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Node.js

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Get started developing with Node.js v4.4 from Red Hat Software Collections 2.2 Beta in under 10 minutes.

Prerequisites section title

Introduction and Prerequisites

Prerequisites section

In this tutorial, you will set your system up to install software from Red Hat Software Collections (RHSCL) Beta, which provides the latest development technologies for Red Hat Enterprise Linux. Then, you will install Node.js and run a simple “Hello, World” application. The whole tutorial should take less than 10 minutes to complete.

Before you begin, you will need a current Red Hat Enterprise Linux 7 server or workstation subscription that allows you to download software and get updates from Red Hat. Developers can get a no-cost Red Hat Enterprise Linux Developer Suite subscription for development purposes by registering and downloading through developers.redhat.com.

If you have problems at any point, see Troubleshooting and FAQ.

Step1 Duration

2 minutes

Step1 Title

Enable Red Hat Software Collections (RHSCL) Beta

Step2 Duration

2 minutes

Step2 Title

Setup your development environment

Step3 Duration

2 minutes

Step3 Title

Hello World and your first application

Step1 Content

In this step you will configure your system to obtain software, including the latest dynamic languages, from the RHSCL Beta software repository. You can add or remove software repositories from the command line using the subscription-manager tool as the root user. Use the --list option to view the available software repositories and verify that you have access to RHSCL:

$ su -
# subscription-manager repos --list | egrep rhscl

If you don’t see any RHSCL repositories in the list, your subscription might not include it. See Troubleshooting and FAQ for more information.

If you are using a workstation edition of Red Hat Enterprise Linux, change -server- to -workstation- in the following commands:

# subscription-manager repos --enable rhel-server-rhscl-7-beta-rpms
# subscription-manager repos --enable rhel-7-server-optional-rpms

Next, configure yum to skip the RHSCL beta repository if it is unavailable. By default, yum will treat any unavailable repository as a fatal error.

# yum-config-manager --save --setopt=rhel-server-rhscl-7-beta-rpms.skip_if_unavailable=true

Step2 Content

In this next step you will install Node.js v4.4 from RHSCL 2.2 Beta:

$ su -
# yum install rh-nodejs4

Note: The V8 JavaScript runtime is installed automatically as a dependency.

If you need help, see Troubleshooting and FAQ.

Step3 Content

Under your normal user ID, start a Terminal window. First, use scl enable to add Node.js to your environment, then start node to check the version.

$ scl enable rh-nodejs4 bash
$ node --version
v4.4.2

The next step is to create a JavaScript program that can be run from the command line. Using your preferred text editor, create a file named hello.js:

$ nano hello.js

Add the following text to the file:

console.log("Hello, Red Hat Developers World from Node " + process.version)

Save it and exit the editor. Run it with the node command:

$ node ./hello.js
Hello, Red Hat Developers World from Node v4.4.2

If you get the error: node command not found, you need to run scl enable rh-nodejs4 bash first.

The next step is to try a slightly larger Node.js example that implements a tiny web server. Using your preferred text editor, create a file named hello-http.js:

$ nano hello-http.js

Add the following text to the file:

var http = require('http');
var port = 8000;
var laddr = '127.0.0.1';
http.createServer(function (req, res) {
    res.writeHead(200, {'Content-Type': 'text/plain'});
    res.end('Hello, Red Hat Developers World from ' +
	    process.version + '!\n');
    console.log('Processed request for '+ req.url);
}).listen(port, laddr);
console.log('Server running at http://' + laddr + ':' + port + '/');

Save it and exit the editor. Run it with the node command:

$ node ./hello-http.js

Now use curl, or a browser such as Firefox, to connect to the Node.js web server http://localhost:8000/:

$ curl http://localhost:8000/
Hello, Red Hat Developers World from v4.4.2!

Working with RHSCL packages

The software packages in RHSCL are designed to allow multiple versions of software to be installed concurrently. To accomplish this, the desired package is added to your runtime environment as needed with the scl enable command. When scl enable runs, it modifies environment variables and then runs the specified command. The environmental changes only affect the command that is run by scl and any processes that are run from that command. The steps in this tutorial run the command bash to start a new interactive shell to work in the updated environment. The changes aren’t permanent. Typing exit will return to the original shell with the original environment. Each time you login, or start a new terminal session, scl enable needs to be run again.

