Learn Clojurescript and Docker

While "It works on my computer" might give you an excuse to close a bug ticket in the backlog, it doesn't really work when you're working on a team.

You need to ensure that your application can run regardless of what hardware your teammates are running or libraries they have installed.

Docker solves this problem by collecting everything your application needs to run into a container.

Containers aren't just for source code. They can hold configuration, scripts, and even their own filesystem. It's similar to a Virtual Machine, without having to bring a full operating system along for the ride.

Because containers run in isolation, there is some configuration involved to allow for files to be saved and containers to communicate with one another.

One of the most useful ways to get your head around Docker is to see it in action.

Follow along with Joel Lord as he works through the process of preparing an application to run in separate containers for the frontend and backend of an application that searches for gifs and re-encodes them with a caption supplied by the user.

You'll see how to configure the separate containers to communicate with one another, work with environment variables, and persist data to your local machine. Along the way, you'll pick up some tips on useful commands and bash scripting. Finally, you'll learn how to use Docker Compose to make it easy to run multiple containers simultaneously.


Docker containers wrap a piece of software in a complete filesystem that contains everything needed to run: code, runtime, system tools, system libraries – anything that can be installed on a server. This guarantees that the software will always run the same, regardless of its environment.

docker

Containerize Full-Stack JavaScript Applications with Docker

Docker Fundamentals

In this course we will take a simple Node.js app that connects to a MongoDB database and uses an Express web server, and learn how to setup a full software development deployment process as well as how to properly “Dockerize” the app. 

We’ll step through setting up proper version control techniques, managing configuring within the environment, setting up proper build/deploy/run processes, and all with abiding by Docker best practices. We’ll also make sure our deployment is setup for scale, and have consistent development practices in place for reliable app deployments.

Build a Twelve-Factor Node.js App with Docker

Docker containers are stateless by default. In order to persist filesystem changes, you must use docker volumes. In this lesson, we will go over how to copy files over to Docker containers, how to create volumes and copy data to them, and also how to mount remote folders for persisting updates.

Create Docker Volumes for Persistent Storage

In this lesson we will cover proper version tagging when building Docker images, creating a docker-compose.yml file for proper release management, and running the tagged release by using Docker Compose to launch app resources as Docker containers.

Build, Release and Run Containers with Docker Compose

NGINX is a free, open-source, high-performance HTTP server and reverse proxy, as well as an IMAP/POP3 proxy server. 

nginx

Learn about the concepts of managing data within Docker volumes, including all of the commands to create and manage volumes. We'll demonstrate how to mount a Docker volume to one or many containers by creating and mounting a volume to an Nginx proxy, and then verify the output with curl. You'll also see how changes to files within volumes of one container propagate to other containers with the same volume mounted, and learn various commands to inspect Docker volumes.

Manage Data within Docker Volumes

In this lesson we will cover how to build your own custom Docker image from scratch. We'll walk through the process of starting a Debian container, installing packages and working through configuration issues, as well as a strategy for building a Dockerfile.

Build Your Own Custom Docker Image

In this lesson, we will look at `docker container prune` to remove old docker containers. We can also use `docker system prune` to clean up any containers, images, volumes, and networks all in one command.

Prune Old Unused Docker Containers and Images

In this lesson, we'll find out the basics of running Docker containers. We'll go over how to download images from Docker Hub, what happens when you stop containers, how to restart a container once it's been stopped, and also how to remove containers.

Run, Stop and Remove Docker Containers

Learn how to build a simple Node.js web server with Docker. In this lesson, we'll create a Dockerfile for a simple Node.js script, copy and build it into a Docker image, and start a container to run the web server.

Build a Simple Node.js Web Server with Docker

Learn the benefits of running one-off, short-lived Docker containers. Short-Lived containers are useful to execute one-line commands or setup scheduled tasks. We'll demonstrate setting up a cronjob from the host machine to tap into the benefits of running automated, timed scripts with Docker.

Run Short-Lived Docker Containers

We’ll learn how to host a complex Twitter bot (a bot that requires external tools that need to be installed on the system) with Heroku and Docker. We'll learn how to configure our Docker file, using an image that already has node installed on it. We'll use the Heroku Container Registry to deploy an app to heroku that was created with a local container, and deploy it as a worker app.

Host a Complex Bot using Heroku and Docker

Learn how to setup an Nginx proxy server with Docker that sits in front of a Node.js app. You can use a proxy to control the flow of frontend requests hitting your app, as well as to achieve better performance and scalability. We'll create a sample Node.js app, configure a default Nginx configuration file for proxying web requests, build both Node.js and Nginx Docker images, and learn how to link everything up and get it running with Docker specifics.

Setup an Nginx Proxy for a Node.js App with Docker

Learn the basics of downloading and pulling Docker images from Docker Hub. Learn the difference between default tags and version specific tags. Also learn how to display all images, and different ways to remove images.

Download and Remove Docker Images

Getting nodejs to run inside of Docker is relatively simple. Getting nodejs to run inside of Docker while using recommended best practices takes some planning. In this lesson, I’ll show you how to get a simple nodejs web server running in Docker on your local workstation while adhering to best practices.

Deploy Node.js on Docker

Docker containers should be designed to be stateless, meaning that they can survive system reboots and container terminations gracefully, and without the loss of data. Designing with stateless containers in mind will also help your app grow and make future horizontal scaling trivial. 

In this lesson, we will review an app that saves uploaded files to the filesystem. Then we will learn how to setup a persistent volume for the uploaded files so they can survive Docker container halts, restarts, stops and respawns.

Run Stateless Docker Containers

By default, Docker is locked down and no ports are exposed. We’ll cover how to expose ports when building your image with a `Dockerfile`, and how to export that port as a service when running containers. 

Export Services with Docker Port Binding

Node.js apps built with Docker cannot scale horizontally by themselves. In this lesson we will spawn out multiple Node.js processes/containers, and move the incoming request handler to an Nginx proxy to load balance and properly scale our Node.js app.

Scale Docker Horizontally with Nginx Load Balancing

A properly scaled Docker architecture should be able to kill off random containers at any time, and continue to run by implementing a crash-only design methodology. We will learn how to setup our architecture to auto-spawn new Docker containers when other containers are deemed unhealthy or in a terminated state. We will also learn how to scale containers easily with Compose in the event we need to quickly scale horizontally.

Ensure Containers Run with High-Availability

Docker makes it easy to have near-full environment parity between dev, stage and prod. In this lesson we’ll go over a typical setup within Docker Compose, and how to manage backing services between dev, stage and prod.

Run Consistent Dev, Stage & Prod Docker Environments

Since Docker filesystems are ephemeral, it's important to take into account anything that writes or appends to disk, such as log files. It is standard practice when running Docker containers to pipe log file output to the console, to allow for simple diagnostic and to avoid append-only files from consuming disk space. 

In this lesson, we’ll show you how to append output to `STDOUT`, and how to view log output from your running containers.