diff --git a/.markdownlint.yaml b/.markdownlint.yaml
index dc7d9de..5264fb5 100644
--- a/.markdownlint.yaml
+++ b/.markdownlint.yaml
@@ -13,3 +13,4 @@ MD033: # no-inline-html
- code
- details
- summary
+ - sup
diff --git a/knowledge base/cloud computing/aws/eks.md b/knowledge base/cloud computing/aws/eks.md
index 73e4521..c09bfe4 100644
--- a/knowledge base/cloud computing/aws/eks.md
+++ b/knowledge base/cloud computing/aws/eks.md
@@ -1126,10 +1126,8 @@ Installation:
'aws-load-balancer-controller' 'aws-load-balancer-controller' \
--namespace 'kube-system' \
--set 'clusterName'='DeepThought' \
- --set 'serviceAccount.create'='true' \
- --set 'serviceAccount.name'='aws-load-balancer-controller' \
- --set 'region'='eu-west-1' \
- --set 'vpcId'='vpc-01234567'
+ --set 'serviceAccount.create'='true' --set 'serviceAccount.name'='aws-load-balancer-controller' \
+ --set 'region'='eu-west-1' --set 'vpcId'='vpc-01234567'
```
diff --git a/knowledge base/kubernetes/cluster autoscaler.md b/knowledge base/kubernetes/cluster autoscaler.md
index f18d85b..70600df 100644
--- a/knowledge base/kubernetes/cluster autoscaler.md
+++ b/knowledge base/kubernetes/cluster autoscaler.md
@@ -1,18 +1,25 @@
# Cluster autoscaler
-Automatically adjusts the number of nodes in Kubernetes clusters.
+Automatically adjusts the number of nodes in Kubernetes clusters to meet their current needs.
1. [TL;DR](#tldr)
+1. [Best practices](#best-practices)
1. [Further readings](#further-readings)
1. [Sources](#sources)
## TL;DR
-Acts when one of the following conditions is true:
+The purpose of Cluster Autoscaler is to get pending pods a place to run on.
-- Pods failed to run in the cluster due to insufficient resources.
-- Nodes in the cluster have been underutilized for an extended period of time, and their pods can be placed on other
- existing nodes.
+The autoscaler acts when one of the following conditions is true:
+
+- Pods failed to run in the cluster due to insufficient resources.
+ This triggers a scale-**up** event, where it will try to **add** a new node.
+- Nodes in the cluster have been consistently underutilized for a significant amount of time, and their pods can be
+ moved on other existing nodes.
+ This triggers a scale-**down** event, where it will try to **remove** an existing node.
+
+The time required for node provisioning depends on the cloud provider and other Kubernetes components.
Setup
@@ -31,27 +38,36 @@ helm --namespace 'kube-system' uninstall 'cluster-autoscaler'
-
-
Real world use cases
```sh
-helm --namespace 'kube-system' upgrade --install 'cluster-autoscaler' 'autoscaler/cluster-autoscaler' \
- --set 'cloudProvider'='aws' --set 'awsRegion'='eu-west-1' \
- --set 'autoDiscovery.clusterName'='defaultCluster' --set 'rbac.serviceAccount.name'='cluster-autoscaler-aws'
+aws eks --region 'eu-west-1' update-kubeconfig --name 'custom-eks-cluster' \
+&& helm --namespace 'kube-system' upgrade --install --repo 'https://kubernetes.github.io/autoscaler' \
+ 'cluster-autoscaler' 'cluster-autoscaler' \
+ --set 'cloudProvider'='aws' --set 'awsRegion'='eu-west-1' --set 'autoDiscovery.clusterName'='custom-eks-cluster' \
+ --set 'rbac.serviceAccount.name'='cluster-autoscaler-aws' \
+ --set 'replicaCount'='2' \
+ --set 'resources.requests.cpu'='40m' --set 'resources.requests.memory'='50Mi' \
+ --set 'resources.limits.cpu'='100m' --set 'resources.limits.memory'='300Mi' \
+ --set 'affinity.podAntiAffinity.preferredDuringSchedulingIgnoredDuringExecution[0].weight'='100' \
+ --set 'affinity.podAntiAffinity.preferredDuringSchedulingIgnoredDuringExecution[0].podAffinityTerm.topologyKey'='kubernetes.io/hostname' \
+ --set 'affinity.podAntiAffinity.preferredDuringSchedulingIgnoredDuringExecution[0].podAffinityTerm.labelSelector.matchExpressions[0].key'='app.kubernetes.io/name' \
+ --set 'affinity.podAntiAffinity.preferredDuringSchedulingIgnoredDuringExecution[0].podAffinityTerm.labelSelector.matchExpressions[0].operator'='In' \
+ --set 'affinity.podAntiAffinity.preferredDuringSchedulingIgnoredDuringExecution[0].podAffinityTerm.labelSelector.matchExpressions[0].values[0]'='aws-cluster-autoscaler'
```
+## Best practices
+
+- Do **not** modify nodes belonging to autoscaled node groups directly.
