Docker-Pi – DB and Visualisation

During my docker trials and tribulations, I found two great tools for storing measurement and then displaying them..

InfluxDB

It’s not a complex database like MySQL – it’s a simple way of storing time-lapse measurements.  I’ll late use it for storing temperature and humidity measurements, but for now we’ll get it setup and drop in some resource stats from the Pi.

Thankfully, someone’s already compiled Influx for the Raspberry Pi and Docker..

HypriotOS/armv7: pirate@black-pearl in ~
$ docker run -d -p 8083:8083 -p 8086:8086 --expose 8090 --expose 8099 -v /var/docker_data/influxdb:/data --name influxsrv sbiermann/rpi-influxdb

InfluxDB exposes two webports:

• 8083 – is a web-based UI for basic DB administration and querying
• 8086 – is a HTTP API for posting/getting data

The default username and password for influx is root/root.

Getting System Stats

It’s useful to know what your Pi is up to and how the resource utilisation looks, especially if you start pushing some heavy scripts or apps to it.  Telegraf has been compiled for the Pi architecture here.  Don’t follow the instructions about creating a dedicated data folder.. let Docker do this for you.

Now- the default rpi-telegraf configuration tries to send data to influx using localhost:8086 – this will fail as we’re not running influx inside the same container.  To fix this we need to do two things..

Firstly – add the ‘–link’ command to the docker run CLI to link the influxdb container to the telegraf container.

• –link influxsrv:influxsrv – docker will create a DNS entry internally and map the influxsrv hostname to the dynamic IP of the influx container

Secondly – modify the telegraf configuration to point to the right influx hostname. To do this, you’ll need to run telegraf once and then use the docker inspect to find the data directory and edit the telegraf.conf file.

Run telegraf with the link:

HypriotOS/armv7: pirate@black-pearl in /var/docker_data
$ docker run -ti -v /data –link influxsrv:influxsrv –name telegraf apicht/rpi-telegraf

And then kill the process

Find the config config:

As we’ve been creating a dedicated store for our container’s data, you should find the telegraf data in /var/docker_data/telegraf

Edit the telegraf.conf file and the influxdb section:

[[outputs.influxdb]]
## The full HTTP or UDP endpoint URL for your InfluxDB instance.
## 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://influxsrv:8086”] # required
## The target database for metrics (telegraf will create it if not exists).
database = “telegraf” # required

Now telegraf can be run as a daemon container:

HypriotOS/armv7: pirate@black-pearl in ~
$ docker run -d -v /data –link influxsrv:influxsrv –name telegraf apicht/rpi-telegraf

Docker-Pi – Getting Started

Setup Raspberry Pi2 with HypriotOS

Assign static addressing

auto eth0
iface eth0 inet static
 address 192.168.1.111/24
 gateway 192.168.1.1
 dns-nameservers 192.168.1.1
 dns-search jimleach.co.uk

Getting Persistance

Docker instances are non-persistant, but for most of the things I want to use them for, I need some consistent storage I can present to them.  Don’t do this if you want your containers to be portable! A better way would be to present some storage via NFS and map that instead.. something a bit less host-centric.

HypriotOS/armv7: pirate@black-pearl in /var/docker_data
$ pwd
/var/docker_data

Create directories for:

• dockerui
• influxdb
• telegraf
• grafana

We’ll need these later as we build up our stack of containers..

Docker-UI

By trying to run the image without first downloading, you prompt docker into pulling it automatically from the Docker Hub and then starting it.

• -d – Puts the instance into daemon mode
• -p 9000:9000 – maps port 9000 on the localhost (the RiPi) to port 9000 on the instance
• -v – Maps our local storage to a volume/directory in the container (local:container)
• –name – gives us a recognisable name to reference the container with

Now if you browse to the Pi’s address on port 9000 – you should get the Docker UI:

Pi-Docker Failure