diff --git a/knowledge base/kubectl.md b/knowledge base/kubectl.md
index 8c63b7d..fc8da7b 100644
--- a/knowledge base/kubectl.md	
+++ b/knowledge base/kubectl.md	
@@ -3,41 +3,420 @@
 ## TL;DR
 
 ```shell
-# list resources
+# Shot the merged configuration.
+kubectl config view
+
+# Get specific values from the configuration.
+kubectl config view -o jsonpath='{.users[].name}'
+kubectl config view -o jsonpath='{.users[*].name}'
+kubectl config view -o jsonpath='{.users[?(@.name == "e2e")].user.password}'
+
+# Set config values.
+kubectl config set-context --current --namespace=keda
+kubectl config set-context gce --user=cluster-admin --namespace=foo
+kubectl config set-credentials \
+  kubeuser/foo.kubernetes.com --username=kubeuser --password=kubepassword
+
+# Delete config values.
+kubectl config unset users.foo
+
+# Use multiple config files at once.
+# This will merge them in one big temporary config file.
+KUBECONFIG="path/to/kube/config1:path/to/kube/configN"
+
+# List contexts.
+kubectl config get-contexts
+kubectl config current-context
+
+# Set context as the default one.
+kubectl config use-context docker-desktop
+kubectl config use-context gce
+
+# List and filter resources.
 kubectl get pods
 kubectl get pods -n kube-system coredns-845757d86-47np2
-kubectl get namespaces --show-labels
-kubectl get services -o wide
+kubectl get namespaces,pods --show-labels
+kubectl get deployment nginx -o yaml
+kubectl get services -A -o wide
+kubectl get replicasets --sort-by=.metadata.name
+kubectl get pods --sort-by='.status.containerStatuses[0].restartCount'
+kubectl get pv --sort-by=.spec.capacity.storage
+kubectl get configmap myconfig -o jsonpath='{.data.ca\.crt}'
+kubectl get node -L='!node-role.kubernetes.io/master'
+kubectl get pods --field-selector=status.phase=Running
+kubectl get pods --selector=app=cassandra -o \
+  jsonpath='{.items[*].metadata.labels.version}'
 
-# start a pod
+# List all pods in status 'Shutdown'.
+kubectl get pods -A \
+  -0 jsonpath='{.items[?(@.status.reason=="Shutdown")].metadata.name}'
+
+# Show detailed information about resources.
+kubectl describe node pi
+kubectl describe pods redis-0,redis-1
+
+# Start a Pod.
 kubectl run nginx --image nginx
+kubectl run --rm -i --tty -n keda busybox --image=busybox -- sh
 
-# taint a node
+# Start a Pod and write its specs into a file.
+kubectl run nginx --image=nginx --dry-run=client -o yaml > pod.yaml
+
+# Create a single instance deployment of 'nginx'.
+kubectl create deployment nginx --image=nginx
+
+# Start a Job using an existing Job as template
+kubectl create job backup-before-upgrade-13.6.2-to-13.9.2 \
+  --from=cronjob.batch/backup -n gitlab
+
+# Wait for a pod to be 'ready'.
+kubectl wait --for 'condition=ready' \
+  pod -L 'app.kubernetes.io/component=controller' --timeout 120s
+
+# Attach to a running container.
+kubectl attach my-pod -i
+
+# Run command in existing Pods.
+kubectl exec my-pod -- ls /
+kubectl exec my-pod -c my-container -- ls /
+
+# Show metrics for a given Pod and its containers.
+kubectl top pod busybox --containers
+
+# Get logs from resources.
+kubectl logs redis-0
+kubectl logs -l name=myLabel
+kubectl logs my-pod -c my-container
+
+# Follow logs.
+kubectl logs -f my-pod
+kubectl logs -f my-pod -c my-container
+kubectl logs -f -l name=myLabel --all-containers
+
+# Get logs for a previous instantiation of a container.
+kubectl logs nginx --previous
+
+# Get the logs of the first Pod matching ID.
+kubectl logs \
+  $(kubectl get pods | grep $ID | head -n 1 | awk -F ' ' '{print $1}')
+
+# Sort events by timestamp.
+kubectl get events --sort-by .metadata.creationTimestamp
+
+# Show the documentation for Pods' manifests.
