Add ZooKeeper Quickstart (#634)

* Add ZooKeeper Quickstart

Signed-off-by: AbdullahAlShaad <[email protected]>

docs/examples/zookeeper/quickstart/zoo.yaml

@@ -0,0 +1,17 @@
+apiVersion: kubedb.com/v1alpha2
+kind: ZooKeeper
+metadata:
+  name: zk-quickstart
+  namespace: demo
+spec:
+  version: "3.9.1"
+  adminServerPort: 8080
+  replicas: 3
+  storage:
+    resources:
+      requests:
+        storage: "1Gi"
+    storageClassName: "standard"
+    accessModes:
+      - ReadWriteOnce
+  terminationPolicy: "WipeOut"

docs/guides/README.md

@@ -28,4 +28,5 @@ Guides to show you how to perform tasks with KubeDB:
 - [ProxySQL](/docs/guides/proxysql/README.md). Shows how to manage ProxySQL using KubeDB.
 - [Redis](/docs/guides/redis/README.md). Shows how to manage Redis using KubeDB.
 - [Kafka](/docs/guides/kafka/README.md). Shows how to manage Kafka using KubeDB.
+- [ZooKeeper](/docs/guides/zookeeper/README.md). Shows how to manage ZooKeeper using KubeDB.
 - [SingleStore](/docs/guides/singlestore/README.md). Shows how to manage SingleStore using KubeDB.

docs/guides/zookeeper/README.md

@@ -0,0 +1,48 @@
+---
+title: ZooKeeper
+menu:
+  docs_{{ .version }}:
+    identifier: zk-readme-zookeeper
+    name: ZooKeeper
+    parent: zk-zookeeper-guides
+    weight: 10
+menu_name: docs_{{ .version }}
+section_menu_id: guides
+url: /docs/{{ .version }}/guides/zookeeper/
+aliases:
+  - /docs/{{ .version }}/guides/zookeeper/README/
+---
+
+> New to KubeDB? Please start [here](/docs/README.md).
+
+## Supported ZooKeeper Features
+| Features                                                                  | Availability |
+|---------------------------------------------------------------------------|:------------:|
+| Ensemble                                                                  |   ✓   |
+| Standalone                                                                |   ✓   |
+| Authentication & Autorization                                             |   ✓   | 
+| Custom Configuration                                                      |   ✓   | 
+| Grafana Dashboards                                                        |   ✓   | 
+| Externally manageable Auth Secret                                         |   ✓   |
+| Reconfigurable Health Checker                                             |   ✓   |
+| Backup/Recovery: Instant, Scheduled ([KubeStash](https://kubestash.com/)) |   ✓   | 
+| Persistent Volume                                                         |   ✓   |
+| Initializing from Snapshot ( [Stash](https://stash.run/) )                |   ✓   |
+| Builtin Prometheus Discovery                                              |   ✓   | 
+| Using Prometheus operator                                                 |   ✓   |
+
+## Life Cycle of a ZooKeeper Object
+
+<p align="center">
+  <img alt="lifecycle"  src="/docs/images/zookeeper/zookeeper-lifecycle.png">
+</p>
+
+## User Guide
+
+- [Quickstart ZooKeeper](/docs/guides/zookeeper/quickstart/quickstart.md) with KubeDB Operator.
+- Detail Concept of [ZooKeeper Object](/docs/guides/zookeeper/concepts/zookeeper.md).
+
+
+## Next Steps
+
+- Want to hack on KubeDB? Check our [contribution guidelines](/docs/CONTRIBUTING.md).

docs/guides/zookeeper/_index.md

@@ -0,0 +1,10 @@
+---
+title: ZooKeeper
+menu:
+  docs_{{ .version }}:
+    identifier: zk-zookeeper-guides
+    name: ZooKeeper
+    parent: guides
+    weight: 12
+menu_name: docs_{{ .version }}
+---

docs/guides/zookeeper/concepts/_index.md

@@ -0,0 +1,10 @@
+---
+title: ZooKeeper Concepts
+menu:
+  docs_{{ .version }}:
+    identifier: zk-concepts-zookeeper
+    name: Concepts
+    parent: zk-zookeeper-guides
+    weight: 20
+menu_name: docs_{{ .version }}
+---

