In the beginning, Docker only supported amd64 and only ran on Linux. Later, Docker started supporting different architectures like Windows 64-bit and ARM. You could run Docker on these platforms, but the image support has been a work in progress. For a long time, some images would create a fork that supported armhf, but then you would have a separate tag for the armhf architecture. Since the default for Docker is to pull the latest tag, running something like docker pull ubuntuwouldn’t pull the correct architecture.

Docker recently created a new manifest format for the registry that allows for multiple images of different architectures to share the same tag. One of our users, @longquan, made a pull request on our Docker images offering a method to have a single Dockerfile build multiple architectures. We adapted this pull request and, with the additional help of @jcberthon, we merged support for ARMv7 32-bit and ARMv8 64-bit.

That means the InfluxData stack can be run with Docker out of the box on platforms like the Raspberry Pi. This is perfect if you want a cheap and easy computer to set up for monitoring something in your home! In this post, we are going to run InfluxDB on our own laptop and configure a Telegraf instance to report to our laptop over a local network.

What You Will Need

  • The Raspberry Pi
  • A computer (such as a laptop)
  • A router with both computers being connected to the same router
  • An internet connection

Install Docker on the Laptop

Install Docker on your laptop using the appropriate method from the Docker Documentation. I am using Mac OS X, so I am using docker-machine as a virtual machine.

Once you have installed Docker on your computer, verify it works by using ping and then pulling down the InfluxDB image.

$ docker ping
$ docker pull influxdb

We can now run InfluxDB and Chronograf on our laptop with few simple commands.

# Create a shared network for influxdb and chronograf to communicate over.
$ docker network create influxdb
# Launch the influxdb image.
$ docker run -d --name=influxdb --net=influxdb -p 8086:8086 influxdb
# Launch the chronograf image.
$ docker run -d --name=chronograf --net=influxdb -p 8888:8888 chronograf --influxdb-url http://influxdb:8086

We create a shared network for influxdb and chronograf to communicate over. While it looks complicated, this simplifies networking the two containers. We then launch each one of the images using this network and expose the ports that need to be exposed to the outside world. For InfluxDB, this is port 8086. For Chronograf, this is 8888. Now, try visiting Chronograf using your computer’s web browser. If you are running Docker natively on your computer, this should be as simple as going to http://localhost:8888. If you are using docker-machine (such as on Mac OS X), you can use the https://github.com/jsternberg/docker-machine-proxy I created for this demo. It will proxy ports from the Docker Machine to localhost so internetwork connections between computers work correctly.

When this is working and you are able to access Chronograf at localhost, you should see the Chronograf dashboard and Chronograf should say that no hosts were found.

Before we add a host, there is one more thing we must do.

Retrieve the IP Address

Retrieve the IP address that your router gave you for your computer. If you are on Linux or Mac OS X, you can use ifconfig. Here is an example of my output:

> ifconfig
lo0: flags=8049<UP,LOOPBACK,RUNNING,MULTICAST> mtu 16384
        options=1203<RXCSUM,TXCSUM,TXSTATUS,SW_TIMESTAMP>
        inet 127.0.0.1 netmask 0xff000000
        inet6 ::1 prefixlen 128
        inet6 fe80::1%lo0 prefixlen 64 scopeid 0x1
        nd6 options=201<PERFORMNUD,DAD>
gif0: flags=8010<POINTOPOINT,MULTICAST> mtu 1280
stf0: flags=0<> mtu 1280
en0: flags=8863<UP,BROADCAST,SMART,RUNNING,SIMPLEX,MULTICAST> mtu 1500
        ether ac:bc:32:cd:96:f3
        inet6 fe80::1c:121a:e9d5:fe98%en0 prefixlen 64 secured scopeid 0x4
        inet6 2605:6000:1522:c065:854:a83:ba74:7e05 prefixlen 64 autoconf secured
        inet6 2605:6000:1522:c065:9c91:edf6:d09a:e266 prefixlen 64 autoconf temporary
        inet 192.168.1.113 netmask 0xffffff00 broadcast 192.168.1.255
        nd6 options=201<PERFORMNUD,DAD>
        media: autoselect
        status: active
en1: flags=963<UP,BROADCAST,SMART,RUNNING,PROMISC,SIMPLEX> mtu 1500
        options=60<TSO4,TSO6>
        ether 6a:00:01:52:70:20
        media: autoselect <full-duplex>
        status: active

The en0 interface is the only one that looks like it has an IP address so we will use 192.168.1.113 for this example. For your own computer, you need to use your own IP address! I am running this command on Mac OS X so the name of the interface may be different if you are using another operating system. On Windows computers, you can use cmd.exe and ipconfig to find your local IP address.

