Mongo Shell Commands

 Following commands can be used in mongo db shell.

show dbs

• list of all the databases

use shops

• switch to a specific database or creates a database (shops) 

db.createCollection("products")

• creating the collection (products)

show collections

• display a list of all the collections 

 db.products.insertOne({"name":"prod_name1"})

• insert a document into a collection

db.products.insertMany([{"name":"prod_name2"},{"name":"prod_name3"}])

• insert many products in one command

db.products.insertOne({"name":"test_prod4","vendor":{"name":"vendor_1","address":"address_1"}})

• insert many products in one command with multiple objects

db.student.insertOne({"name":"test_prod5",,"vendor":{"name":"vendor_1","address":{"address_line1":"line1","address_line2":"line2","city":"city"}}})

• insert many products in one command with multiple objects

db.products.find()

• retrieve all documents

db.products.update({name:"test_prod1"},{$set:{price:"120.00"}})

• update a document in the "products" collection. updates first document only for name:"test_prod1" 

db.student.update({"name":"test_6"},{$set:{age:26}},{multi:true})

• updating all document

db.student.update({_id:ObjectId("64dc5856e4cebb07084d8c45")},{$unset:{price:"120.00"}})

• updating the document using object id and remove price attribute

db.teaches.update({"th_name":"test_th_2"},{$set:{student:[{"std_name":"test_1"},{"std_name":"test_2"}]}})

• adding the Student object field

db.student.find({$and:[{"name":"test_4"},{"age":"40"}]})

• AND operation. returns all objects with name =test_4 and age=40

db.student.find({$or:[{"name":"test_4"},{"name":"test_2"}]})

• OR operation and returns name = test_2 or test_4

db.student.drop()

• drop student collection

db.teaches.remove({"name":"t_name1"})

• remove document name =t_name1

db.teaches.deleteOne({"name":"t_name2"})

• remove one document with name=t_name2

db.student.aggregate([{$lookup:{from:"teaches",localField:"std_name",foreignField:"student.std_name",as:"studentDetails"}}])

• aggregation operation in MongoDB to join the "student" collection with the "teaches" collection

db.mycol.find().pretty() 

• return results in formatted way

#!/bin/bash

ps -ef |grep "java -jar" > /apps/appcheck

x=$(cat /apps/appcheck |grep "TestApp.jar" |wc -l)
echo $x

        if [ $x = 0 ]

        then
                date
                echo ""
                echo "starting... check logs "
                cd /apps/sujith/test
                nohup java -jar -Xms128m -Xmx256m TestApp.jar 2 >> TestApp.log &
        elif [ $x = 1 ]

        then
                date
                echo "stopping..."
                cat /apps/appcheck|grep "TestApp.jar" | awk -F " " '{print $2}' | xargs kill -9
                echo "stopped"
                date
                echo "starting..."
                cd /apps/sujith/test
                nohup java -jar -Xms128m -Xmx256m ThripleNine.jar 2>> TestApp.log &

        else
                echo "error occurred. check."

        fi

kubernetes pod sample files

simple nginx pod

apiVersion: v1

kind: Pod

metadata:

    name: nginx-pod

    labels:

        app: nginx

        tier: dev

spec:

    containers:

        - name: nginx-container

          image: nginx

multiple containers in one pod

apiVersion: v1

kind: Pod

metadata:

  name: nginx-caching-server

  labels:

    purpose: demonstrate-multi-container-pod

spec:

  containers:

  - name: nginx-container1

    image: nginx

  - name: busybox-container2

    image: busybox

    command:

      - sleep

      - "3600"

replica controller

apiVersion: v1

kind: ReplicationController

metadata:

  name: nginx-rc

spec:

  replicas: 3

  template:

    metadata:

      name: nginx-pod

      labels:

        app: nginx-app

    spec:

      containers:

      - name: nginx-container

        image: nginx

        ports:

        - containerPort: 80

  selector:

    app: nginx-app

replica set

apiVersion: apps/v1

kind: ReplicaSet

metadata:

  name: nginx-rs

spec:

  replicas: 3

  template:

    metadata:

      name: nginx-pod

      labels:

        app: nginx-app

        tier: frontend

    spec:

      containers:

      - name: nginx-container

        image: nginx

        ports:

