aws-ssh-connector

#!/usr/bin/env bash
#
# $Id$
#
# Simple wrapper around aws tools to connect by instance id

########### CONFIGURATION START ###########
# the bastion base name host
_bastion_base='bastion'
_bastion_end='company.com'

# region map
declare -A _region_map=(
	[eu1]=eu-west-1
	[us1]=us-west-1
	[ap1]=ap-southeast-1
)

# your username on the bastion host
_personal_user='username'

########### CONFIGURATION END ###########

#set -x
set -e

# how we named this thing
_app_name=$( basename $0 )

# first 3 letters are region
_region_short=$( echo ${_app_name} | cut -c 1-3 )

# next 3 is command (support ssh/scp)
_command=$( echo ${_app_name} | cut -c 4- )

# check if we have a valid command
if [ $( echo ${_app_name} | wc -c ) -lt 6 ]; then
	# too short command
	echo "I don't know how to handle such combination ( region: ${_region_short}, command: ${_command} )"
	exit 9
fi

# now get the full names
_full_region=${_region_map[${_region_short}]}

# do we have a region
if [ -z ${_full_region} ] ; then
	echo 'I have no valid region'
	exit 9
fi

# _temp the $1 and let's start parsing
_temp=${1}

if echo ${_temp} | egrep -q '@' ; then
	# so we have a username probably. Assign and cut
	_username=$( echo ${_temp} | cut -d\@ -f 1 )
	_t=$( echo ${_temp} | cut -d\@ -f 2 )
	_temp=${_t}
	unset _t
fi

if echo ${_temp} | egrep -q ':' ; then
	# we might be trying scp
	echo 'scp not fully supported'
	_fileinfo=$( echo ${_temp} | cut -d\: -f2- )
	_t=$( echo ${_temp} | cut -d\: -f 1 )
	_temp=${_t}
	unset _t
fi

# now hopefully the host is clean
_host="i-${_temp#i-*}"
shift

echo -en "AWS Region:\t${_full_region}\n"
echo -en "Instance id:\t${_host}\n\n"

# Prep a temporary config file so we can be fancy
mkdir -p ~/.ssh/tempconfs
conf_file=$( mktemp ~/.ssh/tempconfs/${_host}.XXXXXX )
trap "rm -f ${conf_file}" EXIT ERR

#echo ${conf_file}
cat > ${conf_file} <<CONFEND
# final defaults
Host *
        SendEnv LC_*
        ServerAliveCountMax 5
        ServerAliveInterval 30
        TCPKeepAlive yes
        # VisualHostKey yes
        ForwardAgent yes
        ConnectTimeout 60
        User ${_username:-root}
        PreferredAuthentications publickey
        IdentitiesOnly yes
	IdentityFile ~/.ssh/id_rsa_${_full_region}
	StrictHostKeyChecking no
	CheckHostIP no
	UserKnownHostsFile /dev/null

Host bastion
        Hostname ${_bastion_base}.${_full_region}a.${_bastion_end}
        User ${_personal_user}
        IdentityFile ~/.ssh/id_rsa

CONFEND

# Get the full public name of the instance
instance_addr=$( ec2-describe-instances --region ${_full_region} ${_host} | awk '/INSTANCE/{print $5}' )
if [ -z ${instance_addr} ] ; then exit 9 ; fi

# Finish writing the config file
echo "Host ${_host}" >> ${conf_file}
echo -e "\tHostname ${instance_addr}" >> ${conf_file}
echo -e "\tProxyCommand ssh cc1eu exec nc %h %p 2>/dev/null" >> ${conf_file}

# and now just connect
if [[ "x${_command}x" == "xscpx" ]] ; then
	${_command} -F ${conf_file} ${_host}:${_fileinfo} "$@"
else
	${_command} -F ${conf_file} ${_host} "$@"
fi