Notes--Docker

Infrastructure As Code

• Create a Docker File in the same directory as the app.

Example:

FROM ubuntu:latest

# Commands to run to install dependencies.
RUN apt-get update -y
RUN apt-get install -y python3

# When you pass commands to the container, what should interpret them.
# ENTRYPOINT ["python3"]
# Command to run when the container starts.
# CMD ["app.py"]
# `python3 app.py` will run by default.

# Working directory.
WORKDIR /app

# Copy apps from the local folder to the Docker container.
COPY app.py app.py
COPY alternate.py alternate.py

# Make port available.
EXPOSE 8080

1. Create the "Docker Image" docker image build -t app-name-here .

• Builds a Docker image with the tag of "app-name-here" in the current directory.

1. Confirm your build with docker images command.
2. Create a container based on the image.

• docker run -p 8080:8080 -d app-name-here

• Select the tag.

• Using the -d options allows you to run something like a server, without that process needing your open CLI window. It instead runs the process in the background.

• To get a list of running containers use docker ps. PS stands for process status.

• Docker creates three networks for you by default. Use docker network ls to list them.

• Use docker images to list all docker images.

• docker rmi image-name to remove images.

• Use docker stop my_container to stop.

• To run a shell on the container use docker exec -it container-id /bin/bash.

• To verify exposed ports use docker ps.

• Use docker container ls to list docker containers.

8 Protips to Start Killing It When Dockerizing Node.js

Common Errors

• "Bind for 0.0.0.0:8080 failed: port is already allocated."
• "You need to make sure that the previous container you launched is killed, before launching a new one that uses the same port."

docker container ls
docker rm -f <container-name>