        - containerPort: 80

  selector:

    matchLabels:

      app: nginx-app

    matchExpressions:

      - {key: tier, operator: In, values: [frontend]}

daemon set

daemon set guarantee to up and run one instance in every node

apiVersion: apps/v1

kind: DaemonSet

metadata:

  name: fluentd-ds

spec:

  template:

    metadata:

      labels:

        name: fluentd

    spec:

      containers:

      - name: fluentd

        image: gcr.io/google-containers/fluentd-elasticsearch:1.20

  selector:

    matchLabels:

      name: fluentd

up and run pods for special nodes only using daemon set(diskType=ssd)

apiVersion: apps/v1

kind: DaemonSet

metadata:

  name: nginx-ds

spec:

  template:

    metadata:

      labels:

        name: nginx

    spec:

      containers:

      - name: nginx-container

        image: nginx

      nodeSelector:

        disktype: ssd

  selector:

    matchLabels:

      name: nginx

batch execution pod. it will print 9 to 1 when execution.

apiVersion: batch/v1

kind: Job

metadata:

  name: countdown

spec:

  template:

    metadata:

      name: countdown

    spec:

      containers:

      - name: counter

        image: centos:7

        command:

         - "bin/bash"

         - "-c"

         - "for i in 9 8 7 6 5 4 3 2 1 ; do echo $i ; done"

      restartPolicy: Never

nginx deployment pod

apiVersion: apps/v1

kind: Deployment

metadata:

  name: nginx-deploy

  labels:

    app: nginx-app

spec:

  replicas: 3

  template:

    metadata:

      labels:

        app: nginx-app

    spec:

      containers:

      - name: nginx-container

        image: nginx

        ports:

        - containerPort: 80

  selector:

    matchLabels:

      app: nginx-app

redis deployment using Recreate

In "Recreate", it will terminate all containers at once and restart required containers.

apiVersion: apps/v1

kind: Deployment

metadata:

  name: redis-deployment

  labels:

    app: redis

spec:

  replicas: 10

  selector:

    matchLabels:

      app: redis

  strategy:

    type: Recreate

  template:

    metadata:

      labels:

        app: redis

    spec:

      containers:

        - name: redis-container

          image: redis:5.0

redis deployment using RollingUpdate

in "RollingUpdate", requested number of containers will be updated.

new instance will up and old instance will down in this scenario.

apiVersion: apps/v1

kind: Deployment

metadata:

  name: redis-deployment

  labels:

    app: redis

spec:

  replicas: 15

  selector:

    matchLabels:

      app: redis

  strategy:

    type: RollingUpdate

    rollingUpdate:

      maxSurge: 2

      maxUnavailable: 2

  minReadySeconds: 10

  template:

    metadata:

      labels:

        app: redis

    spec:

      containers:

        - name: redis-container

          image: redis:6.0 #Upgrade to 6.0 --> 6.0.16 --> 6.2.6

volume usage

when using volume, it can replicate to every containers config in pod file

apiVersion: v1

kind: Pod

metadata:

  name: sidecar-pod

spec:

  volumes:

  - name: logs

    emptyDir: {}

  containers:

  - name: app-container

    image: alpine

    command: ["/bin/sh"]

    args: ["-c", "while true; do date >> /var/log/app.log; sleep 5; done"]

    volumeMounts:

    - name: logs

      mountPath: /var/log

     

  - name: log-exporter-sidecar

    image: nginx

    ports:

      - containerPort: 80

    volumeMounts:

    - name: logs

      mountPath: /usr/share/nginx/html

volume "emptyDir" usage

apiVersion: v1

kind: Pod

metadata:

  name: nginx-emptydir

spec:

  containers:

  - name: nginx-container

    image: nginx

    volumeMounts:

    - name: test-vol

      mountPath: /test-mnt

  volumes:

  - name: test-vol

    emptyDir: {}

nginx deploymnet with 2 replicas

apiVersion: apps/v1

kind: Deployment

metadata:

  name: nginx-deployment

spec:

  selector:

    matchLabels:

      app: nginx

  replicas: 2 # tells deployment to run 2 pods matching the template

  template:

    metadata:

      labels:

        app: nginx

    spec:

      containers:

      - name: nginx

        image: nginx:1.14.2

        ports:

        - containerPort: 80

 

