NodeJS Docker image

This repository contains the source for building various versions of the Node.JS application as a reproducible Docker image using source-to-image. Users can choose between RHEL and CentOS based builder images. The resulting image can be run using Docker.

Usage

To build a simple nodejs-sample-app application using standalone S2I and then run the resulting image with Docker execute:

For RHEL based image

$ s2i build https://github.com/sclorg/s2i-nodejs-container.git --context-dir=4/test/test-app/ rhscl/nodejs-4-rhel7 nodejs-sample-app
$ docker run -p 8080:8080 nodejs-sample-app

For CentOS based image

$ s2i build https://github.com/sclorg/s2i-nodejs-container.git --context-dir=4/test/test-app/ centos/nodejs-44-centos7 nodejs-sample-app
$ docker run -p 8080:8080 nodejs-sample-app

Accessing the application:

$ curl 127.0.0.1:8080

Repository organization

<nodejs-version>
- Dockerfile
  
  CentOS based Dockerfile.
- Dockerfile.rhel7
  
  RHEL based Dockerfile. In order to perform build or test actions on this Dockerfile you need to run the action on a properly subscribed RHEL machine.
- s2i/bin/
  
  This folder contains scripts that are run by S2I:
  - assemble
    
    Used to install the sources into the location where the application will be run and prepare the application for deployment (eg. installing modules using npm, etc.)
  - run
    
    This script is responsible for running the application, by using the application web server.
  - usage*
    
    This script prints the usage of this image.
- contrib/
  
  This folder contains a file with commonly used modules.
- test/
  
  This folder contains the S2I test framework with simple Node.JS echo server.
  - test-app/
    
    A simple Node.JS echo server used for testing purposes by the S2I test framework.
  - run
    
    This script runs the S2I test framework.

Environment variables

Application developers can use the following environment variables to configure the runtime behavior of this image:

NAME	Description
NODE_ENV	NodeJS runtime mode (default: "production")
DEV_MODE	When set to "true", `nodemon` will be used to automatically reload the server while you work (default: "false"). Setting `DEV_MODE` to "true" will change the `NODE_ENV` default to "development" (if not explicitly set).
NPM_RUN	Select an alternate / custom runtime mode, defined in your `package.json` file's `scripts` section (default: npm run "start"). These user-defined run-scripts are unavailable while `DEV_MODE` is in use.
HTTP_PROXY	Use an npm proxy during assembly
HTTPS_PROXY	Use an npm proxy during assembly
NPM_MIRROR	Use a custom NPM registry mirror to download packages during the build process

One way to define a set of environment variables is to include them as key value pairs in your repo's .s2i/environment file.

Example: DATABASE_USER=sampleUser

NOTE: Define your own "`DEV_MODE`":

The following package.json example includes a scripts.dev entry. You can define your own custom NPM_RUN scripts in your application's package.json file.

Note: Setting logging output verbosity

To alter the level of logs output during an npm install the npm_config_loglevel environment variable can be set. See npm-config.

Development Mode

This image supports development mode. This mode can be switched on and off with the environment variable DEV_MODE. DEV_MODE can either be set to true or false. Development mode supports two features:

Hot Deploy
Debugging

The debug port can be specified with the environment variable DEBUG_PORT. DEBUG_PORT is only valid if DEV_MODE=true.

A simple example command for running the docker container in development mode is:

docker run --env DEV_MODE=true my-image-id

To run the container in development mode with a debug port of 5454, run:

$ docker run --env DEV_MODE=true DEBUG_PORT=5454 my-image-id

To run the container in production mode, run:

$ docker run --env DEV_MODE=false my-image-id

By default, DEV_MODE is set to false, and DEBUG_PORT is set to 5858, however the DEBUG_PORT is only relevant if DEV_MODE=true.

Hot deploy

As part of development mode, this image supports hot deploy. If development mode is enabled, any souce code that is changed in the running container will be immediately reflected in the running nodejs application.

Using Docker's exec

To change your source code in a running container, use Docker's exec command:

$ docker exec -it <CONTAINER_ID> /bin/bash

After you Docker exec into the running container, your current directory is set to /opt/app-root/src, where the source code for your application is located.

Using OpenShift's rsync

If you have deployed the container to OpenShift, you can use oc rsync to copy local files to a remote container running in an OpenShift pod.

Warning:

The default behaviour of the s2i-nodejs docker image is to run the Node.js application using the command npm start. This runs the start script in the package.json file. In developer mode, the application is run using the command nodemon. The default behaviour of nodemon is to look for the main attribute in the package.json file, and execute that script. If the main attribute doesn't appear in the package.json file, it executes the start script. So, in order to achieve some sort of uniform functionality between production and development modes, the user should remove the main attribute.

Below is an example package.json file with the main attribute and start script marked appropriately:

{
    "name": "node-echo",
    "version": "0.0.1",
    "description": "node-echo",
    "main": "example.js", <--- main attribute
    "dependencies": {
    },
    "devDependencies": {
        "nodemon": "*"
    },
    "engine": {
        "node": "*",
        "npm": "*"
    },
    "scripts": {
        "dev": "nodemon --ignore node_modules/ server.js",
        "start": "node server.js" <-- start script
    },
    "keywords": [
        "Echo"
    ],
    "license": "",
}

Note:

oc rsync is only available in versions 3.1+ of OpenShift.

Anderen2/s2i-nodejs-container