improvements

- Consolidate status reads
- Pre-allocate descriptors
- Add read_only disk label
- Remove dead stdin field
- Guard nil pool maps
- Add error-path tests
- Add go vet to flake

CLAUDE.md

@@ -0,0 +1,75 @@
+# pve-local-exporter
+
+Proxmox VE local metrics exporter for Prometheus, written in Go. Collects VM and storage metrics directly from the host (no PVE API) by reading /proc, /sys, /etc/pve, and running `qm monitor`.
+
+Reimplementation of the Python exporter at `../pvemon`.
+
+## Build & Test
+
+```sh
+nix develop             # shell with go + gopls
+nix develop -c go test ./...   # run tests (from src/)
+nix build               # build static binary
+nix flake check         # evaluate + check flake outputs
+```
+
+Go source lives in `src/`. The Nix build uses `buildGoModule` with `CGO_ENABLED=0`.
+
+After changing go.mod dependencies, run `go mod tidy` then update `vendorHash` in `default.nix` (set to a bogus hash, run `nix build`, copy the correct hash from the error).
+
+## Architecture
+
+All I/O is behind interfaces for testability. No test touches the real filesystem or runs real commands.
+
+```
+src/
+  main.go                          HTTP server, signal handling, log setup
+  internal/
+    config/                        CLI flag parsing -> Config struct
+    cache/                         TTLCache[K,V] (with jitter), MtimeCache[V] (file change detection)
+    procfs/                        /proc parsing: process discovery, CPU, IO, memory, threads, ctx switches
+    sysfs/                         /sys reading: NIC stats, block device sizes
+    qmmonitor/                     qm monitor pipe I/O + TTL cache, network/block output parsers
+    pveconfig/                     /etc/pve parsers: user.cfg (pools), storage.cfg (storage defs)
+    storage/                       statvfs wrapper, zpool list parser
+    collector/                     Prometheus Collector wiring all packages together
+```
+
+### Key interfaces (defined alongside their real implementations)
+
+- `procfs.ProcReader` -- process discovery and /proc/{pid}/* parsing
+- `sysfs.SysReader` -- /sys/class/net stats, /sys/block sizes
+- `qmmonitor.QMMonitor` -- `RunCommand(vmid, cmd)`, `InvalidateCache(vmid, cmd)`
+- `storage.StatFS` -- `Statfs(path)` for dir/nfs/cephfs sizing
+- `collector.CommandRunner` -- `Run(name, args...)` for zpool list
+- `collector.FileReaderIface` -- `ReadFile(path)` for config files
+
+### Concurrency
+
+Bounded goroutine pool (16 workers) for parallel NIC + disk collection per VM, matching the Python ThreadPoolExecutor(max_workers=16).
+
+## Conventions
+
+- Indent nix files with tabs
+- No emoji in code or text
+- Tests use fixture data / mock interfaces, never real /proc or /sys
+- Parser functions are exported and pure (take string, return parsed struct) so tests are straightforward
+- `storage.cfg` parser: section headers start at column 0, properties are indented (tab or space)
+- `user.cfg` pool format: `pool:name:comment:vmlist` (colon-separated, vmlist is comma-separated VM IDs)
+- Memory extended label keys are lowercase without trailing colon (e.g., `vmrss`, `vmpeak`)
+
+## CLI Flags
+
+| Flag | Default | Description |
+|------|---------|-------------|
+| `--port` | 9116 | HTTP listen port |
+| `--host` | 0.0.0.0 | Bind address |
+| `--collect-running-vms` | true | Collect KVM VM metrics |
+| `--collect-storage` | true | Collect storage pool metrics |
+| `--metrics-prefix` | pve | Prefix for all metric names |
+| `--loglevel` | INFO | DEBUG, INFO, WARNING, ERROR |
+| `--qm-terminal-timeout` | 10s | qm monitor command timeout |
+| `--qm-max-ttl` | 600s | TTL cache for qm monitor data |
+| `--qm-rand` | 60s | Jitter range for cache expiry |
+| `--qm-monitor-defer-close` | true | Defer closing unresponsive qm sessions |
+| `--version` | | Print version and exit |

