02-redis.md

2️⃣ deploy redis

use official docker.io/librery/redis

• get image full registry name by running:

  docker pull redis

• Result

  Using default tag: latest
  latest: Pulling from library/redis
  Digest: sha256:a89cb097693dd354de598d279c304a1c73ee550fbfff6d9ee515568e0c749cfe
  Status: Image is up to date for redis:latest
  docker.io/library/redis:latest

  🔔 In result above image redis's full name is really docker.io/library/redis:latest (docker.io - docker maintained registry, library officially maintained by docker team, latest becuse we didn't specify is default version)

  🔔 the latest tag's digest sha -> sha256:a89cb097693dd354de598d279c304a1c73ee550fbfff6d9ee515568e0c749cfe

  🔔 So the exact version of the image is docker.io/library/redis:latest:sha256@a89cb097693dd354de598d279c304a1c73ee550fbfff6d9ee515568e0c749cfe

Generate a deployemnt.yaml - declerative configuration

• Create deployment for redis:
  • image name: docker.io/library/redis:
  • image version: latest:sha256@a89cb097693dd354de598d279c304a1c73ee550fbfff6d9ee515568e0c749cfe

# 🔔 note: --dry-run=client -oyaml > ./deployment/kustomize/manifests/redis/deployment.yaml for reuse

kubectl create deployment --image=docker.io/library/redis:latest@sha256:a89cb097693dd354de598d279c304a1c73ee550fbfff6d9ee515568e0c749cfe redis --port=6379 --dry-run=client -oyaml > ./deployment/kustomize/manifests/redis/deployment.yaml

apply deployment from ./deployment/kustomize/manifests/redis/deployment.yaml

📓 -> Any yaml file including kubernes configuration, in our example, a deployment object, can be done via kubectl apply -f /path/to/file [ -f another-file ] ...

kubectl apply -f ./deployment/kustomize/manifests/redis/deployment.yaml

validate redis is functional:

📓 the pod id presented below, may differ in your setup ...

kubectl get po 
NAME                     READY   STATUS    RESTARTS   AGE
redis-7dcd746c6-sj9w8   1/1     Running   0          88m

get pod by label:

The following command will help make this command more user-freindly using the label/selector of the deployment:

kubectl get po -l app=redis

using port-froward to pod (reach a pod which is part fo the deployment object)

• This is equivalent in docker -> docker run without -p (sevice not accessibel via host) ... and we must docker attach <contaoerId>

kubectl port-forward  redis-7dcd746c6-sj9w8 6379:6379

using service to expose a deployment to other services in the cluster

For a service to be able to access another service in the cluster, we need a service of type ClusterIP which is the default kuberentes service type (more on the other later ...), once you have a service name foo pointing to a deployment by using tags + selctors:

e.g.

# from ./deployment/kustomize/manifests/redis/deployment.yaml
...
spec:
  replicas: 1
  selector:
    matchLabels:
      app: redis
  strategy: {}
  template:
    metadata:
      creationTimestamp: null
      labels:
        app: redis
...

generate the service file ../deployment/kustomize/manifests/redis/svc.yaml

Using kubectl expose deployment

kubectl expose deployment redis --port=6379 --dry-run=client -oyaml > ./deployment/kustomize/manifests/redis/svc.yaml

apply svc from ./deployment/kustomize/manifests/redis/svc.yaml

kubectl apply -f ./deployment/kustomize/manifests/redis/svc.yaml

using port-froward to svc (points to the deployment instance / replica)

kubectl port-forward svc/redis 6379:6379

Checking connection using kubectl exec:

kubectl exec -it `kubectl  get pod -l app=redis | grep redis| awk '{print $1}'` -- redis-cli GET pings

should yield:

""

After we deploy pinger we will run this again ...

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🆙 next deploy - microservices