Main Flashcards
Imperative Command for Creating a Pod
kubectl run nginx –image=nginx
Imperative Command for Creating a Deployment
kubectl create deployment –image=nginx nginx
How do commands and arguments in Kubernetes overwrite what’s written in the DockerFile?
The attribute, “command:[“sleep2.0”]” inside the containers attribute overwrites the Docker command: ENTRYPOINT[“sleep”]. Same thing with args:[“10”] overwriting CMD[“5”]
Create a command defined in Kubernetes that will execute once a container has launched
containers:
- name: ubuntu
image: ubuntu
command: [“sleep”]
args: [“10”]
How does one use ConfigMaps/Secrets?
- Create ConfigMap Object
2. Attach ConfigMap Object to Pod
How do you define environment variables in a pod (No configmap)?
env:
- name: APP_COLOR
value: PINK
How do you attach a ConfigMap object to a pod?
containers:
- name: simple-webapp
image: simple-webapp
envFrom:
- configMapRef:
name: {NameOfConfigMap}How do you add a pod/deployment/replicaset to a namespace (2 methods)?
- Using imperative command: –namespace={namespace}
2. Adding namespace dictionary value to metadata attribute in yaml config
What has the –dry-run command changed to?
–dry-run=client
How do you format secret object values (2 methods)?
- Imperative commands: kubectl create secret –from-literal=key:value –from-literal=key2:value2
- a. Linux commands: echo -n ‘{secret}’ | base64 –decode
b. kubectl create -f
c.
data:
secret: decodedvalue
How do you attach a Secret object to a container?
containers:
- name: simple-webapp
image: simple-webapp
envFrom:
- secretRef:
name: {nameOfSecretObject}How do you attach a Secret to a pod (in pod definition)?
env:
- name: {secretName}
valueFrom:
secretKeyRef:
name: app-secret
key: {secretValue}How do you attach a Secret to a pod (using volumes)?
volumes:
- name: app-secret-volume
secret:
secretName: app-secret
How do you check who’s listed as the security context for running a particular container?
- kubectl exec ubuntu-sleeper – whoami
2. Do an -o yaml and see security context
How do you format a security context for a pod?
spec:
securityContext:
runAsUser: 1000
runAsGroup: 2000
How do you format a security context object for a container?
spec:
containers:
- name: ubuntu
image: ubuntu
command ["sleep", "23"]
securityContext:
runAsUser: 1000
runAsGroup: 2000Does a security context on a pod or container take precedence?
Pod security contexts overwrite container security contexts.
How do you create a service account?
kubectl create serviceaccount {serviceAccountName}
How do you get a service account token?
- Find the secret ID: kubectl describe serviceaccount {serviceAccountName}
- Describe secret with secret ID: kubectl describe secret {secretID}
How do you make a call to the kubernetes api endpoint using a service account?
- Get Service Account token (see question 20)
2. curl {endpont url} –insecure –header “Authorization: Bearer {token}”
At what level do you set resource requirements in a pod definition file?
The container level. Example:
containers:
- name: simplewebapp
image: simple-webapp
resources:
requests:
memory: "1Gi"
cpu: 1
limits:
memory: "2Gi"
cpu: 2
Can a container use more than its resource limit for cpu and memory?
If a container reaches its limit for cpu, the node will throttle the cpu. If a container reaches its limit for memory, it can go above its limit, but if it keeps doing this, the pod will be destroyed.
How do you taint a node?
kubectl taint nodes {nodeName} key:value:taintEffect
Example: kubectl taint nodes node1 app=blue:NoSchedule
What is the difference between taints and tolerations?
Taints are applied to nodes while tolerations are applied to pods. A pod needs to have x toleration in order to land on x taint.
What is the taint effect, NoSchedule?
Pods will not be scheduled on the node
What is the taint effect, PreferNoSchedule?
Pods will have a preference to not be scheduled on the node.
What is the taint effect, NoExecute?
New pods will not be scheduled on the node, existing pods will be evicted from the node.
How do you label nodes?
kubectl label nodes {nodeName} {labelKey}:{labelValue}
example: kubectl label nodes node-1 size=Large
