DOCKER LESSONS

Dockerfile

Line 1: base image
Line 2: specify working directory
Line 3: COPY package.json to working directory.
Line 4: Build time commands.
Line 5: Copy rest of the files to working directory
Line 6: Expose Port numbers

Line 7: Run time commands.

Sample Dockerfile:

FROM node:16
WORKDIR /app
COPY package.json .
RUN npm install
COPY . ./
EXPOSE 8080
CMD ["node", "index.js"]

Important Docker Commands.

To build an image: docker build -t imageName:semantic-versioning.RELEASE path-to-dockerfile

example:
```
docker build -t dibyajyotimishra/dockerized-app:0.0.1.RELEASE .
```
To delete an image:
```
docker rm image_id
```
To view all images:
```
docker image ls
```
To run a docker app: docker run -d -p portOnHostMachine:portOnContainer --name=name-of-container imageName

example:
```
docker run -d -p 8080:8081 --name=my-dockerized-container dibyajyotimishra/dockerized-app:0.0.1.RELEASE
```
To see all running containers:
```
docker ps
```

To check contents of docker app:

docker exec -it my-dockerized-container bash

To create volumes to preserve data: docker run -v path-to-folder-on-host-machine:path-to-folder-on-docker-container -p port-on-host-machine:port-on-docker-container -d --name=name-of-container imageName

example:
```
docker run -v $(pwd):/app -v /app/node_modules -p 8080:8081 --name=my-dockerized-container dibyajyotimishra/dockerized-app:0.0.1.RELEASE
```
To load environment variables: docker run -v path-to-folder-on-host-machine:path-to-folder-on-docker-container -p port-on-host-machine:port-on-docker-container --env KEY=VALUE -d --name=name-of-container imageName

example:
```
docker run -v $(pwd):/app -v /app/node_modules --env PORT=8082 -p 8080:8082 --name=my-dockerized-container dibyajyotimishra/dockerized-app:0.0.1.RELEASE
```
To load environment variables from file: docker run -v path-to-folder-on-host-machine:path-to-folder-on-docker-container -p port-on-host-machine:port-on-docker-container --env-file path-to-environment-variables-file -d --name=name-of-container imageName

example:
```
docker run -v $(pwd):/app -v /app/node_modules --env-file ./.env -p 8080:8082 --name=my-dockerized-container dibyajyotimishra/dockerized-app:0.0.1.RELEASE
```
To delete docker containers and associated volumes: docker rm nameOfContainer -fv

example:
```
docker rm my-dockerized-container -fv
```

Docker Compose:

Docker Compose file

Line 1: Specify version of docker-compose
Line 2: Under services put the name of each service that docker-compose is going to manage.
Line 3: Specify the name of each service.
Line 4: Specify the path of Dockerfile under the build command.
Line 5: Specify the list of ports to be exposed under ports section.
Line 6: Specify the list of environment variables for your application under environment section.
Line 7: Specify the filepath of .env if any under env-file section.
Line 8: Add volumes under the volumes section.
Line 9: overwrite buildtime command using the command option.

Sample docker-compose.yml file:
```
version: '3.8'
services:
  node-docker-app:
      build: .
      ports:
          - "8080:8080"
      environment:
          - PORT=8080
      volumes:
          - ./:/app:ro
          - /app/node_modules
```
Important Docker Compose Commands.
- To build and run using docker-compose:
```
docker-compose up -d --build
```
  --build : to rebuild from start everytime.
- To kill running container and associated volumes:
```
docker-compose down -v
```
- To run from multiple docker-compose configs: docker-compose up -f docker-compose-file1.yml -f docker-compose-file2.yml -f docker-compose-file3.yml ... -d --build
```
docker-compose up -f docker-compose.yml -f docker-compose.dev.yml -d --build
```

Deploy to production using Docker on Ubuntu VM on am EC2 instance:

Step 1: Setup an instance: Head over to console.aws.amazon.com and create an EC2 instance with Ubuntu OS and download the pem key.
Obtain Permissions to access the pem key: Launch the terminal and hit the following command:
```
chmod 0400 key-name.pem
```
SSH into the instance: Copy the public IP of the instance and ssh into the instance using the following command.
```
ssh -i key-name.pem ubuntu@publicip
```
Install docker in the instance: Copy the following command to get the docker installer script.

```console
curl -fsSL https://get.docker.com -o install-docker.sh
```

Now run the script to install docker on your instance.

```console
sudo sh install-docker.sh
```

Verify installation by running the command ```docker -v```.

Now install Docker Compose:

download and install docker-compose:

```console
sudo curl -L "https://github.com/docker/compose/releases/download/1.29.2/docker-compose-$(uname -s)-$(uname -m)" -o /usr/local/bin/docker-compose
```

obtain permissions:

```console
sudo chmod +x /usr/local/bin/docker-compose
```

verify installation:

```console
docker-compose -v
```

- ***Setup environment variables for your application:*** Create a ```.env``` file to hold the environment variables.  

```console
sudo vi .env
```

Hit `i` to get into insert mode and put all your environment variables and hit `esc` to exit insert mode and finally hit `:wq` to save the changes.

To load the environment variables, open the `.bashrc` or the `.bash_profile` and add the followingg commands:

```console
set -o allexport; source path-to-env-file; set +o allexport;
```

Now all the environment variables will be loaded up.

DibyajyotiMishra/Docker-Lessons

DOCKER LESSONS

Dockerfile

Important Docker Commands.

Docker Compose:

Docker Compose file

Important Docker Compose Commands.

Deploy to production using Docker on Ubuntu VM on am EC2 instance: