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Table of Content

  1. odo
  2. azure
  3. container
  4. openshift
  5. quarkus
  6. sample app
  7. crc
  8. minishift
  9. cheatsheet
  10. iac

OpenShift is a Kubernetes platform

iac

  • infrastructure as code (IAC) with Templates
  • openshift REST api v3.11 based on kubernates v1.14
    • on top it has for example Template API
  • you can write Template from scratch or export existing resource to yaml, json, ...

API reference

  • you can use the CLI reference to list all resources
$ oc api-resources

NAME                                  SHORTNAMES       APIGROUP                              NAMESPACED   KIND
...
pods                                  po                                                     true         Pod
imagestreams                          is               image.openshift.io                    true         ImageStream
templates                                              template.openshift.io                 true         Template
...
  • the full object schema
$ oc explain templates
  • find out more about an attribute
oc explain templates.objects

links

odo

  • odo: OpenShift Do
  • developer-focused CLI for OpenShift
  • get odo
curl -L https://mirror.openshift.com/pub/openshift-v4/clients/odo/latest/odo-linux-amd64 -o odo
  • make it runnable
chmod +x odo
  • list developer catalog
odo catalog list components

openshift on azure

https://github.com/kedacore/keda/wiki/Using-Keda-and-Azure-Functions-on-Openshift-4

docker container alternatives

  • OCI container: buildah, google jib, ...

openshift

container

Containers in OpenShift Container Platform are based on OCI- or Docker-formatted container images.

(container) image, builder image / base image, custom / application image, image streams

OpenShift Container Image; created with UMlet

OpenShift in Action

  • Image streams monitor for changes and trigger new deployments and builds for applications.
  • Build configs track everything required to build an application deployment.
  • Deployment configs keep track of all information required to deploy an application.
  • Pods are the default unit of work. They’re where your application code is served.
  • Deployments are unique deployed versions of an application.
  • Container images are the template used to deploy application pods.
  • Services are a consistent interface for all the application pods for a deployment.
  • Routes are external-facing, DNS-based load-balancer entries that are connected to services.
  • Replication controllers ensure that the desired number of application pods is running at all times.

application components:

  • Custom container images
  • Image streams
  • Application pods
  • Build configs
  • Deployment configs
  • Deployments
  • Services

how OpenShift creates and uses custom container images for each application.

Each application deployment in OpenShift creates a custom container image to serve your application. This image is created using the application’s source code and a custom base image called a builder image.

  1. OpenShift creates a custom container image using your source code and the builder image template you specified. For example, app-cli and app-gui use the PHP builder image.
  2. This image is uploaded to the OpenShift container image registry.
  3. OpenShift creates a build config to document how your application is built. This includes which image was created, the builder image used, the location of the source code, and other information.
  4. OpenShift creates a deployment config to control deployments and deploy and update your applications. Information in deployment configs includes the number of replicas, the upgrade method, and application-specific variables and mounted volumes.
  5. OpenShift creates a deployment, which represents a single deployed version of an application. Each unique application deployment is associated with your application’s deployment config component.
  6. The OpenShift internal load balancer is updated with an entry for the DNS record for the application. This entry will be linked to a component that’s created by Kubernetes, which we’ll get to shortly.
  7. OpenShift creates an image stream component. In OpenShift, an image stream monitors the builder image, deployment config, and other components for changes. If a change is detected, image streams can trigger application redeployments to reflect changes.

build strategies

  • Docker build
    • expects a repository with a Dockerfile
  • Source-to-Image (S2I) build
    • builder image: injecting sourcecode into a container (base/builder) image and assemble a new image.
    • OpenShift Container Platform also supplies builder images that assist with creating new images by adding your code or configuration to existing images.
    • base image (docker context): A base image has FROM scratch in its Dockerfile.
  • Custom build
  • Pipeline build strategy (CI/CD)
    • Pipeline workflows are defined in a Jenkinsfile or embedded directly in the build configuration
  • https://docs.openshift.com/container-platform/4.2/builds/understanding-image-builds.html
  • Override the build strategy by setting the --strategy flag to either pipeline or source.
$ oc new-app /home/user/code/myapp --strategy=docker

UBI Images

create builder image

example

  • folder: s2i-payara/
  • created with:
s2i create <imageName> <destination>
s2i create payara-builderimage s2i-payara

links

S2I

Let see what the tool s2i https://github.com/openshift/source-to-image/releases/ says:

Source-to-image (S2I) is a tool for building repeatable docker images.

A command line interface that injects and assembles source code into a docker image.

quarkus example

https://quarkus.io/guides/deploying-to-openshift-s2i

create app

oc new-app quay.io/quarkus/ubi-quarkus-native-s2i:19.2.1~https://github.com/quarkusio/quarkus-quickstarts.git --context-dir=getting-started --name=quarkus-quickstart-native

expose service to the outside world

oc expose svc/quarkus-quickstart-native

delete all resources

oc delete all --selector app=quarkus-quickstart-native

sample application

Simple demonstration of S2I. OpenShift will pull source (our webapp) and build an image based on Wildfly (Application Server).

Our Webapp has a index.html page and one REST API.

OpenShift Console index page REST API: hearbeat

CodeReady Containers

  • OpenShift 4 on local machine with CodeReady Containers, KVM, ...
  • CodeReady Containers isn't Minishift- it's an entirely new approach to running Kubernetes locally.

