Jsonnet - Jsonnet Configuration Language

A configuration language
for app and tool developers

Generate config data
Side-effect free
Organize, simplify, unify
Manage sprawling config

A simple extension of JSON

Open source (Apache 2.0)
Familiar syntax
Reformatter, linter
Editor & IDE integrations
Formally specified

Eliminate duplication with object-orientation:

➡

output.json

        {
          "person1": {
            "name": "Alice",
            "welcome": "Hello Alice!"
          },
          "person2": {
            "name": "Bob",
            "welcome": "Hello Bob!"
          }
        }

➡

output.json

        {
          "person1": {
            "name": "Alice",
            "welcome": "Hello Alice!"
          },
          "person2": {
            "name": "Bob",
            "welcome": "Hello Bob!"
          }
        }

Integrate with existing / custom applications.
Generate JSON, YAML, INI, and other formats.

local application = 'my-app';
        local module = 'uwsgi_module';
        local dir = '/var/www';
        local permission = 644;

{
          'uwsgi.ini': std.manifestIni({
            sections: {
              uwsgi: {
                module: module,
                pythonpath: dir,
                socket: dir + '/uwsgi.sock',
                'chmod-socket': permission,
                callable: application,
                logto: '/var/log/uwsgi/uwsgi.log',
              },
            },
          }),

'init.sh': |||
            #!/usr/bin/env bash
            mkdir -p %(dir)s
            touch %(dir)s/initialized
            chmod %(perm)d %(dir)s/initialized
          ||| % {dir: dir, perm: permission},

'cassandra.conf': std.manifestYamlDoc({
            cluster_name: application,
            seed_provider: [
              {
                class_name: 'SimpleSeedProvider',
                parameters: [{ seeds: '127.0.0.1' }],
              },
            ],
          }),
        }

➡

cassandra.conf

init.sh

uwsgi.ini

        "cluster_name": "my-app"
        "seed_provider":
        - "class_name": "SimpleSeedProvider"
          "parameters":
          - "seeds": "127.0.0.1"

        #!/usr/bin/env bash
        mkdir -p /var/www
        touch /var/www/initialized
        chmod 644 /var/www/initialized

        [uwsgi]
        callable = my-app
        chmod-socket = 644
        logto = /var/log/uwsgi/uwsgi.log
        module = uwsgi_module
        pythonpath = /var/www
        socket = /var/www/uwsgi.sock

The name Jsonnet is a portmanteau of JSON and sonnet, pronounced "jay sonnet". It began life early 2014 as a 20% project and was launched on Aug 6. The design is influenced by several configuration languages internal to Google, and embodies years of experience configuring some of the world's most complex IT systems. Jsonnet is now used by many companies and projects. Jsonnet is not an official Google product (experimental or otherwise), it is just code that happens to be owned by Google.