fingerprint: implement client fingerprinting of reservable cores

on Linux systems this is derived from the configure cpuset cgroup parent (defaults to /nomad)
for non Linux systems and Linux systems where cgroups are not enabled, the client defaults to using all cores

command/agent/agent.go

@@ -14,6 +14,8 @@ import (
 	"sync"
 	"time"
 
+	"github.com/hashicorp/nomad/lib/cpuset"
+
 	metrics "github.com/armon/go-metrics"
 	consulapi "github.com/hashicorp/consul/api"
 	"github.com/hashicorp/consul/lib"
@@ -613,6 +615,13 @@ func convertClientConfig(agentConfig *Config) (*clientconfig.Config, error) {
 	res.Memory.MemoryMB = int64(agentConfig.Client.Reserved.MemoryMB)
 	res.Disk.DiskMB = int64(agentConfig.Client.Reserved.DiskMB)
 	res.Networks.ReservedHostPorts = agentConfig.Client.Reserved.ReservedPorts
+	if agentConfig.Client.Reserved.Cores != "" {
+		cores, err := cpuset.Parse(agentConfig.Client.Reserved.Cores)
+		if err != nil {
+			return nil, fmt.Errorf("failed to parse client > reserved > cores value %q: %v", agentConfig.Client.Reserved.Cores, err)
+		}
+		res.Cpu.ReservedCpuCores = cores.ToSlice()
+	}
 
 	conf.Version = agentConfig.Version
 
@@ -661,6 +670,8 @@ func convertClientConfig(agentConfig *Config) (*clientconfig.Config, error) {
 	}
 	conf.BindWildcardDefaultHostNetwork = agentConfig.Client.BindWildcardDefaultHostNetwork
 
+	conf.CgroupParent = agentConfig.Client.CgroupParent
+
 	return conf, nil
 }
 

command/agent/config.go

@@ -299,6 +299,10 @@ type ClientConfig struct {
 	// matching any destination address (true). Defaults to true
 	BindWildcardDefaultHostNetwork bool `hcl:"bind_wildcard_default_host_network"`
 
+	// CgroupParent sets the parent cgroup for subsystems managed by Nomad. If the cgroup
+	// doest not exist Nomad will attempt to create it during startup. Defaults to '/nomad'
+	CgroupParent string `hcl:"cgroup_parent"`
+
 	// ExtraKeysHCL is used by hcl to surface unexpected keys
 	ExtraKeysHCL []string `hcl:",unusedKeys" json:"-"`
 }
@@ -720,18 +724,11 @@ type Resources struct {
 	MemoryMB      int    `hcl:"memory"`
 	DiskMB        int    `hcl:"disk"`
 	ReservedPorts string `hcl:"reserved_ports"`
+	Cores         string `hcl:"cores"`
 	// ExtraKeysHCL is used by hcl to surface unexpected keys
 	ExtraKeysHCL []string `hcl:",unusedKeys" json:"-"`
 }
 
-// CanParseReserved returns if the reserved ports specification is parsable.
-// The supported syntax is comma separated integers or ranges separated by
-// hyphens. For example, "80,120-150,160"
-func (r *Resources) CanParseReserved() error {
-	_, err := structs.ParsePortRanges(r.ReservedPorts)
-	return err
-}
-
 // devModeConfig holds the config for the -dev and -dev-connect flags
 type devModeConfig struct {
 	// mode flags are set at the command line via -dev and -dev-connect
@@ -1741,6 +1738,9 @@ func (r *Resources) Merge(b *Resources) *Resources {
 	if b.ReservedPorts != "" {
 		result.ReservedPorts = b.ReservedPorts
 	}
+	if b.Cores != "" {
+		result.Cores = b.Cores
+	}
 	return &result
 }