Remember, you want the IP address given to the computer by your router. You do not want your public IP address to the internet itself. Most home networks have their networks start with 192.168.*.*, but some may also start with 10.*.*.* or 172.*.*.*.

Boot Your Raspberry Pi

Connect your Raspberry Pi to your router. If you have never installed an operating system, I suggest Raspbian. It’s easy to install and use and the one I used for this article.

You can then run the following to install Docker. First, download the script that Docker offers for making things easy.

$ curl https://get.docker.com > get-docker.sh
$ sudo bash get-docker.sh

After this command finishes, you will see a message like this in the output:

If you would like to use Docker as a non-root user, you should now consider
adding your user to the "docker" group with something like:

  sudo usermod -aG docker pi
  
Remember that you will have to log out and back in for this to take effect!

There will be more and a warning. If you are planning to use this in production and security is something you must consider, it might be best to skip this step. For our purposes, we are going to enter the above command so we don’t have to type sudoin front of the docker commands. Run the above command and then reboot your Raspberry Pi.

After the Pi is back up and running, open the Terminal again and run the following:

$ docker run --rm telegraf telegraf config > telegraf.conf

You just ran Telegraf on your Raspberry Pi for the first time! But we’re not quite done. We generated a configuration file. Open telegraf.conf and go to the [[outputs.influxdb]] section. It should look like this:

[[outputs.influxdb]]
  ## The HTTP or UDP URL for your InfluxDB instance.  Each item should be
  ## of the form:
  ##   scheme "://" host [ ":" port]
  ##
  ## Multiple urls can be specified as part of the same cluster,
  ## this means that only ONE of the urls will be written to each interval.
  # urls = ["udp://localhost:8089"] # UDP endpoint example
  urls = ["http://localhost:8086"] # required
  ## The target database for metrics (telegraf will create it if not exists).
  database = "telegraf" # required

Modify the urls option so it looks like this, but replaced with your own IP address that we found earlier:

[[outputs.influxdb]]
  ## The HTTP or UDP URL for your InfluxDB instance.  Each item should be
  ## of the form:
  ##   scheme "://" host [ ":" port]
  ##
  ## Multiple urls can be specified as part of the same cluster,
  ## this means that only ONE of the urls will be written to each interval.
  # urls = ["udp://localhost:8089"] # UDP endpoint example
  urls = ["http://192.168.1.13:8086"] # required
  ## The target database for metrics (telegraf will create it if not exists).
  database = "telegraf" # required

Now we need to execute Telegraf using our custom configuration file.

$ docker run -d --name=telegraf -v $PWD/telegraf.conf:/etc/telegraf/telegraf.conf:ro telegraf

Now wait a bit. If you want to check if Telegraf is working, you can use docker logs -f telegraf and it will follow along with the log messages. You might need to refresh the Chronograf page. If all goes well, you should see your Raspberry Pi and metrics coming in from the container on the Raspberry Pi!

While this demo showed how to use Telegraf on the Raspberry Pi, all of the InfluxData products now support running them with Docker on ARM.

Help and Caveats

For those who are using an older ARM architecture without native float support, docker pull will not work. This is because multiple architecture support in Docker is still ongoing. When pulling from an ARM 32-bit (armhf), it may pull down the version built with emulated floating point support (armel). Because of this limitation, the Dockerfiles support building on armel, but we do not upload these images to the official repository. If you need to use the Docker images and have armelas your architecture, you can build the images from source here.

To determine which architecture you have, you can run dpkg --print-architecture. If you see armhf, that’s the one that is uploaded and we support. If you see armel, that’s the one you need to build from source.

For those who need help, please visit our https://community.influxdata.com website. If you think something isn’t working correctly with the images, please file a bug in the repository.

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