While it is possible to change the system profile to make RHSCL packages part of the system’s global environment, this is not recommended. Doing this can cause conflicts and unexpected problems with other applications because the system version of the package is obscured by having the RHSCL version in the path first.

Permanently enable RHSCL in your development environment

To make one or more RHSCL packages a permanent part of your development environment, you can add it to the login script for your specific user ID. this is the recommend approach for development as only processes run under your user ID will be affected.

Using your preferred text editor, add the following line to ~/.bashrc:

source scl_source enable rh-nodejs4

After making the change, you should log out and log back in again.

When you deliver an application that uses RHSCL packages, a best practice is to have your startup script handle the scl enable step for your application. You should not ask your users to change their environment as this is likely to create conflicts with other applications.

Where to go next?

Learn Node.js and JavaScript using NodeSchool.io tutorials

Now that you have Node.js installed, use the tutorials from nodeschool.io to learn Node.js and JavaScript. You need to have already run scl enable rh-nodejs4 bash or have added Node.js permanently to your development environment.

Install the JavaScript and Node.js tutorials into your current directory:

$ npm install javascripting
$ npm install learnyounode

Temporarily add node_modules/.bin to your PATH:

$ export PATH=$PATH:$PWD/node_modules/.bin

Run the JavaScript tutorial:

$ javascripting

Run the Node.js tutorial:

$ learnyounode

View documentation on the Nodejs.org web site
http://nodejs.org/documentation/

Find additional RHSCL Node.js modules
$ yum list available rh-nodejs4\*

View the list of software available in RHSCL 2.2 Beta
$ yum --disablerepo="*" --enablerepo="rhel-server-rhscl-7-beta-rpms" list available

More Resources

Become a Red Hat developer: developers.redhat.com

Red Hat delivers the resources and ecosystem of experts to help you be more productive and build great solutions. Register for free at developers.redhat.com.

Faq section title

Troubleshooting and FAQ

Faq section

  1. The RHSCL repository is not available or is not found on my system.

    The name of the repository depends on whether you have a server or workstation version of Red Hat Enterprise Linux installed.

    Some Red Hat Enterprise Linux subscriptions do not include access to RHSCL. See How to use Red Hat Software Collections (RHSCL) or Red Hat Developer Toolset (DTS).

    You can use subscription --list to view the available software repositories and verify that you have access to RHSCL:

    $ su -
# subscription-manager repos --list | egrep rhscl

  2. As a developer, how can I get a Red Hat Enterprise Linux subscription that includes Red Hat Software Collections?

    Developers can get a no-cost Red Hat Enterprise Linux Developer Suite subscription for development purposes by registering and downloading through developers.redhat.com. We recommend you follow our Getting Started Guide which covers downloading and installing Red Hat Enterprise Linux on a physical system or virtual machine (VM) using your choice of VirtualBox, VMware, Microsoft Hyper-V, or Linux KVM/Libvirt. For more information, see Frequently asked questions: no-cost Red Hat Enterprise Linux Developer Suite.

  3. When I run yum install, it fails due to a missing dependency.

    These packages are in the optional RPMs repository, which is not enabled by default. See [Enable Red Hat Software Collections] for how to enable both the optional RPMs and RHSCL repositories.

  4. How can I find out what RHSCL packages are installed?

    scl --list will show the list of RHSCL packages that have been installed, whether they are enabled or not.

    $ scl --list
rh-nodejs4

  5. How do I find out if there is a newer version of Node.js in RHSCL?

    How do I find out what version of Node.js is available in the current RHSCL?

    I have the RHSCL repository enabled, but I can’t find the Node.js version listed in this tutorial.

    Use the following command to find packages with matching names:

    # yum list available nodejs\*

  6. I’ve installed Node.js from RHSCL, but node is not in my path.

    I can’t find the node command.

    RHSCL does not alter the system path. You need to use scl enable to change the environment for your session:

    $ scl enable rh-nodejs4 bash

    For more information see the Red Hat Software Collection documentation.

  7. When I try to run node, I get an error about a missing shared library.

    This is due to not having run scl enable first. When scl enable runs, in addition to setting up the command search PATH, it also sets up the search path for shared libraries, LD_LIBRARY_PATH.