vssh - significantly faster ssh for vagrant

vssh

#!/bin/bash -e

# vssh - significantly faster Vagrant SSHing
# Usage: vssh [vagrant host] [regular ssh arguments]

# find the .vagrant directory scanning up from $PWD
find_vagrant_dir() {
	cdir="$PWD"
	while ! [[ -d "$cdir/.vagrant" ]] && [[ "$cdir" != "/" ]]; do
		cdir="$(dirname "$cdir")"
	done

	echo "$cdir/.vagrant"
}

get_host_uuid() {
	host="$1"
	cat "$vagrant_dir/machines/$host/virtualbox/id"
}

cache_ssh_config() {
	{
		echo "ControlMaster auto"
		echo "ControlPath $HOME/.ssh/master-%r@%h:%p"
		echo "ControlPersist 120s"
		vagrant ssh-config "$host"
	} > "$ssh_config"
}

get_ssh_config_date() {
	date +%s -r "$ssh_config"
}

get_vm_date_in_vbox_format() {
	vm="$1"
	uuid="$(get_host_uuid "$vm")"
	# load the variable directly rather than parsing with "sed -r" so we can work on OS X too
	. <(
		VBoxManage showvminfo --machinereadable "$uuid" | grep ^VMStateChangeTime
	)
	echo "$VMStateChangeTime"
}

get_vm_date() {
	vm="$1"
	date +%s --date="$(get_vm_date_in_vbox_format "$vm")"
}

refresh_ssh_config_cache() {
	if ! [[ -f "$ssh_config" ]] \
		|| [[ "$(get_vm_date "$host")" -ge "$(get_ssh_config_date)" ]]; then
		cache_ssh_config
	fi
}

vagrant_dir="$(find_vagrant_dir)"
# extract host arg
host=default
if ! [[ -z "$1" ]] && [[ -d "$vagrant_dir"/machines/"$1" ]]; then
	host="$1"
	shift
fi
ssh_config="$vagrant_dir/ssh-config-$host"

refresh_ssh_config_cache

ssh -F "$ssh_config" "$host" "$@"

This script was put together mainly as a PoC for hashicorp/vagrant#3057