snappy-swarm

The following steps/scripts will build a "snappy" Docker swarm using Ubuntu's Snappy core release.

If being run on a host with a decent number of cores and ram, then start from the beginning and install all of the pieces on that host. Otherwise you can create vm's running snappy which then are added to the swarm.

Preparing the Host

The bin/prep-host script will perform the steps listed below. The steps are listed below with commentary for reference.

This assumes a 64-bit server which is running Ubuntu 14.04. Verify that updates are installed:

    sudo apt-get update
	
    sudo apt-get upgrade -y

uv-tool, kvm, and Ubuntu core

1. Install uv-tool (from directions located at Snappy Ubuntu Core and uvtool):

       sudo apt-add-repository ppa:snappy-dev/tools
       sudo apt-get update
       sudo apt-get -y install uvtool
   

2. If you don't have a ~/.ssh/id_rsa.pub then:

       ssh-keygen
   

3. Download the images

       uvt-simplestreams-libvirt sync --snappy flavor=core release=devel
   

Install Docker

We want a recent/new version of Docker, so we need to use a different set of repositories than the "default". These instructions follow the Docker on Ubuntu installation instructions.

1. Do the "easy" install:

       curl -sSL https://get.docker.com/ubuntu/ | sudo sh
   

2. To eliminate the need to sudo every time you run docker do the following:

   Note: there is a potential security issue; see Docker Daemon Attack Surface for details.

       sudo groupadd docker
       sudo gpasswd -a ${USER} docker
       sudo service docker restart
   

3. Modify the Docker start script to bind to a port on the private network in addition to the file socket:

      sudo service docker stop
      sudo sh -c 'echo DOCKER_OPTS=\"-H tcp://192.168.122.1:4243 -H unix:///var/run/docker.sock\" >> /etc/default/docker'
      sudo service docker start
   

Install and Configure go

1. Install the go binaries:

       sudo apt-get install -y golang-go golang-go.tools
   

2. Configure the environment. We're going to set up some global variables and ensure that they're loaded into subsequent shell sessions:

       sudo sh -c "cat > /etc/profile.d/golang-env.sh" <<EOF
      	export GOROOT=/usr/share/go
       export GOPATH=\${GOROOT}
       export PATH=\${PATH}:\${GOROOT}/bin
       EOF
   
       . /etc/profile.d/golang-env.sh
   

Install swarm

We're installing it to the global position; in order to do this we need to "cheat" a little bit & specify an environmental variable to tell it where to install:

sudo GOPATH=$GOPATH go get -u github.com/docker/swarm

Logout

Logout and log back in to ensure all the environment settings are captured.

Prepare the swarm

In order to create our swarm, run bin/create-cluster N where N is the number of members in the swarm.

etc/config is used to override any parameters for the swarm members. By default a member has the following properties:

Property	Default Value	Notes
cpu	1	Number of Cores
memory	512	Amount of system RAM in MB
disk	8	Size of the OS disk in GB
log-console-output	STDOUT	Log output to a disk file on the host instead of STDOUT
unsafe-caching	false	Do not flush guest syncs to the host on the OS disk. This can improve guest I/O performance at the cost of losing data on host power failure. This option is useful for ephemeral guest machines that do not need to be persistent beyond a host power cycle.
bridge	none	Replace the first defined NIC with one that connects to the given host bridge.