Learn Docker Beginner

If you are in Software industry then you must use this phrase to prove yourself.

But I m sure after reading this tutorial you won't be able to say this again.

1. What is Docker Docker is a software platform designed to make it easier to create, deploy, and run applications by using containers. It allows developers to package up an application with all the parts it needs in a container, and then ship it out as one package
2. Virtual Machines vs. Docker Virtual machines have a full OS with its own memory management installed with the associated overhead of virtual device drivers. Every guest OS runs as an individual entity from the host system.

On the other hand Docker containers are executed with the Docker engine rather than the hypervisor.

3. Introduction to Dockerfiles, images and containers

A Dockerfile is a text file that Docker reads in from top to bottom. It contains a bunch of instructions which informs Docker HOW the Docker image should get built.

A Docker image gets built by running a Docker command (which uses that Dockerfile)

A Docker container is a running instance of a Docker image

If you are too much into object oriented design then you can assume Docker image as a class, where as a Docker container is an instance of that class.


4. The Docker Hub

Docker Hub is a cloud-based repository in which Docker users and partners create, test, store and distribute container images which you can get from here.

https://hub.docker.com/


Create and Run docker image

prerequisite : Must have docker installed in system

https://librakblog.blogspot.com/2019/01/install-docker-on-ubuntu.html


In this scenario, you'll learn how to create a Docker Image for running a static HTML website using Nginx.
The scenario will explain how to build a Docker Image running Nginx with your HTML site.
The aim is to help you understand how to create and run Docker Images created by yourself.

create folder Docker and add file hello.html file into that.

Hello.html

<h1>Hello World</h1>

add one more file name Dockerfile make sure file name should be like this only without ant extension.

Open terminal and reach at folder Docker

vikash@vikash-pc:~/D-Drive/RKS_DOCS$ cd /home/vikash/D-Drive/RKS_DOCS/Docker/
vikash@vikash-pc:~/D-Drive/RKS_DOCS/Docker$ ls -lrt
total 8
-rw-rw-r-- 1 vikash vikash 20 Jan 27 16:03 Hello.html
-rw-rw-r-- 1 vikash vikash 49 Jan 27 16:04 Dockerfile

Step 1 - Create Dockerfile


Copy the below content in your Dockerfile for building your image.

Copy to EditorFROM nginx:alpine

COPY . /usr/share/nginx/html

The first line defines our base image.

The second line copies the content of the current directory into a particular location inside the container.

Step 2 - Build Docker Image
The Dockerfile is used by the Docker CLI build command. The build command executes each instruction within the Dockerfile. The result is a built Docker Image that can be launched and run your configured app. The build command takes in some different parameters.
The format is

docker build -t <build-directory>

The -t parameter allows you to specify a friendly name for the image and a tag, commonly used as a version number. This allows you to track built images and be confident about which version is being started.

sudo docker build -t webserver-image:v1 .

Result:

vikash@vikash-pc:~/D-Drive/RKS_DOCS/Docker$ sudo docker build -t webserver-image:v1 .
[sudo] password for vikash: 
Sending build context to Docker daemon  3.072kB
Step 1/2 : FROM nginx:alpine
alpine: Pulling from library/nginx
cd784148e348: Pull complete 
6e3058b2db8a: Pull complete 
7ca4d29669c1: Pull complete 
a14cf6997716: Pull complete 
Digest: sha256:385fbcf0f04621981df6c6f1abd896101eb61a439746ee2921b26abc78f45571
Status: Downloaded newer image for nginx:alpine
 ---> 315798907716
Step 2/2 : COPY . /usr/share/nginx/html
 ---> 6c54defc9f09
Successfully built 6c54defc9f09
Successfully tagged webserver-image:v1

As you can see in above output that above command executes all given steps in Dockerfile one by one.