README.md

@@ -0,0 +1,108 @@
+# pve-local-exporter
+
+Prometheus exporter for Proxmox VE that collects VM and storage metrics directly from the host without using the PVE API. Written in Go.
+
+Metrics are gathered by reading `/proc`, `/sys`, `/etc/pve`, and running `qm monitor` commands.
+
+## Building
+
+Requires [Nix](https://nixos.org/):
+
+```sh
+nix build               # build static binary
+nix flake check         # evaluate flake + run go vet
+```
+
+The output binary is statically linked (`CGO_ENABLED=0`).
+
+## Development
+
+```sh
+nix develop                          # shell with go + gopls
+nix develop -c go test ./... -race   # run tests with race detector
+nix develop -c go vet ./...          # static analysis
+```
+
+Go source lives in `src/`. After changing `go.mod` dependencies, run `go mod tidy` then update `vendorHash` in `default.nix` (set to a bogus hash, run `nix build`, copy the correct hash from the error).
+
+## Usage
+
+```sh
+pve_local_exporter [flags]
+```
+
+### Flags
+
+| Flag | Default | Description |
+|------|---------|-------------|
+| `--port` | 9116 | HTTP listen port |
+| `--host` | 0.0.0.0 | Bind address |
+| `--collect-running-vms` | true | Collect KVM VM metrics |
+| `--collect-storage` | true | Collect storage pool metrics |
+| `--metrics-prefix` | pve | Prefix for all metric names |
+| `--loglevel` | INFO | DEBUG, INFO, WARNING, ERROR |
+| `--qm-terminal-timeout` | 10s | qm monitor command timeout |
+| `--qm-max-ttl` | 600s | TTL cache for qm monitor data |
+| `--qm-rand` | 60s | Jitter range for cache expiry |
+| `--qm-monitor-defer-close` | true | Defer closing unresponsive qm sessions |
+| `--version` | | Print version and exit |
+
+## Exported metrics
+
+All metric names are prefixed with the configured `--metrics-prefix` (default `pve`).
+
+### Per-VM metrics
+
+| Metric | Labels | Description |
+|--------|--------|-------------|
+| `_kvm` | id, name, cpu, pid, pool, pool_levels, pool1-3 | VM info (value 1) |
+| `_kvm_cpu` | id, mode | CPU time (user/system/iowait) |
+| `_kvm_vcores` | id | Allocated vCPU count |
+| `_kvm_maxmem` | id | Maximum memory in bytes |
+| `_kvm_memory_percent` | id | RSS as percent of host memory |
+| `_kvm_memory_extended` | id, type | Detailed memory fields from /proc status |
+| `_kvm_threads` | id | Thread count |
+| `_kvm_ctx_switches` | id, type | Context switches (voluntary/involuntary) |
+| `_kvm_io_read_bytes` | id | I/O read bytes |
+| `_kvm_io_write_bytes` | id | I/O write bytes |
+| `_kvm_io_read_chars` | id | I/O read chars |
+| `_kvm_io_write_chars` | id | I/O write chars |
+| `_kvm_io_read_count` | id | I/O read syscalls |
+| `_kvm_io_write_count` | id | I/O write syscalls |
+| `_kvm_nic` | id, ifname, netdev, queues, type, model, macaddr | NIC info (value 1) |
+| `_kvm_nic_queues` | id, ifname | NIC queue count |
+| `_kvm_nic_*` | id, ifname | Per-NIC sysfs counters (rx_bytes, tx_bytes, etc.) |
+| `_kvm_disk` | id, disk_name, block_id, disk_path, disk_type, ... | Disk info (value 1) |
+| `_kvm_disk_size` | id, disk_name | Disk size in bytes |
+
+### Storage metrics
+
+| Metric | Labels | Description |
+|--------|--------|-------------|
+| `_node_storage` | name, type, ... | Storage pool info (value 1) |
+| `_node_storage_size` | name, type | Total storage size in bytes |
+| `_node_storage_free` | name, type | Free storage space in bytes |
+
+## Architecture
+
+All I/O is behind interfaces for testability. No test touches the real filesystem or runs real commands.
+
+```
+src/
+  main.go                          HTTP server, signal handling
+  internal/
+    config/                        CLI flag parsing
+    cache/                         TTLCache (with jitter), MtimeCache (file change detection)
+    procfs/                        /proc parsing: process discovery, CPU, IO, memory, threads
+    sysfs/                         /sys reading: NIC stats, block device sizes
+    qmmonitor/                     qm monitor pipe I/O + TTL cache, network/block parsers
+    pveconfig/                     /etc/pve parsers: pools (user.cfg), storage (storage.cfg)
+    storage/                       statvfs wrapper, zpool list parser
+    collector/                     Prometheus Collector wiring all packages together
+```
+
+Concurrent NIC and disk collection uses a bounded goroutine pool (16 workers).
+
+## License
+
+See [LICENSE](LICENSE) if present.

flake.nix

@@ -17,6 +17,28 @@
 			default = pve-local-exporter;
 		});
 
+		checks = forAllSystems (system: let
+			pkgs = nixpkgs.legacyPackages.${system};
+			pkg = self.packages.${system}.pve-local-exporter;
+		in {
+			vet = pkgs.runCommand "go-vet" {
+				nativeBuildInputs = [ pkgs.go ];
+				inherit (pkg) src goModules;
+				CGO_ENABLED = 0;
+			} ''
+				export HOME=$TMPDIR
+				export GOPATH=$TMPDIR/go
+				workdir=$TMPDIR/src
+				mkdir -p $workdir
+				cp -r $src/* $workdir/
+				chmod -R u+w $workdir
+				ln -s $goModules $workdir/vendor
+				cd $workdir
+				go vet -mod=vendor ./...
+				touch $out
+			'';
+		});
+
 		devShells = forAllSystems (system: let
 			pkgs = nixpkgs.legacyPackages.${system};
 		in {

src/internal/cache/mtimecache_test.go

@@ -1,6 +1,7 @@
 package cache
 
 import (
+	"sync"
 	"testing"
 	"time"
 )
@@ -37,3 +38,20 @@ func TestMtimeCache_HitAndMiss(t *testing.T) {
 		t.Fatalf("expected hit with 'world', got %q ok=%v", v, ok)
 	}
 }
+
+func TestMtimeCache_Concurrent(t *testing.T) {
+	mtime := time.Now()
+	stat := func(path string) (time.Time, error) { return mtime, nil }
+	c := NewMtimeCache[int]("/test", stat)
+
+	var wg sync.WaitGroup
+	for i := range 100 {
+		wg.Add(1)
+		go func(n int) {
+			defer wg.Done()
+			c.Set(n)
+			c.Get()
+		}(i)
+	}
+	wg.Wait()
+}

src/internal/cache/ttlcache_test.go

@@ -1,6 +1,7 @@
 package cache
 
 import (
+	"sync"
 	"testing"
 	"time"
 )
@@ -42,6 +43,24 @@ func TestTTLCache_Invalidate(t *testing.T) {
 	}
 }
 
+func TestTTLCache_Concurrent(t *testing.T) {
+	c := NewTTLCache[string, int](time.Hour, 0)
+	var wg sync.WaitGroup
+	for i := range 100 {
+		wg.Add(1)
+		go func(n int) {
+			defer wg.Done()
+			key := "key"
+			c.Set(key, n)
+			c.Get(key)
+			c.Invalidate(key)
+			c.Set(key, n+1)
+			c.Get(key)
+		}(i)
+	}
+	wg.Wait()
+}
+
 func TestTTLCache_JitterRange(t *testing.T) {
 	c := NewTTLCache[string, int](time.Second, 500*time.Millisecond)
 	// jitteredTTL should be in [500ms, 1500ms]

src/internal/collector/collector.go

@@ -4,6 +4,7 @@ import (
 	"log/slog"
 	"os"
 	"os/exec"
+	"slices"
 	"strconv"
 	"strings"
 	"sync"
@@ -36,6 +37,20 @@ type PVECollector struct {
 	storageCache *cache.MtimeCache[[]pveconfig.StorageEntry]
 
 	prefix string
+
+	// Pre-allocated metric descriptors for fixed-label metrics.
+	descCPU          *prometheus.Desc
+	descVcores       *prometheus.Desc
+	descMaxmem       *prometheus.Desc
+	descMemPct       *prometheus.Desc
+	descMemExt       *prometheus.Desc
+	descThreads      *prometheus.Desc
+	descCtxSwitches  *prometheus.Desc
+	descNicInfo      *prometheus.Desc
+	descNicQueues    *prometheus.Desc
+	descDiskSize     *prometheus.Desc
+	descStorageSize  *prometheus.Desc
+	descStorageFree  *prometheus.Desc
 }
 
 type poolData struct {
@@ -93,6 +108,7 @@ func New(cfg config.Config) *PVECollector {
 func NewWithDeps(cfg config.Config, proc procfs.ProcReader, sys sysfs.SysReader,
 	qm qmmonitor.QMMonitor, statFS storage.StatFS, cmd CommandRunner, fr FileReaderIface) *PVECollector {
 
