Ansible Operator Advanced Options

This document shows the advanced options available to a developer of an ansible operator.

Runner Directory

The ansible runner will keep information about the ansible run in the container. This is located /tmp/ansible-operator/runner/<group>/<version>/<kind>/<namespace>/<name>. To learn more about the runner directory you can read the ansible-runner docs.

Owner Reference Injection

Owner references enable Kubernetes Garbage Collection to clean up after a CR is deleted. Owner references are injected by ansible operators by default by the proxy.

Owner references only apply to resources in the same namespace as the CR. Resources outside the namespace of the CR will automatically be annotated with operator-sdk/primary-resource and operator-sdk/primary-resource-type to track creation. These resources will not be automatically garbage collected. To handle deletion of these resources, use a finalizer.

You may want to manage what your operator watches and the owner references. This means that your operator will need to understand how to clean up after itself when your CR is deleted. To disable these features you will need to edit your Dockerfile to include the line below.

NOTE: That if you use this feature there will be a warning that dependent watches is turned off but there will be no error. WARNING: Once a CR is deployed without owner reference injection, there is no automatic way to add those references.

ENTRYPOINT ["/usr/local/bin/entrypoint", "--inject-owner-ref=false"]

If you have created resources without owner reference injection, it is possible to manually to update resources following this guide.

Max Concurrent Reconciles

Increasing the number of concurrent reconciles allows events to be processed concurrently, which can improve reconciliation performance.

The maximum number of concurrent reconciles can be set in two ways. Operator authors and admins can set the max concurrent reconciles default by including extra args to the operator container in config/manager/manager.yaml and the patch in config/default/auth_proxy_patch.yaml. (Otherwise, the default is the maximum number of logical CPUs available for the process obtained using runtime.NumCPU().)

NOTE: Admins using OLM should use the environment variable instead of the extra args.

- name: manager
  image: "quay.io/asmacdo/memcached-operator:v0.0.0"
  imagePullPolicy: "Always"
  args:
    - "--max-concurrent-reconciles"
    - "3"

Operator admins can override the value by setting an environment variable in the format MAX_CONCURRENT_RECONCILES_<kind>_<group>. This variable must be all uppercase, and periods (e.g. in the group name) are replaced with underscores.

For the memcached operator example, the component parts are retrieved with a GET on the operator:

$ kubectl get memcacheds example-memcached -o yaml

apiVersion: cache.example.com/v1alpha1
kind: Memcached
metadata:
  name: example-memcached
  namespace: default

From this data, we can see that the environment variable will be MAX_CONCURRENT_RECONCILES_MEMCACHED_CACHE_EXAMPLE_COM, which we can then add to config/manager/manager.yaml and config/default/auth_proxy_patch.yaml:

- name: manager
  image: "quay.io/asmacdo/memcached-operator:v0.0.0"
  imagePullPolicy: "Always"
  args:
    # This default is overridden.
    - "--max-concurrent-reconciles"
    - "3"
  env:
    # This value is used
    - name: MAX_CONCURRENT_RECONCILES_MEMCACHED_CACHE_EXAMPLE_COM
      value: "6"

Ansible Verbosity

Setting the verbosity at which ansible-runner is run controls how verbose the output of ansible-playbook will be. The normal rules for verbosity apply here, where higher values mean more output. Acceptable values range from 0 (only the most severe messages are output) to 7 (all debugging messages are output).

There are three ways to configure the verbosity argument to the ansible-runner command:

  1. Operator authors and admins can set the Ansible verbosity by including extra args to the operator container in the operator deployment.
  2. Operator admins can set Ansible verbosity by setting an environment variable in the format ANSIBLE_VERBOSITY_<kind>_<group>. This variable must be all uppercase and all periods (e.g. in the group name) are replaced with underscore.
  3. Operator users, authors, and admins can set the Ansible verbosity by setting the "ansible.sdk.operatorframework.io/verbosity" annotation on the Custom Resource.