You can view a list of all the images on the host using

sudo docker images

Output:

vikash@vikash-pc:~/D-Drive/RKS_DOCS/Docker$ sudo docker images
REPOSITORY          TAG                 IMAGE ID            CREATED             SIZE
webserver-image     v1                  6c54defc9f09        2 minutes ago       17.8MB
hello-world         latest              fce289e99eb9        3 weeks ago         1.84kB
nginx               alpine              315798907716        4 weeks ago         17.8MB

The built image will have the name webserver-image with a tag of v1.

Step 3 - Run


Launch our newly built image providing the friendly name and tag. As it's a web server, bind port 80 to our host using the -p parameter.

docker run -d -p 80:80 webserver-image:v1

Once started, you'll be able to access the results of port 80 via

http://localhost/Hello.html


You now have a static HTML website being served by Nginx.

Install docker on Ubuntu

Step :1  

Open terminal using command Ctrl+T.

Step 2:

Update your existing list of packages.

sudo apt update

Step 3:

Install prerequisite packages which let apt use packages over HTTPS:

sudo apt install apt-transport-https ca-certificates curl software-properties-common

Step 4:

Add GPG key for the official Docker repository to your system:

curl -fsSL https://download.docker.com/linux/ubuntu/gpg | sudo apt-key add -

Step 5:
Add the Docker repository to APT sources:

sudo add-apt-repository "deb [arch=amd64] https://download.docker.com/linux/ubuntu bioni

Step 6:

Update the package database 

sudo apt update

Step 7:

Make sure you are about to install from the Docker repo instead of the default Ubuntu repo:

apt-cache policy docker-ce

You'll see output like this, although the version number for Docker may be different:

Notice that docker-ce is not installed

Step 8:

Finally, install Docker:

sudo apt install docker-ce

Step 9:

Docker should now be installed, the daemon started, and the process enabled to start on boot. Check that it's running:

sudo systemctl status docker

Installing Docker now gives you not just the Docker service (daemon) but also the docker command line utility,


Step 10:

To view system-wide information about Docker, use:

docker info

This will give you permission error so try with sudo you can check more on how to avoid using sudo everytime

sudo docker info

To check whether you can access and download images from Docker Hub, type:


Step 11:

sudo docker run hello-world

To see the images that have been downloaded to your computer, type:

sudo docker images

The output should look similar to the following:


The hello-world container you ran in the previous step is an example of a container that runs and exits after emitting a test message. Containers can be much more useful than that, and they can be interactive.

After using Docker for a while, you'll have many active (running) and inactive containers on your computer. To view the active ones, use:

sudo docker ps

check latest one

sudo docker ps -l

  

To view all containers — active and inactive, run docker ps with the -a switch:

sudo docker ps -a

Thats all in terms of installing Docker and some basic commands.

Template for API gateway creation using CI-CD

Below is the template which can be used for api gateway creation in AWS.

Template :

AWSTemplateFormatVersion: '2010-09-09'
Transform: AWS::Serverless-2016-10-31
Description: >
  Application containing RestAPI for First

Globals:
  Function:
    Timeout: 30

Parameters:
  #s3 bucket name
  BucketName:
    Type: String
    Description: Bucket to be used
    Default: lambda-deployment-d1

  EnvironmentName:
    Type: 'AWS::SSM::Parameter::Value<String>'
    Default: /<parameterPath>/EnvironmentName                        
    # /myDemo/d1/EnvironmentName

  StageName:
    Type: 'AWS::SSM::Parameter::Value<String>'
    Default: /<parameterPath>/StageName                             
    # /myDemo/d1/EnvironmentName

  BucketPrefix:
    Type: String
    Description: bucket prefix
    Default: first-project-api                                   
    # /myDemo/d1/EnvironmentName

  CertificateARN:
    Type: 'AWS::SSM::Parameter::Value<String>'
    Default: /<parameterPath>/CertificateARN    
    # /myDemo/d1/CertificateARN

  DomainName:
    Type: 'AWS::SSM::Parameter::Value<String>'
    Default: /<parameterPath>/DomainName        
    # /myDemo/d1/DomainName



Resources:

