Why docker was added

Because the team at wix-playground forked Skyline and dockerized in its simplest context.

Merging the wix-playground’s changes Skyline had to be tested running on docker and with that, the docker event horizon was crossed.

Docker does add a lot of potential in terms of developing Skyline in integrate with other things.

So Skyline can now be run on docker in a meaningful way, with thanks going to the team @wix-playground for pulling Skyline over the docker event horizon.

Docker should only be used for testing and it is probably not suitable for production. Running the Skyline Docker application should only be done on a developer or test machine until you are familiar with the docker application and can modify it to fit with docker practices and standards for your environment.

Not suitable for production

Although important directories are persisted to local directories using volumes one of the containers WILL lose data!!!! If OOMkiller kicks in on the host and the mysql container is killed the data CAN BE LOST as the new mysql image initialises the mounted volume and goes back to default. You have been warned.

Docker application

Seeing as it is possible to ran anything on docker and your localhost, the entire Skyline stack can be composed with docker with every dependencies provided for by a container, constructing a docker-compose multi-container Docker application for Skyline.

The Skyline Docker application provides the following containers:

  • busybox: to provide a shared /tmp/docker volume for a Redis unix socket
  • mysql
  • redis
  • memcached
  • graphite-statsd
  • skyline

Running on a Docker user defined network.

The use of docker is EXPERIMENTAL. It has a lot more components than it requires to be just a simple Skyline docker container. It is not really container friendly yet. Containers should run one thing each, here this is not the case, the Skyline docker application is basically a group of containerised VMs.

No extensive testing has been done with Skyline on docker and no security or docker best practices have been applied.

The experimental Skyline docker implementation uses the graphite-statsd docker image to provide Skyline with data.


  • git
  • rsync
  • docker (Docker Engine version 17.09.0 and higher)
  • docker-compose

Notable docker aspects

Feel free to skip to start of the Installation section if you are not interested in the docker internals.

The docker Skyline container currently runs on the debian:stretch docker image, not debian:latest which was recently bumped to up to buster. This is less than ideal seeing as this image ships with more vulnerabilities than any other popular docker OS image. All future docker work should be focused on getting Skyline to run on the alpine image with each Skyline application running as individual containers.

For now it is a monolithic stretch container, which is useful for development purposes at least.

There are hard coded variables in terms of the user defined network which is subnet called skylinenetwork. For all the container static IPs see the docker-compose.yml file.

Installation - quick start

The data for the Skyline, Graphite, Redis and MySQL containers are persisted in the below patterns.

There is a convenience build script for testing purposes only in utils/dawn/ see see Development - dawn-docker section or you can follow the simple steps below.


Ensure you provide the appropriate ownership and permissions to the below specified directories for the user you wish to run the Skyline process as.

If you want to modify the default docker settings that is deployed, after cloning add the file /opt/skyline/github/skyline/skyline/ with your desired settings based on the cloned /opt/skyline/github/skyline/skyline/

# Create the required directories for persisting data
# NOTE if you change this, you will have to modify all the paths in the
# skyline/Dockerfile to match
# Also NOTE due to docker processes running as root you will need to use
# sudo to read or clean up these dirs or files
sudo mkdir -p /opt/skyline/github

# If your group is different from your username like on MacOS it will probably
# be staff
sudo chown -R $USER:$YOUR_GROUP /opt/skyline

# Define SKYLINE_DOCKER_HOME directory

mkdir -p $SKYLINE_DOCKER_HOME/skyline-docker-skyline-1/skyline
mkdir -p $SKYLINE_DOCKER_HOME/skyline-docker-mysql-1/var/lib/mysql
mkdir -p $SKYLINE_DOCKER_HOME/skyline-docker-redis-1/var/lib/redis
mkdir -p $SKYLINE_DOCKER_HOME/skyline-docker-graphite-statsd-1/opt/graphite/storage
mkdir -p $SKYLINE_DOCKER_HOME/skyline-docker-graphite-statsd-1/var/log
mkdir -p $SKYLINE_DOCKER_HOME/skyline-docker-skyline-1/opt/skyline/ionosphere
mkdir -p $SKYLINE_DOCKER_HOME/skyline-docker-skyline-1/var/log/skyline
mkdir -p $SKYLINE_DOCKER_HOME/skyline-docker-skyline-1/var/log/apache2

cd /opt/skyline/github
git clone
# Switch to a branch or git commitref if you want to

