Module ngx_stream_js_module

Example Configuration
Directives
     js_access
     js_filter
     js_include
     js_preread
     js_set
Session Object Properties

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

This module is not built by default, it should be compiled with the nginScript module using the --add_module configuration parameter:

./configure --add-module=path-to-njs/nginx

The repository with the nginScript module can be cloned with the following command (requires Mercurial client):

hg clone http://hg.nginx.org/njs

This module can also be built as dynamic:

./configure --add-dynamic_module=path-to-njs/nginx

Example Configuration

stream {
    js_include stream.js;

    js_set $foo foo;
    js_set $bar bar;

    server {
        listen 12345;

        js_preread qux;
        return     $foo;
    }

    server {
        listen 12346;

        js_access  xyz;
        proxy_pass 127.0.0.1:8000;
        js_filter  baz;
    }
}

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

The stream.js file:

var req = '';
var matched = 0;
var line = '';

function qux(s) {
    var n = s.buffer.indexOf('\n');
    if (n == -1) {
        return s.AGAIN;
    }

    line = s.buffer.substr(0, n);
}

function foo(s) {
    return line;
}

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

// The filter processes one buffer per call.
// The buffer is available in s.buffer both for
// reading and writing.  Called for both directions.

function baz(s) {
    if (s.fromUpstream || matched) {
        return;
    }

    // Disable certain addresses.

    if (s.remoteAddress.match('^192.*')) {
        return s.ERROR;
    }

    // Read HTTP request line.
    // Collect bytes in 'req' until request
    // line is read.  Clear current buffer to
    // disable output.

    req = req + s.buffer;
    s.buffer = '';

    var n = req.search('\n');

    if (n != -1) {
        // Inject a new HTTP header.
        var rest = req.substr(n + 1);
        req = req.substr(0, n + 1);

        var addr = s.remoteAddress;

        s.log('req:' + req);
        s.log('rest:' + rest);

        // Output the result and skip further
        // processing.

        s.buffer = req + 'Foo: addr_' + addr + '\r\n' + rest;
        matched = 1;
    }
}

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

Directives

Syntax: js_access function;
Default:
Context: stream, server

Sets an nginScript function which will be called at the access phase.

Syntax: js_filter function;
Default:
Context: stream, server

Sets a data filter.

Syntax: js_include file;
Default:
Context: stream

Specifies a file that implements server and variable handlers in nginScript.

Syntax: js_preread function;
Default:
Context: stream, server

Sets an nginScript function which will be called at the preread phase.

Syntax: js_set $variable function;
Default:
Context: stream

Sets an nginScript function for the specified variable.

Session Object Properties

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

The session object has the following properties:

remoteAddress
client address, read-only
eof
a boolean read-only property, true if the current buffer is the last buffer
fromUpstream
a boolean read-only property, true if the current buffer is from the upstream server to the client
buffer
the current buffer, writable
variables{}
nginx variables object, read-only
OK
the OK return code
DECLINED
the DECLINED return code
AGAIN
the AGAIN return code
ERROR
the ERROR return code
ABORT
the ABORT return code

The session object has the following methods:

log(string)
writes a sent string to the error log