qu

⚠️ This project was archived on September 25th, 2020 and is no longer maintained ⚠️

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qu is a data platform created to serve our public data sets. You can use it to serve your data sets, as well.

The goals of this platform are to:

• Import data in our Google-Dataset-inspired format
• Query data using our Socrata-Open-Data-API-inspired API
• Export data in JSON or CSV format

Developing with Vagrant

If you are using Vagrant, life is clean and easy for you! Go to our Vagrant documentation to get started.

Getting started without Vagrant

Prerequisites

In order to work on qu, you need the following languages and tools installed:

• Node.js
• Grunt
• Bower
• Java
• Leiningen
• MongoDB

Setup

Front-end assets

Once you have the prerequisites installed and the code downloaded and expanded into a directory (which we will call "qu"), run the following commands:

cd qu
lein deps
npm install -g grunt-cli bower
npm install && bower install
grunt

If editing the JavaScript or CSS, run the following to watch the JS and CSS and make sure your changes are compiled:

grunt watch

You can run grunt to compile the files once.

Vagrant

Start a VM by running vagrant up. Provisioning will take a few minutes.

After a VM is started, you should be able to run vagrant ssh to SSH to the VM. Then run:

cd /vagrant

to change the working directory to the Qu codebase.

Clojure

To start a Clojure REPL to work with the software, run:

lein repl

In order to run the API as a web server, run:

lein run

Go to http://localhost:3000 (or http://localhost:3333 if using Vagrant) and you should see the app running.

Before starting the API, you will want to start MongoDB and load some data into it.

Configuration

All the settings below are shown via environment variables, but they can also be set via Java properties. See [the documentation for environ][https://github.com/weavejester/environ/blob/master/README.md] for more information on how to use Java properties if you prefer.

Configuration file

Besides using environment variables, you can also use a configuration file. This file must contain a Clojure map with your configuration set in it. Unlike with environment variables, where each setting is uppercased and SNAKE_CASED, these settings must be lowercase keywords with dashes, like so:

{ :http-port 8080
  :mongo-host "127.0.0.1" }

In order to use a configuration file, set QU_CONFIG to the file's location, like so:

QU_CONFIG=/etc/qu-conf.clj

Note that the configuration file overrides environment variables.

HTTP server

By default, the server will come up on port 3000 and 4 threads will be allocated to handle requests. The server will be bound to localhost. You can change these settings via environment variables:

HTTP_IP=0.0.0.0
HTTP_PORT=3000
HTTP_THREADS=4

You can also do this in the QU_CONFIG config file:

{ :http-ip "0.0.0.0"
:http-port 3000
:http-threads 50 }

MongoDB

In development mode, the application will connect to your local MongoDB server. In production, or if you want to connect to a different Mongo server in dev, you will have to specify the Mongo host and port.

You can do this via setting environment variables:

MONGO_HOST=192.168.21.98
MONGO_PORT=27017

You can also do this in the QU_CONFIG config file:

{ :mongo-host "192.168.21.98"
:mongo-port 27017 }

If you prefer to connect via a URI, use MONGO_URI.

If you need to connect to several servers to read from multiple replica sets, set specific Mongo options, or authenticate, you will have to set your configuration in a file as specified under QU_CONFIG. Your configuration should look like the following:

{
  ;; General settings
  :http-ip "0.0.0.0"
  :http-port 3000
  :http-threads 50

  ;; Set a vector of vectors, each made up of the IP address and port.
  :mongo-hosts [["127.0.0.1" 27017] ["192.168.1.1" 27017]]
  
  ;; Mongo options should be in a map.
  :mongo-options {:connections-per-host 20
                  :connect-timeout 60}
                  
  ;; Authentication should be a map of database names to vectors containing username and password.
  ;; If you have a user on the admin database with the roles "readWriteAnyDatabase", that user should
  ;; work for running the entire API. To load data, that user needs the roles "clusterAdmin" and
  ;; "dbAdminAnyDatabase" as well.
  ;; If you choose not to have a user on the admin database, you will need a user for every dataset
  ;; and for the "metadata" database.
  :mongo-auth {
    :admin ["admin-user" "s3cr3t"]
    :slicename ["admin-user" "s3cr3t"]
    :metadata ["admin-user" "s3cr3t"]
    :query_cache ["admin-user" "s3cr3t"]}
}

See the Monger documentation for all available Mongo connection options.

StatsD

The application can generate metrics related to its execution and send them to statsd.

However by default metrics publishing is disabled. To enable it you need to provide statsd hostname in the configuration file:

{
  :statsd-host "localhost"
  ;; Standard statsd port
  :statsd-port 8125
}

App URL

To control the HREF of the links that are created for data slices, you can set the APP_URL environment variable.

For example, given a slice at /data/a_resource/a_slice, setting the APP_URL variable like so

APP_URL=https://my.data.platform/data-api

will create links such as

_links":[{"rel":"self","href":"https://my.data.platform/data-api/data/a_resource/a_slice.json?...."}]

when emitted in JSON, JSONP, XML, and so on.

If the variable is not set, then relative HREFs such as /data/a_resource/a_slice.json are used. This variable is most useful in production hosting situations where an application server is behind a proxy, and you wish to granularly control the HREFs that are created independent of how the application server sees the request URI.

API Name

In order for your API to show a custom name (such as "Spiffy Lube API"), set the API_NAME environment variable. This is probably best set in an external config file.

Loading data

Make sure you have MongoDB started. To load some sample data, run lein repl and enter the following:

(go)
(load-dataset "census") ; Takes quite a while to run; can skip.
(stop)

Testing

To execute the project's tests, run:

lein test

We also have integration tests that run tests against a Mongo database. To run these tests:

lein with-profile integration embongo test

or, even more easily:

lein inttest

Nginx

We recommend serving Qu behind a proxy. Nginx works well for this, and there is a sample configuration file available.