Fleet Join/Leave is a feature that allows a member cluster to join and leave a fleet(Hub) in the fleet control plane.
This guide has two parts,
- Steps to run agents on Kind clusters
- Steps to run agents on AKS clusters
For the kind clusters everything needed to run the agents is already predefined in the makefile no changes are needed. But for the AKS cluster we need to make some changes to files within the fleet repo.
1. Clone the repo to your machine
$ git clone https://github.com/Azure/fleet2. Navigate to fleet directory
$ cd fleet3. Set up hub and member kind clusters
The makefile uses kindest/node:v1.23.3 if your version is higher/lower use the following command to pull the image for v1.23.3
$ docker pull kindest/node:v1.23.3then run,
$ make create-hub-kind-cluster create-member-kind-cluster4. Build and load images to kind clusters (since we are testing locally we don't have access to fleet packages)
$ OUTPUT_TYPE=type=docker make docker-build-hub-agent docker-build-member-agent docker-build-refresh-token
$ make load-hub-docker-image load-member-docker-image5. Install hub and member agents helm charts
$ make install-member-agent-helm6. Apply memberCluster to the hub cluster
$ kind export kubeconfig --name hub-testing
$ kubectl apply -f examples/fleet_v1alpha1_membercluster.yaml 7. Check to make sure the memberCluster & internalMemberCluster resources status have been updated to 'Joined'
$ kubectl describe membercluster kind-member-testingResult
Name: kind-member-testing
Namespace:
Labels: <none>
Annotations: <none>
API Version: fleet.azure.com/v1alpha1
Kind: MemberCluster
Metadata:
Creation Timestamp: 2022-07-08T01:42:35Z
Generation: 1
Resource Version: 868
UID: 67cec7a4-3386-4fd5-9de2-20397e7b0029
Spec:
Identity:
API Group:
Kind: ServiceAccount
Name: member-agent-sa
Namespace: fleet-system
Lease Duration Seconds: 30
State: Join
Status:
Allocatable:
Cpu: 8
Memory: 2032532Ki
Capacity:
Cpu: 8
Memory: 2032532Ki
Conditions:
Last Transition Time: 2022-07-08T01:42:36Z
Message:
Observed Generation: 1
Reason: InternalMemberClusterHeartbeatReceived
Status: True
Type: HeartbeatReceived
Last Transition Time: 2022-07-08T01:42:36Z
Message:
Observed Generation: 1
Reason: MemberClusterJoined
Status: True
Type: Joined
Events:
Type Reason Age From Message
---- ------ ---- ---- -------
Normal NamespaceCreated 81s memberCluster Namespace was created
Normal InternalMemberClusterCreated 81s memberCluster Internal member cluster was created
Normal RoleCreated 81s memberCluster role was created
Normal RoleBindingCreated 81s memberCluster role binding was created
Normal MemberClusterJoined 81s memberCluster member cluster is joined
$ kubectl describe internalmembercluster kind-member-testing -n fleet-member-kind-member-testingResult
Name: kind-member-testing
Namespace: fleet-kind-member-testing
API Version: fleet.azure.com/v1alpha1
Kind: InternalMemberCluster
Metadata:
Creation Timestamp: 2022-07-08T01:42:36Z
Generation: 1
Owner References:
API Version: fleet.azure.com/v1alpha1
Controller: true
Kind: MemberCluster
Name: kind-member-testing
UID: 67cec7a4-3386-4fd5-9de2-20397e7b0029
Resource Version: 865
UID: 1b544873-81b8-4bac-9624-d4208aa21fd1
Spec:
Lease Duration Seconds: 60
