Creating Docker Image

Hello to all the readers!

In this post I will be creating a docker image out of the simple tutorial posted on Docker’s documentation.

Let us begin with the steps.

Clone the repository

git clone https://github.com/docker/getting-started.git
cd getting-started/app

Create Dockerfile. Dockerfile is a set of instructions to build the docker image.

FROM node:18-alpine
WORKDIR /app
COPY . .
RUN yarn install --production
CMD ["node", "src/index.js"]
EXPOSE 3000

Next is to build the image.

docker build -t getting-started .

Sending build context to Docker daemon  4.626MB
Step 1/6 : FROM node:18-alpine
18-alpine: Pulling from library/node
31e352740f53: Pull complete 
560412e561fb: Pull complete 
02735cb6c78b: Pull complete 
86d562f7b855: Pull complete 
Digest: sha256:8942c014f3c3c445bb74f2ae6dfe0a024fe4b56990dabfcd87c06134d9797f98
Status: Downloaded newer image for node:18-alpine
 ---> f85482183a4f
Step 2/6 : WORKDIR /app
 ---> Running in 664ea2f0964b
Removing intermediate container 664ea2f0964b
 ---> ae0ad6105707
Step 3/6 : COPY . .
 ---> f53d252cebee
Step 4/6 : RUN yarn install --production
 ---> Running in b13e265f6d73
yarn install v1.22.19
[1/4] Resolving packages...
[2/4] Fetching packages...
[3/4] Linking dependencies...
[4/4] Building fresh packages...
Done in 12.08s.
Removing intermediate container b13e265f6d73
 ---> 7f2048e66dd4
Step 5/6 : CMD ["node", "src/index.js"]
 ---> Running in a0399302bb39
Removing intermediate container a0399302bb39
 ---> 7ed5a668000d
Step 6/6 : EXPOSE 3000
 ---> Running in 140d45449049
Removing intermediate container 140d45449049
 ---> 52ed8b2d5023
Successfully built 52ed8b2d5023
Successfully tagged getting-started:latest

This builds the docker image. Let us see it in the list of images.

docker image ls             
                                                                                                                                                  
REPOSITORY                        TAG            IMAGE ID       CREATED          SIZE
getting-started                   latest         52ed8b2d5023   53 seconds ago   265MB

Let us now start the docker container out of the above created image.

docker run -dp 3000:3000 getting-started

docker container ls                                                                                                                                                                  

CONTAINER ID   IMAGE             COMMAND                  CREATED         STATUS         PORTS                                       NAMES
0e287c2bc2e4   getting-started   "docker-entrypoint.s…"   7 seconds ago   Up 5 seconds   0.0.0.0:3000->3000/tcp, :::3000->3000/tcp   zen_khayyam

This is a sample todo application written in Node.js and we can now access it on localhost:3000. Option “-d” means to run the container in detached mode in background.

There is another way to list the docker containers.

docker ps            
                                                                                                                                                                 
CONTAINER ID   IMAGE             COMMAND                  CREATED              STATUS              PORTS                                       NAMES
0e287c2bc2e4   getting-started   "docker-entrypoint.s…"   About a minute ago   Up About a minute   0.0.0.0:3000->3000/tcp, :::3000->3000/tcp   zen_khayyam

Now we can stop and remove the container

docker stop 0e287c2bc2e4
docker rm 0e287c2bc2e4

Container is now not available to be started again. It won’t be found in “docker container ls –all”.