+	p := cfg.MetricsPrefix
 	c := &PVECollector{
 		cfg:        cfg,
 		proc:       proc,
@@ -101,7 +117,20 @@ func NewWithDeps(cfg config.Config, proc procfs.ProcReader, sys sysfs.SysReader,
 		statFS:     statFS,
 		cmdRunner:  cmd,
 		fileReader: fr,
-		prefix:     cfg.MetricsPrefix,
+		prefix:     p,
+
+		descCPU:         prometheus.NewDesc(p+"_kvm_cpu", "KVM CPU time", []string{"id", "mode"}, nil),
+		descVcores:      prometheus.NewDesc(p+"_kvm_vcores", "vCores allocated", []string{"id"}, nil),
+		descMaxmem:      prometheus.NewDesc(p+"_kvm_maxmem", "Maximum memory bytes", []string{"id"}, nil),
+		descMemPct:      prometheus.NewDesc(p+"_kvm_memory_percent", "Memory percent of host", []string{"id"}, nil),
+		descMemExt:      prometheus.NewDesc(p+"_kvm_memory_extended", "Extended memory info", []string{"id", "type"}, nil),
+		descThreads:     prometheus.NewDesc(p+"_kvm_threads", "Threads used", []string{"id"}, nil),
+		descCtxSwitches: prometheus.NewDesc(p+"_kvm_ctx_switches", "Context switches", []string{"id", "type"}, nil),
+		descNicInfo:     prometheus.NewDesc(p+"_kvm_nic", "NIC info", []string{"id", "ifname", "netdev", "queues", "type", "model", "macaddr"}, nil),
+		descNicQueues:   prometheus.NewDesc(p+"_kvm_nic_queues", "NIC queue count", []string{"id", "ifname"}, nil),
+		descDiskSize:    prometheus.NewDesc(p+"_kvm_disk_size", "Disk size bytes", []string{"id", "disk_name"}, nil),
+		descStorageSize: prometheus.NewDesc(p+"_node_storage_size", "Storage total size", []string{"name", "type"}, nil),
+		descStorageFree: prometheus.NewDesc(p+"_node_storage_free", "Storage free space", []string{"name", "type"}, nil),
 	}
 	c.poolCache = cache.NewMtimeCache[poolData]("/etc/pve/user.cfg", fileMtime)
 	c.storageCache = cache.NewMtimeCache[[]pveconfig.StorageEntry]("/etc/pve/storage.cfg", fileMtime)
@@ -110,7 +139,7 @@ func NewWithDeps(cfg config.Config, proc procfs.ProcReader, sys sysfs.SysReader,
 
 func (c *PVECollector) Describe(ch chan<- *prometheus.Desc) {
 	// Dynamic metrics - use empty desc to signal unchecked collector
-	ch <- prometheus.NewDesc(c.prefix+"_kvm_cpu", "KVM CPU time", nil, nil)
+	ch <- c.descCPU
 }
 
 func (c *PVECollector) Collect(ch chan<- prometheus.Metric) {
@@ -137,11 +166,6 @@ func (c *PVECollector) collectVMs(ch chan<- prometheus.Metric) {
 	}
 
 	// Parallel NIC + disk collection with bounded worker pool
-	type workItem struct {
-		proc procfs.QEMUProcess
-		fn   func()
-	}
-
 	sem := make(chan struct{}, maxWorkers)
 	var wg sync.WaitGroup
 
@@ -179,47 +203,34 @@ func (c *PVECollector) collectVMMetrics(ch chan<- prometheus.Metric, proc procfs
 			{"system", cpu.System},
 			{"iowait", cpu.IOWait},
 		} {
-			ch <- prometheus.MustNewConstMetric(
+			ch <- prometheus.MustNewConstMetric(c.descCPU, prometheus.GaugeValue, m.val, id, m.mode)
-				prometheus.NewDesc(c.prefix+"_kvm_cpu", "KVM CPU time", []string{"id", "mode"}, nil),
-				prometheus.GaugeValue, m.val, id, m.mode,
-			)
 		}
 	}
 
 	// Vcores
-	ch <- prometheus.MustNewConstMetric(
+	ch <- prometheus.MustNewConstMetric(c.descVcores, prometheus.GaugeValue, float64(proc.Vcores), id)
-		prometheus.NewDesc(c.prefix+"_kvm_vcores", "vCores allocated", []string{"id"}, nil),
-		prometheus.GaugeValue, float64(proc.Vcores), id,
-	)
 
 	// MaxMem (kB to bytes)
-	ch <- prometheus.MustNewConstMetric(
+	ch <- prometheus.MustNewConstMetric(c.descMaxmem, prometheus.GaugeValue, float64(proc.MaxMem*1024), id)
-		prometheus.NewDesc(c.prefix+"_kvm_maxmem", "Maximum memory bytes", []string{"id"}, nil),
-		prometheus.GaugeValue, float64(proc.MaxMem*1024), id,
-	)
 
