5.2. Hello World [hello]

As is customary for any programming class, our first lab outputs "Hello World!" When acting as a web server, NGINX serves static content from files stored on disk. By using the js_content directive NGINX can serve dynamic content generated by JavaScript code. In this example, our code simply returns the string "Hello World!" and sets the return code to 200.

Step 1: Copy and paste the following commands to start your NGINX container with this lab's files:

EXAMPLE='hello'
docker run --rm --name njs_example  -v $(pwd)/conf/$EXAMPLE.conf:/etc/nginx/nginx.conf:ro  -v $(pwd)/njs/$EXAMPLE.js:/etc/nginx/example.js:ro -v $(pwd)/njs/utils.js:/etc/nginx/utils.js:ro -p 80:80 -p 8090:8090 -d nginx

Step 2: Now let's use curl to test our NGINX server:

curl http://localhost/
Hello world!

curl http://localhost/version
0.4.1

docker stop njs_example

Code Snippets

Our JavaScript code is in two files so we need two js_import lines to load them into our NGINX configuration. Notice in the js_content directives how we use a namespace to identify in which file a JavaScript function is located.

nginx.conf
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load_module modules/ngx_http_js_module.so;

events {}

http {
  js_import utils.js;
  js_import main from example.js;

  server {
    listen 80;

    location = /version {
       js_content utils.version;
    }

    location / {
      js_content main.hello;
    }
  }
}

The Javascript code to generate "Hello World!":

example.js
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function hello(r) {
  r.return(200, "Hello world!\n");
}

export default {hello}

The utils.js file will be part of all of our labs. It has one function that displays the version of the njs module in use on this NGINX server.

utils.js
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function version(r) {
    r.return(200, njs.version);
}

export default {version}