client: add disk_total_mb and disk_free_mb config options (#15852)

.changelog/15852.txt

@@ -0,0 +1,3 @@
+```release-note:improvement
+client/fingerprint/storage: Added config options disk_total_mb and disk_free_mb to override detected disk space
+```

client/config/config.go

@@ -113,6 +113,14 @@ type Config struct {
 	// determined dynamically.
 	MemoryMB int
 
+	// DiskTotalMB is the default node total disk space in megabytes if it cannot be
+	// determined dynamically.
+	DiskTotalMB int
+
+	// DiskFreeMB is the default node free disk space in megabytes if it cannot be
+	// determined dynamically.
+	DiskFreeMB int
+
 	// MaxKillTimeout allows capping the user-specifiable KillTimeout. If the
 	// task's KillTimeout is greater than the MaxKillTimeout, MaxKillTimeout is
 	// used.

client/fingerprint/storage.go

@@ -41,6 +41,17 @@ func (f *StorageFingerprint) Fingerprint(req *FingerprintRequest, resp *Fingerpr
 		return fmt.Errorf("failed to determine disk space for %s: %v", storageDir, err)
 	}
 
+	if cfg.DiskTotalMB > 0 {
+		total = uint64(cfg.DiskTotalMB) * bytesPerMegabyte
+	}
+	if cfg.DiskFreeMB > 0 {
+		free = uint64(cfg.DiskFreeMB) * bytesPerMegabyte
+	}
+
+	if total < free {
+		return fmt.Errorf("detected more free disk space (%d) than total disk space (%d), use disk_total_mb and disk_free_mb to correct", free, total)
+	}
+
 	resp.AddAttribute("unique.storage.volume", volume)
 	resp.AddAttribute("unique.storage.bytestotal", strconv.FormatUint(total, 10))
 	resp.AddAttribute("unique.storage.bytesfree", strconv.FormatUint(free, 10))

command/agent/agent.go

@@ -668,6 +668,12 @@ func convertClientConfig(agentConfig *Config) (*clientconfig.Config, error) {
 	if agentConfig.Client.MemoryMB != 0 {
 		conf.MemoryMB = agentConfig.Client.MemoryMB
 	}
+	if agentConfig.Client.DiskTotalMB != 0 {
+		conf.DiskTotalMB = agentConfig.Client.DiskTotalMB
+	}
+	if agentConfig.Client.DiskFreeMB != 0 {
+		conf.DiskFreeMB = agentConfig.Client.DiskFreeMB
+	}
 	if agentConfig.Client.MaxKillTimeout != "" {
 		dur, err := time.ParseDuration(agentConfig.Client.MaxKillTimeout)
 		if err != nil {

command/agent/config.go

@@ -227,6 +227,12 @@ type ClientConfig struct {
 	// MemoryMB is used to override any detected or default total memory.
 	MemoryMB int `hcl:"memory_total_mb"`
 
+	// DiskTotalMB is used to override any detected or default total disk space.
+	DiskTotalMB int `hcl:"disk_total_mb"`
+
+	// DiskFreeMB is used to override any detected or default free disk space.
+	DiskFreeMB int `hcl:"disk_free_mb"`
+
 	// ReservableCores is used to override detected reservable cpu cores.
 	ReserveableCores string `hcl:"reservable_cores"`
 
@@ -2006,6 +2012,12 @@ func (a *ClientConfig) Merge(b *ClientConfig) *ClientConfig {
 	if b.MemoryMB != 0 {
 		result.MemoryMB = b.MemoryMB
 	}
+	if b.DiskTotalMB != 0 {
+		result.DiskTotalMB = b.DiskTotalMB
+	}
+	if b.DiskFreeMB != 0 {
+		result.DiskFreeMB = b.DiskFreeMB
+	}
 	if b.MaxKillTimeout != "" {
 		result.MaxKillTimeout = b.MaxKillTimeout
 	}

website/content/docs/configuration/client.mdx

@@ -65,6 +65,15 @@ client {
 - `memory_total_mb` `(int:0)` - Specifies an override for the total memory. If set,
   this value overrides any detected memory.
 
+- `disk_total_mb` `(int:0)` - Specifies an override for the total disk space
+  fingerprint attribute. This value is not used by the scheduler unless you have
+  constraints set on the attribute `unique.storage.bytestotal`. The actual total
+  disk space can be determined via the [Read Stats API](https://github.com/api-docs/client#read-stats)
+
+- `disk_free_mb` `(int:0)` - Specifies the disk space free for scheduling
+  allocations. If set, this value overrides any detected free disk space. This
+  value can be seen in `nomad node status` under Allocated Resources.
+
 - `min_dynamic_port` `(int:20000)` - Specifies the minimum dynamic port to be
   assigned. Individual ports and ranges of ports may be excluded from dynamic
   port assignment via [`reserved`](#reserved-parameters) parameters.