Kubernetes Commands

kubectl get nodes returns available nodes in k8s cluster

kubectl get po returns available pods in k8s cluster

kubectl get po -o wide return ip address and other details of pod 

kubectl create -f poddemo.yml create pod using yml file. this will create a pod with nginx

Sample yaml file for pod creation 

apiVersion: v1
kind: Pod
metadata:
    name: nginx-pod
    labels:
        app: nginx
        tier: dev
spec:
    containers:
        - name: nginx-container
          image: nginx

kubectl describe pod nginx-pod returns details about pod

kubectl delete pod nginx-pod delete pod nginx-pod

kubectl delete pod --all delete all pods

kubectl expose pod nginx-pod --type="NodePort" --port=8080 expose pod in 8080 port as a service

kubectl get svc returns services exposed

kubectl delete svc nginx-pod delete service  nginx-pod

kubectl exec -it nginx-caching-server bash access to nginx-caching-server bash terminal

kubectl exec -it nginx-caching-server -c busybox-container2 sh access nginx-caching-server pod's container "busybox-container2" for sh

kubectl get rc returns returns replica controllers

kubectl get rs returns replica set

kubectl scale rc nginx-rc --replicas=5 scale replica controller size to 5 for nginx-rc

kubectl delete  rc --all delete all replica controllers

kubectl delete  rs --all delete all replica sets

kubectl label nodes node2 diskType=ssd change node 2's diskType to ssh

kubectl get nodes --show-labels returns all labels

kubectl get job return batch job details

kubectl describe jobs countdown retrieve details about countdown pod's job

kubectl logs countdown-rmc97 returns logs of "countdown-rmc97" container

kubectl get deploy returns deployments

kubectl delete deploy --all delete all deployments 

kubectl describe deploy nginx-deploy returns details of "nginx-deploy" deployment

kubectl set image deploy nginx-deploy nginx-container=nginx:1.9.1 --record change the image of nginx to 1.9.1

kubectl rollout status deployment/nginx-deploy returns rollout status of nginx-deploy

kubectl rollout history deployment/nginx-deploy returns rollout history of nginx-deploy

kubectl rollout undo deployment/nginx-deploy undo the changes 

kubectl rollout status deployment/nginx-deploy returns rollout status of nginx-deploy

kubectl describe deploy nginx-deploy | grep -i image returns image details of nginx-deploy

kubectl edit deployment redis-deployment edit the deployment configurations of "redis-deployment"

Enable RabbitMQ plugins

In RabbitMQ command prompt, use following commands to enable plugins.

rabbitmq-plugins enable rabbitmq_management

Docker Commands-Updated

• docker -v  returns docker version 

• docker login login to docker hub using command line

• docker pull hello-world retrieve hello-world docker image from docker hub

• docker run hello-world execute hello-world docker image

• docker ps -a list all processes in docker

• docker rmi hello-world --force delete hello-world image from docker forcefully 

• docker rm container_id --force delete container from docker forcefully 

• docker run -d nginx run nginx server in background

• docker ps list running processes in docker

• docker container inspect container_id get the all information about docker container 

• docker run -d -p 3600:80 --name sujith-nginx nginx port forwarding with docker images execution 

• docker exec -it container_d redis redis-cli access redis-cli after docker image execution

• set myvalue 5 set value redis

• get myvalue retrieve value

• docker run -it ubuntu bash run ubuntu with bash access in docker

• apt-get install git tree -y install git inside ubuntu

• ctrl + p + q exit to run git in background 

• docker container commit --author "sujith" -m "my custom image" running_container_id my_ubuntu_git_image create image using running git installed ubuntu container

• docker docker tag my_ubuntu_git_image sujithdc/my_ubuntu_git_image tagging docker image to push to docker hub

• docker push sujithdc/my_ubuntu_image push image to docker hub

fatal: Authentication failed git resolution

 If you have changed your certificate of your git repository, you will receive the following error message.

fatal: Authentication failed for for 'https://bitbucket.*****/***/usermgt*.git/'

You can follow following steps to resolve the issue.

1. Retrieve the remote URL

git remote -v

2. Remove the remote URL

git remote rm origin

3. Add URL as new remote URL

git remote add origin  https://bitbucket.*****/***/usermgt*.git

4. Make changes and push

git push origin master