Module ngx_stream_js_module

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.

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};

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

The function is called once at the moment when the stream session reaches the access phase for the first time. The function is called with the following arguments:

s

the Stream Session object

At this phase, it is possible to perform initialization or register a callback with the s.on() method for each incoming data chunk until one of the following methods are called: s.allow(), s.decline(), s.done(). As soon as one of these methods is called, the stream session processing switches to the next phase and all current s.on() callbacks are dropped.

js_context_reuse 128;

Sets a maximum number of JS context to be reused for QuickJS engine. Each context is used for a single stream session. The finished context is put into a pool of reusable contexts. If the pool is full, the context is destroyed.

js_engine njs;

Sets a JavaScript engine to be used for njs scripts. The njs parameter sets the njs engine, also used by default. The qjs parameter sets the QuickJS engine.

js_fetch_buffer_size 16k;

Sets the size of the buffer used for reading and writing with Fetch API.

js_fetch_ciphers HIGH:!aNULL:!MD5;

Specifies the enabled ciphers for HTTPS connections with Fetch API. The ciphers are specified in the format understood by the OpenSSL library.

The full list can be viewed using the “openssl ciphers” command.

js_fetch_max_response_buffer_size 1m;

Sets the maximum size of the response received with Fetch API.

js_fetch_protocols TLSv1 TLSv1.1 TLSv1.2;

Enables the specified protocols for HTTPS connections with Fetch API.

js_fetch_timeout 60s;

Defines a timeout for reading and writing for Fetch API. The timeout is set only between two successive read/write operations, not for the whole response. If no data is transmitted within this time, the connection is closed.

Specifies a file with trusted CA certificates in the PEM format used to verify the HTTPS certificate with Fetch API.

js_fetch_verify on;

Enables or disables verification of the HTTPS server certificate with Fetch API.

js_fetch_verify_depth 100;

Sets the verification depth in the HTTPS server certificates chain with Fetch API.

Sets a data filter. Since 0.4.0, a module function can be referenced. The filter function is called once at the moment when the stream session reaches the content phase.

The filter function is called with the following arguments:

s

the Stream Session object

At this phase, it is possible to perform initialization or register a callback with the s.on() method for each incoming data chunk. The s.off() method may be used to unregister a callback and stop filtering.

As the js_filter handler returns its result immediately, it supports only synchronous operations. Thus, asynchronous operations such as ngx.fetch() or setTimeout() are not supported.

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.

The directive can be specified on the server level since 0.7.7.

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 was made obsolete in version 0.4.0 and was removed in version 0.7.1. The js_import directive should be used instead.

Sets an additional path for njs modules.

The directive can be specified on the server level since 0.7.7.

Specifies a content handler to run at regular interval. The handler receives a session object as its first argument, it also has access to global objects such as ngx.

The optional interval parameter sets the interval between two consecutive runs, by default, 5 seconds.

The optional jitter parameter sets the time within which the location content handler will be randomly delayed, by default, there is no delay.

By default, the js_handler is executed on worker process 0. The optional worker_affinity parameter allows specifying particular worker processes where the location content handler should be executed. Each worker process set is represented by a bitmask of allowed worker processes. The all mask allows the handler to be executed in all worker processes.

Example:

example.conf:

location @periodics {
    # to be run at 1 minute intervals in worker process 0
    js_periodic main.handler interval=60s;

    # to be run at 1 minute intervals in all worker processes
    js_periodic main.handler interval=60s worker_affinity=all;

    # to be run at 1 minute intervals in worker processes 1 and 3
    js_periodic main.handler interval=60s worker_affinity=0101;

    resolver 10.0.0.1;
    js_fetch_trusted_certificate /path/to/ISRG_Root_X1.pem;
}

example.js:

async function handler(s) {
    let reply = await ngx.fetch('https://nginx.org/en/docs/njs/');
    let body = await reply.text();

    ngx.log(ngx.INFO, body);
}

Preloads an immutable object at configure time. The name is used as a name of the global variable though which the object is available in njs code. If the name is not specified, the file name will be used instead.

js_preload_object map.json;

Here, the map is used as a name while accessing the preloaded object.

Several js_preload_object directives can be specified.

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

The function is called once at the moment when the stream session reaches the preread phase for the first time. The function is called with the following arguments:

s

the Stream Session object

At this phase, it is possible to perform initialization or register a callback with the s.on() method for each incoming data chunk until one of the following methods are called: s.allow(), s.decline(), s.done(). When one of these methods is called, the stream session switches to the next phase and all current s.on() callbacks are dropped.

As the js_preread handler returns its result immediately, it supports only synchronous callbacks. Thus, asynchronous callbacks such as ngx.fetch() or setTimeout() are not supported. Nevertheless, asynchronous operations are supported in s.on() callbacks in the preread phase. See this example for more information.

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.

Since 0.8.6, when optional argument nocache is provided the handler is called every time it is referenced. Due to current limitations of the rewrite module, when a nocache variable is referenced by the set directive its handler should always return a fixed-length value.

As the js_set handler returns its result immediately, it supports only synchronous callbacks. Thus, asynchronous callbacks such as ngx.fetch() or setTimeout() are not supported.

The directive can be specified on the server level since 0.7.7.

Sets the name and size of the shared memory zone that keeps the key-value dictionary shared between worker processes.

By default the shared dictionary uses a string as a key and a value. The optional type parameter allows redefining the value type to number.

The optional timeout parameter sets the time in milliseconds after which all shared dictionary entries are removed from the zone. If some entries require a different removal time, it can be set with the timeout argument of the add, incr, and set methods (0.8.5).

The optional evict parameter removes the oldest key-value pair when the zone storage is exhausted.

Example:

example.conf:
    # Creates a 1Mb dictionary with string values,
    # removes key-value pairs after 60 seconds of inactivity:
    js_shared_dict_zone zone=foo:1M timeout=60s;

    # Creates a 512Kb dictionary with string values,
    # forcibly removes oldest key-value pairs when the zone is exhausted:
    js_shared_dict_zone zone=bar:512K timeout=30s evict;

    # Creates a 32Kb permanent dictionary with number values:
    js_shared_dict_zone zone=num:32k type=number;

example.js:
    function get(r) {
        r.return(200, ngx.shared.foo.get(r.args.key));
    }

    function set(r) {
        r.return(200, ngx.shared.foo.set(r.args.key, r.args.value));
    }

    function del(r) {
        r.return(200, ngx.shared.bar.delete(r.args.key));
    }

    function increment(r) {
        r.return(200, ngx.shared.num.incr(r.args.key, 2));
    }

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

The directive can be specified on the server level since 0.7.7.

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