function hide_output { # This function hides the output of a command unless the command fails # and returns a non-zero exit code. # Get a temporary file. OUTPUT=$(tempfile) # Execute command, redirecting stderr/stdout to the temporary file. $@ &> $OUTPUT # If the command failed, show the output that was captured in the temporary file. if [ $? != 0 ]; then # Something failed. echo echo FAILED: $@ echo ----------------------------------------- cat $OUTPUT echo ----------------------------------------- fi # Remove temporary file. rm -f $OUTPUT } function apt_install { # Report any packages already installed. PACKAGES=$@ TO_INSTALL="" ALREADY_INSTALLED="" for pkg in $PACKAGES; do if dpkg -s $pkg 2>/dev/null | grep "^Status: install ok installed" > /dev/null; then if [[ ! -z "$ALREADY_INSTALLED" ]]; then ALREADY_INSTALLED="$ALREADY_INSTALLED, "; fi ALREADY_INSTALLED="$ALREADY_INSTALLED$pkg (`dpkg -s $pkg | grep ^Version: | sed -e 's/.*: //'`)" else TO_INSTALL="$TO_INSTALL""$pkg " fi done # List the packages already installed. if [[ ! -z "$ALREADY_INSTALLED" ]]; then echo already installed: $ALREADY_INSTALLED fi # List the packages about to be installed. if [[ ! -z "$TO_INSTALL" ]]; then echo installing $TO_INSTALL... fi # 'DEBIAN_FRONTEND=noninteractive' is to prevent dbconfig-common from asking you questions. # # Although we could pass -qq to apt-get to make output quieter, many packages write to stdout # and stderr things that aren't really important. Use our hide_output function to capture # all of that and only show it if there is a problem (i.e. if apt_get returns a failure exit status). # # Also note that we still include the whole original package list in the apt-get command in # case it wants to upgrade anything, I guess? Maybe we can remove it. Doesn't normally make # a difference. DEBIAN_FRONTEND=noninteractive \ hide_output \ apt-get -y install $PACKAGES } function get_default_hostname { # Guess the machine's hostname. It should be a fully qualified # domain name suitable for DNS. None of these calls may provide # the right value, but it's the best guess we can make. set -- $(hostname --fqdn 2>/dev/null || hostname --all-fqdns 2>/dev/null || hostname 2>/dev/null) printf '%s\n' "$1" # return this value } function get_default_publicip { # Get the machine's public IP address. The machine might have # an IP on a private network, but the IP address that we put # into DNS must be one on the public Internet. Try a public # API, but if that fails (maybe we don't have Internet access # right now) then use the IP address that this machine knows # itself as. get_publicip_from_web_service 4 || get_default_privateip 4 } function get_default_publicipv6 { get_publicip_from_web_service 6 || get_default_privateip 6 } function get_publicip_from_web_service { # This seems to be the most reliable way to determine the # machine's public IP address: asking a very nice web API # for how they see us. Thanks go out to icanhazip.com. # See: https://major.io/icanhazip-com-faq/ # # Pass '4' or '6' as an argument to this function to specify # what type of address to get (IPv4, IPv6). curl -$1 --fail --silent --max-time 15 icanhazip.com 2>/dev/null } function get_default_privateip { # Return the IP address of the network interface connected # to the Internet. # # We used to use `hostname -I` and then filter for either # IPv4 or IPv6 addresses. However if there are multiple # network interfaces on the machine, not all may be for # reaching the Internet. # # Instead use `ip route get` which asks the kernel to use # the system's routes to select which interface would be # used to reach a public address. We'll use 8.8.8.8 as # the destination. It happens to be Google Public DNS, but # no connection is made. We're just seeing how the box # would connect to it. There many be multiple IP addresses # assigned to an interface. `ip route get` reports the # preferred. That's good enough for us. See issue #121. # # Also see ae67409603c49b7fa73c227449264ddd10aae6a9 and # issue #3 for why/how we originally added IPv6. # # Pass '4' or '6' as an argument to this function to specify # what type of address to get (IPv4, IPv6). target=8.8.8.8 # For the IPv6 route, use the corresponding IPv6 address # of Google Public DNS. Again, it doesn't matter so long # as it's an address on the public Internet. if [ "$1" == "6" ]; then target=2001:4860:4860::8888; fi ip -$1 -o route get $target \ | grep -v unreachable \ | sed "s/.* src \([^ ]*\).*/\1/" } function ufw_allow { if [ -z "$DISABLE_FIREWALL" ]; then # ufw has completely unhelpful output ufw allow $1 > /dev/null; fi } function restart_service { hide_output service $1 restart }