parallel provisioning with Vagrant

go.sh

#!/bin/sh

# concurrency is hard, let's have a beer

MAX_PROCS=4

parallel_provision() {
    while read box; do
        echo "Provisioning '$box'. Output will be in: $box.out.txt" 1>&2
        echo $box
    done | xargs -P $MAX_PROCS -I"BOXNAME" \
        sh -c 'vagrant provision BOXNAME >BOXNAME.out.txt 2>&1 || echo "Error Occurred: BOXNAME"'
}

## -- main -- ##

# start boxes sequentially to avoid vbox explosions
vagrant up --no-provision

# but run provision tasks in parallel
cat <<EOF | parallel_provision
centos_5_64
centos_5_32
ubuntu_1004_32
ubuntu_1004_64
EOF

not bad. reduced the sensu package builds from 30min to 10min