Using Ansible inside an Operator

Using Ansible inside an Operator

After you are familiar with using the Kubernetes Collection for Ansible locally, you can trigger the same Ansible logic inside of an Operator when a custom resource (CR) changes. This example maps an Ansible role to a specific Kubernetes resource that the Operator watches. This mapping is done in the watches.yaml file.

Custom resource files

Operators use the Kubernetes extension mechanism, custom resource definitions (CRDs), so your custom resource (CR) looks and acts just like the built-in, native Kubernetes objects.

The CR file format is a Kubernetes resource file. The object has mandatory and optional fields:

Table 1. Custom resource fields
Field	Description
`apiVersion`	Version of the CR to be created.
`kind`	Kind of the CR to be created.
`metadata`	Kubernetes-specific metadata to be created.
`spec` (optional)	Key-value list of variables which are passed to Ansible. This field is empty by default.
`status`	Summarizes the current state of the object. For Ansible-based Operators, the `status` subresource is enabled for CRDs and managed by the `operator_sdk.util.k8s_status` Ansible module by default, which includes `condition` information to the CR `status`.
`annotations`	Kubernetes-specific annotations to be appended to the CR.

The following list of CR annotations modify the behavior of the Operator:

Table 2. Ansible-based Operator annotations
Annotation	Description
`ansible.operator-sdk/reconcile-period`	Specifies the reconciliation interval for the CR. This value is parsed using the standard Golang package `time`. Specifically, `ParseDuration` is used which applies the default suffix of `s`, giving the value in seconds.

Example Ansible-based Operator annotation

apiVersion: "test1.example.com/v1alpha1"
kind: "Test1"
metadata:
  name: "example"
annotations:
  ansible.operator-sdk/reconcile-period: "30s"

Testing an Ansible-based Operator locally

You can test the logic inside of an Ansible-based Operator running locally by using the make run command from the top-level directory of your Operator project. The make run Makefile target runs the ansible-operator binary locally, which reads from the watches.yaml file and uses your ~/.kube/config file to communicate with a Kubernetes cluster just as the k8s modules do.

You can customize the roles path by setting the environment variable ANSIBLE_ROLES_PATH or by using the ansible-roles-path flag. If the role is not found in the ANSIBLE_ROLES_PATH value, the Operator looks for it in {{current directory}}/roles.

Prerequisites

Ansible Runner version v1.1.0+
Ansible Runner HTTP Event Emitter plug-in version v1.0.0+
Performed the previous steps for testing the Kubernetes Collection locally

Procedure

Install your custom resource definition (CRD) and proper role-based access control (RBAC) definitions for your custom resource (CR):

$ make install

Example output

/usr/bin/kustomize build config/crd | kubectl apply -f -
customresourcedefinition.apiextensions.k8s.io/memcacheds.cache.example.com created

Run the make run command:

$ make run

Example output

/home/user/memcached-operator/bin/ansible-operator run
{"level":"info","ts":1612739145.2871568,"logger":"cmd","msg":"Version","Go Version":"go1.15.5","GOOS":"linux","GOARCH":"amd64","ansible-operator":"v1.3.0","commit":"1abf57985b43bf6a59dcd18147b3c574fa57d3f6"}
...
{"level":"info","ts":1612739148.347306,"logger":"controller-runtime.metrics","msg":"metrics server is starting to listen","addr":":8080"}
{"level":"info","ts":1612739148.3488882,"logger":"watches","msg":"Environment variable not set; using default value","envVar":"ANSIBLE_VERBOSITY_MEMCACHED_CACHE_EXAMPLE_COM","default":2}
{"level":"info","ts":1612739148.3490262,"logger":"cmd","msg":"Environment variable not set; using default value","Namespace":"","envVar":"ANSIBLE_DEBUG_LOGS","ANSIBLE_DEBUG_LOGS":false}
{"level":"info","ts":1612739148.3490646,"logger":"ansible-controller","msg":"Watching resource","Options.Group":"cache.example.com","Options.Version":"v1","Options.Kind":"Memcached"}
{"level":"info","ts":1612739148.350217,"logger":"proxy","msg":"Starting to serve","Address":"127.0.0.1:8888"}
{"level":"info","ts":1612739148.3506632,"logger":"controller-runtime.manager","msg":"starting metrics server","path":"/metrics"}
{"level":"info","ts":1612739148.350784,"logger":"controller-runtime.manager.controller.memcached-controller","msg":"Starting EventSource","source":"kind source: cache.example.com/v1, Kind=Memcached"}
{"level":"info","ts":1612739148.5511978,"logger":"controller-runtime.manager.controller.memcached-controller","msg":"Starting Controller"}
{"level":"info","ts":1612739148.5512562,"logger":"controller-runtime.manager.controller.memcached-controller","msg":"Starting workers","worker count":8}

With the Operator now watching your CR for events, the creation of a CR will trigger your Ansible role to run.

Consider an example config/samples/<gvk>.yaml CR manifest:

apiVersion: <group>.example.com/v1alpha1
kind: <kind>
metadata:
  name: “<kind>-sample”

Because the spec field is not set, Ansible is invoked with no extra variables. Passing extra variables from a CR to Ansible is covered in another section. It is important to set reasonable defaults for the Operator.