+kubectl explain pods
+
+# Create resources from manifests.
+kubectl apply -f ./manifest.yaml
+kubectl apply -f ./m1.yaml -f ./m2.yaml
+kubectl apply -f ./dir
+kubectl apply -f https://git.io/vPieo
+cat <<-EOF | kubectl apply -f -
+  apiVersion: v1
+  kind: Pod
+  metadata:
+    name: busybox-sleep
+  spec:
+    containers:
+    - name: busybox
+      image: busybox
+      args:
+      - sleep
+      - "1000000"
+  ---
+  apiVersion: v1
+  kind: Pod
+  metadata:
+    name: busybox-sleep-less
+  spec:
+    containers:
+    - name: busybox
+      image: busybox
+      args:
+      - sleep
+      - "1000"
+EOF
+cat <<-EOF | kubectl apply -f -
+  apiVersion: v1
+  kind: Secret
+  metadata:
+    name: mysecret
+  type: Opaque
+  data:
+    password: $(echo -n "s33msi4" | base64 -w0)
+    username: $(echo -n "jane" | base64 -w0)
+EOF
+
+# Compare the current state of the cluster against the state it would be in if
+# a manifest was applied
+kubectl diff -f ./manifest.yaml
+
+# Verify user's permissions on the cluster.
+kubectl auth can-i create roles
+
+# Taint a Node.
 kubectl taint nodes node1 key1=value1:NoSchedule
 
-# taint all nodes in a certain nodepool (azure aks)
+# Taint all nodes in a certain nodepool (Azure AKS).
 kubectl get nodes \
   -l "agentpool=nodepool1" \
   -o jsonpath='{.items[*].metadata.name}'
 | xargs -n1 -I{} -p kubectl taint nodes {} key1=value1:NoSchedule
 
-# remove a taint
-# notice the '-' sign at the end
+# Remove a taint.
+# Notice the '-' sign at the end.
 kubectl taint nodes node1 key1=value1:NoSchedule-
 
-# delete non-default service accounts
+# If a taint with that key and effect already exists, replace its value.
+kubectl taint nodes foo dedicated=special-user:NoSchedule
+
+# Mark Nodes as unschedulable.
+kubectl cordon my-node
+
+# Mark my-node as schedulable.
+kubectl uncordon my-node
+
+# Drain my-node in preparation for maintenance.
+kubectl drain my-node
+
+# Show metrics for a given node.
+kubectl top node my-node
+
+# Display addresses of the master and services.
+kubectl cluster-info
+
+# Dump the complete current cluster state.
+kubectl cluster-info dump
+kubectl cluster-info dump --output-directory=/path/to/cluster-state
+
+# Listen on port 5000 on the local machine and forward connections to port 6000
+# of my-pod
+kubectl port-forward my-pod 5000:6000
+
+# List supported resources types along with their short name, API group, Kind,
+# and whether they are namespaced.
+kubectl api-resources
+kubectl api-resources --namespaced=true
+kubectl api-resources -o name
+kubectl api-resources -o wide
+kubectl api-resources --verbs=list,get
+
+# Delete non-default service accounts.
 kubectl delete serviceaccounts \
   $(kubectl get serviceaccounts -o jsonpath="{.items[?(@.metadata.name!='default')].metadata.name}" \
     | tr ' ' ',')
+
+# Show the ExternalIO value for all nodes.
+kubectl get nodes \
+  -o jsonpath='{.items[*].status.addresses[?(@.type=="ExternalIP")].address}'
+
+# List ready nodes.
+JSONPATH='{range .items[*]}{@.metadata.name}:{range @.status.conditions[*]}{@.type}={@.status};{end}{end}' \
+  && kubectl get nodes -o jsonpath="$JSONPATH" | grep "Ready=True"
+
+# List all images excluding "k8s.gcr.io/coredns:1.6.2"
+kubectl get pods -A -o=custom-columns='DATA:spec.containers[?(@.image!="k8s.gcr.io/coredns:1.6.2")].image'
+
+# List all the images running in a cluster.
+kubectl get pods -A -o=custom-columns='DATA:spec.containers[*].image'
+
+# List all fields under '.metadata' regardless of their name.