+- All nodes within the same autoscaled node group should have the same capacity, labels and system pods running on them.
+- Specify requests for all the pods one can.
+- Should one need to prevent pods from being deleted too abruptly, consider using PodDisruptionBudgets.
+- Check one's cloud provider's quota is big enough **before** specifying min/max settings for clusters' node pools.
+- Do **not** run **any** additional node group autoscaler (**especially** those from one's own cloud provider).
+
## Further readings
- [Main repository]
diff --git a/knowledge base/kubernetes/metrics server.md b/knowledge base/kubernetes/metrics server.md
index 5ecaaf8..11bde25 100644
--- a/knowledge base/kubernetes/metrics server.md
+++ b/knowledge base/kubernetes/metrics server.md
@@ -29,7 +29,14 @@ Depending on the metrics-server version it uses:
```sh
kubectl apply -f 'https://github.com/kubernetes-sigs/metrics-server/releases/latest/download/components.yaml'
helm -n 'kube-system' upgrade --install --repo 'https://kubernetes-sigs.github.io/metrics-server' \
- 'metrics-server' 'metrics-server' --set 'containerPort'='10251'
+ 'metrics-server' 'metrics-server' \
+ --set 'replicas'='2' --set 'addonResizer.enabled'='true' \
+ --set 'containerPort'='10251' \
+ --set 'affinity.podAntiAffinity.preferredDuringSchedulingIgnoredDuringExecution[0].weight'='100' \
+ --set 'affinity.podAntiAffinity.preferredDuringSchedulingIgnoredDuringExecution[0].podAffinityTerm.topologyKey'='kubernetes.io/hostname' \
+ --set 'affinity.podAntiAffinity.preferredDuringSchedulingIgnoredDuringExecution[0].podAffinityTerm.labelSelector.matchExpressions[0].key'='app.kubernetes.io/name' \
+ --set 'affinity.podAntiAffinity.preferredDuringSchedulingIgnoredDuringExecution[0].podAffinityTerm.labelSelector.matchExpressions[0].operator'='In' \
+ --set 'affinity.podAntiAffinity.preferredDuringSchedulingIgnoredDuringExecution[0].podAffinityTerm.labelSelector.matchExpressions[0].values[0]'='metrics-server'
```
diff --git a/snippets/helm.sh b/snippets/helm.sh
index 6934ad9..c7f7844 100644
--- a/snippets/helm.sh
+++ b/snippets/helm.sh
@@ -23,9 +23,24 @@ helm --namespace 'gitlab' upgrade --install --create-namespace --version '0.64.1
helm upgrade --install 'keda' 'keda' --repo 'https://kedacore.github.io/charts' --namespace 'keda' --create-namespace
helm get manifest 'wordpress'
+helm --namespace 'kube-system' get values 'metrics-server'
helm -n 'monitoring' delete 'grafana'
helm plugin list
helm plugin install 'https://github.com/databus23/helm-diff'
helm -n 'pocs' diff upgrade --repo 'https://dl.gitea.com/charts/' 'gitea' 'gitea' -f 'values.yaml'
+
+aws eks --region 'eu-west-1' update-kubeconfig --name 'custom-eks-cluster' \
+&& helm --namespace 'kube-system' upgrade --install --repo 'https://kubernetes.github.io/autoscaler'
+ 'cluster-autoscaler' 'cluster-autoscaler' \
+ --set 'cloudProvider'='aws' --set 'awsRegion'='eu-west-1' --set 'autoDiscovery.clusterName'='custom-eks-cluster' \
+ --set 'rbac.serviceAccount.name'='cluster-autoscaler-aws' \
+ --set 'replicaCount'='2' \
+ --set 'resources.requests.cpu'='40m' --set 'resources.requests.memory'='50Mi' \
+ --set 'resources.limits.cpu'='100m' --set 'resources.limits.memory'='300Mi' \
+ --set 'affinity.podAntiAffinity.preferredDuringSchedulingIgnoredDuringExecution[0].weight'='100' \
+ --set 'affinity.podAntiAffinity.preferredDuringSchedulingIgnoredDuringExecution[0].podAffinityTerm.topologyKey'='kubernetes.io/hostname' \
+ --set 'affinity.podAntiAffinity.preferredDuringSchedulingIgnoredDuringExecution[0].podAffinityTerm.labelSelector.matchExpressions[0].key'='app.kubernetes.io/name' \
+ --set 'affinity.podAntiAffinity.preferredDuringSchedulingIgnoredDuringExecution[0].podAffinityTerm.labelSelector.matchExpressions[0].operator'='In' \
+ --set 'affinity.podAntiAffinity.preferredDuringSchedulingIgnoredDuringExecution[0].podAffinityTerm.labelSelector.matchExpressions[0].values[0]'='aws-cluster-autoscaler'