multi: add minimum disk space check

lncfg/healthcheck.go

@@ -1,6 +1,7 @@
 package lncfg
 
 import (
+	"errors"
 	"fmt"
 	"time"
 )
@@ -23,11 +24,27 @@ var (
 // the lnd runs.
 type HealthCheckConfig struct {
 	ChainCheck *CheckConfig `group:"chainbackend" namespace:"chainbackend"`
+
+	DiskCheck *DiskCheckConfig `group:"diskspace" namespace:"diskspace"`
 }
 
 // Validate checks the values configured for our health checks.
 func (h *HealthCheckConfig) Validate() error {
-	return h.ChainCheck.validate("chain backend")
+	if err := h.ChainCheck.validate("chain backend"); err != nil {
+		return err
+	}
+
+	if err := h.DiskCheck.validate("disk space"); err != nil {
+		return err
+	}
+
+	if h.DiskCheck.RequiredRemaining < 0 ||
+		h.DiskCheck.RequiredRemaining >= 1 {
+
+		return errors.New("disk required ratio must be in [0:1)")
+	}
+
+	return nil
 }
 
 type CheckConfig struct {
@@ -63,3 +80,11 @@ func (c *CheckConfig) validate(name string) error {
 
 	return nil
 }
+
+// DiskCheckConfig contains configuration for ensuring that our node has
+// sufficient disk space.
+type DiskCheckConfig struct {
+	RequiredRemaining float64 `long:"diskrequired" description:"The minimum ratio of free disk space to total capacity that we allow before shutting lnd down safely."`
+
+	*CheckConfig
+}