docs/guides/zookeeper/concepts/appbinding.md

@@ -0,0 +1,140 @@
+---
+title: AppBinding CRD
+menu:
+  docs_{{ .version }}:
+    identifier: zk-appbinding-concepts
+    name: AppBinding
+    parent: zk-concepts-zookeeper
+    weight: 30
+menu_name: docs_{{ .version }}
+section_menu_id: guides
+---
+
+> New to KubeDB? Please start [here](/docs/README.md).
+
+# AppBinding
+
+## What is AppBinding
+
+An `AppBinding` is a Kubernetes `CustomResourceDefinition`(CRD) which points to an application using either its URL (usually for a non-Kubernetes resident service instance) or a Kubernetes service object (if self-hosted in a Kubernetes cluster), some optional parameters and a credential secret. To learn more about AppBinding and the problems it solves, please read this blog post: [The case for AppBinding](https://appscode.com/blog/post/the-case-for-appbinding).
+
+If you deploy a database using [KubeDB](https://kubedb.com/docs/0.11.0/concepts/), `AppBinding` object will be created automatically for it. Otherwise, you have to create an `AppBinding` object manually pointing to your desired database.
+
+KubeDB uses [Stash](https://appscode.com/products/stash/) to perform backup/recovery of databases. Stash needs to know how to connect with a target database and the credentials necessary to access it. This is done via an `AppBinding`.
+
+## AppBinding CRD Specification
+
+Like any official Kubernetes resource, an `AppBinding` has `TypeMeta`, `ObjectMeta` and `Spec` sections. However, unlike other Kubernetes resources, it does not have a `Status` section.
+
+An `AppBinding` object created by `KubeDB` for ZooKeeper database is shown below,
+
+```yaml
+apiVersion: appcatalog.appscode.com/v1alpha1
+kind: AppBinding
+metadata:
+  annotations:
+    kubectl.kubernetes.io/last-applied-configuration: |
+      {"apiVersion":"kubedb.com/v1alpha2","kind":"ZooKeeper","metadata":{"annotations":{},"name":"zk-cluster","namespace":"demo"},"spec":{"podTemplate":{"spec":{"containers":[{"name":"zookeeper","resources":{"requests":{"cpu":"720m","memory":"846Mi"}}}]}},"replicas":3,"serviceTemplates":[{"alias":"primary","spec":{"type":"LoadBalancer"}}],"storage":{"accessModes":["ReadWriteOnce"],"resources":{"requests":{"storage":"1Gi"}},"storageClassName":"standard"},"terminationPolicy":"WipeOut","version":"3.9.1"}}
+  creationTimestamp: "2024-05-02T10:02:45Z"
+  generation: 2
+  labels:
+    app.kubernetes.io/component: database
+    app.kubernetes.io/instance: zk-cluster
+    app.kubernetes.io/managed-by: kubedb.com
+    app.kubernetes.io/name: zookeepers.kubedb.com
+  name: zk-cluster
+  namespace: demo
+  ownerReferences:
+    - apiVersion: kubedb.com/v1alpha2
+      blockOwnerDeletion: true
+      controller: true
+      kind: ZooKeeper
+      name: zk-cluster
+      uid: 20e00408-abf1-470b-a049-bdf272b3e994
+  resourceVersion: "3548"
+  uid: 8fd15549-ab9c-4523-b85d-77275f620bb5
+spec:
+  appRef:
+    apiGroup: kubedb.com
+    kind: ZooKeeper
+    name: zk-cluster
+    namespace: demo
+  clientConfig:
+    service:
+      name: zk-cluster
+      port: 2181
+      scheme: http
+  secret:
+    name: zk-cluster-auth
+  type: kubedb.com/zookeeper
+  version: 3.9.1
+```
+
+Here, we are going to describe the sections of an `AppBinding` crd.
+
+### AppBinding `Spec`
+
+An `AppBinding` object has the following fields in the `spec` section:
+
+#### spec.type
+
+`spec.type` is an optional field that indicates the type of the app that this `AppBinding` is pointing to. Stash uses this field to resolve the values of `TARGET_APP_TYPE`, `TARGET_APP_GROUP` and `TARGET_APP_RESOURCE` variables of [BackupBlueprint](https://appscode.com/products/stash/latest/concepts/crds/backupblueprint/) object.
+
