juttle-service

juttle-service

juttle-service is an API-based execution engine for juttle programs.

It exposes an API for executing and managing a set of running juttle jobs. Each job executes in a separate node.js subprocess and either returns the results immediately or creates a websocket over which results are streamed using the JSDP protocol.

Getting Started

Installation

Make sure you have node (with npm) installed.

Use npm to install juttle and juttle-service:

$ npm install juttle
$ npm install juttle-service

We've tested with nodejs 4.2.3 and npm 2.14.17. Other combinations of nodejs and npm likely work, but we haven't tested all combinations.

Ecosystem

Here's how the juttle-service module fits into the overall Juttle Ecosystem:

Options and Configuration

Here are the full command line options supported by the daemon:

juttle-service

usage: [--port <port>] [--root <path>]
       [--config <juttle-config-path>] [--daemonize]
       [--output <logfile>] [--log-config <log4js-config-path>]
       [--log-level <level] [--help]
       -p, --port <port>:                     Run juttle-service on the specified port
       -r, --root <path>:                     Use <path> as the root directory for juttle programs
       -c, --config <juttle-config-path>:     Read juttle config from <juttle-config-path>
       -d, --daemonize:                       Daemonize juttle-service and log to configured log file
       -o, --output <logfile>:                Log to specififed file when daemonized
       -L, --log-config <log4js-config-path>: Configure logging from <log4js-config-path>. Overrides any value of -o
       -l, --log-level <level>:               Use a default log level of <level>. Overridden by any log level specified in -L
       -h, --help:                            Print this help and exit

juttle-service uses log4js for logging and by default logs to the console when in the foreground, /var/log/juttle-service.log when in the background.

Juttle config file

The Juttle compiler and runtime within juttle-service are also configured via the juttle configuration file, typically at $(HOME)/.juttle/config.json. For more information on the juttle configuration file, see the juttle configuration documentation.

The Juttle Service configuration options (default values shown):

// config.json
{
    "juttle-service": {
        // Whether HTTP responses should be compressed when
        // the client supports it.
        "compress_response": true,

        // Time (in ms) a finished job should wait for the first websocket
        // to connect before disposing of the results.
        "delayed_job_cleanup": 10000,

        // The number messages job should buffer for sending to
        // websockets that join after the job has started.
        "max_saved_messages": 1024,

        // After a job has finished, wait this many ms before closing the
        // websocket connection associated with the job. A well behaved
        // client should close the socket before this time, but we close it
        // server-side to avoid leaking sockets.
        "delayed_endpoint_close": 600000
    },
    "adapters": { ... }
}

In addition, all command-line arguments other than --config can also be specified in juttle/config.json via their long arguments. When specified, command line arguments override any values found in the configuration file.

Module resolution

For information on how modules are resolved, see the "Importing Modules" section in the general juttle documentation on programming constructs.

Testing

To run unit tests:

npm test

Both are run automatically by Travis.