Description
Node.js 20 available as container is a base platform for building and running various Node.js 20 applications and frameworks. Node.js is a platform built on Chrome's JavaScript runtime for easily building fast, scalable network applications. Node.js uses an event-driven, non-blocking I/O model that makes it lightweight and efficient, perfect for data-intensive real-time applications that run across distributed devices. Usage
For this, we will assume that you are using the rhel8/nodejs-20 image, available via nodejs:18 imagestream tag in Openshift. Building a simple nodejs-sample-app application in Openshift can be achieved with the following step:
$ oc new-app nodejs:20~https://github.com/sclorg/s2i-nodejs-container.git --context-dir=20/test/test-app/
The same application can also be built using the standalone S2I application on systems that have it available:
$ s2i build https://github.com/sclorg/s2i-nodejs-container.git --context-dir=20/test/test-app/ rhel8/nodejs-20 nodejs-sample-app
Accessing the application:
$ curl 127.0.0.1:8080
Environment variables
Application developers can use the following environment variables to configure the runtime behavior of this image:
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 container in development mode is:
podman run --env DEV_MODE=true my-image-id
To run the container in development mode with a debug port of 5454, run:
$ podman run --env DEV_MODE=true DEBUG_PORT=5454 my-image-id
To run the container in production mode, run:
$ podman 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 Podman's exec
To change your source code in a running container, use Podman's exec command:
$ podman exec -it /bin/bash
After you Podman 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 container 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. See also
Dockerfile and other sources are available on https://github.com/sclorg/s2i-nodejs-container. In that repository you also can find another versions of Python environment Dockerfiles. Dockerfile for CentOS is called Dockerfile, Dockerfile for RHEL7 is called Dockerfile.rhel7, for RHEL8 it's Dockerfile.rhel8 and the Fedora Dockerfile is called Dockerfile.fedora.