-	// Memory percent
+	// Status (threads, memory, context switches) -- single /proc/{pid}/status read
-	if memPct, err := c.proc.GetMemoryPercent(proc.PID); err == nil {
+	if status, err := c.proc.GetStatus(proc.PID); err == nil {
-		ch <- prometheus.MustNewConstMetric(
+		// Memory percent
-			prometheus.NewDesc(c.prefix+"_kvm_memory_percent", "Memory percent of host", []string{"id"}, nil),
+		if memPct, err := c.proc.GetMemoryPercent(proc.PID, status.VmRSS); err == nil {
-			prometheus.GaugeValue, memPct, id,
+			ch <- prometheus.MustNewConstMetric(c.descMemPct, prometheus.GaugeValue, memPct, id)
-		)
-	}
-
-	// Memory extended
-	if memExt, err := c.proc.GetMemoryExtended(proc.PID); err == nil {
-		desc := prometheus.NewDesc(c.prefix+"_kvm_memory_extended", "Extended memory info", []string{"id", "type"}, nil)
-		for key, val := range memExt {
-			ch <- prometheus.MustNewConstMetric(desc, prometheus.GaugeValue, float64(val), id, key)
 		}
-	}
 
-	// Threads
+		// Memory extended
-	if threads, err := c.proc.GetNumThreads(proc.PID); err == nil {
+		for key, val := range status.MemoryExtended {
-		ch <- prometheus.MustNewConstMetric(
+			ch <- prometheus.MustNewConstMetric(c.descMemExt, prometheus.GaugeValue, float64(val), id, key)
-			prometheus.NewDesc(c.prefix+"_kvm_threads", "Threads used", []string{"id"}, nil),
+		}
-			prometheus.GaugeValue, float64(threads), id,
+
-		)
+		// Threads
+		ch <- prometheus.MustNewConstMetric(c.descThreads, prometheus.GaugeValue, float64(status.Threads), id)
+
+		// Context switches
+		ch <- prometheus.MustNewConstMetric(c.descCtxSwitches, prometheus.GaugeValue, float64(status.CtxSwitches.Voluntary), id, "voluntary")
+		ch <- prometheus.MustNewConstMetric(c.descCtxSwitches, prometheus.GaugeValue, float64(status.CtxSwitches.Involuntary), id, "involuntary")
 	}
 
 	// IO counters
@@ -242,13 +253,6 @@ func (c *PVECollector) collectVMMetrics(ch chan<- prometheus.Metric, proc procfs
 		}
 	}
 
-	// Context switches
-	if cs, err := c.proc.GetCtxSwitches(proc.PID); err == nil {
-		desc := prometheus.NewDesc(c.prefix+"_kvm_ctx_switches", "Context switches", []string{"id", "type"}, nil)
-		ch <- prometheus.MustNewConstMetric(desc, prometheus.GaugeValue, float64(cs.Voluntary), id, "voluntary")
-		ch <- prometheus.MustNewConstMetric(desc, prometheus.GaugeValue, float64(cs.Involuntary), id, "involuntary")
-	}
-
 	// VM info metric
 	poolName := vmPoolMap[id]
 	poolInfo := pools[poolName]
@@ -275,20 +279,13 @@ func (c *PVECollector) collectNICMetrics(ch chan<- prometheus.Metric, proc procf
 	nics := qmmonitor.ParseNetworkInfo(raw)
 	for _, nic := range nics {
 		// NIC info metric
-		ch <- prometheus.MustNewConstMetric(
+		ch <- prometheus.MustNewConstMetric(c.descNicInfo, prometheus.GaugeValue, 1,
-			prometheus.NewDesc(c.prefix+"_kvm_nic", "NIC info", []string{
-				"id", "ifname", "netdev", "queues", "type", "model", "macaddr",
-			}, nil),
-			prometheus.GaugeValue, 1,
 			id, nic.Ifname, nic.Netdev, strconv.Itoa(nic.Queues),
 			nic.Type, nic.Model, nic.Macaddr,
 		)
 
 		// NIC queues
-		ch <- prometheus.MustNewConstMetric(
+		ch <- prometheus.MustNewConstMetric(c.descNicQueues, prometheus.GaugeValue, float64(nic.Queues), id, nic.Ifname)
-			prometheus.NewDesc(c.prefix+"_kvm_nic_queues", "NIC queue count", []string{"id", "ifname"}, nil),
-			prometheus.GaugeValue, float64(nic.Queues), id, nic.Ifname,
-		)
 
 		// NIC stats from sysfs
 		stats, err := c.sys.ReadInterfaceStats(nic.Ifname)
@@ -345,10 +342,7 @@ func (c *PVECollector) collectDiskMetrics(ch chan<- prometheus.Metric, proc proc
 		}
 
 		if diskSize > 0 {
-			ch <- prometheus.MustNewConstMetric(
+			ch <- prometheus.MustNewConstMetric(c.descDiskSize, prometheus.GaugeValue, float64(diskSize), id, diskName)
-				prometheus.NewDesc(c.prefix+"_kvm_disk_size", "Disk size bytes", []string{"id", "disk_name"}, nil),
-				prometheus.GaugeValue, float64(diskSize), id, diskName,
-			)
 		}
 
 		// Disk info metric - collect all labels
@@ -420,14 +414,8 @@ func (c *PVECollector) collectStorage(ch chan<- prometheus.Metric) {
 			continue
 		}
 
-		ch <- prometheus.MustNewConstMetric(
+		ch <- prometheus.MustNewConstMetric(c.descStorageSize, prometheus.GaugeValue, float64(size.Total), storageName, storageType)
-			prometheus.NewDesc(c.prefix+"_node_storage_size", "Storage total size", []string{"name", "type"}, nil),
+		ch <- prometheus.MustNewConstMetric(c.descStorageFree, prometheus.GaugeValue, float64(size.Free), storageName, storageType)
-			prometheus.GaugeValue, float64(size.Total), storageName, storageType,
-		)
-		ch <- prometheus.MustNewConstMetric(
-			prometheus.NewDesc(c.prefix+"_node_storage_free", "Storage free space", []string{"name", "type"}, nil),
-			prometheus.GaugeValue, float64(size.Free), storageName, storageType,
-		)
 	}
 }
 
