lower memory requirements to 512MB, display a warning if system memory is below 768MB. (#952)

CHANGELOG.md

@@ -10,6 +10,10 @@ Control panel:
 * Status checks failed if the system doesn't support iptables
 * Add support for SSHFP records when sshd listens on non-standard ports
 
+System:
+
+* Lower memory requirements to 512MB, display a warning if system memory is below 768MB.
+
 v0.20 (September 23, 2016)
 --------------------------
 

setup/preflight.sh

@@ -19,20 +19,26 @@ fi
 
 # Check that we have enough memory.
 #
-# /proc/meminfo reports free memory in kibibytes. Our baseline will be 768 MB,
-# which is 750000 kibibytes.
+# /proc/meminfo reports free memory in kibibytes. Our baseline will be 512 MB,
+# which is 500000 kibibytes.
+#
+# We will display a warning if the memory is below 768 MB which is 750000 kibibytes
 #
 # Skip the check if we appear to be running inside of Vagrant, because that's really just for testing.
 TOTAL_PHYSICAL_MEM=$(head -n 1 /proc/meminfo | awk '{print $2}')
-if [ $TOTAL_PHYSICAL_MEM -lt 750000 ]; then
+if [ $TOTAL_PHYSICAL_MEM -lt 500000 ]; then
 if [ ! -d /vagrant ]; then
 	TOTAL_PHYSICAL_MEM=$(expr \( \( $TOTAL_PHYSICAL_MEM \* 1024 \) / 1000 \) / 1000)
 	echo "Your Mail-in-a-Box needs more memory (RAM) to function properly."
-	echo "Please provision a machine with at least 768 MB, 1 GB recommended."
+	echo "Please provision a machine with at least 512 MB, 1 GB recommended."
 	echo "This machine has $TOTAL_PHYSICAL_MEM MB memory."
 	exit
 fi
 fi
+if [ $TOTAL_PHYSICAL_MEM -lt 750000 ]; then
+	echo "WARNING: Your Mail-in-a-Box has less than 768 MB of memory."
+	echo "         It might run unreliably when under heavy load."
+fi
 
 # Check that tempfs is mounted with exec
 MOUNTED_TMP_AS_NO_EXEC=$(grep "/tmp.*noexec" /proc/mounts)