https://katacoda.com/courses/openshift/playground

oc new-project mygitea
oc new-app -f https://github.com/pschiffe/cloud2/raw/master/gitea-template.yml
oc get all

Wait until:

NAME               READY     STATUS    RESTARTS   AGE
po/gitea-1-ln2jn   1/1       Running   0          44s

Get url:

NAME           HOST/PORT                                                         PATH      SERVICES   PORT      TERMINATION   WILDCARD
routes/gitea   gitea-myproject.2886795373-80-simba02.environments.katacoda.com             gitea      <all>                   None

Install Gitea with following options:

Database Type: SQLite3
Domain: gitea-myproject.2886795373-80-simba02.environments.katacoda.com
Application URL: http:https://gitea-myproject.2886795373-80-simba02.environments.katacoda.com/

Create user in Admin Account Settings.

Click Install Gitea

After the installation is done, you should be logged in your Gitea instance. If you see HTTPS error, accept self-signed certificate, or use HTTP version of the site.

In top right corner click on the plus icon and choose New Migration. Fill in:

Clone Address: https://github.com/pschiffe/ocp-go-webserver.git
Repository Name: ocp-go-webserver

Copy raw url of file openshift/templates/go-web.yml. In OpenShift on Katacoda, create new project and deploy your example app:

oc new-project myapp
oc new-app -f https://github.com/pschiffe/ocp-go-webserver-play/raw/master/openshift/templates/go-web.yml --param=SOURCE_REPOSITORY_URL=https://github.com/pschiffe/ocp-go-webserver-play.git
oc get all

Wait until:

NAME                READY     STATUS      RESTARTS   AGE
po/go-web-1-939bh   1/1       Running     0          5m

Get url and test it in the browser:

NAME            HOST/PORT                                                      PATH      SERVICES   PORT      TERMINATION   WILDCARD
routes/go-web   go-web-myapp.2886795306-80-simba02.environments.katacoda.com             go-web     <all>                   None

You should see Welcome to my website!

oc scale dc/go-web --replicas=5
oc get all

Observe.

In OpenShift, get url of webhook:

oc describe bc/go-web

Webhook Generic:
  URL:  https://172.17.0.42:8443/oapi/v1/namespaces/myapp/buildconfigs/go-web/webhooks/5dRNoPIGPVRkbHo3YHKGexnKORCSaKUd8C4mfrNu/generic

Replace 172.17.0.42:8443 with url of your Dashboard url from left pane, something like 2886795306-8443-simba02.environments.katacoda.com, so the proper webhook is https://2886795306-8443-simba02.environments.katacoda.com/oapi/v1/namespaces/myapp/buildconfigs/go-web/webhooks/5dRNoPIGPVRkbHo3YHKGexnKORCSaKUd8C4mfrNu/generic.

Now copy this webhook to the repo settings in your Gitea. There is Settings button in upper right area under the Fork button, then Webhooks and Add Webhook -> Gitea. Fill in:

Payload URL: https://2886795306-8443-simba02.environments.katacoda.com/oapi/v1/namespaces/myapp/buildconfigs/go-web/webhooks/5dRNoPIGPVRkbHo3YHKGexnKORCSaKUd8C4mfrNu/generic
When should this webhook be triggered?: Just the push event

Click Add Webhook.

In Gitea edit main.go file, change string on line fmt.Fprintf(w, "Welcome to my website!") to something different and save changes. With oc get all you can see now, that new build was started and in a moment, new version of your app will be deployed.

strategy:
  type: Recreate

https://docs.openshift.org/latest/dev_guide/deployments/deployment_strategies.html#recreate-strategy

oc edit dc/go-web

Vim will be opened by default, if you don't know how to use it, run:

EDITOR=nano oc edit dc/go-web

strategy:
  type: Rolling
  rollingParams:
    updatePeriodSeconds: 15
    timeoutSeconds: 60

https://docs.openshift.org/latest/dev_guide/deployments/deployment_strategies.html#rolling-strategy

Instead of:

  http.HandleFunc("/", func (w http.ResponseWriter, r *http.Request) {
    w.Write([]byte("Welcome to my website!"))
  })

Try:

  http.HandleFunc("/", func (w http.ResponseWriter, r *http.Request) {
    w.WriteHeader(http.StatusInternalServerError)
    w.Write([]byte("500 - Something bad happened!"))
  })

oc edit dc/go-web

And delete following sections:

livenessProbe:
  httpGet:
    path: /
    port: 8080
    scheme: HTTP
  initialDelaySeconds: 10
  timeoutSeconds: 1
  periodSeconds: 10
  successThreshold: 1

and

readinessProbe:
  httpGet:
    path: /
    port: 8080
    scheme: HTTP
  initialDelaySeconds: 5
  timeoutSeconds: 1
  periodSeconds: 10
  successThreshold: 1
  failureThreshold: 3

Observe.. and when you have enough:

oc rollout undo --to-revision=2 dc/go-web

If Katacoda is breaking too much for you, fork my repo ocp-go-webserver on GitHub: https://github.com/pschiffe/ocp-go-webserver and use that as a repository instead of Gitea. You can configure webhook as well the same way as described above.

This section doesn't need git or source or anything, just demonstrates advanced deployment strategies.

oc new-project blue-green

oc new-app openshift/deployment-example:v1 --name=example-green
oc new-app openshift/deployment-example:v2 --name=example-blue

oc expose svc/example-green --name=bluegreen-example

oc edit route/bluegreen-example

to:
  name: example-blue

https://docs.openshift.org/latest/dev_guide/deployments/advanced_deployment_strategies.html#advanced-deployment-strategies-blue-green-deployments

oc new-project ab

oc new-app openshift/deployment-example:v1 --name=ab-example-a
oc new-app openshift/deployment-example:v2 --name=ab-example-b

oc expose svc/ab-example-a --name=ab-example

oc set route-backends ab-example ab-example-a=66 ab-example-b=33

oc annotate --overwrite routes/ab-example haproxy.router.openshift.io/disable_cookies=true

https://docs.openshift.org/latest/dev_guide/deployments/advanced_deployment_strategies.html#advanced-deployment-a-b-deployment