@@ -439,7 +427,7 @@ func (c *PVECollector) getPoolInfo() (map[string]string, map[string]pveconfig.Po
 	content, err := c.fileReader.ReadFile("/etc/pve/user.cfg")
 	if err != nil {
 		slog.Error("read user.cfg", "err", err)
-		return nil, nil
+		return make(map[string]string), make(map[string]pveconfig.PoolInfo)
 	}
 
 	vmPoolMap, pools := pveconfig.ParsePoolConfig(content)
@@ -468,12 +456,7 @@ func sortedKeys(m map[string]string) []string {
 	for k := range m {
 		keys = append(keys, k)
 	}
-	// Simple insertion sort for typically small maps
+	slices.Sort(keys)
-	for i := 1; i < len(keys); i++ {
-		for j := i; j > 0 && keys[j] < keys[j-1]; j-- {
-			keys[j], keys[j-1] = keys[j-1], keys[j]
-		}
-	}
 	return keys
 }
 

src/internal/collector/collector_test.go

@@ -1,6 +1,7 @@
 package collector
 
 import (
+	"fmt"
 	"strings"
 	"testing"
 
@@ -15,17 +16,16 @@ import (
 // Mock implementations
 
 type mockProcReader struct {
-	procs     []procfs.QEMUProcess
+	procs    []procfs.QEMUProcess
-	cpuTimes  map[int]procfs.CPUTimes
+	procsErr error
-	ioCount   map[int]procfs.IOCounters
+	cpuTimes map[int]procfs.CPUTimes
-	threads   map[int]int
+	ioCount  map[int]procfs.IOCounters
-	memPct    map[int]float64
+	status   map[int]procfs.StatusInfo
-	memExt    map[int]procfs.MemoryExtended
+	memPct   map[int]float64
-	ctxSwitch map[int]procfs.CtxSwitches
 }
 
 func (m *mockProcReader) DiscoverQEMUProcesses() ([]procfs.QEMUProcess, error) {
-	return m.procs, nil
+	return m.procs, m.procsErr
 }
 func (m *mockProcReader) GetCPUTimes(pid int) (procfs.CPUTimes, error) {
 	return m.cpuTimes[pid], nil
@@ -33,18 +33,12 @@ func (m *mockProcReader) GetCPUTimes(pid int) (procfs.CPUTimes, error) {
 func (m *mockProcReader) GetIOCounters(pid int) (procfs.IOCounters, error) {
 	return m.ioCount[pid], nil
 }
-func (m *mockProcReader) GetNumThreads(pid int) (int, error) {
+func (m *mockProcReader) GetStatus(pid int) (procfs.StatusInfo, error) {
-	return m.threads[pid], nil
+	return m.status[pid], nil
 }
-func (m *mockProcReader) GetMemoryPercent(pid int) (float64, error) {
+func (m *mockProcReader) GetMemoryPercent(pid int, rssBytes int64) (float64, error) {
 	return m.memPct[pid], nil
 }
-func (m *mockProcReader) GetMemoryExtended(pid int) (procfs.MemoryExtended, error) {
-	return m.memExt[pid], nil
-}
-func (m *mockProcReader) GetCtxSwitches(pid int) (procfs.CtxSwitches, error) {
-	return m.ctxSwitch[pid], nil
-}
 func (m *mockProcReader) VMConfigExists(vmid string) bool { return true }
 
 type mockSysReader struct {
@@ -160,14 +154,15 @@ func TestCollector_BasicVMMetrics(t *testing.T) {
 		ioCount: map[int]procfs.IOCounters{
 			1234: {ReadChars: 1000, WriteChars: 2000, ReadSyscalls: 10, WriteSyscalls: 20, ReadBytes: 500, WriteBytes: 1000},
 		},
-		threads: map[int]int{1234: 50},
+		status: map[int]procfs.StatusInfo{
-		memPct:  map[int]float64{1234: 25.5},
+			1234: {
-		memExt: map[int]procfs.MemoryExtended{
+				Threads:        50,
-			1234: {"vmrss:": 1048576, "vmpeak:": 2097152},
+				VmRSS:          1048576,
-		},
+				MemoryExtended: procfs.MemoryExtended{"vmrss": 1048576, "vmpeak": 2097152},
-		ctxSwitch: map[int]procfs.CtxSwitches{
+				CtxSwitches:    procfs.CtxSwitches{Voluntary: 100, Involuntary: 10},
-			1234: {Voluntary: 100, Involuntary: 10},
+			},
 		},
+		memPct: map[int]float64{1234: 25.5},
 	}
 
 	sys := &mockSysReader{
@@ -302,12 +297,12 @@ func TestCollector_NICMetrics(t *testing.T) {
 		procs: []procfs.QEMUProcess{
 			{PID: 1, VMID: "100", Name: "vm", Vcores: 1, MaxMem: 1024},
 		},
-		cpuTimes:  map[int]procfs.CPUTimes{1: {}},
+		cpuTimes: map[int]procfs.CPUTimes{1: {}},
-		ioCount:   map[int]procfs.IOCounters{1: {}},
+		ioCount:  map[int]procfs.IOCounters{1: {}},
-		threads:   map[int]int{1: 1},
+		status: map[int]procfs.StatusInfo{
-		memPct:    map[int]float64{1: 0},
+			1: {Threads: 1, MemoryExtended: procfs.MemoryExtended{}},
-		memExt:    map[int]procfs.MemoryExtended{1: {}},
+		},
-		ctxSwitch: map[int]procfs.CtxSwitches{1: {}},
+		memPct: map[int]float64{1: 0},
 	}
 
