docker-node-setup

What

This repo contains a sample Node application and support scripts for a nice Docker-based development setup. The sample application consists of 2 Node services, both of which depend on a 3rd local Node module.

The current workflow and support scripts support the following goals:

1. Restarting of service when service code edited on host (on OS X or Linux host)
2. Restarting of service when local dependency module edited on host (on OS X or Linux host)
3. Installation of 3rd party dependencies as separate image build step that is cached unless dependencies actually change
4. Easy way to pull new code and "run" or "test", knowing everything is bult and up to date

Currently, there is a lot of Dockerfile boilerplate and many support scripts to get this to work the way I want. The support scripts will have to revisited as Docker for Mac and Docker for Windows become available.

Usage

In this app, file watching is performed on the host to get around the fact that monitoring a directory mounted from OS X doesn't work (see Docker issue here). This might be easier once Docker for Mac becomes available, but for now you need to install a watching tool on the host. If on OS X, you will need to install fswatch, as described here. On a Debian based Linux distro, you can install inotifywait from the inotify-tools package.

Then, in a docker terminal, navigate to this repository's directory and run ./up.sh.

This will look at docker-compose.yml and docker-compose.dev.yml to determine that there are 2 services, and it will continue to build the service1 and service2 images. They will then be started up.

At the end of the output, you should see:

service2_1  | Listening on port 3000
service1_1  | Listening on port 3000

Only service1 is exposed to the Docker host, which is linked to and depends on service2.

Open a browser and browse to to an following endpoint on service1, using the IP of the Docker host (typically 192.168.99.100 on OS X).

http://192.168.99.100/hello

You should see the following output:

Hello World from service1
Using lodash version 4.12.0
...

Now, open service1/index.js, edit the output text, and save the file. The up.sh script should detect the file change, and that it only affects service1. It will send a signal to a wrapping process inside the container which will quickly restart the Node service with the updated code. Refresh the browser window and you should see the updated text.

Now, open and edit the text of module1/index.js. This change will trigger a restart of both service1 and service2 since it is in the Node dependency tree of both services.

Finally, you can ctrl+c the up.sh script and start it again. This will quickly rebuild the service images with your updated code, but will not redo the npm install step since that is separated off and cached by Docker, and you haven't edited a package.json file.