# If you do not want to use the default settings add your desired settings
# to /opt/skyline/github/skyline/skyline/ based on the
# cloned /opt/skyline/github/skyline/skyline/

# Now copy the repo to the container directory
rsync -az --exclude .git/ /opt/skyline/github/skyline/ $SKYLINE_DOCKER_HOME/skyline-docker-skyline-1/skyline/
cd $SKYLINE_DOCKER_HOME/skyline-docker-skyline-1/skyline

docker-compose build

docker-compose up  # first run takes a while for all the apps to start and initialise
# After 2 or 3 minutes when all the apps have started and are logging
# consistently you can Ctrl+c to stop the containers and then start detached
# Ctrl+c
docker-compose up -d

Working with the Docker stack on localhost

To access the Skyline and Graphite applications on your localhost you need to add the following entries to your /etc/hosts file (or the equivalent)

echo " skyline-docker-skyline-1" >> /etc/hosts
echo " skyline-docker-graphite-statsd-1" >> /etc/hosts

You can now access the apps in your browser (using the default username and password if you did not add your own via:

You need to accept the self signed SSL certificates for each in your browser.

In this scenario metric transport can be provided from your localhost directly to the skyline-docker-graphite-statsd-1 via various means. You can configure any local Graphite compatible metric collector to send metrics directly to skyline-docker-graphite-statsd-1:2013. Using telegraf for instance:

telegraf —> skyline-docker-graphite-statsd-1:2013 —> skyline-docker-skyline-1

telegraf.conf would need:

The Skyline docker container is configured and deployed at build using:

  • utils/docker/
  • utils/docker/
  • with the utils/docker/configs/skyline/skyline/etc/skyline/skyline.dawn.conf configuration variables.
  • and skyline/ (or skyline/ if you provided it)

Accessing the Skyline containers via the command line:

# List the containers
docker ps
# Skyline container access
docker exec -it skyline_skyline-docker-skyline-1_1 /bin/bash
# Graphite container access
docker exec -it skyline-docker-graphite-statsd-1 /bin/sh
# Redis container access
docker exec -it skyline-docker-redis-1 /bin/bash
# MySQL container access
docker exec -it skyline-docker-mysql-1 /bin/bash
# memcached container access
docker exec -it skyline-docker-memcached-1 /bin/bash

You can also change the Skyline for the docker instance directly on the skyline_skyline-docker-skyline-1_1 container in /opt/skyline/github/skyline/skyline/ or in the source on the host filesystem $SKYLINE_DOCKER_HOME/skyline-docker-skyline-1/skyline/skyline/, then stop the Skyline container and start it again.

docker stop skyline_skyline-docker-skyline-1_1
docker start skyline_skyline-docker-skyline-1_1

Or restart the Skyline apps one by one in the container itself.

Other app configurations can be changed in the relevant configuration files in the relevant local app volume directories as well, e.g.

  • /opt/skyline/github/skyline/utils/docker/configs/skyline/redis/etc/redis (container volume /etc/redis)
  • /opt/skyline/docker/skyline-docker-skyline-1/skyline/utils/docker/configs/skyline/graphite-statsd/opt/graphite/conf (container volume /opt/graphite/conf)
  • /opt/skyline/docker/skyline-docker-skyline-1/skyline/utils/docker/configs/skyline/graphite-statsd/opt/statsd/config (container volume /opt/statsd/config)
  • /opt/skyline/docker/skyline-docker-skyline-1/skyline/utils/docker/configs/skyline/graphite-statsd/etc/nginx (container volume /etc/nginx)
  • /opt/skyline/docker/skyline-docker-skyline-1/skyline/utils/docker/configs/skyline/graphite-statsd/etc/logrotate.d (container volume /etc/logrotate.d)

Skyline optimisations for containerisation

Changes were made to Skyline from using Python multiprocessing Manager().list() to using Redis sets to reduce the overall footprint greatly especially in terms of process count and resident segment sizes.