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Add readiness probe and fix readme (#63)
* Add readiness probe and fix readme Signed-off-by: galal-hussein <hussein.galal.ahmed.11@gmail.com> * typos and fixes Signed-off-by: galal-hussein <hussein.galal.ahmed.11@gmail.com> --------- Signed-off-by: galal-hussein <hussein.galal.ahmed.11@gmail.com>
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Hussein Galal
@@ -8,11 +8,47 @@ An example on creating a k3k cluster on an RKE2 host using k3kcli
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[](https://asciinema.org/a/eYlc3dsL2pfP2B50i3Ea8MJJp)
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## Usage
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## Architecture
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K3K consists of a controller and a cli tool, the controller can be deployed via a helm chart and the cli can be downloaded from the releases page.
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### Deploy Controller
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### Controller
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The K3K controller will watch a CRD called `clusters.k3k.io`. Once found, the controller will create a separate namespace and it will create a K3S cluster as specified in the spec of the object.
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Each server and agent is created as a separate pod that runs in the new namespace.
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### CLI
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The CLI provides a quick and easy way to create K3K clusters using simple flags, and automatically exposes the K3K clusters so it's accessible via a kubeconfig.
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## Features
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### Isolation
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Each cluster runs in a sperate namespace that can be isolated via netowrk policies and RBAC rules, clusters also run in a sperate network namespace with flannel as the backend CNI. Finally, each cluster has a separate datastore which can be persisted.
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In addition, k3k offers a persistence feature that can help users to persist their datatstore, using dynamic storage class volumes.
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### Portability and Customization
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The "Cluster" object is considered the template of the cluster that you can re-use to spin up multiple clusters in a matter of seconds.
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K3K clusters use K3S internally and leverage all options that can be passed to K3S. Each cluster is exposed to the host cluster via NodePort, LoadBalancers, and Ingresses.
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| | Separate Namespace (for each tenant) | K3K | vcluster | Separate Cluster (for each tenant) |
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|-----------------------|---------------------------------------|------------------------------|-----------------|------------------------------------|
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| Isolation | Very weak | Very strong | strong | Very strong |
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| Access for tenants | Very restricted | Built-in k8s RBAC / Rancher | Vclustser admin | Cluster admin |
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| Cost | Very cheap | Very cheap | cheap | expensive |
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| Overhead | Very low | Very low | Very low | Very high |
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| Networking | Shared | Separate | shared | separate |
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| Cluster Configuration | | Very easy | Very hard | |
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## Usage
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### Deploy K3K Controller
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[Helm](https://helm.sh) must be installed to use the charts. Please refer to
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Helm's [documentation](https://helm.sh/docs) to get started.
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@@ -2,10 +2,10 @@ replicaCount: 1
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namespace: k3k-system
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image:
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repository: briandowns/k3k
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repository: rancher/k3k
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pullPolicy: Always
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# Overrides the image tag whose default is the chart appVersion.
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tag: "dev"
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tag: "v0.0.0-alpha6"
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imagePullSecrets: []
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nameOverride: ""
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@@ -2,7 +2,6 @@ package server
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import (
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"context"
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"fmt"
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"strconv"
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"github.com/rancher/k3k/pkg/apis/k3k.io/v1alpha1"
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@@ -12,6 +11,7 @@ import (
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"k8s.io/apimachinery/pkg/api/resource"
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metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
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"k8s.io/apimachinery/pkg/types"
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"k8s.io/apimachinery/pkg/util/intstr"
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"k8s.io/utils/pointer"
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"sigs.k8s.io/controller-runtime/pkg/client"
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)
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@@ -20,6 +20,8 @@ const (
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serverName = "k3k-"
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k3kSystemNamespace = serverName + "system"
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initServerName = serverName + "init-server"
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initContainerName = serverName + "server-check"
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initContainerImage = "alpine/curl"
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)
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// Server
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@@ -107,13 +109,11 @@ func (s *Server) Deploy(ctx context.Context, init bool) (*apps.Deployment, error
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volumeMounts = append(volumeMounts, volumeMount)
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}
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podSpec := s.podSpec(ctx, image, name, false)
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podSpec := s.podSpec(ctx, image, name, false, init)
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podSpec.Volumes = append(podSpec.Volumes, volumes...)
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podSpec.Containers[0].VolumeMounts = append(podSpec.Containers[0].VolumeMounts, volumeMounts...)
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fmt.Printf("XXX - Pod Spec\n %#v\n", podSpec)
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return &apps.Deployment{
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TypeMeta: metav1.TypeMeta{
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Kind: "Deployment",
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@@ -146,7 +146,7 @@ func (s *Server) Deploy(ctx context.Context, init bool) (*apps.Deployment, error
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}, nil
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}
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func (s *Server) podSpec(ctx context.Context, image, name string, statefulSet bool) v1.PodSpec {
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func (s *Server) podSpec(ctx context.Context, image, name string, statefulSet, init bool) v1.PodSpec {
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args := append([]string{"server", "--config", "/opt/rancher/k3s/config.yaml"}, s.cluster.Spec.ServerArgs...)
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podSpec := v1.PodSpec{
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@@ -258,6 +258,33 @@ func (s *Server) podSpec(ctx context.Context, image, name string, statefulSet bo
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},
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)
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}
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// Adding readiness probes to deployment
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podSpec.Containers[0].ReadinessProbe = &v1.Probe{
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InitialDelaySeconds: 60,
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FailureThreshold: 5,
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TimeoutSeconds: 10,
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ProbeHandler: v1.ProbeHandler{
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TCPSocket: &v1.TCPSocketAction{
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Port: intstr.FromInt(6443),
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Host: "127.0.0.1",
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},
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},
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}
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if !init {
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podSpec.InitContainers = []v1.Container{
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{
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Name: initContainerName,
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Image: initContainerImage,
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Command: []string{
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"sh",
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"-c",
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"until curl -qk https://k3k-server-service.$(cat /var/run/secrets/kubernetes.io/serviceaccount/namespace).svc.cluster.local:6443/v1-k3s/readyz; do echo waiting for init server to be up; sleep 2; done",
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},
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},
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}
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}
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return podSpec
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}
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@@ -342,7 +369,7 @@ func (s *Server) StatefulServer(ctx context.Context, cluster *v1alpha1.Cluster,
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"init": strconv.FormatBool(init),
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},
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},
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Spec: s.podSpec(ctx, image, name, true),
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Spec: s.podSpec(ctx, image, name, true, init),
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},
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},
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}
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