Module ngx_stream_js_module

Example Configuration
Directives
     js_access
     js_filter
     js_import
     js_include
     js_path
     js_preread
     js_set
     js_var
Session Object Properties

The ngx_stream_js_module module is used to implement handlers in njs — a subset of the JavaScript language.

Download and install instructions are available here.

Example Configuration

The example works since 0.4.0.

stream {
    js_import stream.js;

    js_set $bar stream.bar;
    js_set $req_line stream.req_line;

    server {
        listen 12345;

        js_preread stream.preread;
        return     $req_line;
    }

    server {
        listen 12346;

        js_access  stream.access;
        proxy_pass 127.0.0.1:8000;
        js_filter  stream.header_inject;
    }
}

http {
    server {
        listen 8000;
        location / {
            return 200 $http_foo\n;
        }
    }
}

The stream.js file:

var line = '';

function bar(s) {
    var v = s.variables;
    s.log("hello from bar() handler!");
    return "bar-var" + v.remote_port + "; pid=" + v.pid;
}

function preread(s) {
    s.on('upload', function (data, flags) {
        var n = data.indexOf('\n');
        if (n != -1) {
            line = data.substr(0, n);
            s.done();
        }
    });
}

function req_line(s) {
    return line;
}

// Read HTTP request line.
// Collect bytes in 'req' until
// request line is read.
// Injects HTTP header into a client's request

var my_header =  'Foo: foo';
function header_inject(s) {
    var req = '';
    s.on('upload', function(data, flags) {
        req += data;
        var n = req.search('\n');
        if (n != -1) {
            var rest = req.substr(n + 1);
            req = req.substr(0, n + 1);
            s.send(req + my_header + '\r\n' + rest, flags);
            s.off('upload');
        }
    });
}

function access(s) {
    if (s.remoteAddress.match('^192.*')) {
        s.deny();
        return;
    }

    s.allow();
}

export default {bar, preread, req_line, header_inject, access};

Directives

Syntax: js_access function | module.function;
Default:
Context: stream, server

Sets an njs function which will be called at the access phase. Since 0.4.0, a module function can be referenced.

Syntax: js_filter function | module.function;
Default:
Context: stream, server

Sets a data filter. Since 0.4.0, a module function can be referenced.

Syntax: js_import module.js | export_name from module.js;
Default:
Context: stream

This directive appeared in version 0.4.0.

Imports a module that implements location and variable handlers in njs. The export_name is used as a namespace to access module functions. If the export_name is not specified, the module name will be used as a namespace.

js_import stream.js;

Here, the module name stream is used as a namespace while accessing exports. If the imported module exports foo(), stream.foo is used to refer to it.

Several js_import directives can be specified.

Syntax: js_include file;
Default:
Context: stream

Specifies a file that implements server and variable handlers in njs:

nginx.conf:
js_include stream.js;
js_set     $js_addr address;
server {
    listen 127.0.0.1:12345;
    return $js_addr;
}

stream.js:
function address(s) {
    return s.remoteAddress;
}

The directive is deprecated since 0.4.0, the js_import directive should be used instead.

Syntax: js_path path;
Default:
Context: stream

This directive appeared in version 0.3.0.

Sets an additional path for njs modules.

Syntax: js_preread function | module.function;
Default:
Context: stream, server

Sets an njs function which will be called at the preread phase. Since 0.4.0, a module function can be referenced.

Syntax: js_set $variable function | module.function;
Default:
Context: stream

Sets an njs function for the specified variable. Since 0.4.0, a module function can be referenced.

The function is called when the variable is referenced for the first time for a given request. The exact moment depends on a phase at which the variable is referenced. This can be used to perform some logic not related to variable evaluation. For example, if the variable is referenced only in the log_format directive, its handler will not be executed until the log phase. This handler can be used to do some cleanup right before the request is freed.

Syntax: js_var $variable [value];
Default:
Context: stream

This directive appeared in version 0.5.3.

Declares a writable variable. The value can contain text, variables, and their combination.

Session Object Properties

Each stream njs handler receives one argument, a stream session object.