Setup Etcd-Druid Locally

This document will guide you on how to setup etcd-druid on your local machine and how to provision and manage Etcd cluster(s).

00-Prerequisites

Before we can setup etcd-druid and use it to provision Etcd clusters, we need to prepare the development environment. Follow the Prepare Dev Environment Guide for detailed instructions.

01-Setting up KIND cluster

etcd-druid uses kind as it's local Kubernetes engine. The local setup is configured for kind due to its convenience only. Any other Kubernetes setup would also work.

Bash

make kind-up

This command sets up a new Kind cluster and stores the kubeconfig at ./hack/kind/kubeconfig. Additionally, this command also deploys a local container registry as a docker container. This ensures faster image push/pull times. The local registry can be accessed as localhost:5001 for pushing and pulling images.

To target this newly created cluster, set the KUBECONFIG environment variable to the kubeconfig file.

Bash

export KUBECONFIG=$PWD/hack/kind/kubeconfig

Note: If you wish to configure kind cluster differently then you can directly invoke the script and check its help to know about all configuration options.

Bash

./hack/kind-up.sh -h
  usage: kind-up.sh [Options]
  Options:
    --cluster-name  <cluster-name>   Name of the kind cluster to create. Default value is 'etcd-druid-e2e'
    --skip-registry                  Skip creating a local docker registry. Default value is false.
    --feature-gates <feature-gates>  Comma separated list of feature gates to enable on the cluster.

02-Setting up etcd-druid

Configuring etcd-druid

Prior to deploying etcd-druid, it can be configured via CLI-args and environment variables.

• To configure CLI args you can modify charts/druid/values.yaml. For e.g. if you wish to auto-reconcile any change done to Etcd CR then you should set enableEtcdSpecAutoReconcile to true. By default this will be switched off.
• DRUID_E2E_TEST=true : sets specific configuration for etcd-druid for optimal e2e test runs, like a lower sync period for the etcd controller.

Deploying etcd-druid

Any variant of make deploy-* command uses helm and skaffold to build and deploy etcd-druid to the target Kubernetes cluster. In addition to deploying etcd-druid it will also install the Etcd CRD and EtcdCopyBackupTask CRD.

Regular mode

Bash

make deploy

The above command will use skaffold to build and deploy etcd-druid to the k8s kind cluster pointed to by KUBECONFIG environment variable.

Dev mode

Bash

make deploy-dev

This is similar to make deploy but additionally starts a skaffold dev loop. After the initial deployment, skaffold starts watching source files. Once it has detected changes, you can press any key to update the etcd-druid deployment.

Debug mode

Bash

make deploy-debug

This is similar to make deploy-dev but additionally configures containers in pods for debugging as required for each container's runtime technology. The associated debugging ports are exposed and labelled so that they can be port-forwarded to the local machine. Skaffold disables automatic image rebuilding and syncing when using the debug mode as compared to dev mode.

Go debugging uses Delve. Please see the skaffold debugging documentation how to setup your IDE accordingly.

Note

Resuming or stopping only a single goroutine (Go Issue 25578, 31132) is currently not supported, so the action will cause all the goroutines to get activated or paused.

This means that when a goroutine is paused on a breakpoint, then all the other goroutines are also paused. This should be kept in mind when using skaffold debug.

03-Configure Backup [Optional]

Deploying a Local Backup Store Emulator

Info

This section is Optional and is only meant to describe steps to deploy a local object store which can be used for testing and development. If you either do not wish to enable backups or you wish to use remote (infra-provider-specific) object store then this section can be skipped.

An Etcd cluster provisioned via etcd-druid provides a capability to take regular delta and full snapshots which are stored in an object store. You can enable this functionality by ensuring that you fill in spec.backup.store section of the Etcd CR.

Backup Store Variant	Setup Guide
Azure Object Storage Emulator	Manage Azurite (Steps 00-03)
S3 Object Store Emulator	Manage LocalStack (Steps 00-03)

Setting up Cloud Provider Object Store Secret

Info

This section is Optional. If you have disabled backup functionality or if you are using local storage or one of the supported object store emulators then you can skip this section.

A Kubernetes Secret needs to be created for cloud provider Object Store access. You can refer to the Secret YAML templates here. Replace the dummy values with the actual configuration and ensure that you have added the metadata.name and metadata.namespace to the secret.

Tip

• Secret should be deployed in the same namespace as the Etcd resource.
• All the values in the data field of the secret YAML should in base64 encoded format.

To apply the secret run:

Bash

kubectl apply -f <path/to/secret>

04-Preparing Etcd CR

Choose an appropriate variant of Etcd CR from samples directory.

If you wish to enable functionality to backup delta & full snapshots then uncomment spec.backup.store section.

YAML

# Configuration for storage provider
store:
  secretRef:
    name: etcd-backup-secret-name
  container: object-storage-container-name
  provider: aws # options: aws,azure,gcp,openstack,alicloud,dell,openshift,local
  prefix: etcd-test

Brief explanation of the keys:

• secretRef.name is the name of the secret that was applied as mentioned above.
• store.container is the object storage bucket name.
• store.provider is the bucket provider. Pick from the options mentioned in comment.
• store.prefix is the folder name that you want to use for your snapshots inside the bucket.

Tip

For developer convenience we have provided object store emulator specific etcd CR variants which can be used as if as well.

05-Applying Etcd CR

Create the Etcd CR (Custom Resource) by applying the Etcd yaml to the cluster

Bash

kubectl apply -f <path-to-etcd-cr-yaml>

06-Verify the Etcd Cluster

To obtain information on the etcd cluster you can invoke the following command:

Bash

kubectl get etcd -o=wide

We adhere to a naming convention for all resources that are provisioned for an Etcd cluster. Refer to etcd-cluster-components document to get details of all resources that are provisioned.

Verify Etcd Pods' Functionality

etcd-wrapper uses a distroless image, which lacks a shell. To interact with etcd, use an Ephemeral container as a debug container. Refer to this documentation for building and using an ephemeral container which gets attached to the etcd-wrapper pod.

Bash

# Put a key-value pair into the etcd 
etcdctl put <key1> <value1>
# Retrieve all key-value pairs from the etcd db
etcdctl get --prefix ""

For a multi-node etcd cluster, insert the key-value pair using the etcd container of one etcd member and retrieve it from the etcd container of another member to verify consensus among the multiple etcd members.

07-Updating Etcd CR

Etcd CR can be updated with new changes. To ensure that etcd-druid reconciles the changes you can refer to options that etcd-druid provides here.

08-Cleaning up the setup

If you wish to only delete the Etcd cluster then you can use the following command:

Bash

kubectl delete etcd <etcd-name>

This will add the deletionTimestamp to the Etcd resource. At the time the creation of the Etcd cluster, etcd-druid will add a finalizer to ensure that it cleans up all Etcd cluster resources before the CR is removed.

YAML

  finalizers:
  - druid.gardener.cloud/etcd-druid

etcd-druid will automatically pick up the deletion event and attempt clean up Etcd cluster resources. It will only remove the finaliser once all resources have been cleaned up.

If you only wish to remove etcd-druid but retain the kind cluster then you can use the following make target:

Bash

make undeploy

If you wish to delete the kind cluster then you can use the following make target:

Bash

make kind-down

This cleans up the entire setup as the kind cluster gets deleted.