REMARK: you need a redhat account: https://cloud.redhat.com/openshift/install/crc/installer-provisioned

install

  • you need to download the compress image file from redhad ~ 2GB
https://mirror.openshift.com/pub/openshift-v4/clients/crc/latest/

tar -xvJf crc-linux-amd64.tar.xz
  • create a symbolic link
ln -s crc-linux-1.17.0-amd64/ crc
  • add path to crc in your ~/.profile file and reload it
PATH="$HOME/development/crc:$PATH"
source .profile
  • finally the setup
crc setup

...
Checking if CRC bundle is cached in '$HOME/.crc' 
write NetworkManager config in /etc/NetworkManager/conf.d/crc-nm-dnsmasq.conf
...

quickstart

  • start: crc start (promt for access token / pull_secret)
  • initially around ~10GB will be extracted
Extracting bundle: crc_libvirt_4.5.14.crcbundle ...
  • stop: crc stop
  • open web console: crc console
  • openshift cli: ~/.crc/bin/oc (add bin directory in your path)

virtualbox

CRC virtual machine on ubuntu

  • setup based on with KVM / libvirt (native hypervisor)
  • stop the CodeReady Containers virtual machine and OpenShift cluster: crc stop
  • crc start for debug: crc start --log-level debug
    • you will once prompt for a image pull secret (a personalized secret)
INFO To access the cluster, first set up your environment by following 'crc oc-env' instructions 
INFO Then you can access it by running 'oc login -u developer -p developer https://api.crc.testing:6443' 
INFO To login as an admin, username is 'kubeadmin' and password is 
INFO                                              
INFO You can now run 'crc console' and use these credentials to access the OpenShift web console
  • open web console
$ crc console
Opening the OpenShift Web Console in the default browser...
  • show status
$ crc status
CRC VM:          Running
OpenShift:       Running (v4.2.8)
Disk Usage:      9.364GB of 32.2GB (Inside the CRC VM)
Cache Usage:     11.01GB
Cache Directory: /home/code/.crc/cache

troubleshooting 0

$ crc status
ERRO Unable to connect to the server: dial tcp: lookup api.crc.testing: no such host
 - exit status 1

troubleshooting 1

.crc/machines/crc/crc.qcow2' was not specified in the image metadata (See https://libvirt.org/kbase/backing_chains.html for troubleshooting)')

qemu-img info ~/.crc/cache/crc_libvirt_4.5.14/crc.qcow2
qemu-img rebase -f qcow2 -F qcow2 -b /home/${USER}/.crc/cache/crc_libvirt_4.5.14/crc.qcow2 /home/${USER}/.crc/machines/crc/crc.qcow2
  • now you will face permission issues. either move to libvirt dir OR add path to /etc/apparmor.d/libvirt/TEMPLATE.qemu
sudo mv /home/${USER}/.crc/machines/crc/crc.qcow2 /var/lib/libvirt/images

profile LIBVIRT_TEMPLATE flags=(attach_disconnected) {
  #include <abstractions/libvirt-qemu>
  /home/${USER}/.crc/cache/crc_libvirt_4.5.14/crc.qcow2 rk,
}

links

minishift

  • OpenShift on local machine with CKD, Minishift, Virtualbox

about

  • this description covers the setup with virtualbox under windows. but virtualbox runs also on Linux and Mac.

precondition

  • ensure that you have installed VirtualBox on your (local) host machine

steps to do

  1. our starting point: https://www.okd.io/minishift/

  2. download minishift release https://github.com/minishift/minishift/releases

  3. add minishift dir to Path

  4. set VirtualBox to minishift

minishift config set vm-driver virtualbox
  1. start minishift
  • i choose version 3.9.0 because versions above make trouble on my machine.
  • if you leave memory flag then 4G is default value
minishift start --openshift-version v3.9.0 --memory 8G
  • you can list available openshift versions with the following command
minishift openshift version list
  1. set the oc path to environment
minishift oc-env
  • output:
SET PATH=%userprofile%\.minishift\cache\oc\v3.9.0\windows;%PATH%
REM Run this command to configure your shell:
REM     @FOR /f "tokens=*" %i IN ('minishift oc-env') DO @call %i
  1. now you are ready do use oc cli
oc status
In project My Project (myproject) on server https://192.168.99.100:8443
  1. further commands
  • stop minishift
minishift stop
  • delete minishift
minishift delete
minishift delete --force --clear-cache
  • access (openshift) docker
minishift ssh -- docker ps
  1. centos
  • default login root:centos
  1. troubleshooting
  • if you have connection to port 8443, then ensure to stop process virtualbox DCHP in task / process manager.
Error: Get https://192.168.0.20:8443/healthz/ready: dial tcp 192.168.0.20:8443: connectex: No connection could be made because the target machine actively refused it

cheatsheet

oc create: Create a resource by filename or stdin

oc apply: Apply a configuration to a resource by filename or stdin.

oc new-app: Create a new application by specifying source code, templates, and/or images

oc process: Process template into a list of resources specified in filename or stdin

oc <command> -h or oc <command> --help: for more information about a given command.

oc get: Display one or many resources

oc get template: list templates in project

oc delete template <template>: delete a template in project

oc delete all --selector app=<app>: delete all resources belongs to app

oc get is -n <namespace> or oc get imagestreams -n <namespace>: list images for given namespace

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cookbook for openshift

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virtualbox openshift machine cookbook webapp minishift

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