[preinst] Check for pre-existing pgp key (#143)

package-scripts/datadog-agent/preinst

@@ -35,10 +35,15 @@ if [ "$DISTRIBUTION" != "Darwin" ]; then
 
     # Prepare the GPG keys rotation:
     # Add the new one to the list of trusted APT keys.
+    # Some servers are on severely restricted networks.
+    # Check if key already exists.
     echo "Prepare Datadog Agent keys rotation"
     echo -n "  Add the new 'Datadog, Inc <package@datadoghq.com>' key to the list of APT trusted keys."
-    apt-key adv --recv-keys --keyserver hkp://keyserver.ubuntu.com:80 382E94DE >/dev/null 2>&1 && echo " ... OK" || echo " ... failed"
-
+    if $( apt-key finger | grep -q 'A292 3DFF 56ED A6E7 6E55  E492 D3A8 0E30 382E 94DE' ); then
+        echo "... key already installed"
+    else
+        apt-key adv --recv-keys --keyserver hkp://keyserver.ubuntu.com:80 382E94DE >/dev/null 2>&1 && echo " ... OK" || echo " ... failed" 
+    fi
     #DEBHELPER#
 
   elif [ -f "/etc/redhat-release" ] || [ -f "/etc/system-release" ] || [ -f "/etc/SuSE-release" ] || [ "$DISTRIBUTION" == "RedHat" ] || [ "$DISTRIBUTION" == "CentOS" ] || [ "$DISTRIBUTION" == "openSUSE" ] || [ "$DISTRIBUTION" == "Amazon" ] || [ "$DISTRIBUTION" == "SUSE" ] || [ "$LINUX_DISTRIBUTION" == "Arista" ]; then