 	sys := &mockSysReader{
@@ -341,3 +336,81 @@ func TestCollector_NICMetrics(t *testing.T) {
 		t.Errorf("tx_bytes = %v", txBytes)
 	}
 }
+
+// mockFileReaderErr returns an error for a specific path.
+type mockFileReaderErr struct {
+	files   map[string]string
+	errPath string
+}
+
+func (m *mockFileReaderErr) ReadFile(path string) (string, error) {
+	if path == m.errPath {
+		return "", fmt.Errorf("read error: %s", path)
+	}
+	return m.files[path], nil
+}
+
+func TestCollector_PoolReadError(t *testing.T) {
+	cfg := config.Config{
+		CollectRunningVMs: true,
+		CollectStorage:    false,
+		MetricsPrefix:     "pve",
+	}
+
+	proc := &mockProcReader{
+		procs: []procfs.QEMUProcess{
+			{PID: 1, VMID: "100", Name: "vm", Vcores: 1, MaxMem: 1024},
+		},
+		cpuTimes: map[int]procfs.CPUTimes{1: {}},
+		ioCount:  map[int]procfs.IOCounters{1: {}},
+		status: map[int]procfs.StatusInfo{
+			1: {Threads: 1, MemoryExtended: procfs.MemoryExtended{}},
+		},
+		memPct: map[int]float64{1: 0},
+	}
+
+	fr := &mockFileReaderErr{
+		files:   map[string]string{},
+		errPath: "/etc/pve/user.cfg",
+	}
+
+	c := NewWithDeps(cfg, proc, &mockSysReader{}, &mockQMMonitor{responses: map[string]string{
+		"100:info network": "",
+		"100:info block":   "",
+	}}, &mockStatFS{}, &mockCmdRunner{}, fr)
+
+	metrics := collectMetrics(c)
+
+	// Should still produce VM info with empty pool
+	infoMetrics := metrics["pve_kvm"]
+	if len(infoMetrics) != 1 {
+		t.Fatalf("expected 1 kvm info metric, got %d", len(infoMetrics))
+	}
+	m := findMetricWithLabels(infoMetrics, map[string]string{"pool": ""})
+	if m == nil {
+		t.Error("expected empty pool label when user.cfg unreadable")
+	}
+}
+
+func TestCollector_ProcessDiscoveryError(t *testing.T) {
+	cfg := config.Config{
+		CollectRunningVMs: true,
+		CollectStorage:    false,
+		MetricsPrefix:     "pve",
+	}
+
+	proc := &mockProcReader{
+		procsErr: fmt.Errorf("permission denied"),
+	}
+
+	fr := &mockFileReader{files: map[string]string{"/etc/pve/user.cfg": ""}}
+	c := NewWithDeps(cfg, proc, &mockSysReader{}, &mockQMMonitor{responses: map[string]string{}},
+		&mockStatFS{}, &mockCmdRunner{}, fr)
+
+	metrics := collectMetrics(c)
+
+	// No VM metrics should be emitted
+	if len(metrics) != 0 {
+		t.Errorf("expected 0 metrics on discovery error, got %d metric names", len(metrics))
+	}
+}

src/internal/procfs/procfs.go

@@ -46,15 +46,21 @@ type CtxSwitches struct {
 // MemoryExtended holds memory info from /proc/{pid}/status (values in bytes).
 type MemoryExtended map[string]int64
 
+// StatusInfo holds all fields parsed from /proc/{pid}/status in a single read.
+type StatusInfo struct {
+	Threads        int
+	VmRSS          int64 // bytes
+	MemoryExtended MemoryExtended
+	CtxSwitches    CtxSwitches
+}
+
 // ProcReader abstracts /proc access for testability.
 type ProcReader interface {
 	DiscoverQEMUProcesses() ([]QEMUProcess, error)
 	GetCPUTimes(pid int) (CPUTimes, error)
 	GetIOCounters(pid int) (IOCounters, error)
-	GetNumThreads(pid int) (int, error)
+	GetStatus(pid int) (StatusInfo, error)
-	GetMemoryPercent(pid int) (float64, error)
+	GetMemoryPercent(pid int, rssBytes int64) (float64, error)
-	GetMemoryExtended(pid int) (MemoryExtended, error)
-	GetCtxSwitches(pid int) (CtxSwitches, error)
 	VMConfigExists(vmid string) bool
 }
 
@@ -143,32 +149,15 @@ func (r *RealProcReader) GetIOCounters(pid int) (IOCounters, error) {
 	return ParseIO(string(data))
 }
 
-func (r *RealProcReader) GetNumThreads(pid int) (int, error) {
+func (r *RealProcReader) GetStatus(pid int) (StatusInfo, error) {
 	data, err := os.ReadFile(filepath.Join(r.ProcPath, strconv.Itoa(pid), "status"))
 	if err != nil {
-		return 0, err
+		return StatusInfo{}, err
 	}
-	return ParseThreads(string(data))
+	return ParseStatus(string(data))
 }
 
-func (r *RealProcReader) GetMemoryPercent(pid int) (float64, error) {
+func (r *RealProcReader) GetMemoryPercent(pid int, rssBytes int64) (float64, error) {
-	// Read process RSS and total memory to compute percentage
-	statusData, err := os.ReadFile(filepath.Join(r.ProcPath, strconv.Itoa(pid), "status"))
-	if err != nil {
-		return 0, err
-	}
-	rss := int64(0)
-	for _, line := range strings.Split(string(statusData), "\n") {
-		if strings.HasPrefix(line, "VmRSS:") {
-			parts := strings.Fields(line)
-			if len(parts) >= 2 {
-				rss, _ = strconv.ParseInt(parts[1], 10, 64)
-				rss *= 1024 // kB to bytes
-			}
-			break
-		}
-	}
-
 	meminfoData, err := os.ReadFile(filepath.Join(r.ProcPath, "meminfo"))
 	if err != nil {
 		return 0, err
@@ -187,23 +176,7 @@ func (r *RealProcReader) GetMemoryPercent(pid int) (float64, error) {
 	if totalMem == 0 {
 		return 0, nil
 	}
-	return float64(rss) / float64(totalMem) * 100.0, nil
+	return float64(rssBytes) / float64(totalMem) * 100.0, nil
-}
-
-func (r *RealProcReader) GetMemoryExtended(pid int) (MemoryExtended, error) {
-	data, err := os.ReadFile(filepath.Join(r.ProcPath, strconv.Itoa(pid), "status"))
-	if err != nil {
-		return nil, err
-	}
-	return ParseMemoryExtended(string(data)), nil
-}
-
-func (r *RealProcReader) GetCtxSwitches(pid int) (CtxSwitches, error) {
-	data, err := os.ReadFile(filepath.Join(r.ProcPath, strconv.Itoa(pid), "status"))
-	if err != nil {
-		return CtxSwitches{}, err
-	}
-	return ParseCtxSwitches(string(data))
 }
 
 // ParseCmdline splits a null-byte separated /proc/{pid}/cmdline.
@@ -339,56 +312,49 @@ func ParseIO(data string) (IOCounters, error) {
 	return io, nil
 }
 
