# Cloud Data Logging with Raspberry Pi

[Raspberry Pi](https://www.raspberrypi.org/) is a credit-card-sized single-board computer. Because it is low-cost and easy to equip with various types of sensors, using Raspberry Pi as a cloud data logger is one of its ideal use cases.

![Cloud Data Logger by Raspberry Pi](../.gitbook/assets/raspberry-pi-cloud-data-logger.png)

This article introduces how to transport sensor data from Raspberry Pi to the cloud, using Fluentd as the data collector. For the cloud side, we'll use the [Treasure Data](https://www.fluentd.org/treasuredata) cloud data service as an example, but you can use any cloud service in its place.

## Install Raspbian

[Raspbian](http://www.raspbian.org/) is a free operating system based on Debian, optimized for the Raspberry Pi. Please install Raspbian on your Raspberry Pi by following the instructions in the blog post below:

* [Getting Started with Raspberry Pi: Installing Raspbian](https://www.andrewmunsell.com/blog/getting-started-raspberry-pi-install-raspbian)

## Install Fluentd

Next, we'll install Fluentd on Raspbian. Raspbian Stretch with desktop and recommended software bundles Ruby 2.3.3 by default, but we need the extra development package to install Fluentd:

```text
$ sudo aptitude install ruby-dev
```

We'll now install Fluentd and the necessary plugins:

```text
$ sudo gem install fluentd
$ sudo fluent-gem install fluent-plugin-td
```

## Configure and Launch Fluentd

Please sign up to Treasure Data from the [sign up page](https://console.treasuredata.com/users/sign_up). Its free plan lets you store and analyze millions of data points. You can get your account's API key from the [users page](https://console.treasuredata.com/users/current).

Please prepare the `fluentd.conf` file with the following information, including your API key:

```text
<match td.*.*>
  @type tdlog
  apikey YOUR_API_KEY_HERE

  auto_create_table
  <buffer>
    @type file
    path /home/pi/fluentd/td
  </buffer>
</match>

<source>
  @type http
  port 8888
</source>

<source>
  @type forward
</source>
```

Finally, please launch Fluentd via your terminal:

```text
$ fluentd -c fluent.conf
```

## Upload Test

To test the configuration, just post a JSON message to Fluentd via HTTP:

```text
$ curl -X POST -d 'json={"sensor1":3123.13,"sensor2":321.3}' \
  http://localhost:8888/td.testdb.raspberrypi
```

NOTE: If you're using Python, you can use Fluentd's [python logger](../language-bindings/python.md) library.

Now, access the databases page to confirm that your data has been uploaded to the cloud properly.

* [Treasure Data: List of Databases](https://console.treasuredata.com/databases)

You can now issue queries against the imported data.

* [Treasure Data: New Query](https://console.treasuredata.com/query_forms/new)

For example, these queries calculate the average `sensor1` value and the sum of `sensor2` values:

```text
SELECT AVG(sensor1) FROM raspberrypi;
SELECT SUM(sensor2) FROM raspberrypi;
```

## Conclusion

Raspberry Pi is an ideal platform for prototyping data logger hardware. Fluentd helps Raspberry Pi transfer the collected data to the cloud easily and reliably.