+This field follows the following format: `<app group>/<resource kind>`. The above AppBinding is pointing to a `zookeeper` resource under `kubedb.com` group.
+
+Here, the variables are parsed as follows:
+
+|       Variable        | Usage                                                                                                                          |
+| --------------------- |--------------------------------------------------------------------------------------------------------------------------------|
+| `TARGET_APP_GROUP`    | Represents the application group where the respective app belongs (i.e: `kubedb.com`).                                         |
+| `TARGET_APP_RESOURCE` | Represents the resource under that application group that this appbinding represents (i.e: `zookeeper`).                           |
+| `TARGET_APP_TYPE`     | Represents the complete type of the application. It's simply `TARGET_APP_GROUP/TARGET_APP_RESOURCE` (i.e: `kubedb.com/zookeeper`). |
+
+#### spec.secret
+
+`spec.secret` specifies the name of the secret which contains the credentials that are required to access the database. This secret must be in the same namespace as the `AppBinding`.
+
+This secret must contain the following keys:
+
+| Key        | Usage                                          |
+| ---------- | ---------------------------------------------- |
+| `username` | Username of the target database.               |
+| `password` | Password for the user specified by `username`. |
+
+
+
+#### spec.appRef
+appRef refers to the underlying application. It has 4 fields named `apiGroup`, `kind`, `name` & `namespace`.
+
+#### spec.clientConfig
+
+`spec.clientConfig` defines how to communicate with the target database. You can use either a URL or a Kubernetes service to connect with the database. You don't have to specify both of them.
+
+You can configure following fields in `spec.clientConfig` section:
+
+- **spec.clientConfig.url**
+
+  `spec.clientConfig.url` gives the location of the database, in standard URL form (i.e. `[scheme://]host:port/[path]`). This is particularly useful when the target database is running outside of the Kubernetes cluster. If your database is running inside the cluster, use `spec.clientConfig.service` section instead.
+
+> Note that, attempting to use a user or basic auth (e.g. `user:password@host:port`) is not allowed. Stash will insert them automatically from the respective secret. Fragments ("#...") and query parameters ("?...") are not allowed either.
+
+- **spec.clientConfig.service**
+
+  If you are running the database inside the Kubernetes cluster, you can use Kubernetes service to connect with the database. You have to specify the following fields in `spec.clientConfig.service` section if you manually create an `AppBinding` object.
+
+  - **name :** `name` indicates the name of the service that connects with the target database.
+  - **scheme :** `scheme` specifies the scheme (i.e. http, https) to use to connect with the database.
+  - **port :** `port` specifies the port where the target database is running.
+
+- **spec.clientConfig.insecureSkipTLSVerify**
+
+  `spec.clientConfig.insecureSkipTLSVerify` is used to disable TLS certificate verification while connecting with the database. We strongly discourage to disable TLS verification during backup. You should provide the respective CA bundle through `spec.clientConfig.caBundle` field instead.
+
+- **spec.clientConfig.caBundle**
+
+  `spec.clientConfig.caBundle` is a PEM encoded CA bundle which will be used to validate the serving certificate of the database.
+
+## Next Steps
+
+- Learn how to use KubeDB to manage various databases [here](/docs/guides/README.md).
+- Want to hack on KubeDB? Check our [contribution guidelines](/docs/CONTRIBUTING.md).