-// ParseThreads extracts the Threads count from /proc/{pid}/status.
+// ParseStatus parses /proc/{pid}/status in one pass, extracting threads, VmRSS,
-func ParseThreads(data string) (int, error) {
+// memory extended fields, and context switches.
-	for _, line := range strings.Split(data, "\n") {
+func ParseStatus(data string) (StatusInfo, error) {
-		if strings.HasPrefix(line, "Threads:") {
+	var info StatusInfo
-			parts := strings.Fields(line)
+	info.MemoryExtended = make(MemoryExtended)
-			if len(parts) >= 2 {
+	foundThreads := false
-				return strconv.Atoi(parts[1])
-			}
-		}
-	}
-	return 0, fmt.Errorf("Threads field not found")
-}
 
-// ParseMemoryExtended parses /proc/{pid}/status for Vm*/Rss*/Hugetlb* lines.
-// Returns map with lowercase keys (trailing colon preserved) to values in bytes.
-func ParseMemoryExtended(data string) MemoryExtended {
-	m := make(MemoryExtended)
-	for _, line := range strings.Split(data, "\n") {
-		if strings.HasPrefix(line, "Vm") || strings.HasPrefix(line, "Rss") || strings.HasPrefix(line, "Hugetlb") {
-			parts := strings.Fields(line)
-			if len(parts) >= 2 {
-				key := strings.ToLower(parts[0]) // keeps trailing colon
-				val, err := strconv.ParseInt(parts[1], 10, 64)
-				if err != nil {
-					continue
-				}
-				if len(parts) >= 3 && parts[2] == "kB" {
-					val *= 1024
-				}
-				m[key] = val
-			}
-		}
-	}
-	return m
-}
-
-// ParseCtxSwitches parses voluntary/involuntary context switches from /proc/{pid}/status.
-func ParseCtxSwitches(data string) (CtxSwitches, error) {
-	var cs CtxSwitches
 	for _, line := range strings.Split(data, "\n") {
 		parts := strings.Fields(line)
 		if len(parts) < 2 {
 			continue
 		}
-		switch parts[0] {
+
-		case "voluntary_ctxt_switches:":
+		switch {
-			cs.Voluntary, _ = strconv.ParseUint(parts[1], 10, 64)
+		case parts[0] == "Threads:":
-		case "nonvoluntary_ctxt_switches:":
+			n, err := strconv.Atoi(parts[1])
-			cs.Involuntary, _ = strconv.ParseUint(parts[1], 10, 64)
+			if err != nil {
+				return StatusInfo{}, fmt.Errorf("parse Threads: %w", err)
+			}
+			info.Threads = n
+			foundThreads = true
+		case parts[0] == "voluntary_ctxt_switches:":
+			info.CtxSwitches.Voluntary, _ = strconv.ParseUint(parts[1], 10, 64)
+		case parts[0] == "nonvoluntary_ctxt_switches:":
+			info.CtxSwitches.Involuntary, _ = strconv.ParseUint(parts[1], 10, 64)
+		case strings.HasPrefix(line, "Vm") || strings.HasPrefix(line, "Rss") || strings.HasPrefix(line, "Hugetlb"):
+			key := strings.ToLower(strings.TrimSuffix(parts[0], ":"))
+			val, err := strconv.ParseInt(parts[1], 10, 64)
+			if err != nil {
+				continue
+			}
+			if len(parts) >= 3 && parts[2] == "kB" {
+				val *= 1024
+			}
+			info.MemoryExtended[key] = val
+			if key == "vmrss" {
+				info.VmRSS = val
+			}
 		}
 	}
-	return cs, nil
+
+	if !foundThreads {
+		return StatusInfo{}, fmt.Errorf("Threads field not found")
+	}
+	return info, nil
 }

src/internal/procfs/procfs_test.go

@@ -147,59 +147,107 @@ cancelled_write_bytes: 0
 	}
 }
 
-func TestParseThreads(t *testing.T) {
+func TestParseStatus(t *testing.T) {
 	data := `Name:	qemu-system-x86
 Threads:	50
-VmPeak:	1234 kB
-`
-	n, err := ParseThreads(data)
-	if err != nil {
-		t.Fatal(err)
-	}
-	if n != 50 {
-		t.Errorf("got %d, want 50", n)
-	}
-}
-
-func TestParseMemoryExtended(t *testing.T) {
-	data := `Name:	qemu-system-x86
 VmPeak:	1000 kB
 VmRSS:	500 kB
 VmData:	200 kB
 RssAnon:	100 kB
 HugetlbPages:	0 kB
-`
-	m := ParseMemoryExtended(data)
-	if m["vmpeak:"] != 1000*1024 {
-		t.Errorf("VmPeak = %d", m["vmpeak:"])
-	}
-	if m["vmrss:"] != 500*1024 {
-		t.Errorf("VmRSS = %d", m["vmrss:"])
-	}
-	if m["vmdata:"] != 200*1024 {
-		t.Errorf("VmData = %d", m["vmdata:"])
-	}
-	if m["rssanon:"] != 100*1024 {
-		t.Errorf("RssAnon = %d", m["rssanon:"])
-	}
-	if m["hugetlbpages:"] != 0 {
-		t.Errorf("HugetlbPages = %d", m["hugetlbpages:"])
-	}
-}
-
-func TestParseCtxSwitches(t *testing.T) {
-	data := `Name:	qemu
 voluntary_ctxt_switches:	1234
 nonvoluntary_ctxt_switches:	56
 `
-	cs, err := ParseCtxSwitches(data)
+	info, err := ParseStatus(data)
 	if err != nil {
 		t.Fatal(err)
 	}
-	if cs.Voluntary != 1234 {
+
-		t.Errorf("Voluntary = %d", cs.Voluntary)
+	// Threads
+	if info.Threads != 50 {
+		t.Errorf("Threads = %d, want 50", info.Threads)
 	}
-	if cs.Involuntary != 56 {
+
-		t.Errorf("Involuntary = %d", cs.Involuntary)
+	// VmRSS
+	if info.VmRSS != 500*1024 {
+		t.Errorf("VmRSS = %d, want %d", info.VmRSS, 500*1024)
+	}
+
+	// Memory extended
+	if info.MemoryExtended["vmpeak"] != 1000*1024 {
+		t.Errorf("VmPeak = %d", info.MemoryExtended["vmpeak"])
+	}
+	if info.MemoryExtended["vmrss"] != 500*1024 {
+		t.Errorf("VmRSS = %d", info.MemoryExtended["vmrss"])
+	}
+	if info.MemoryExtended["vmdata"] != 200*1024 {
+		t.Errorf("VmData = %d", info.MemoryExtended["vmdata"])
+	}
+	if info.MemoryExtended["rssanon"] != 100*1024 {
+		t.Errorf("RssAnon = %d", info.MemoryExtended["rssanon"])
+	}
+	if info.MemoryExtended["hugetlbpages"] != 0 {
+		t.Errorf("HugetlbPages = %d", info.MemoryExtended["hugetlbpages"])
+	}
+
+	// Context switches
+	if info.CtxSwitches.Voluntary != 1234 {
+		t.Errorf("Voluntary = %d", info.CtxSwitches.Voluntary)
+	}
+	if info.CtxSwitches.Involuntary != 56 {
+		t.Errorf("Involuntary = %d", info.CtxSwitches.Involuntary)
+	}
+}
+
+func TestParseStatus_NoThreads(t *testing.T) {
+	data := `Name:	qemu
+VmRSS:	100 kB
+`
+	_, err := ParseStatus(data)
+	if err == nil {
+		t.Fatal("expected error for missing Threads")
+	}
+}
+
+func TestParseStat_Malformed(t *testing.T) {
+	tests := []struct {
+		name string
+		data string
+	}{
+		{"no_closing_paren", "12345 (qemu S 1 12345"},
+		{"truncated", "12345 (qemu) S 1 2 3"},
+		{"empty", ""},
+	}
+	for _, tc := range tests {
+		t.Run(tc.name, func(t *testing.T) {
+			_, err := ParseStat(tc.data)
+			if err == nil {
+				t.Fatal("expected error for malformed stat")
+			}
+		})
+	}
+}
+
+func TestParseIO_Empty(t *testing.T) {
+	io, err := ParseIO("")
+	if err != nil {
+		t.Fatal(err)
+	}
+	if io.ReadChars != 0 || io.WriteChars != 0 {
+		t.Errorf("expected zero counters, got %+v", io)
+	}
+}
+
+func TestParseIO_MalformedLines(t *testing.T) {
+	data := "rchar: notanumber\nbadline\nwchar: 100\n"
+	io, err := ParseIO(data)
+	if err != nil {
+		t.Fatal(err)
+	}
+	if io.ReadChars != 0 {
+		t.Errorf("ReadChars = %d, want 0 (parse failure)", io.ReadChars)
+	}
+	if io.WriteChars != 100 {
+		t.Errorf("WriteChars = %d, want 100", io.WriteChars)
 	}
 }

