Automating Ubuntu 16 Updates With Vultr Startup Scripts

Ubuntu 16 and newer performs periodic tasks related to apt (such as updating the package list, and applying unattended upgrades) using a systemd timer. This timer is usually triggered at the start of launching an Ubuntu 16 VPS, which can cause apt tools (apt, apt-get) to fail with an error similar to the following:

E: Could not get lock /var/lib/dpkg/lock - open (11: Resource temporarily unavailable)

A common use case of Vultr startup scripts is to update the system packages. Without checking the error codes returned from apt or apt-get, system updates can fail. When the lock condition is encountered, apt will typically return code 100.

This sample script can be used as a Vultr startup script to retry installing system updates. You can modify it to fit your needs.

#!/bin/bash

UPGRADE_ATTEMPT_COUNT=100

UPGRADE_STATE=1

for i in `seq 1 $UPGRADE_ATTEMPT_COUNT`;

do

    if [ "$UPGRADE_STATE" -eq "1" ]; then

        apt-get -y update

        if [ "`echo $?`" -eq "0" ]; then

            echo "package list updated."

            UPGRADE_STATE=2;

        fi

    fi



    if [ "$UPGRADE_STATE" -eq "2" ]; then

        apt-get -y upgrade

        if [ "`echo $?`" -eq "0" ]; then

            echo "packages updated."

            UPGRADE_STATE=3;

        fi

    fi



    if [ "$UPGRADE_STATE" -eq "3" ]; then

        break

    fi



    sleep 5

done



if [ "$UPGRADE_STATE" -ne "3" ]; then

    echo "ERROR: packages failed to update after $UPGRADE_ATTEMPT_COUNT attempts."

fi

More information about Automatic Updates is available in the Ubuntu LTS documentation.