With this project I want to compare 3 approaches of deploying same applications to Kubernetes cluster:
- k8s - the entire deployment is done with
kubectl- Kubernetes command line tool, - helm - the deployment is done by using Helm charts,
- helmfile - very similar to previous one, but this time with installed helmfile plugin for Helm.
Enter one of the folders to find out about one of the approaches.
This project is based on my previous one - Kanban Board (source code).
It contains 3 components:
- postgres - database
- kanban-app - backend service, serving REST endpoints for a frontend
- kanban-ui - frontend service
And here is a simplified schema of what I would like to achieve:
On it you there is an additional component - adminer. It's GUI application for managing the database.
A full picture of Kubernetes cluster that is created with each approach is presented below:
Before testing any of described approaches you need first go through following steps:
- Installing Docker - https://docs.docker.com/install/
- Installing minikube - https://kubernetes.io/docs/tasks/tools/install-minikube/
- Installing kubectl - https://kubernetes.io/docs/tasks/tools/install-kubectl/
In order to run a minikube cluster:
$ minikube start
😄 minikube v1.25.2 on Ubuntu 20.04 (amd64)
✨ Automatically selected the docker driver
👍 Starting control plane node minikube in cluster minikube
🚜 Pulling base image ...
🔥 Creating docker container (CPUs=2, Memory=2200MB) ...
🐳 Preparing Kubernetes v1.23.3 on Docker 20.10.12 ...
▪ kubelet.housekeeping-interval=5m
▪ Generating certificates and keys ...
▪ Booting up control plane ...
▪ Configuring RBAC rules ...
🔎 Verifying Kubernetes components...
▪ Using image gcr.io/k8s-minikube/storage-provisioner:v5
🌟 Enabled addons: default-storageclass, storage-provisioner
🏄 Done! kubectl is now configured to use "minikube" cluster and "default" namespace by defaultTo check the status of the cluster:
$ minikube status
host: Running
kubelet: Running
apiserver: Running
kubeconfig: ConfiguredTo check that kubectl is properly configured:
$ kubectl cluster-info
Kubernetes master is running at https://127.0.0.1:32768
KubeDNS is running at https://127.0.0.1:32768/api/v1/namespaces/kube-system/services/kube-dns:dns/proxy
To further debug and diagnose cluster problems, use 'kubectl cluster-info dump'.Next, we need to run another command to enable Ingress addon:
$ minikube addons enable ingress
▪ Using image k8s.gcr.io/ingress-nginx/kube-webhook-certgen:v1.1.1
▪ Using image k8s.gcr.io/ingress-nginx/kube-webhook-certgen:v1.1.1
▪ Using image k8s.gcr.io/ingress-nginx/controller:v1.1.1
🔎 Verifying ingress addon...
🌟 The 'ingress' addon is enabledAs I want to have two different URLs to enter the adminer (database management tool) and kanban app you need to config your hosts file - add following lines:
127.0.0.1 adminer.k8s.com
127.0.0.1 kanban.k8s.com
Location of hosts file on different OS:
To access one of these addresses one last thing is needed - running following command:
$ minikube tunnel
✅ Tunnel successfully started
📌 NOTE: Please do not close this terminal as this process must stay alive for the tunnel to be accessible ...
Official kubectl cheatsheet:
https://kubernetes.io/docs/reference/kubectl/cheatsheet/
Minikube provides a Dashboard for entire cluster, after typing following command it will open
$ minikube dashboard
🔌 Enabling dashboard ...
▪ Using image kubernetesui/dashboard:v2.3.1
▪ Using image kubernetesui/metrics-scraper:v1.0.7
🤔 Verifying dashboard health ...
🚀 Launching proxy ...
🤔 Verifying proxy health ...
🎉 Opening http://127.0.0.1:46801/api/v1/namespaces/kubernetes-dashboard/services/http:kubernetes-dashboard:/proxy/ in your default browser...
👉 http://127.0.0.1:46801/api/v1/namespaces/kubernetes-dashboard/services/http:kubernetes-dashboard:/proxy/To see a resource (CPU, memory) consumption of services you can enable metrics-server minikube addon (they will be visible on a dashboard):
$ minikube addons enable metrics-server
▪ Using image k8s.gcr.io/metrics-server/metrics-server:v0.4.2
🌟 The 'metrics-server' addon is enabledIf your pod is not starting properly you can investigate it by describe pods command:
$ kubectl describe pods postgres-6fd67d4976-ljd2j
Name: postgres-6fd67d4976-ljd2j
Namespace: default
Priority: 0
Node: m01/172.17.0.2
Start Time: Tue, 24 Mar 2020 07:50:28 +0100
Labels: app=postgres
pod-template-hash=6fd67d4976
type=db
Annotations: <none>
Status: Pending
IP: 172.18.0.4
IPs:
IP: 172.18.0.4
Controlled By: ReplicaSet/postgres-6fd67d4976
Containers:
postgres:
Container ID:
Image: postgres:9.6-alpine
Image ID:
Port: 5432/TCP
Host Port: 0/TCP
State: Waiting
Reason: CreateContainerConfigError
Ready: False
Restart Count: 0
Environment:
POSTGRES_DB: kanban
POSTGRES_USER: kanban
POSTGRES_PASSWORD: kanban
Mounts:
/var/lib/postgresql/data from postgres-storage (rw,path="postgres")
/var/run/secrets/kubernetes.io/serviceaccount from default-token-nlb25 (ro)
Conditions:
Type Status
Initialized True
Ready False
ContainersReady False
PodScheduled True
Volumes:
postgres-storage:
Type: PersistentVolumeClaim (a reference to a PersistentVolumeClaim in the same namespace)
ClaimName: postgres-persistent-volume-claim
ReadOnly: false
default-token-nlb25:
Type: Secret (a volume populated by a Secret)
SecretName: default-token-nlb25
Optional: false
QoS Class: BestEffort
Node-Selectors: <none>
Tolerations: node.kubernetes.io/not-ready:NoExecute for 300s
node.kubernetes.io/unreachable:NoExecute for 300s
Events:
Type Reason Age From Message
---- ------ ---- ---- -------
Normal Scheduled 2m3s default-scheduler Successfully assigned default/postgres-6fd67d4976-ljd2j to m01
Normal Pulled 6s (x11 over 2m2s) kubelet, m01 Container image "postgres:9.6-alpine" already present on machine
Warning Failed 6s (x11 over 2m2s) kubelet, m01 Error: stat /tmp/hostpath-provisioner/pvc-f5d9b781-9cdf-4a4c-8c9b-2edb8330d139: no such file or directory