State: Join
Status:
Allocatable:
Cpu: 8
Memory: 2032532Ki
Capacity:
Cpu: 8
Memory: 2032532Ki
Conditions:
Last Transition Time: 2022-07-08T01:42:36Z
Message:
Observed Generation: 1
Reason: InternalMemberClusterHeartbeatReceived
Status: True
Type: HeartbeatReceived
Last Transition Time: 2022-07-08T01:42:36Z
Message:
Reason: ReconcileSuccess
Status: True
Type: Synced
Last Transition Time: 2022-07-08T01:42:36Z
Message:
Observed Generation: 1
Reason: InternalMemberClusterJoined
Status: True
Type: Joined
Last Transition Time: 2022-07-08T01:42:36Z
Message:
Observed Generation: 1
Reason: InternalMemberClusterHealthy
Status: True
Type: Healthy
Events:
Type Reason Age From Message
---- ------ ---- ---- -------
Normal InternalMemberClusterHeartbeatReceived 8s (x6 over 4m8s) InternalMemberClusterController internal member cluster heartbeat received
Normal InternalMemberClusterJoined 8s (x6 over 4m8s) InternalMemberClusterController internal member cluster has joined
Normal InternalMemberClusterHealthy 8s (x6 over 4m8s) InternalMemberClusterController internal member cluster healthy
8. Change the state for memberCluster yaml file to be Leave and apply the change
$ kubectl apply -f examples/fleet_v1alpha1_membercluster.yaml 9. Check to make sure the memberCluster resource status have been updated to 'Left'
$ kubectl describe membercluster kind-member-testingResult
Name: kind-member-testing
Namespace:
Labels: <none>
Annotations: <none>
API Version: fleet.azure.com/v1alpha1
Kind: MemberCluster
Metadata:
Creation Timestamp: 2022-07-08T01:42:35Z
Generation: 2
Resource Version: 1565
UID: 67cec7a4-3386-4fd5-9de2-20397e7b0029
Spec:
Identity:
API Group:
Kind: ServiceAccount
Name: member-agent-sa
Namespace: fleet-system
Lease Duration Seconds: 30
State: Leave
Status:
Allocatable:
Cpu: 8
Memory: 2032532Ki
Capacity:
Cpu: 8
Memory: 2032532Ki
Conditions:
Last Transition Time: 2022-07-08T01:42:36Z
Message:
Observed Generation: 1
Reason: InternalMemberClusterHeartbeatReceived
Status: True
Type: HeartbeatReceived
Last Transition Time: 2022-07-08T01:49:10Z
Message:
Observed Generation: 2
Reason: MemberClusterLeft
Status: False
Type: Joined
Last Transition Time: 2022-07-08T01:49:10Z
Message:
Reason: ReconcileSuccess
Status: True
Type: Synced
Events:
Type Reason Age From Message
---- ------ ---- ---- -------
Normal NamespaceCreated 6m56s memberCluster Namespace was created
Normal InternalMemberClusterCreated 6m56s memberCluster Internal member cluster was created
Normal RoleCreated 6m56s memberCluster role was created
Normal RoleBindingCreated 6m56s memberCluster role binding was created
Normal MemberClusterJoined 6m56s memberCluster member cluster is joined
Normal InternalMemberClusterSpecUpdated 22s memberCluster internal member cluster spec is marked as Leave
Normal NamespaceDeleted 22s memberCluster namespace is deleted for member cluster
Normal MemberClusterLeft 22s memberCluster member cluster has left
delete kind clusters setup
$ make clean-e2e-testsBefore starting create a text file and have a list of variables and their associated values for anything with double quotes put it in this text file to keep track, since we need to make changes to most of the commands before using them.
