A personal cheat sheet for running local Node project in a Docker container

Docker shell commands.sh

# See list of docker virtual machines on the local box
$ docker-machine ls
NAME      ACTIVE   URL          STATE     URL                         SWARM   DOCKER   ERRORS
default   *        virtualbox   Running   tcp://192.168.99.100:2376           v1.9.1 

# Note the host URL 192.168.99.100 - it will be used later!

# Build an image from current folder under given image name
$ docker build -t gleb/demo-app .

# see list of build images
$ docker images
REPOSITORY           TAG                 IMAGE ID            CREATED             VIRTUAL SIZE
gleb/demo-app        latest              506bf31537d4        17 minutes ago      904.5 MB
node                 5.0                 c4f955829812        10 weeks ago        642.2 MB

# Note both the original Node:5 and the built images are there

# Let us run the image under name 'demo'
$ docker run --name demo -p 5000:1337 -d gleb/demo-app
9f9f3ae62038805504c3c23cce4e9229008ba6bd9ea16b560a7a9e1cfa932e57

# A good security practice is to run the Docker image (if possible) in read-only mode
# by adding --read-only flag
# See "Docker security" talk at mark 22:00 https://www.youtube.com/watch?v=oANurUSaOFs

# Run docker image with a folder from HOST machine mounted
$ docker run -v /usr/source:/destination --name demo -d gleb/demo-app
# inside the container /destination folder will be pointing at /usr/source from the HOST

# Note: you can pass environment variable values to the `docker run` command
# docker run -e USER=name
# or, if the USER is already an environment var
# docker run -e USER
# or put all env variables into a file and pass its name
# docker run --env-file=<filename>
# You can check all the options passed into the running container
# docker inspect demo

# It prints the long container ID, but we can use our name "demo"
# We also mapped outside port 5000 to container's exposed port 1337
# Let us see running containers
$ docker ps
CONTAINER ID    IMAGE             COMMAND             CREATED              STATUS              PORTS                    NAMES
9f9f3ae62038    gleb/demo-app     "node server.js"    About a minute ago   Up About a minute   0.0.0.0:5000->1337/tcp   demo

# Let us make a dummy request to the app running inside the container
# We will use the virtual machine's IP and outside port 5000
$ curl 192.168.99.100:5000
Not Found

# Let us see the app's console log to confirm that it has received our request
$ docker logs demo
listening on port 1337 { subdomainOffset: 2, proxy: false, env: 'development' }
started server
  <-- GET /
  --> GET / 404 6ms -
# you can follow the logs along using -f (--follow) option

# Jump into the running container to run any commands
# -i option means bind STDIO from the current shell
docker exec -it demo bash
root@9f9f3ae62038:/usr/src/demo-server# ls
... list of files
root@9f9f3ae62038:/usr/src/demo-server# exit

# If you want to quickly list files in the docker container (default folder)
# you can use `docker exec`
$ docker exec -t demo ls
# ... list of files in /usr/src folder

# We can even copy files from the container back into our system
docker cp demo:/usr/src/demo-server/file.txt file.txt
# look at file.txt locally

# Running Docker container in terminal
# If you want to see the output / enter commands *inside the container* right from the terminal
# just skip -d option (-d is for detached mode)
$ docker run --name demo -it gleb/demo-app

# if the container stops (like the command terminates due to error)
# a nice trick is to run the container with dummy infinite command
# then shell into the container and find the problem
$ docker run --name demo -d gleb/demo-app tail -f /dev/null
$ docker exec -it demo bash

# Nice!
# To stop the running container
$ docker stop demo

Dockerfile

# simple docker file
# assumes located in the same folder as the application itself

# start with node 5 base image
FROM node:5.0

# run as non-root user inside the docker container
# see https://vimeo.com/171803492 at 17:20 mark
RUN groupadd -r nodejs && useradd -m -r -g nodejs nodejs
# now run as new user nodejs from group nodejs
USER nodejs

# Create an app directory (in the Docker container)
RUN mkdir -p /usr/src/demo-server
WORKDIR /usr/src/demo-server

# Copy .npm settings and package.json into container
COPY package.json /usr/src/demo-server
COPY .npmrc /usr/src/demo-server
# and install dependencies
RUN npm install

# Copy our source into container
COPY src /usr/src/demo-server/src
COPY server.js /usr/src/demo-server

# If our server uses 1337 by default
# expose it from Docker container
EXPOSE 1337

# Finally start the container command
CMD ["node", "server.js"]

Extra info.md

Tips & tricks

Setup an alias to start Node container and map the current folder for quick isolated Linux environment. Add to ~/.alias file

# Creates Node container with mapped current folder and runs Bash shell
alias node-box='docker run -v $PWD:/src -w /src -u node -it node /bin/bash'

Additional information

• Dockerizing a Node.js web app
• NodeUp Docker podcast episode
• Node Dockerhub images - list of Docker images with different Node versions
• Docker cheat sheet
• fuge - Node microservices and sites with nice development workflow
  • Microservices with fuge - my blog post showing local development workflow
• Run Node in a docker container with file access
• If you have multiple Docker files, you can pick the one to use during build docker build -f <name> .
• Good video from NodeSource Need to Node: Getting Started with Node.js, Docker and Kubernetes
• You can run very simple process for managing system signals inside the docker container and that can start your actual process. yelp/dumb-init
• 8 Protips to Start Killing It When Dockerizing Node.js includes how to make separate user, caching, etc.

troubleshooting.md

Troubleshooting

If you open a new terminal, you need the Docker environment variables again. You can set them up in the current shell by running (assuming the name default for the Docker machine)

eval "$(docker-machine env default)"

If the Docker machine becomes unresponsive with status UNKNOWN when running docker-machine ls try rebuilding it

$ docker-machine rm -y default && docker-machine create -d virtualbox default && eval $(docker-machine env)

To delete all running containers and images (use -f option to force)

#!/bin/bash
# Delete all containers
docker rm $(docker ps -a -q)
# Delete all unused images
docker rmi $(docker images --filter dangling=true)
# Delete all images
docker rmi $(docker images -q)

To stop all running containers

IDS=$(docker ps -q)
docker stop $IDS
# or as a single command
docker stop $(docker ps -q)

If you have a container "demo" and would like to investigate it, start it in the interactive mode with a "bash" as entry

docker run -it --entrypoint bash demo

Is it possible to enter a docker container and interact with it through a command-line node application?