From ba22b101131ce67aa8189409272d97fd03f4c3a5 Mon Sep 17 00:00:00 2001
From: Simon Pasquier <spasquie@redhat.com>
Date: Wed, 25 Jul 2018 15:51:27 +0200
Subject: [PATCH] prometheus: log virtual memory limits

Signed-off-by: Simon Pasquier <spasquie@redhat.com>
---
 ...{fdlimits_default.go => limits_default.go} | 28 +++++++++++++++----
 ...{fdlimits_windows.go => limits_windows.go} |  5 ++++
 cmd/prometheus/main.go                        |  1 +
 3 files changed, 29 insertions(+), 5 deletions(-)
 rename cmd/prometheus/{fdlimits_default.go => limits_default.go} (59%)
 rename cmd/prometheus/{fdlimits_windows.go => limits_windows.go} (89%)

diff --git a/cmd/prometheus/fdlimits_default.go b/cmd/prometheus/limits_default.go
similarity index 59%
rename from cmd/prometheus/fdlimits_default.go
rename to cmd/prometheus/limits_default.go
index 197810e28..f93fc6207 100644
--- a/cmd/prometheus/fdlimits_default.go
+++ b/cmd/prometheus/limits_default.go
@@ -21,12 +21,30 @@ import (
 	"syscall"
 )
 
-// FdLimits returns the soft and hard limits for file descriptors
-func FdLimits() string {
-	flimit := syscall.Rlimit{}
-	err := syscall.Getrlimit(syscall.RLIMIT_NOFILE, &flimit)
+var unlimited int64 = syscall.RLIM_INFINITY
+
+func limitToString(v uint64) string {
+	if v == uint64(unlimited) {
+		return "unlimited"
+	}
+	return fmt.Sprintf("%d", v)
+}
+
+func getLimits(resource int) string {
+	rlimit := syscall.Rlimit{}
+	err := syscall.Getrlimit(resource, &rlimit)
 	if err != nil {
 		log.Fatal("Error!")
 	}
-	return fmt.Sprintf("(soft=%d, hard=%d)", flimit.Cur, flimit.Max)
+	return fmt.Sprintf("(soft=%s, hard=%s)", limitToString(rlimit.Cur), limitToString(rlimit.Max))
+}
+
+// FdLimits returns the soft and hard limits for file descriptors.
+func FdLimits() string {
+	return getLimits(syscall.RLIMIT_NOFILE)
+}
+
+// VmLimits returns the soft and hard limits for virtual memory.
+func VmLimits() string {
+	return getLimits(syscall.RLIMIT_AS)
 }
diff --git a/cmd/prometheus/fdlimits_windows.go b/cmd/prometheus/limits_windows.go
similarity index 89%
rename from cmd/prometheus/fdlimits_windows.go
rename to cmd/prometheus/limits_windows.go
index 3fcff4905..d18d58041 100644
--- a/cmd/prometheus/fdlimits_windows.go
+++ b/cmd/prometheus/limits_windows.go
@@ -19,3 +19,8 @@ package main
 func FdLimits() string {
 	return "N/A"
 }
+
+// VmLimits not supported on Windows
+func VmLimits() string {
+	return "N/A"
+}
diff --git a/cmd/prometheus/main.go b/cmd/prometheus/main.go
index 5a44e21f7..271cc939b 100644
--- a/cmd/prometheus/main.go
+++ b/cmd/prometheus/main.go
@@ -223,6 +223,7 @@ func main() {
 	level.Info(logger).Log("build_context", version.BuildContext())
 	level.Info(logger).Log("host_details", Uname())
 	level.Info(logger).Log("fd_limits", FdLimits())
+	level.Info(logger).Log("vm_limits", VmLimits())
 
 	var (
 		localStorage  = &tsdb.ReadyStorage{}