Merge pull request #2378 from DataDog/olivielpeau/ignore-update-failure

[install script] Ignore `apt-get update` failures + use https for apt repo

packaging/datadog-agent/source/install_agent.sh

@@ -131,10 +131,10 @@ if [ $OS = "RedHat" ]; then
     $sudo_cmd yum -y --disablerepo='*' --enablerepo='datadog' install datadog-agent
 elif [ $OS = "Debian" ]; then
     printf "\033[34m\n* Installing apt-transport-https\n\033[0m\n"
-    $sudo_cmd apt-get update
+    $sudo_cmd apt-get update || printf "\033[31m'apt-get update' failed, the script will not install the latest version of apt-transport-https.\033[0m\n"
     $sudo_cmd apt-get install -y apt-transport-https
     printf "\033[34m\n* Installing APT package sources for Datadog\n\033[0m\n"
-    $sudo_cmd sh -c "echo 'deb http://apt.datadoghq.com/ stable main' > /etc/apt/sources.list.d/datadog.list"
+    $sudo_cmd sh -c "echo 'deb https://apt.datadoghq.com/ stable main' > /etc/apt/sources.list.d/datadog.list"
     $sudo_cmd apt-key adv --recv-keys --keyserver hkp://keyserver.ubuntu.com:80 C7A7DA52
 
     printf "\033[34m\n* Installing the Datadog Agent package\n\033[0m\n"