`juttle`: The Juttle Command Line

juttle is the command line interface for running juttle programs. It reads data from configured backends via adapters, executes juttle programs, and provides terminal-oriented visualizations that allow you to view the output of programs.

For more complex visualizations, you can use juttle engine, which provides browser-based visualizations and support for input controls.

Usage

juttle is run as follows:

usage: juttle [--version] [--mode <mode>] [--config <config>] [--color/--no-color]
              [--show-locations] [--optimize] [--input name=val] [juttle-file]
     --version show juttle CLI version
     --mode <mode>: one of "parse", "semantic", "build", "flowgraph", "compile", "run"
     --config <config>: path to the juttle interpreter configuration file
     --optimize runs optimization
     --show-locations displays locations in the parse tree
     --color/--no-color turns CLI output coloring on and off
     --input name=val defines input `name` with value `val`
     --e <juttle-src>: run the juttle source and exit
     [juttle-file]: run the provided juttle file and exit

Running juttle with no arguments launches a read-eval-print loop with the prompt:

juttle>

Ways to run juttle programs

juttle provides 3 different ways to run juttle programs:

Directly within the CLI:

juttle> emit -limit 1 | view table
┌────────────────────────────────────┐
│ time                               │
├────────────────────────────────────┤
│ 2015-12-18T21:40:18.555Z           │
└────────────────────────────────────┘

From the command line, via the -e <juttle source> command line argument:

$ juttle -e 'emit -limit 1 | view table'
┌────────────────────────────────────┐
│ time                               │
├────────────────────────────────────┤
│ 2015-12-18T21:40:18.555Z           │
└────────────────────────────────────┘

From a file, by naming a file on the command line:

$ cat my-program.juttle
emit -limit 1 | view table
$ juttle my-program.juttle
┌────────────────────────────────────┐
│ time                               │
├────────────────────────────────────┤
│ 2015-12-18T21:40:18.555Z           │
└────────────────────────────────────┘

CLI Features

Command line editing

You can edit command lines via the typical set of editor keys (arrows plus ^f/^b/^a/^e/etc.)

Command history

juttle maintains a command history. You can navigate through this history via the typical set of editor keys (arrows plus ^n/^p/etc.). This history is saved to $HOME/.juttle/history.

Multi-line input

To run multi-line juttle programs from the read-eval-print loop, begin a multi-line program with a < and finish it with a .:

juttle> <
Starting multi-line input. End input with a line containing a single ".":
emit -limit 1
   | view table
.
┌────────────────────────────────────┐
│ time                               │
├────────────────────────────────────┤
│ 2015-12-18T22:06:36.141Z           │
└────────────────────────────────────┘

Help

Typing help provides a summary of the commands available:

juttle> help
usage:
mode {mode} - change mode
src {path} - source file as juttle program
< - start multi-line input
{juttle} - evaluate juttle program
. - end multi-line input
exit, \q - close shell and exit
help, \? - print this usage
clear, \c - clear the terminal screen

Views

table

juttle supports table and text views:

juttle> emit -limit 1 | view table
┌────────────────────────────────────┐
│ time                               │
├────────────────────────────────────┤
│ 2015-12-18T22:09:44.478Z           │
└────────────────────────────────────┘

text

juttle> emit -limit 1 | view text
[
{"time":"2015-12-18T22:10:12.101Z"}
]
juttle>

If a program does not contain a view, juttle automatically adds one based on the value of the implicit_view configuration item (see below).

Errors

If your juttle program contains syntax or runtime errors, juttle provides details on the error and highlights the section of the program that led to the error:

juttle> emit limit 1 | view table
<input>:1:6:
1:emit limit 1 | view table
^
Expected ";", "|" or option but "l" found. (SYNTAX-ERROR-WITH-EXPECTED)

juttle> import 'no-such-module.juttle' as mymodule; emit -limit 1 | table;
<input>:1:1:
1:import 'no-such-module.juttle' as mymodule; emit -limit 1 | table;
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
Error: could not find module "no-such-module.juttle" (MODULE-NOT-FOUND)

juttle> import 'm1.juttle' as mymodule; emit -limit 1 | table;
In module included from <input>:
m1.juttle:1:8:
1:export consty foo=bar;
^
Expected "function", "reducer", "sub" or processor but "c" found. (SYNTAX-ERROR-WITH-EXPECTED)

Configuration

The CLI tries to read runtime configuration from various locations on the filesystem, in the following order:

<cwd>/.juttle-config.json
<cwd>/.juttle-config.js
<$HOME>/.juttle/config.json
<$HOME>/.juttle/config.js

The .json files are processed as JSON while the .js files are loaded with require and therefore need a single module.exports entry, see here more details on node module exports.

Generally juttle-config is used to configure adapters to various backends. The only juttle-specific configuration item is implicit_view, which defines what the default view is at the end of your flowgraph when not explicitly specified. For example if you set it to text like so:

.juttle-config.json:

{
"implicit_view": "text"
}

And then executed:

juttle> emit -limit 10

You would get:

[
{"time":"2015-12-07T22:32:06.483Z"},
{"time":"2015-12-07T22:32:07.483Z"},
{"time":"2015-12-07T22:32:08.483Z"},
{"time":"2015-12-07T22:32:09.483Z"},
{"time":"2015-12-07T22:32:10.483Z"},
{"time":"2015-12-07T22:32:11.483Z"},
{"time":"2015-12-07T22:32:12.483Z"},
{"time":"2015-12-07T22:32:13.483Z"},
{"time":"2015-12-07T22:32:14.483Z"},
{"time":"2015-12-07T22:32:15.483Z"}
]

Module Resolution

When juttle programs contain modules, juttle resolves modules by searching the following paths, in this order:

The current working directory
Any paths listed in the environment variable JUTTLE_MODULE_PATH, which is a colon-separated list of directories.

The first module file found is used.

Configuring Adapters

Connections to external adapters are configured in the "adapters" section of the configuration. Each entry should be the name of the adapter along with any adapter-specific configuration. By default, the CLI will try to load the adapter by executing require(adapter) but if the path attribute exists then it will try to load the adapter from the specified path.

For example, to configure the Elasticsearch adapter, first run npm install juttle-elastic-adapter and add the following to your juttle-config file, updating the address and port to point to the location of your Elasticsearch cluster.

{
    "adapters": {
        "elastic": {
            "address": "localhost",
            "port": 9200
        }
    }
}

By default, the runtime will try to load the adapter from an npm module matching the name juttle-<type>-adapter, so for the above example to work properly, you need to make sure that juttle-elastic-adapter exists somewhere in your npm load path.

To load an adapter from a different location, add a path attribute to the adapter configuration that contains the module path to be used when loading the adapter.

Logging

juttle uses log4js for logging, and can be controlled via the standard log4js.json file. In addition, unless the environment variable DEBUG is set to 1, juttle sets the default log level to 'info'.

juttle: The Juttle Command Line