Workshop

Nomenclature

• OKD: Origin Community Distribution of Kubernetes, see: https://www.okd.io/
• docker multistage: https://docs.docker.com/develop/develop-images/multistage-build/
• s2i: source2image, see down below
• oc: OpenShift Client (CLI) commands
  • oc new-project
  • oc new-build
  • oc start-build
  • oc get
  • oc describe
  • oc logs
  • oc ... -o yaml
  • creating, processing oc process and using oc apply templates
• Please research the following concepts yourself
  • build vs. buildConfig (bc)
  • secret
  • configMap
  • container vs. pod
  • image vs. imageStream (is)
  • deployment vs. deploymentConfig (dc)

01-basic-components

1. Start minishift OR login to an cluster
2. Check if everything is working (is your client working, are you logged in on CLI?)
3. 01-basic-components/setup.sh # to setup a project

02-docker-multistage

Goal: To give you the understanding about docker multistage builds, play around with and get a feel for it. Understand the concepts, commands and how to chain different stages together. Check out the Dockerfile.

cd 02-docker-multistage
IMAGE_NAME=spring-test

docker build -t $IMAGE_NAME . # builds default stage
docker build -t ${IMAGE_NAME}:runtime-alpine --target runtime-alpine . #builds runtime-alpine stage
docker build -t ${IMAGE_NAME}:debug --target debug . # builds debug stage


TAG_TO_RUN=runtime-alpine
docker run --rm -p 8080:8080 ${IMAGE_NAME}:${TAG_TO_RUN}

# Now let's translate this to OpenShift v3.9

Docker basics

COPY VS ADD

"Although ADD and COPY are functionally similar, generally speaking, COPY is preferred. That’s because it’s more transparent than ADD. COPY only supports the basic copying of local files into the container, while ADD has some features (like local-only tar extraction and remote URL support) that are not immediately obvious. Consequently, the best use for ADD is local tar file auto-extraction into the image, as in ADD rootfs.tar.xz /."

Entrypoint https://docs.docker.com/engine/reference/builder/#entrypoint

--init # https://github.com/krallin/tini

ENTRYPOINT VS. CMD

https://docs.docker.com/engine/reference/builder/#entrypoint

Further resoruces

• https://medium.com/@tonistiigi/advanced-multi-stage-build-patterns-6f741b852fae
• https://docs.docker.com/develop/develop-images/dockerfile_best-practices/

Source2image: 03-okd-s2i

Goal: We want to translate a multistage build now to OpenShift. For that we're using at the first step a s2i appraoch to build the first part of the chain.

You'll see how to use the source2image tool within openshift.

Used base images: https://hub.docker.com/r/fabric8/s2i-java // https://github.com/fabric8io-images/s2i

cd 03-okd-s2i

Steps

1. Import the base image:

   oc import-image -h # check which params you can set

   oc apply -f imagestream.yml # create imagestream

2. create s2i-build-config:

# process template via: oc process -f s2i.yml -p APPLICATION_NAME=XY -p REPOSITORY_URL=re...
oc process -f s2i.yml \
  -p APPLICATION_NAME=spring-boot \
  -p REPOSITORY_URL=https://github.com/spring-guides/gs-spring-boot.git \
  -p CONTEXT_DIR=complete \
  | oc apply -f -

3. start a build: oc start-build spring-boot-dev -w # -w watches the output
4. wait till the build finishes or add the following to the next command:--allow-missing-imagestream-tags
5. Create svc and dc: oc new-app --image-stream spring-boot

Resources

https://docs.openshift.com/online/dev_guide/builds/advanced_build_operations.html https://docs.openshift.com/online/dev_guide/builds/build_strategies.html

04-okd-chained-build

Goal: Build a secon buildConfig which builds our runtime image.

See README.md in 04-okd-chained-build. You'll see how to chain build to get a minimal runtime-image and automatically trigger the second build after the previous ran.

Platform pattern

• Single node multi container: sidecar, ambassador, adapter
• Multi node: leader election, work queue, scatter/gather

Goal: Use examples and get a feel for the platform pattern

Run the files via oc apply -f <file/directory>

Ambassador / proxy - 05-ambassador

The main container communicates or gets called through an ambassador. (Proxy, name resolver, ...) https://github.com/openshift/oauth-proxy/blob/master/contrib/sidecar.yaml

Sidecar - 06-sidecar

Enhances basic pod functionality. Logging, circut breaker, ...

Adapter - 07-adapter

Like an adapter in software development. Changes the interface or converts the requests from or to the main container

Adapter - 08-12factor

Goal: See secrets and configmaps in action. Checkout the OpenShift web-ui, open a terminal within a running pod and see the mounted or as environment available configs and secrets.

cd 08-12factor
oc apply -f . # creates secret, configMap, and two pods

# checkout the two pods with the secrets and configs within web-ui and via CLI

Cleanup

oc delete project <yourProject>

Openshift guide

https://github.com/openshift-labs/devops-guides