  LambdaRoleForVPCResources:
    Type: AWS::IAM::Role                                            
    # https://serverless.com/framework/docs/providers/aws/guide/resources/
    Properties:
      AssumeRolePolicyDocument:
        Version: "2012-10-17"
        Statement:
        - Effect: "Allow"
          Principal:
            Service:
            - "lambda.amazonaws.com"
          Action:
          - "sts:AssumeRole"
      Policies:
      #policy name
      - PolicyName: "LambdaVpcPolicy"
        PolicyDocument:
          Version: "2012-10-17"
          Statement:
          - Effect: "Allow"
            Action:
            - "logs:CreateLogGroup"
            - "logs:CreateLogStream"
            - "logs:PutLogEvents"
            - "ec2:CreateNetworkInterface"
            - "ec2:DescribeNetworkInterfaces"
            - "ec2:DeleteNetworkInterface"
            - "dynamodb:*"
            - "apigateway:*"
            Resource: "*"

  # creates api gateway using swagger.yml


FirstRestAPI:
    Type: AWS::Serverless::Api                 
    # https://docs.aws.amazon.com/serverless-alication-model/latest/developerguide/serverless-sam-template.html
    Properties:
      Name: !Join ['', [' first-rest-api-', !Ref EnvironmentName]]
      StageName: !Ref StageName
      # https://docs.aws.amazon.com/AWSCloudFormation/latest/UserGuide/intrinsic-function-reference-transform.html
      DefinitionBody:
        'Fn::Transform':        
         # Fn::Transform specifies a macro to perform custom processing on part of a stack template. 
          Name: 'AWS::Include'
          # Replace <bucket> with your bucket name
          Parameters:
            Location: !Join ['', [ 's3://',!Ref BucketName, '/',!Ref BucketPrefix, '/swagger.yaml'  ] ]

  FirstRestAPIGetByItem:
    Type: AWS::Serverless::Function 
    # https://docs.aws.amazon.com/AWSCloudFormation/latest/UserGuide/intrinsic-function-reference-transform.html
    FunctionName: !Join ['', [ 'FirstRestAPIGetByItem-', !Ref EnvironmentName ] ]
    Properties:
      #python code base containg lambdas which process request
      CodeUri: First-rest-api/build/
      #lambda name and its method
      Handler: ItemByName.lambda_handler
      Runtime: python3.7
      #role of lambda
      Role: !GetAtt LambdaRoleForVPCResources.Arn
      #these are environment variable which are required for lambda
      Environment:
        Variables:
          First_TABLE:  !Join ['', [ 'Item-table-', !Ref EnvironmentName ] ]
         
      Events:
        #listner of lambda fucntion ...this can be api kinesis or any aws service
        SubscribeToEvents:
        #type of service to subscribe
          Type: Api
          Properties:
            #name of service this is declared above
            RestApiId: !Ref FirstRestAPI
            #path to access api this is also maed to swagger.yml
            Path: /item
            #method type
            Method: post



    #done for static name creation --create name of api
  ApiDomainName:
    Type: 'AWS::ApiGateway::DomainName'
    Properties:
      CertificateArn: !Ref CertificateARN
      DomainName: !Join ['', ['first-api-', !Ref EnvironmentName, '.', !Ref DomainName]]
   
   #done for static name creation -- create mapping for api
  APIMaing:    
    Type: 'AWS::ApiGateway::BasePathMapping'
    Properties:
      BasePath: v1
      DomainName: !Ref ApiDomainName
      RestApiId: !Ref FirstRestAPI
      Stage: !Ref StageName


#generates output url for the generated services      
Outputs:

  ItemByNameApiUrl:
    Description: URL of API endpoint
    Value: !Join
    - ''
    - - https://
      - !Ref FirstRestAPI
      - '.execute-api.'
      - !Ref 'AWS::Region'
      - '.amazonaws.com/'
      - !Ref StageName
      - '/item'



   #shows details of all created api's
  FirstRestAPIGetByItem:
    Description: " Rest API Function ARN"
    Value: !GetAtt FirstRestAPIGetByItem.Arn