Retrieve SSH public keys from GitHub and install to authorized_keys.

install-keys.sh

#!/bin/bash
# vim:set ts=4 sw=4 et ai:
# Retrieve SSH public keys from GitHub and install to authorized_keys.

GITHUB_USERS=(USER1 USER2)
INSTALL_FILE=/home/USER/.ssh/authorized_keys
TMP_KEY=/tmp/ssh.key

CURL=/usr/bin/curl
CURLOPTS="--retry 3 --retry-delay 2 --silent --fail -o $TMP_KEY"

if [ ! -d `dirname $INSTALL_FILE` ]; then
	mkdir -p -m 700 `dirname $INSTALL_FILE`
fi

# Backup existing key
if [ -f $INSTALL_FILE ]; then
	mv $INSTALL_FILE $INSTALL_FILE.bak
fi


for GITHUB_USER in ${GITHUB_USERS[@]}; do
	SUCCESS=0
	ATTEMPT=0
	MAX_ATTEMPTS=10
	while [ $SUCCESS -eq 0 -a $ATTEMPT -lt $MAX_ATTEMPTS ] ; do
		# attempt to retrieve the SSH public key and install it
		KEY_URL="https://github.com/$GITHUB_USER.keys"

		$CURL $CURLOPTS $KEY_URL
		if [ $? -eq 0 -a -f $TMP_KEY ]; then
			cat $TMP_KEY >> $INSTALL_FILE
			echo "" >> $INSTALL_FILE
			echo "SSH key added to $INSTALL_FILE from $KEY_URL"
			rm -f $TMP_KEY
			SUCCESS=1
		fi

		# print out status and wait for a bit if we failed
		ATTEMPT=$(($ATTEMPT + 1))
		if [ $SUCCESS -eq 0 ]; then
			echo "SSH key retrieval attempt $ATTEMPT failed"
			sleep 5
		fi
	done
done

# either we got it or we just gave up
if [ -f $INSTALL_FILE ]; then
	chmod 600 $INSTALL_FILE
	echo "SSH Keys Installed"
else
	echo "-=[ FATAL ]=- SSH key could not be retrieved!!!"
	if [ -f $INSTALL_FILE.bak ]; then
		mv $INSTALL_FILE.bak $INSTALL_FILE
	fi
fi