List of variables that's supposed to be in your text file as you go through the commands,
- "RegistryName"
- "RegistryLoginServer"
- "ResourceGroupName"
- "PRINCIPAL_ID"
- "CLIENT_ID"
- "HUB_URL"
- "MemberClusterCRName"
- Valid Azure subscription to create AKS clusters setup subscription
- Resource Group under subscription setup resource group ("ResourceGroupName" name of the resource group created)
- ACR inside the resource group to build & push docker images setup ACR ("RegistryLoginServer" login server field when you navigate to your registry on Azure portal, "RegistryName" name of Registry created)
$ az aks create --resource-group "ResourceGroupName" --name hubCluster --attach-acr "RegistryName" --node-count 1 --generate-ssh-keys --enable-aad --enable-azure-rbac$ az aks create --resource-group "ResourceGroupName" --name memberCluster --attach-acr "RegistryName" --node-count 1 --generate-ssh-keys --enable-managed-identity$ az aks get-credentials --resource-group "ResourceGroupName" --name hubCluster --admin
$ az aks get-credentials --resource-group "ResourceGroupName" --name memberCluster --adminswitching contexts provides access to the corresponding clusters. The contexts are defined in a config file, it's usual file path is /Users/username/.kube/config
$ kubectl config use-context hubCluster-admin
$ kubectl config use-context memberCluster-admin$ az acr login -n "RegistryName"In the Makefile which exists in fleet/Makefile and values.yaml files for both helm charts which exists in fleet/charts/hub-agent/values.yaml & fleet/charts/member-agent/values.yaml
make the necessary changes.
From the fleet directory run the following commands. This builds the docker images from local fleet directory and pushes the images to ACR.
$ make docker-build-hub-agent
$ make docker-build-member-agent
$ make docker-build-refresh-tokenFrom the fleet directory run the following commands,
$ helm install hub-agent ./charts/hub-agent/Each time we create an AKS cluster a resource group gets auto generated for us MC_ResourceGroupName_ClusterName_Location find the resource group and then go and click the agent pool MSI object and get the "PRINCIPAL_ID" which will be the name of the identity for the memberCluster CR, we can also find the "CLIENT_ID" here
copy the code below and navigate to fleet/examples/fleet_v1alpha1_membercluster.yaml, paste the code and replace the "PRINCIPAL_ID"
apiVersion: fleet.azure.com/v1alpha1
kind: MemberCluster
metadata:
name: membercluster-sample
spec:
state: Join
identity:
name: "PRINCIPAL_ID"
kind: User
namespace: fleet-system
apiGroup: rbac.authorization.k8s.io
leaseDurationSeconds: 30then apply the CR,
$ kubectl apply -f ./examples/fleet_v1alpha1_membercluster.yamlswitch cluster context to member cluster and run, "CLIENT_ID" is clientId from the agent pool MSI object, "HUB_URL" can be found in the .kube/config file in the hub cluster context section.
$ helm install member-agent ./charts/member-agent/ --set azure.clientid="CLIENT_ID" --set config.provider=azure --set config.hubURL="HUB_URL" --set config.memberClusterName="MemberClusterCRName"check events to see if member cluster has Joined.
$ kubectl describe membercluster "MemberClusterCRName"After applying the member cluster CR the Join workflow completes and the member cluster gets marked as Joined with a condition.
To trigger the leave workflow change the state from Join to Leave in the member cluster CR or change the CR's spec to Leave in the fleet/examples/fleet_v1alpha1_membercluster.yaml and apply the CR again.
$ kubectl edit membercluster "MemberClusterCRName"check events to see if member cluster has Left.
$ kubectl describe membercluster "MemberClusterCRName"switch cluster context to member cluster,
upgrade the AKS member cluster to use kubernetes version greater than 1.22 because we need ephemeral containers to access the token. we can check the kubernetes version for the AKS cluster by running,
$ kubectl get nodes -Arun this command to get possible upgrades for your cluster if kubernetes version for cluster is less than 1.23,
$ az aks get-upgrades --resource-group "ResourceGroupName" --name memberCluster --output tablethen use a version greater than 1.22 replace the KUBERNETES_VERSION variable in command below this is done because ephemeral debug containers were introduced in 1.23 and run,
az aks upgrade --resource-group "ResourceGroupName" --name memberCluster --kubernetes-version KUBERNETES_VERSIONafter the upgrade run,
$ kubectl debug node/nodeName -it --image=busyboxthis opens a shell to access the files present within the node then run,
$ find . -name provider-tokenwhich returns something similar to this,
Result
/host/var/lib/kubelet/pods/podName/volumes/kubernetes.io~empty-dir/provider-tokennavigate to the directory to find a file called token use vim to open it.
Delete the resource group under which every resource was created. This might take some time.
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