Writing your first Ansible operator for OpenShift

Learn how to implement operators on Red Hat OpenShift without any Go code by using Red Hat Ansible Automation. Explore how operators allow you to manage more than stateless applications on your Red Hat OpenShift platform. Operators allow you to define how to create application-specific clusters (and recover from failure), manage version upgrades, and support backup and restore processes.

Transcript

1. @KeithResar WRITING YOUR FIRST _ANSIBLE OPERATOR_ FOR OPENSHIFT #ANSIBLEFEST
3. @KeithResar Operators are _application aware Kubernetes objects._ Active throughout the application’s lifecycle, they manage instantiation, ongoing state, and destruction. #ANSIBLEFEST
4. @KeithResar FROM VISION TO _PROBLEM_ #ANSIBLEFEST
5. @KeithResar _problem:_ _turnkey management of stateless application_ _solution:_ _kubernetes (we just saw this)_ _S2I, Helm_ #ANSIBLEFEST
6. @KeithResar _problem:_ _I’m a vendor or I create stateful apps, _kubernetes doesn’t know anything about me_ #ANSIBLEFEST
7. @KeithResar etcd is a _distributed key value store_ that provides a reliable way to store data across a cluster of machines. Stand-in for your app #ANSIBLEFEST
8. @KeithResar Create and Destroy • Resize • Failover Rolling upgrade • Backup and Restore Stand-in for your app #ANSIBLEFEST
9. @KeithResar _problem:_ _I’m a vendor or I create stateful apps, _kubernetes doesn’t know anything about me_ _solution:_ _create custom resource definitions (CRD)_ #ANSIBLEFEST
10. @KeithResar --- apiVersion: v1 kind: Service metadata: name: simpleapp spec: ports: - name: 8080-tcp port: 8080 protocol: TCP targetPort: 8080 selector: deploymentconfig: simpleapp sessionAffinity: None type: ClusterIP defining a _service_ resource service resources are a built in object type. #ANSIBLEFEST
11. @KeithResar --- apiVersion: etcd.database.coreos.com/v1beta2 kind: EtcdCluster metadata: name: example-etcd-cluster spec: size: 3 version: 3.2.13 defining an _EtcdCluster_ resource Our custom resource looks pretty similar. #ANSIBLEFEST
15. @KeithResar _problem:_ _golang isn’t going to fly_ _solution:_ _skip go, succeed with helm charts or ansible_ #ANSIBLEFEST
16. @KeithResar EVERY PROBLEM BRINGS A _SOLUTION_ #ANSIBLEFEST
17. @KeithResar DS AS API Server Cluster Workload Compare desired state with actual state Reconcile process converges to desired state
18. @KeithResar DS AS API Server 01010001 01010010 10101011 01011001 0101001 01010001 01010010 10101011 01011001 0101001 Cluster Workload 01010001 01010010 10101011 01011001 0101001 1x simpleapp 2x simpleapp 01010001 01010010 10101011 01011001 0101001 #ANSIBLEFEST
19. @KeithResar DS AS API Server Cluster Workload Native K8s objects like... Pods Services Deployments etc. #ANSIBLEFEST
20. @KeithResar AS DS _* operator_ watch reconcile action _________ _______________________ ______ _____________________________ #ANSIBLEFEST
21. @KeithResar AS DS _Ansible operator_ watch reconcile ansible-runner _________ _______________________ ______ _____________________________ Ansible playbook or role This is the only component you need to worry about! #ANSIBLEFEST
22. @KeithResar kubernetes layer application layer #ANSIBLEFEST
23. @KeithResar kubernetes layer ETCD pod ETCD pod Phase I Manage native K8s objects application layer #ANSIBLEFEST
24. @KeithResar application layer kubernetes layer ETCD pod ETCD pod Phase II Manage application objects 01001 etcd data 01001 etcd data #ANSIBLEFEST
