[CC-7434] Skip collecting data directory metrics in dev mode (#20521)

* Skip collecting data directory stats in dev mode

In dev mode, the data directory is not set, so this metrics collection would
always fail and logs errors.

* Log collection errors at DEBUG level

There isn't much action a user can take to fix these errors, so
logging them as DEBUG rather than ERROR.

lib/hoststats/collector.go

@@ -87,7 +87,7 @@ func (c *Collector) collect() {
 	// Determine up-time
 	uptime, err := host.Uptime()
 	if err != nil {
-		c.logger.Error("failed to collect uptime stats", "error", err)
+		c.logger.Debug("failed to collect uptime stats", "error", err)
 		uptime = 0
 	}
 	hs.Uptime = uptime
@@ -95,7 +95,7 @@ func (c *Collector) collect() {
 	// Collect memory stats
 	mstats, err := c.collectMemoryStats()
 	if err != nil {
-		c.logger.Error("failed to collect memory stats", "error", err)
+		c.logger.Debug("failed to collect memory stats", "error", err)
 		mstats = &MemoryStats{}
 	}
 	hs.Memory = mstats
@@ -103,17 +103,19 @@ func (c *Collector) collect() {
 	// Collect cpu stats
 	cpus, err := c.collectCPUStats()
 	if err != nil {
-		c.logger.Error("failed to collect cpu stats", "error", err)
+		c.logger.Debug("failed to collect cpu stats", "error", err)
 		cpus = []*CPUStats{}
 	}
 	hs.CPU = cpus
 
 	// Collect disk stats
+	if c.dataDir != "" {
 		diskStats, err := c.collectDiskStats(c.dataDir)
 		if err != nil {
-		c.logger.Error("failed to collect dataDir disk stats", "error", err)
+			c.logger.Debug("failed to collect dataDir disk stats", "error", err)
 		}
 		hs.DataDirStats = diskStats
+	}
 
 	// Update the collected status object.
 	c.hostStatsLock.Lock()

lib/hoststats/collector_test.go

@@ -0,0 +1,48 @@
+// Copyright (c) HashiCorp, Inc.
+// SPDX-License-Identifier: BUSL-1.1
+
+package hoststats
+
+import (
+	"testing"
+
+	"github.com/hashicorp/go-hclog"
+	"github.com/stretchr/testify/require"
+
+	"github.com/hashicorp/consul/sdk/testutil"
+)
+
+// TestCollector_collect validates that metrics for host resource usage
+// are collected as expected.
+func TestCollector_collect(t *testing.T) {
+	testcases := map[string]struct {
+		skipDataDir bool
+	}{
+		"WithDataDirectory": {},
+		"NoDataDirectory": {
+			skipDataDir: true,
+		},
+	}
+	for name, tc := range testcases {
+		t.Run(name, func(t *testing.T) {
+			dataDir := ""
+			if !tc.skipDataDir {
+				dataDir = testutil.TempDir(t, "consul-config")
+			}
+
+			collector := initCollector(hclog.NewNullLogger(), dataDir)
+			collector.collect()
+
+			hs := collector.hostStats
+			require.NotNil(t, hs)
+			require.Greater(t, hs.Uptime, uint64(0))
+			require.NotNil(t, hs.Memory)
+			require.NotNil(t, hs.CPU)
+			if !tc.skipDataDir {
+				require.NotNil(t, hs.DataDirStats)
+			} else {
+				require.Nil(t, hs.DataDirStats)
+			}
+		})
+	}
+}