pickett

README

pickett: make for the docker world

How to get it

Assuming you have a modern version of go already installed:

# Set up GOPATH in your home directory
export GOPATH=$HOME/go
mkdir -p $GOPATH/src

# Add $GOPATH/bin to your path so that you can run 'pickett' directly after 'go install'
export PATH=$PATH:$GOPATH/bin

# Get the pickett code
go get github.com/tools/godep
mkdir -p $GOPATH/src/github.com/igneous-systems
cd $GOPATH/src/github.com/igneous-systems
git clone https://github.com/igneous-systems/pickett # can be replaced by your repo

# optional: you can create and checkout a branch here

# ensure dependencies are present
cd $GOPATH/src/github.com/igneous-systems/pickett
godep restore

# build pickett and install it in $GOPATH/bin
go install github.com/igneous-systems/pickett

You should end up with the executable pickett in $GOPATH/bin.

The reason we use git clone instead of godep get to grab the source of pickett here is to enable a fork-based workflow. There are internal references to packages in the github.com/igneous-systems/pickett namespace, which means that any forks of pickett still have to live in $GOPATH/src/github.com/igneous-systems.

How to run the VM

Pickett assumes that you are running a VM with an appropriate version of docker, with /vagrant mounted to your host system's home directory

# Start the VM
cd $GOPATH/src/github.com/igneous-systems/pickett
vagrant up
vagrant ssh
sudo docker -d -H "tcp://0.0.0.0:2375" &
sudo start etcd
exit

How to get a sample project

Assuming you did the above:

# Test that pickett works
cd $GOPATH/src/github.com/igneous-systems
git clone https://github.com/igneous-systems/pickett-samples
export DOCKER_HOST="tcp://localhost:2375"
cd $GOPATH/src/github.com/igneous-systems/pickett-samples/sample1
pickett run weather-client

The file to examine is the Pickett.json.

How to build some stuff

Assuming you

• have a modern version of docker (at least 1.1.1) already installed
• have set your DOCKER_HOST if you not on the machine that runs docker or are using boot2docker
• Are willing to wait, this takes several minutes the first time

cd /tmp/foo/pickett-samples/sample1/
pickett --debug run candidate

That will take a while (minutes) the first time because it creates some docker images that require downloading a lot of software (apt-get install blah blah). Once in steady state, pickett does incremental builds.

You may want to look at the files /tmp/foo/pickett-samples/sample1/container/runner/Dockerfile and /tmp/foo/pickett-samples/sample1/container/builder/Dockerfile to see the commands that take so long.

The --debug flag is just to give you some stuff to read while you are waiting. Normally that is only interesting to pickett developers.

The "candidate" in the command above refers to a tag on a docker container called candidate. After this completes, you may want to try some docker commands like this:

docker images
docker run -it -v candidate /bin/bash

In the former of those commands you'll see "sample1/runner", "sample1/builder", and "sample1/external" which are the containers for running (virgin state), building (has go tools), and the external libraries for the sample system. In the latter, if you look in / you'll see /wuclient and /wuserver. You should note that the system installed in candidate has no build tools (build-essential in ubuntu parlance) nor go installed, just the two executables that are the system to be executed.

For giggles, you may want to to try:

time pickett run candidate

That shows you the elapsed time to just do the dependency checking (the pickett overhead).