25. @KeithResar A GIFT OF THE _DEMO_ TO YOU #ANSIBLEFEST
26. @KeithResar Demo Operator for data service _SimpleDB,_ that manages instantiation and version upgrades. RBAC CRD CR DC #ANSIBLEFEST
27. @KeithResar Create service account, role, and role binding. Our operator uses these to monitor events and reconcile desired and actual states. RBAC CRD CR DC #ANSIBLEFEST
28. @KeithResar AS DS _Ansible operator_ watch reconcile ansible-runner _________ _______________________ ______ _____________________________ #ANSIBLEFEST
29. @KeithResar Define the custom resource SimpleDB. This extends what Kubernetes accepts, but doesn’t actually change any behavior. RBAC CRD CR DC #ANSIBLEFEST
30. @KeithResar Define and deploy the Ansible Operator container which executes an ansible-runner process. RBAC CRD CR DC #ANSIBLEFEST
31. @KeithResar AS DS _Ansible operator_ watch reconcile ansible-runner _________ _______________________ ______ _____________________________ #ANSIBLEFEST
32. @KeithResar RBAC CRD CR DC # Dockerfile FROM quay.io/water-hole/ansible-operator USER root RUN yum -y install MySQL-python && \ pip --no-cache-dir install dnspython COPY roles/ ${HOME}/roles/ COPY playbook.yaml ${HOME}/playbook.yaml COPY watches.yaml ${HOME}/watches.yaml #ANSIBLEFEST
33. @KeithResar AS DS _Ansible operator_ watch reconcile ansible-runner _________ _______________________ ______ _____________________________ #ANSIBLEFEST
34. @KeithResar RBAC CRD CR DC # Dockerfile FROM quay.io/water-hole/ansible-operator USER root RUN yum -y install MySQL-python && \ pip --no-cache-dir install dnspython COPY roles/ ${HOME}/roles/ COPY playbook.yaml ${HOME}/playbook.yaml COPY watches.yaml ${HOME}/watches.yaml #ANSIBLEFEST
35. @KeithResar RBAC CRD CR DC # roles/SimpleDB/tasks/main.yml --- #ANSIBLEFEST
36. @KeithResar RBAC CRD CR DC # roles/SimpleDB/tasks/main.yml --- # … (skip setting some variables) #ANSIBLEFEST
37. @KeithResar RBAC CRD CR DC # roles/SimpleDB/tasks/main.yml --- # … (skip setting some variables) # If no service defined then run our install playbook # This is idempotent so we could run it regardless - include_tasks: mariadb_install.yml when: mysql_ip == "NXDOMAIN" #ANSIBLEFEST
38. @KeithResar RBAC CRD CR DC # roles/SimpleDB/tasks/main.yml --- # … (skip setting some variables) # If no service defined then run our install playbook # This is idempotent so we could run it regardless - include_tasks: mariadb_install.yml when: mysql_ip == "NXDOMAIN" # Run our upgrade path if we need to change versions - include_tasks: mariadb_upgrade.yml when: version != version_query.json.version #ANSIBLEFEST
39. @KeithResar AS DS _Ansible operator_ watch reconcile ansible-runner _________ _______________________ ______ _____________________________ #ANSIBLEFEST
40. @KeithResar Instantiate our custom resource object. The operator is listening for any SimpleDB events in our namespace. RBAC CRD CR DC #ANSIBLEFEST
41. @KeithResar RBAC CRD CR DC --- apiVersion: example.com/v1alpha1 kind: SimpleDB metadata: name: simpledb spec: # Add fields here version: 1 #ANSIBLEFEST
42. @KeithResar AS DS _Ansible operator_ watch reconcile ansible-runner _________ _______________________ ______ _____________________________ Ansible playbook or role This is the only component you need to worry about! #ANSIBLEFEST
43. @KeithResar GO FARTHER WITH THESE _RESOURCES_ • OperatorHub • Introducing the operator framework • water-hole’s ansible-operator repo • ansible-operator-demo repo • Awesome operators in the wild #ANSIBLEFEST