locally for testing, this might get you started.
+It also mimicks what's happening in the [Jenkinsfile](Jenkinsfile).
+
+### Building the container
+
+Using a local container runtime you can build the container and tag it with the current git revision:
+
+```bash
+docker build -t testing/my-component:$(git rev-parse --short=8 HEAD) docker/
+```
+
+### Deploying the helm chart using 
+
+Using a local kubernetes cluster you can deploy the component:
+
+```bash
+kubectl create ns docker-plain
+kind load docker-image testing/my-component:$(git rev-parse --short=8 HEAD)
+helm upgrade --install --wait --atomic --namespace docker-plain --set image.path=testing --set image.name=my-component --set image.tag=$(git rev-parse --short=8 HEAD) docker-plain chart
+```
+
 ## How to create a custom jenkins-agent out of this docker-plain component
 - Remove `odsComponentStageRolloutOpenShiftDeployment(context)` from your `Jenkinsfile`. We only want to build a docker image, not run it outside the pipeline.
 - In your `Dockerfile`, replace `FROM alpine:latest` with the ods-jenkins-agent-base image that is available in the OpenDevStack namespace of your cluster, e.g. `FROM docker-registry.default.svc:5000/ods/jenkins-agent-base:latest`.

docker-plain/files/chart/values.yaml

@@ -14,12 +14,12 @@ fullnameOverride: ""
 # NOTE: By default image Values are injected from CICD Jenkins pipeline, values defined here are used when not being on CICD Jenkins pipeline context.
 # Default values here are provided in case one needs to use the chart without CICD (i.e.: testing the chart).
 image:
-  registry: "docker.io"
-  path: "nginxinc"
-  name: "nginx-unprivileged"
-  tag: "latest"
-  # You might consider using `IfNotPresent` policy, see https://kubernetes.io/docs/concepts/containers/images/#image-pull-policy
-  pullPolicy: Always
+  # registry: "docker.io"
+  # path: "nginxinc"
+  # name: "nginx-unprivileged"
+  # tag: "latest"
+  # see https://kubernetes.io/docs/concepts/containers/images/#image-pull-policy
+  pullPolicy: IfNotPresent
 
 ## Prefer using ingress over openshift routes
 ingress: