nodeJs

integrate with other tech like mongoose, Datastax and firebase and learning something cool.

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Now that i've learned about nodeJs and various stuff within it.

I'm now focusing on best way to deploy nodeJs web application.

Heroku is still one of the best options, But i want something more flexible and controllable. that's where Docker comes in.

So let's learn docker.

docker

There are two different things in the beginning:

1. image
2. container

suppose i've created a simple node app. Now it's time to run, test and deploy it. First thing i'll do is to create a Dockerfile.

Dockerfile

it is set of commands that docker will execute in order to create docker image.

simple file can be:

FROM node 	#	docker will use latest node image to provide runtime env for app

ENV node_env production 	#	setting environment variable

WORKDIR app/	#	create and enter folder `app` in container

COPY [ "package.json", "package-lock.json*", "./" ]	#	copy package.json and package-lock.json file from current dir to folder named `/app` in continer

RUN npm install	#	install all dependencies for node app by reading that package.json

COPY . .	#	copy everything from local active dir to containers' active directory

CMD ["node", "app.js"]	#	command that container executes everytime built image runs

key commands:

• FROM xyz: use latest image of xyz from docker repo.

  • also xyz:12.2.3 is an option, to use specific version of that image.

• RUN: is to execute commands during building the image. you can use multiple RUN in Dockerfile

  • example: RUN npm install

• CMD: is command that execute in the container everytime you run a built image.

  • example: CMD ["node", "app.js"]

this file will give docker the instruction to a build an image.

if there's some files on your local dir that you dont want to be on your container, then use .dockerignore file; it works exactly as .gitignore file.

Build an image

Now let's build an image:

• go to same directory as Dockerfile and execute following

docker build --tag image-name .

this command will create a docker image of name image-name

• you can list all docker images on your local machine using this command:

docker images

now that you've build your first image, you can find that image named image-name in this list.

running our image

It's time to create a container by running that image.

docker run image-name

this command will run your image and will create a container with random name and latest tag.

Another thing to notice here is, containers are isolated from your local machine; means you can't access ports of container without exposing it to communicate with outside world.

docker run -p 80:3000 --name something -d image-name

this command will create a docker container named todo and run it.

flags

• -p 80:3000: exposing container's port 3000 to local machine on port 80

• -d: dispatch means run in background.

Start same container next time,

docker start container-name

Stop a container

docker stop container-name

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List of all running containers

docker ps

List of all containers

docker ps -a

Logs of continer

docker logs container-name

Continous logs of container

docker logs container-name -f

Remove a container

docker rm container-name

remove an image

docker rmi image-name

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change tag of image

docker tag image-name docker-id/image-name

this will create an image alias to image image-name.

push an image to dockerhub repository

docker push docker-id/image-name

pull any public image

docker pull docker-id/image-name

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container as a database

A container can be used as database like mySQL or mongodb;

But the problem is, once you stop the container; all it's runtime data gets erased. To overcome this problem, docker introduced the concept of volumes.

volume & network

volume: It's a persistent memory shared b/w containers and is located on your machine, managed by docker. network: It's user defined bridge newtwork that our application and database will use to talk to each other.

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Let's setup mongodb database in a container with appropriate volumes to persist it's data over multiple runs;

• create volumes
  • we'll create 2 volumes, one for data and other for configuration of MongoDB.

$ docker volume create mongodb
$ docker volume create mongodb_config

• create network, It'll let our app and mongodb container talk to each other.

$ docker newtwork create mongodb

• run MongoDB in a container and attach to volumes and network that we've created above.
  • docker will pull the image from hub and run it locally.

$ docker run -it --rm -d -v mongodb:/data/db \
  -v mongodb_config:/data/configdb \
  -p 26016:26016 \
  --network mongodb \
  --name mongodb \
  mongo