Adjust "vm_memory_high_watermark" code to be more forgiving/strict about bad data (such as a memory limit of zero)

Author: tianon

3.6/alpine/docker-entrypoint.sh

@@ -253,17 +253,27 @@ if [ "$1" = 'rabbitmq-server' ] && [ "$shouldWriteConfig" ]; then
 	)
 
 	# determine whether to set "vm_memory_high_watermark" (based on cgroups)
-	if [ -r /sys/fs/cgroup/memory/memory.limit_in_bytes ] && [ -r /proc/meminfo ]; then
-		memLimitB="$(< /sys/fs/cgroup/memory/memory.limit_in_bytes)"
-		memLimitKb="$(( memLimitB / 1024 ))"
-
+	memTotalKb=
+	if [ -r /proc/meminfo ]; then
 		memTotalKb="$(awk -F ':? +' '$1 == "MemTotal" { print $2; exit }' /proc/meminfo)"
-
-		if [ "$memLimitKb" -gt "$memTotalKb" ]; then
+	fi
+	memLimitB=
+	memLimitKb=
+	if [ -r /sys/fs/cgroup/memory/memory.limit_in_bytes ]; then
+		memLimitB="$(< /sys/fs/cgroup/memory/memory.limit_in_bytes)"
+		if [ "$memLimitB" = '0' ]; then
+			# it appears that "WARNING: No kernel memory limit support" leads to "/sys/fs/cgroup/memory/memory.limit_in_bytes" containing the value "0"
 			memLimitB=
-			memLimitKb=
 		fi
-
+		if [ -n "$memLimitB" ]; then
+			memLimitKb="$(( memLimitB / 1024 ))"
+			if [ -n "$memTotalKb" ] && [ "$memLimitKb" -gt "$memTotalKb" ]; then
+				memLimitB=
+				memLimitKb=
+			fi
+		fi
+	fi
+	if [ -n "$memTotalKb" ] || [ -n "$memLimitB" ]; then
 		# https://github.com/docker-library/rabbitmq/pull/105#issuecomment-242165822
 		vmMemoryHighWatermark=
 		if [ "${RABBITMQ_VM_MEMORY_HIGH_WATERMARK:-}" ]; then
@@ -310,10 +320,8 @@ if [ "$1" = 'rabbitmq-server' ] && [ "$shouldWriteConfig" ]; then
 			rabbitConfig+=( "{ vm_memory_high_watermark, $vmMemoryHighWatermark }" )
 		fi
 	elif [ "${RABBITMQ_VM_MEMORY_HIGH_WATERMARK:-}" ]; then
-		echo >&2 'warning: RABBITMQ_VM_MEMORY_HIGH_WATERMARK was specified, but one of the following is not readable:'
-		echo >&2 '  - /sys/fs/cgroup/memory/memory.limit_in_bytes'
-		echo >&2 '  - /proc/meminfo'
-		echo >&2 '(so "vm_memory_high_watermark" will not be set)'
+		echo >&2 'warning: RABBITMQ_VM_MEMORY_HIGH_WATERMARK was specified, but current system memory or cgroup memory limit cannot be determined'
+		echo >&2 '  (so "vm_memory_high_watermark" will not be set)'
 	fi
 
 	if [ "$haveSslConfig" ]; then

3.6/debian/docker-entrypoint.sh

@@ -253,17 +253,27 @@ if [ "$1" = 'rabbitmq-server' ] && [ "$shouldWriteConfig" ]; then
 	)
 
 	# determine whether to set "vm_memory_high_watermark" (based on cgroups)
-	if [ -r /sys/fs/cgroup/memory/memory.limit_in_bytes ] && [ -r /proc/meminfo ]; then
-		memLimitB="$(< /sys/fs/cgroup/memory/memory.limit_in_bytes)"
-		memLimitKb="$(( memLimitB / 1024 ))"
-
+	memTotalKb=
+	if [ -r /proc/meminfo ]; then
 		memTotalKb="$(awk -F ':? +' '$1 == "MemTotal" { print $2; exit }' /proc/meminfo)"
-
-		if [ "$memLimitKb" -gt "$memTotalKb" ]; then
+	fi
+	memLimitB=
+	memLimitKb=
+	if [ -r /sys/fs/cgroup/memory/memory.limit_in_bytes ]; then
+		memLimitB="$(< /sys/fs/cgroup/memory/memory.limit_in_bytes)"
+		if [ "$memLimitB" = '0' ]; then
+			# it appears that "WARNING: No kernel memory limit support" leads to "/sys/fs/cgroup/memory/memory.limit_in_bytes" containing the value "0"
 			memLimitB=
-			memLimitKb=
 		fi
-
+		if [ -n "$memLimitB" ]; then
+			memLimitKb="$(( memLimitB / 1024 ))"
+			if [ -n "$memTotalKb" ] && [ "$memLimitKb" -gt "$memTotalKb" ]; then
+				memLimitB=
+				memLimitKb=
+			fi
+		fi
+	fi
+	if [ -n "$memTotalKb" ] || [ -n "$memLimitB" ]; then
 		# https://github.com/docker-library/rabbitmq/pull/105#issuecomment-242165822
 		vmMemoryHighWatermark=
 		if [ "${RABBITMQ_VM_MEMORY_HIGH_WATERMARK:-}" ]; then
@@ -310,10 +320,8 @@ if [ "$1" = 'rabbitmq-server' ] && [ "$shouldWriteConfig" ]; then
 			rabbitConfig+=( "{ vm_memory_high_watermark, $vmMemoryHighWatermark }" )
 		fi
 	elif [ "${RABBITMQ_VM_MEMORY_HIGH_WATERMARK:-}" ]; then
-		echo >&2 'warning: RABBITMQ_VM_MEMORY_HIGH_WATERMARK was specified, but one of the following is not readable:'
-		echo >&2 '  - /sys/fs/cgroup/memory/memory.limit_in_bytes'
-		echo >&2 '  - /proc/meminfo'
-		echo >&2 '(so "vm_memory_high_watermark" will not be set)'
+		echo >&2 'warning: RABBITMQ_VM_MEMORY_HIGH_WATERMARK was specified, but current system memory or cgroup memory limit cannot be determined'
+		echo >&2 '  (so "vm_memory_high_watermark" will not be set)'
 	fi
 
 	if [ "$haveSslConfig" ]; then