docs/guides/zookeeper/concepts/catalog.md

@@ -0,0 +1,111 @@
+---
+title: ZooKeeperVersion CRD
+menu:
+  docs_{{ .version }}:
+    identifier: zk-catalog-concepts
+    name: ZooKeeperVersion
+    parent: zk-concepts-zookeeper
+    weight: 20
+menu_name: docs_{{ .version }}
+section_menu_id: guides
+---
+
+> New to KubeDB? Please start [here](/docs/README.md).
+
+# ZooKeeperVersion
+
+## What is ZooKeeperVersion
+
+`ZooKeeperVersion` is a Kubernetes `Custom Resource Definitions` (CRD). It provides a declarative configuration to specify the docker images to be used for [ZooKeeper](https://zookeeper.apache.org/) database deployed with KubeDB in a Kubernetes native way.
+
+When you install KubeDB, a `ZooKeeperVersion` custom resource will be created automatically for every supported ZooKeeper versions. You have to specify the name of `ZooKeeperVersion` crd in `spec.version` field of [ZooKeeper](/docs/guides/zookeeper/concepts/zookeeper.md) crd. Then, KubeDB will use the docker images specified in the `ZooKeeperVersion` crd to create your expected database.
+
+Using a separate crd for specifying respective docker images, and pod security policy names allow us to modify the images, and policies independent of KubeDB operator. This will also allow the users to use a custom image for the database.
+
+## ZooKeeperVersion Specification
+
+As with all other Kubernetes objects, a ZooKeeperVersion needs `apiVersion`, `kind`, and `metadata` fields. It also needs a `.spec` section.
+
+```yaml
+apiVersion: catalog.kubedb.com/v1alpha1
+kind: ZooKeeperVersion
+metadata:
+  annotations:
+    meta.helm.sh/release-name: kubedb
+    meta.helm.sh/release-namespace: kubedb
+  creationTimestamp: "2024-05-02T09:41:52Z"
+  generation: 1
+  labels:
+    app.kubernetes.io/instance: kubedb
+    app.kubernetes.io/managed-by: Helm
+    app.kubernetes.io/name: kubedb-catalog
+    app.kubernetes.io/version: v2024.4.27
+    helm.sh/chart: kubedb-catalog-v2024.4.27
+  name: 3.9.1
+  resourceVersion: "1455"
+  uid: 3c5a4714-4ce2-4b41-8ad9-4899c3127dcc
+spec:
+  db:
+    image: ghcr.io/appscode-images/zookeeper:3.9.1
+  initContainer:
+    image: ghcr.io/kubedb/zookeeper-init:3.7-v1
+  securityContext:
+    runAsUser: 1000
+  version: 3.9.1
+```
+
+### metadata.name
+
+`metadata.name` is a required field that specifies the name of the `ZooKeeperVersion` crd. You have to specify this name in `spec.version` field of [ZooKeeper](/docs/guides/zookeeper/concepts/zookeeper.md) crd.
+
+
+### spec.version
+
+`spec.version` is a required field that specifies the original version of ZooKeeper server that has been used to build the docker image specified in `spec.db.image` field.
+
+### spec.deprecated
+
+`spec.deprecated` is an optional field that specifies whether the docker images specified here is supported by the current KubeDB operator.
+
+The default value of this field is `false`. If `spec.deprecated` is set to `true`, KubeDB operator will skip processing this CRD object and will add a event to the CRD object specifying that the DB version is deprecated.
+
+### spec.db.image
+
+`spec.db.image` is a required field that specifies the docker image which will be used to create Statefulset by KubeDB operator to create expected ZooKeeper server.
+
+### spec.initContainer.image
+
+`spec.initContainer.image` is a required field that specifies the image for init container.
+
+### spec.exporter.image
+
+`spec.exporter.image` is a required field that specifies the image which will be used to export Prometheus metrics.
+
+### spec.stash
+
+This holds the Backup & Restore task definitions, where a `TaskRef` has a `Name` & `Params` section. Params specifies a list of parameters to pass to the task.
+To learn more, visit [stash documentation](https://stash.run/)
+
+### spec.updateConstraints
+
+updateConstraints specifies the constraints that need to be considered during version update. Here `allowList` contains the versions those are allowed for updating from the current version.
+An empty list of AllowList indicates all the versions are accepted except the denyList.
+On the other hand, `DenyList` contains all the rejected versions for the update request. An empty list indicates no version is rejected.
+
+### spec.podSecurityPolicies.databasePolicyName
+
+`spec.podSecurityPolicies.databasePolicyName` is a required field that specifies the name of the pod security policy required to get the database server pod(s) running. To use a user-defined policy, the name of the policy has to be set in `spec.podSecurityPolicies` and in the list of allowed policy names in KubeDB operator like below:
+
+```bash
+helm upgrade -i kubedb oci://ghcr.io/appscode-charts/kubedb \
+  --namespace kubedb --create-namespace \
+  --set additionalPodSecurityPolicies[0]=custom-db-policy \
+  --set-file global.license=/path/to/the/license.txt \
+  --set gloabal.featureGates.ZooKeeper=true \
+  --wait --burst-limit=10000 --debug
+```
+
+## Next Steps
+
+- Learn about ZooKeeper crd [here](/docs/guides/zookeeper/concepts/zookeeper.md).
+- Deploy your first ZooKeeper server with KubeDB by following the guide [here](/docs/guides/zookeeper/quickstart/quickstart.md).