Load balance Docker containers in a Vagrant VM

lb-run.sh

#!/bin/bash
# lb-run.sh: Run load balancer on three app instances

# kill necessary containers
if [ "x$1" == "xkill" ] ; then
  docker rm -f etcd app1 app2 app3 proxy
  exit 0
fi

# run etcd server
docker run -d -p 4001:4001 -p 7001:7001 \
  -v /var/etcd/:/data \
  --name etcd microbox/etcd \
  -name etcd

# run three stateless apps
docker run -d -p 5000 --name app1 training/webapp
docker run -d -p 5000 --name app2 training/webapp
docker run -d -p 5000 --name app3 training/webapp

# set etcd keys
etcdctl set app1 "$(docker inspect -f '{{.NetworkSettings.IPAddress}}' app1)"
etcdctl set app2 "$(docker inspect -f '{{.NetworkSettings.IPAddress}}' app2)"
etcdctl set app3 "$(docker inspect -f '{{.NetworkSettings.IPAddress}}' app3)"

# generate haproxy override config
confd -onetime

# run haproxy with override config
docker run -d -p 80:80 -v ~/override:/haproxy-override --name proxy dockerfile/haproxy

lb-setup.sh

#!/bin/bash
# lb-setup.sh: The setup required for load balancer

# install etcdctl
wget -O /tmp/etcd.tar.gz https://github.com/coreos/etcd/releases/download/v0.4.6/etcd-v0.4.6-linux-amd64.tar.gz
tar -xf /tmp/etcd.tar.gz -C /tmp
sudo mv /tmp/etcd*/etcdctl /usr/bin
rm -rf /tmp/*

# install confd
wget -O /tmp/confd https://github.com/kelseyhightower/confd/releases/download/v0.7.1/confd-0.7.1-linux-amd64
chmod 755 /tmp/confd
sudo mv /tmp/confd /bin/confd

# setup confd directories
sudo mkdir -p /etc/confd/{conf.d,templates}
sudo chown -R vagrant:vagrant /etc/confd

# create confd config
cat > /etc/confd/conf.d/haproxy.toml <<eof
[template]
src = "haproxy.cfg.tmpl"
dest = "/home/vagrant/override/haproxy.cfg"
keys = [
  "/",
]
eof

# create confd template
cat > /etc/confd/templates/haproxy.cfg.tmpl <<eof
frontend train
  timeout client 10s
  bind *:80
  default_backend train-backend

backend train-backend
  timeout connect 10s
  timeout server 1m
  balance roundrobin
  {{range gets "/*"}}server {{base .Key}} {{.Value}}:5000 check
  {{end}}
eof

# setup haproxy directory
mkdir -p ~/override