+kubectl get pods -A -o=custom-columns='DATA:metadata.*'
+
+# List all secrets currently in use by a Pod.
+kubectl get pods -o json \
+ | jq '.items[].spec.containers[].env[]?.valueFrom.secretKeyRef.name' \
+ | grep -v null | sort | uniq
+
+# List the name of Pods belonging to a particular RC.
+SELECTOR=${$(kubectl get rc my-rc --output=json | jq -j '.spec.selector | to_entries | .[] | "\(.key)=\(.value),"')%?}
+kubectl get pods --selector=$SELECTOR --output=jsonpath='{.items..metadata.name}'
+
+# List the containerID of initContainers from all Pods.
+# Helpful when cleaning up stopped containers while avoiding the removal of
+# initContainers
+kubectl get pods --all-namespaces \
+  -o jsonpath='{range .items[*].status.initContainerStatuses[*]}{.containerID}{"\n"}{end}' \
+ | cut -d/ -f3
+
+# Produce a period-delimited tree of all keys returned for nodes.
+# Helpful when trying to locate a specific key within a complex nested JSON
+# structure.
+kubectl get nodes -o json | jq -c 'path(..)|[.[]|tostring]|join(".")'
+
+# Produce a period-delimited tree of all keys returned for Pods, etc
+kubectl get pods -o json | jq -c 'path(..)|[.[]|tostring]|join(".")'
+
+# Update the 'image' field of the 'www' containers from the 'frontend'
+# Deployment.
+# This starts a rolling update.
+kubectl set image deployment/frontend www=image:v2
+
+# Show the history of resources, including the revision.
+kubectl rollout history deployment/frontend
+
+# Rollback resources to the latest previous version.
+kubectl rollout undo deployment/frontend
+
+# Rollback resources to a specific revision.
+kubectl rollout undo deployment/frontend --to-revision=2
+
+# Follow the rolling update status of the 'frontend' Deployment until its
+# completion.
+kubectl rollout status -w deployment/frontend
+
+# Start a rolling restart of the 'frontend' Deployment.
+kubectl rollout restart deployment/frontend
+
+# Replace a Pod based on the JSON passed into stdin.
+cat pod.json | kubectl replace -f -
+
+# Force replacement, deletion and recreation (in this order) of resources.
+# This Will cause a service outage.
+kubectl replace --force -f ./pod.json
+
+# Create a service for a replicated 'nginx'.
+# Set it to serve on port 80 and connect to the containers on port 8000.
+kubectl expose rc nginx --port=80 --target-port=8000
+
+# Update a single-container Pod's image tag.
+kubectl get pod mypod -o yaml \
+ | sed 's/\(image: myimage\):.*$/\1:v4/' \
+ | kubectl replace -f -
+
+# Add Labels to resources.
+kubectl label pods nginx custom-name=awesome
+
+# Add Aannotations.
+kubectl annotate pods alpine icon-url=http://goo.gl/XXBTWq
+
+# Autoscale resources.
+kubectl autoscale deployment foo --min=2 --max=10
+
+# Partially update resources.
+kubectl patch node k8s-node-1 -p '{"spec":{"unschedulable":true}}'
+
+# Update a container's image.
+# 'spec.containers[*].name' is required because it's a merge key.
+kubectl patch pod valid-pod -p '{"spec":{"containers":[{"name":"kubernetes-serve-hostname","image":"new image"}]}}'
+
+# Update a container's image using a JSONPatch with positional arrays.
+kubectl patch pod valid-pod --type='json' \
+  -p='[{"op": "replace", "path": "/spec/containers/0/image", "value":"new image"}]'
+
+# Disable a Deployment's livenessProbe using a JSONPatch with positional arrays.
+kubectl patch deployment valid-deployment --type json \
+  -p='[{"op": "remove", "path": "/spec/template/spec/containers/0/livenessProbe"}]'
+
+# Add a new element to a positional array.
+kubectl patch sa default --type='json' \
+  -p='[{"op": "add", "path": "/secrets/1", "value": {"name": "whatever" } }]'
+
+# Edit the service named docker-registry.
+kubectl edit svc/docker-registry
+KUBE_EDITOR="nano" kubectl edit svc/docker-registry
+
+# Scale a replicaset named 'foo' to 3
+kubectl scale --replicas=3 rs/foo
+
+# Scale a resource specified in "foo.yaml" to 3 replicas.
