Docker Basics

Dockerfile

This is the instructions for docker. A dockerfile is a text file that specifies how to build an image. The instructions in the dockerfile are executed in the container image.

Example Dockerfile

This will launch an nginx server on port 80 that serves the content in the directory /app/dist, a js application.

# Build stage
FROM node:lts-alpine as build
WORKDIR /app
COPY . .
RUN yarn install && yarn build

# Production stage
FROM nginx:stable-alpine
COPY --from=build /app/dist /usr/share/nginx/html
EXPOSE 80
CMD ["nginx", "-g", "daemon off;"]

Building an Image

Now we use the dockerfile to build an image. The command for this is:

docker build -t <image_name> .

This will build an image named . This is a non running container, it is only awaiting to be started. Inside the image is all the code needed to run the container.

Running an Image

Now we can run the image. The command for this is:

docker run -d -p 80:80 <image_name>

This will run the image and expose port 80. The -d flag tells docker to run the image in the background. The -p flag tells docker to expose port 80. The is the name of the image we just built.

Stopping a Container

Now we can stop the container. The command for this is:

docker stop <container_id>

Removing a Container

Now we can remove the container. The command for this is:

docker rm <container_id>

Removing an Image

Now we can remove the image. The command for this is:

docker rmi <image_name>