Completely re-work the server configuration to be separated out better

server/build_settings.go

@@ -0,0 +1,72 @@
+package server
+
+import "math"
+
+// The build settings for a given server that impact docker container creation and
+// resource limits for a server instance.
+type BuildSettings struct {
+	// The total amount of memory in megabytes that this server is allowed to
+	// use on the host system.
+	MemoryLimit int64 `json:"memory_limit"`
+
+	// The amount of additional swap space to be provided to a container instance.
+	Swap int64 `json:"swap"`
+
+	// The relative weight for IO operations in a container. This is relative to other
+	// containers on the system and should be a value between 10 and 1000.
+	IoWeight uint16 `json:"io_weight"`
+
+	// The percentage of CPU that this instance is allowed to consume relative to
+	// the host. A value of 200% represents complete utilization of two cores. This
+	// should be a value between 1 and THREAD_COUNT * 100.
+	CpuLimit int64 `json:"cpu_limit"`
+
+	// The amount of disk space in megabytes that a server is allowed to use.
+	DiskSpace int64 `json:"disk_space"`
+
+	// Sets which CPU threads can be used by the docker instance.
+	Threads string `json:"threads"`
+}
+
+func (s *Server) Build() *BuildSettings {
+	return &s.Config().Build
+}
+
+// Converts the CPU limit for a server build into a number that can be better understood
+// by the Docker environment. If there is no limit set, return -1 which will indicate to
+// Docker that it has unlimited CPU quota.
+func (b *BuildSettings) ConvertedCpuLimit() int64 {
+	if b.CpuLimit == 0 {
+		return -1
+	}
+
+	return b.CpuLimit * 1000
+}
+
+// Set the hard limit for memory usage to be 5% more than the amount of memory assigned to
+// the server. If the memory limit for the server is < 4G, use 10%, if less than 2G use
+// 15%. This avoids unexpected crashes from processes like Java which run over the limit.
+func (b *BuildSettings) MemoryOverheadMultiplier() float64 {
+	if b.MemoryLimit <= 2048 {
+		return 1.15
+	} else if b.MemoryLimit <= 4096 {
+		return 1.10
+	}
+
+	return 1.05
+}
+
+func (b *BuildSettings) BoundedMemoryLimit() int64 {
+	return int64(math.Round(float64(b.MemoryLimit) * b.MemoryOverheadMultiplier() * 1_000_000))
+}
+
+// Returns the amount of swap available as a total in bytes. This is returned as the amount
+// of memory available to the server initially, PLUS the amount of additional swap to include
+// which is the format used by Docker.
+func (b *BuildSettings) ConvertedSwap() int64 {
+	if b.Swap < 0 {
+		return -1
+	}
+
+	return (b.Swap * 1_000_000) + b.BoundedMemoryLimit()
+}