+kubectl scale --replicas=3 -f foo.yaml
+
+# If the Deployment named 'mysql''s current size is 2, scale it to 3.
+kubectl scale --current-replicas=2 --replicas=3 deployment/mysql
+
+# Scale multiple ReplicationControllers at once.
+kubectl scale --replicas=5 rc/foo rc/bar rc/baz
+
+# Delete a Pod using the type and name specified in pod.json.
+kubectl delete -f ./pod.json
+
+# Delete Pods and Services named 'baz' and 'foo'.
+kubectl delete pod,service baz foo
+
+# Delete pods and services with Label name=myLabel.
+kubectl delete pods,services -l name=myLabel
+
+# Delete all pods and services in namespace my-ns.
+kubectl -n my-ns delete pod,svc --all
+
+# Delete all pods matching awk's pattern1 or pattern2.
+kubectl get pods --no-headers=true \
+ | awk '/pattern1|pattern2/{print $1}' \
+ | xargs  kubectl delete pods
+
+# Enable shell completion.
+source <(kubectl completion bash)
+echo "[[ $commands[kubectl] ]] && source <(kubectl completion zsh)" >> ~/.zshrc
 ```
 
+## Configuration
+
+`kubectl` looks for a file named `config` in the `$HOME/.kube` directory by default. One can specify other kubeconfig files by setting the `KUBECONFIG` environment variable or using the `--kubeconfig` flag:
+
+```shell
+KUBECONFIG="config.local:~/.kube/config" kubectl config view
+kubectl config --kubeconfig config.local view
+```
+
+The configuration file can be edited, or acted upon from the command line:
+
+```shell
+# Show the merged configuration.
+kubectl config view
+KUBECONFIG="~/.kube/config:config.local" kubectl config view
+
+# Show specific values only.
+kubectl config view -o jsonpath='{.users[].name}'
+kubectl config view -o jsonpath='{.users[?(@.name == "e2e")].user.password}'
+
+# Add a new user that supports basic auth.
+kubectl config set-credentials kubeuser/foo.kubernetes.com \
+  --username=kubeuser --password=kubepassword
+
+# Delete user 'foo'.
+kubectl config unset users.foo
+
+# List the available contexts.
+kubectl config get-contexts
+
+# Display the current default context name.
+kubectl config current-context
+
+# Set the default context.
+kubectl config use-context minikube
+
+# Permanently setup specific contexts.
+kubectl config set-context --current --namespace=ggckad-s2
+kubectl config set-context gce --user=cluster-admin --namespace=foo
+```
+
+### Configure access to multiple clusters
+
+See [configure access to multiple clusters] for details.
+
 ## Further readings
 
 - [Assigning Pods to Nodes]
 - [Taints and Tolerations]
 - [Commands reference]
+- [Configure access to multiple clusters]
 
+## Sources
+
+- [Cheatsheet]
+- [Run a single-instance stateful application]
+- [Run a replicated stateful application]
+- [Accessing an application on Kubernetes in Docker]
+
+<!-- docs -->
 [assigning pods to nodes]: https://kubernetes.io/docs/concepts/scheduling-eviction/assign-pod-node/
+[cheatsheet]: https://kubernetes.io/docs/reference/kubectl/cheatsheet
+[commands reference]: https://kubernetes.io/docs/reference/generated/kubectl/kubectl-commands
+[configure access to multiple clusters]: https://kubernetes.io/docs/tasks/access-application-cluster/configure-access-multiple-clusters/
 [taints and tolerations]: https://kubernetes.io/docs/concepts/scheduling-eviction/taint-and-toleration/
 
-[commands reference]: https://kubernetes.io/docs/reference/generated/kubectl/kubectl-commands
+<!-- other articles -->
+[accessing an application on kubernetes in docker]: https://medium.com/@lizrice/accessing-an-application-on-kubernetes-in-docker-1054d46b64b1
+[run a replicated stateful application]: https://kubernetes.io/docs/tasks/run-application/run-replicated-stateful-application/
+[run a single-instance stateful application]: https://kubernetes.io/docs/tasks/run-application/run-single-instance-stateful-application/