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cheatsheet-kubernetes
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cheatsheet-kubernetes [2025/10/26 19:59] – sjoerdcheatsheet-kubernetes [2026/02/08 14:49] (current) – external edit 127.0.0.1
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 **Date**: 15 December 2024 \\ **Date**: 15 December 2024 \\
 {{tag>cheatsheet kubernetes}} {{tag>cheatsheet kubernetes}}
 +
 +== Terminology ==
 +
 +**Pods**\\
 +Basic scheduling unit that holds one or more containers.
 +
 +**Nodes**\\
 +Machines (physical or virtual) in the cluster where pods are scheduled.
 +
 +**Cluster**\\
 +Collection of nodes and associated resources.
 +
 +**Kubelet**\\
 +An agent running on each node, responsible for managing the node and its containers.
 +
 +**Kubernetes Controller Manager**\\
 +Manages controllers to regulate the state of the system.
 +
 +**Kube Proxy**\\
 +Maintains network rules to allow communication between pods and external traffic.
 +
 +**etcd**\\
 +Consistent and highly-available key-value store used for all cluster data.
 +
 +**API Server**\\
 +Serves the Kubernetes API and is the primary entry point for administrative tasks.
 +
 +**Scheduler**\\
 +Assigns pods to nodes based on resource requirements and other constraints.
 +
 +**Controller**\\
 +Maintains the desired state of the system, such as ensuring the correct number of replicas for a particular application.
 +
 +**Service**\\
 +Provides a consistent way to access a set of pods.
 +
 +**Namespace**\\
 +A way to divide cluster resources between multiple users.
 +
 +**Volumes**\\
 +Kubernetes supports various types of storage volumes, providing data persistence for pods.
 +
 +**Secrets and ConfigMaps**\\
 +Mechanisms to manage sensitive information and configuration data separately from application code.
 +
 +**Deployment**\\
 +A higher-level resource that manages updates to applications by handling the deployment and scaling of pods.
 +
 +**StatefulSets**\\
 +Manages stateful applications, ensuring stable network identities and persistent storage for pods.
 +
 +**DaemonSets**\\
 +Ensures that specific pods run on all (or specific) nodes for cluster-wide tasks like logging or monitoring.
 +
 +**Jobs and CronJobs**\\
 +Run short-lived or scheduled tasks within the cluster.
 +
 +**Ingress**\\
 +Manages external access to services, typically HTTP.
 +
 +**Network Policies**\\
 +Define how groups of pods can communicate with each other and other network endpoints.
 +
 +**Horizontal Pod Autoscaler**\\
 +Automatically adjusts the number of replica pods to handle varying load.
 +
 +**Vertical Pod Autoscaler**\\
 +Adjusts the resources allocated to individual pods based on their usage.
 +
 +**Operators**\\
 +A way to package, deploy, and manage applications using Kubernetes APIs and controllers.
 +
 +**Kubectl**\\
 +The command-line interface to interact with Kubernetes clusters.
  
 == Kubectl == == Kubectl ==
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 # Start the debug command to connect to the node using an image from a private container registry # Start the debug command to connect to the node using an image from a private container registry
 kubectl debug node/aks-npuser001-34232393-vmss000001 -it --image=acreuwprd.azurecr.io/docker/docker/library/busybox:1.37 kubectl debug node/aks-npuser001-34232393-vmss000001 -it --image=acreuwprd.azurecr.io/docker/docker/library/busybox:1.37
->/code>+</code>
  
 ==== Resources ==== ==== Resources ====
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 </code> </code>
 \\ \\
 +> Restart all deployments in a namespace
 +<code bash>
 +kubectl rollout restart deployment -n shared
 +</code>
 > Apply a manifest > Apply a manifest
 <code bash> <code bash>
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 <code bash> <code bash>
 kubectl scale statefulset myapp1 --replicas=0 kubectl scale statefulset myapp1 --replicas=0
 +</code>
 +\\
 +> Restart a statefulset
 +<code bash>
 +kubectl rollout restart statefulset/myapp1
 +</code>
 +\\
 +> Restart all statefulsets in a namespace
 +<code bash>
 +kubectl rollout restart statefulset -n shared
 </code> </code>
  
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 grafana cli admin reset-admin-password <admin-password> grafana cli admin reset-admin-password <admin-password>
 </code> </code>
-\\ Check for kafka topics+\\ 
 +> Check for kafka topics
 <code bash> <code bash>
 # open a terminal on one of the kafka brokers (eg kafka-kafka-0) # open a terminal on one of the kafka brokers (eg kafka-kafka-0)
 ./bin/kafka-topics.sh --list --bootstrap-server localhost:9092 ./bin/kafka-topics.sh --list --bootstrap-server localhost:9092
 </code> </code>
-\\ Get all resource kinds with their name from a manifest:+\\ 
 +> Get all resource kinds with their name from a manifest:
 <code bash> <code bash>
 cat opentelemetry-operator.yaml | grep -i '^kind\|^  name:' cat opentelemetry-operator.yaml | grep -i '^kind\|^  name:'
 +</code>
 +
 +== Loop commands with kubectl ==
 +
 +Here are some examples I use to perform actions on multiple resources at once.
 +
 +> Remove all finalizers for kafka topics
 +<code bash>
 +kubectl get kafkatopic.kafka.strimzi.io -n shared -o name |
 +while read topic; do
 +    echo "Removing finalizer from $topic"
 +    kubectl patch $topic -n shared -p '{"metadata":{"finalizers":[]}}' --type=merge
 +done
 +</code>
 +\\
 +> Delete all jobs that start with "backup"
 +<code bash>
 +export NAMESPACE=shared
 +kubectl get jobs -n $NAMESPACE -o name | grep backup- |
 +while read job; do
 +    echo "Deleting $job"
 +    kubectl delete $job -n $NAMESPACE
 +done
 </code> </code>
  
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 </script> </script>
 </HTML> </HTML>
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cheatsheet-kubernetes.1761508753.txt.gz · Last modified: by sjoerd