Key Value server and Kubernetes deployment

Structure:

The system is composed of:

2 pods running the main app (explore /app for details) with its static volume (node app won't make any changes to its volume).
Sharded mongodb: The db system has:
- a config volume for storing scripts of mongo init
- 2 shards, 2 replica for each shard, 1 persistent volume for each replica
- 2 config servers, with its own volume, no persistent volume (maybe bad practice)
- 2 mongo router pods (mongos)
- a mongo service

To execute:

First look at the following notes:

Config files details:

config/server.yaml includes:
- Server deployment
- Service of that deployment
config/ingress.yaml includes:
- Ingress for users to access the app, in server.yaml via internet
config/mongo/configserver.yaml includes:
- A statefulSet of mongodb configserver, kubernetes will generate 2 replica with names mongod-configdb-0 and mongod-configdb-1
- A service to expose that statefulset to cluster
config/mongo/router.yaml includes:
- A deployment of mongodb router (mongos), kubernetes will generate 2 replica with prefix mongos
- A service to expose the deployment to cluster, as 'mongo'

Now, following are build steps:

Prerequisite:

docker

sudo apt install docker.io
kubectl and minikube (for local tests): Please follow instruction on kubernetes.io homepage
- An account on hub.docker.com if you would like to explore step 1

Steps for app deployment

Generate app image (optional, means that you could skip this step as you do not care about containerizing step, I've built an image for following step):

I have a Dockerfile which describe and build our 'app' image, just run ./cmd.sh build

Notes: In ./cmd.sh build, the script uses my own credentials (as vinhphuctadang) for logging into 'dockerhub' to push image onto the hub; to make it your own, please custom the name 'vinhphuctadang' to your 'dockerhub' account in order to have the built image pushed, and if you made changes, you should then edit config/server.yaml for correct image which matches your built image

Modify config/server.yaml if you build your own image, at the line where

  image: vinhphuctadang/key-value-server:latest

Run commands: Simply run

./cmd.sh start

Notes: In case the 'mongo' init failed due to mongo component not finishing their booting actions, we should run ./cmd.sh initMongo again

Inspect the address of our server ingress: kubectl get ingress -n myserver (since our namespace has only one ingress, there is only one externally visible IP address)

Example:

NAME                CLASS    HOSTS   ADDRESS      PORTS   AGE
key-value-ingress   <none>   *       172.17.0.3   80      21m

Stop server:

./cmd.sh stop
./cmd.sh clean

Common failure:

Kubectl not found => Check for kubectl installation on kubectl homepage
You see the line: In case this script failed, mostly because components are not booting up completely, you should run ./cmd.sh mongoInit again, first you should check if all mongo components are initialized properly or not, then if something looks like error, you should run ./cmd.sh mongoInit
You cannot find the server IP: Simply type ./cmd.sh ingress then it should show the IP where you could have access to

More about application deployment and devops???

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