Examples

For demonstration purposes, let us assume that we have a database operator that supports two Kinds – MongoDB and PostgreSQL – in the db.example.com Group. We have only recently implemented the support for the MongoDB Kind so we want reconciles for this Kind to be more verbose. Our operator container’s spec in our config/manager/manager.yaml and config/default/auth_proxy_patch.yaml files might contiain something like:

- name: manager
  image: "quay.io/example/database-operator:v1.0.0"
  imagePullPolicy: "Always"
  args:
    # This value applies to all GVKs specified in watches.yaml
    # that are not overriden by environment variables.
    - "--ansible-verbosity"
    - "1"
  env:
    # Override the verbosity for the MongoDB kind
    - name: ANSIBLE_VERBOSITY_MONGODB_DB_EXAMPLE_COM
      value: "4"

Once the Operator is deployed, the only way to change the verbosity is via the "ansible.sdk.operatorframework.io/verbosity" annotation. Continuing with our example, our CR may look like:

apiVersion: "db.example.com/v1"
kind: "PostgreSQL"
metadata:
  name: "example-db"
  annotations:
    "ansible.sdk.operatorframework.io/verbosity": "5"
spec: {}

Custom Resources with OpenAPI Validation

Currently, SDK tool does not support and will not generate automatically the CRD’s using the OpenAPI spec to perform validations.

However, it can be done manually by adding its validations as you can check in the following example.

Example

apiVersion: apiextensions.k8s.io/v1beta1
kind: CustomResourceDefinition
metadata:
  name: memcacheds.cache.example.com
spec:
  group: cache.example.com
  names:
    kind: Memcached
    listKind: MemcachedList
    plural: memcacheds
    singular: memcached
  scope: Namespaced
  subresources:
    status: {}
  validation:
    openAPIV3Schema:
      description: Memcached is the Schema for the memcacheds API
      properties:
        apiVersion:
          description: 'APIVersion defines the versioned schema of this representation
            of an object. Servers should convert recognized schemas to the latest
            internal value, and may reject unrecognized values. More info: https://git.k8s.io/community/contributors/devel/sig-architecture/api-conventions.md#resources'
          type: string
        kind:
          description: 'Kind is a string value representing the REST resource this
            object represents. Servers may infer this from the endpoint the client
            submits requests to. Cannot be updated. In CamelCase. More info: https://git.k8s.io/community/contributors/devel/sig-architecture/api-conventions.md#types-kinds'
          type: string
        metadata:
          type: object
        spec:
          description: MemcachedSpec defines the desired state of Memcached
          properties:
            size:
              description: Size is the size of the memcached deployment
              format: int32
              type: integer
          required:
          - size
          type: object
        status:
          description: MemcachedStatus defines the observed state of Memcached
          properties:
            nodes:
              description: Nodes are the names of the memcached pods
              items:
                type: string
              type: array
          required:
          - nodes
          type: object
      type: object
  versions:
  - name: v1alpha1
    served: true
    storage: true

Passing Arbitrary Arguments to Ansible

You are able to use the flag --ansible-args to pass an arbitrary argument to the Ansible-based Operator. With this option we can, for example, allow a playbook to run a specific part of the configuration without running the whole playbook:

ansible-operator run --ansible-args='--tags "configuration,packages"'
ansible-operator run --ansible-args='--skip-tags "notification"'

Ansible-runner will perform the task relevant to the command specified by the user in the ---ansible-args flag.

Using Ansible-Vault

Ansible Vault allows you to keep sensitive data such as passwords or keys in encrypted files, rather than as plaintext in playbooks or roles. You can specify Ansible-Vault file via an arbitrary argument by using the --ansible-args flag. For example, let’s assume that a playbook reads in a file vars.yml which contains an encrypted text and stores it in a variable secret:

---
- name: Playbook to print debug messages
  hosts: localhost
  tasks:
    - name: Get the decrypted message variable
      include_vars:
        file: vars.yml
        name: secret
    - debug:
        msg: The decrypted value is {{secret.the_secret}}

Now, let’s also assume that we have a password file, pwd.yml, that contains the password to decrypt the encrypted text. Then, by running the command ansible-operator run --ansible-args='--vault-password-file pwd.yml' the operator will read in the encrypted text from the file and perform decryption using the password stored in the pwd.yml file:

--------------------------- Ansible Task StdOut -------------------------------

 TASK [debug] ******************************** 
ok: [localhost] => {
    "msg": "The decrypted value is DECRYPTED-TEST-VALUE"
}

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Last modified September 28, 2020: Disable fact gathering by default (#3933) (80c83e34)