Create an instance of your CR with the default variable state set to present:
```
$ oc apply -f config/samples/<gvk>.yaml
```

Check that the example-config config map was created:

$ oc get configmaps

Example output

NAME                    STATUS    AGE
example-config          Active    3s

Modify your config/samples/<gvk>.yaml file to set the state field to absent. For example:

apiVersion: cache.example.com/v1
kind: Memcached
metadata:
  name: memcached-sample
spec:
  state: absent

Apply the changes:
```
$ oc apply -f config/samples/<gvk>.yaml
```
Confirm that the config map is deleted:
```
$ oc get configmap
```

Testing an Ansible-based Operator on the cluster

After you have tested your custom Ansible logic locally inside of an Operator, you can test the Operator inside of a pod on an OKD cluster, which is prefered for production use.

You can run your Operator project as a deployment on your cluster.

Procedure

Run the following make commands to build and push the Operator image. Modify the IMG argument in the following steps to reference a repository that you have access to. You can obtain an account for storing containers at repository sites such as Quay.io.

Build the image:

$ make docker-build IMG=<registry>/<user>/<image_name>:<tag>

Push the image to a repository:

$ make docker-push IMG=<registry>/<user>/<image_name>:<tag>

The name and tag of the image, for example IMG=<registry>/<user>/<image_name>:<tag>, in both the commands can also be set in your Makefile. Modify the IMG ?= controller:latest value to set your default image name.

Run the following command to deploy the Operator:
```
$ make deploy IMG=<registry>/<user>/<image_name>:<tag>
```
By default, this command creates a namespace with the name of your Operator project in the form <project_name>-system and is used for the deployment. This command also installs the RBAC manifests from config/rbac.

Verify that the Operator is running:

$ oc get deployment -n <project_name>-system

Example output

NAME                                    READY   UP-TO-DATE   AVAILABLE   AGE
<project_name>-controller-manager       1/1     1            1           8m

Ansible logs

Ansible-based Operators provide logs about the Ansible run, which can be useful for debugging your Ansible tasks. The logs can also contain detailed information about the internals of the Operator and its interactions with Kubernetes.

Viewing Ansible logs

Prerequisites

Ansible-based Operator running as a deployment on a cluster

Procedure

To view logs from an Ansible-based Operator, run the following command:

$ oc logs deployment/<project_name>-controller-manager \
    -c manager \(1)
    -n <namespace> (2)

1	View logs from the `manager` container.
2	If you used the `make deploy` command to run the Operator as a deployment, use the `<project_name>-system` namespace.

Example output

{"level":"info","ts":1612732105.0579333,"logger":"cmd","msg":"Version","Go Version":"go1.15.5","GOOS":"linux","GOARCH":"amd64","ansible-operator":"v1.3.0","commit":"1abf57985b43bf6a59dcd18147b3c574fa57d3f6"}
{"level":"info","ts":1612732105.0587437,"logger":"cmd","msg":"WATCH_NAMESPACE environment variable not set. Watching all namespaces.","Namespace":""}
I0207 21:08:26.110949       7 request.go:645] Throttling request took 1.035521578s, request: GET:https://172.30.0.1:443/apis/flowcontrol.apiserver.k8s.io/v1alpha1?timeout=32s
{"level":"info","ts":1612732107.768025,"logger":"controller-runtime.metrics","msg":"metrics server is starting to listen","addr":"127.0.0.1:8080"}
{"level":"info","ts":1612732107.768796,"logger":"watches","msg":"Environment variable not set; using default value","envVar":"ANSIBLE_VERBOSITY_MEMCACHED_CACHE_EXAMPLE_COM","default":2}
{"level":"info","ts":1612732107.7688773,"logger":"cmd","msg":"Environment variable not set; using default value","Namespace":"","envVar":"ANSIBLE_DEBUG_LOGS","ANSIBLE_DEBUG_LOGS":false}
{"level":"info","ts":1612732107.7688901,"logger":"ansible-controller","msg":"Watching resource","Options.Group":"cache.example.com","Options.Version":"v1","Options.Kind":"Memcached"}
{"level":"info","ts":1612732107.770032,"logger":"proxy","msg":"Starting to serve","Address":"127.0.0.1:8888"}
I0207 21:08:27.770185       7 leaderelection.go:243] attempting to acquire leader lease  memcached-operator-system/memcached-operator...
{"level":"info","ts":1612732107.770202,"logger":"controller-runtime.manager","msg":"starting metrics server","path":"/metrics"}
I0207 21:08:27.784854       7 leaderelection.go:253] successfully acquired lease memcached-operator-system/memcached-operator
{"level":"info","ts":1612732107.7850506,"logger":"controller-runtime.manager.controller.memcached-controller","msg":"Starting EventSource","source":"kind source: cache.example.com/v1, Kind=Memcached"}
{"level":"info","ts":1612732107.8853772,"logger":"controller-runtime.manager.controller.memcached-controller","msg":"Starting Controller"}
{"level":"info","ts":1612732107.8854098,"logger":"controller-runtime.manager.controller.memcached-controller","msg":"Starting workers","worker count":4}

Enabling full Ansible results in logs

You can set the environment variable ANSIBLE_DEBUG_LOGS to True to enable checking the full Ansible result in logs, which can be helpful when debugging.

Procedure

Edit the config/manager/manager.yaml and config/default/manager_auth_proxy_patch.yaml files to include the following configuration:

      containers:
      - name: manager
        env:
        - name: ANSIBLE_DEBUG_LOGS
          value: "True"

Enabling verbose debugging in logs

While developing an Ansible-based Operator, it can be helpful to enable additional debugging in logs.

Procedure

Add the ansible.sdk.operatorframework.io/verbosity annotation to your custom resource to enable the verbosity level that you want. For example:

apiVersion: "cache.example.com/v1alpha1"
kind: "Memcached"
metadata:
  name: "example-memcached"
  annotations:
    "ansible.sdk.operatorframework.io/verbosity": "4"
spec:
  size: 4