src/internal/pveconfig/pool.go

@@ -2,8 +2,6 @@ package pveconfig
 
 import (
 	"strings"
-
-	"pve_local_exporter/internal/cache"
 )
 
 // PoolInfo holds parsed pool hierarchy info.
@@ -14,12 +12,6 @@ type PoolInfo struct {
 	Level3     string
 }
 
-// FileReader abstracts file reading for testability.
-type FileReader interface {
-	ReadFile(path string) (string, error)
-	Stat(path string) (cache.StatFunc, error)
-}
-
 // ParsePoolConfig parses /etc/pve/user.cfg for pool definitions.
 // Returns (vm_pool_map, pools).
 // vm_pool_map: vmid -> pool_name

src/internal/pveconfig/storage.go

@@ -23,37 +23,36 @@ func ParseStorageConfig(data string) []StorageEntry {
 	var result []StorageEntry
 	var current *StorageEntry
 
-	for _, line := range strings.Split(data, "\n") {
+	for _, rawLine := range strings.Split(data, "\n") {
-		line = strings.TrimSpace(line)
+		trimmed := strings.TrimSpace(rawLine)
 
-		if line == "" || strings.HasPrefix(line, "#") {
+		if trimmed == "" || strings.HasPrefix(trimmed, "#") {
 			continue
 		}
 
-		if strings.Contains(line, ":") && !strings.HasPrefix(line, "\t") && !strings.HasPrefix(line, " ") {
+		// Section headers start at column 0 (no leading whitespace)
-			// Check if this is a section header (type: name)
+		isIndented := len(rawLine) > 0 && (rawLine[0] == '\t' || rawLine[0] == ' ')
-			colonIdx := strings.Index(line, ":")
-			sectionType := strings.TrimSpace(line[:colonIdx])
-			sectionName := strings.TrimSpace(line[colonIdx+1:])
 
-			// Only treat as header if type has no spaces (it's a single word)
+		if !isIndented && strings.Contains(trimmed, ":") {
-			if !strings.Contains(sectionType, " ") {
+			colonIdx := strings.Index(trimmed, ":")
-				if current != nil {
+			sectionType := trimmed[:colonIdx]
-					result = append(result, *current)
+			sectionName := strings.TrimSpace(trimmed[colonIdx+1:])
-				}
+
-				current = &StorageEntry{
+			if current != nil {
-					Properties: map[string]string{
+				result = append(result, *current)
-						"type": SanitizeKey(sectionType),
-						"name": SanitizeKey(sectionName),
-					},
-				}
-				continue
 			}
+			current = &StorageEntry{
+				Properties: map[string]string{
+					"type": SanitizeKey(sectionType),
+					"name": SanitizeKey(sectionName),
+				},
+			}
+			continue
 		}
 
 		// Key-value property line
 		if current != nil {
-			parts := strings.SplitN(line, " ", 2)
+			parts := strings.SplitN(trimmed, " ", 2)
 			key := SanitizeKey(strings.TrimSpace(parts[0]))
 			if len(parts) > 1 {
 				current.Properties[key] = strings.TrimSpace(parts[1])

src/internal/qmmonitor/block.go

@@ -48,7 +48,14 @@ func ParseBlockInfo(raw string) map[string]DiskInfo {
 		blockID := match[2]
 		diskPath := match[3]
 		diskTypeAndMode := match[4]
-		diskType := strings.Split(diskTypeAndMode, ", ")[0]
+		modeParts := strings.Split(diskTypeAndMode, ", ")
+		diskType := modeParts[0]
+		readOnly := false
+		for _, p := range modeParts[1:] {
+			if p == "read-only" {
+				readOnly = true
+			}
+		}
 
 		// Skip EFI disks
 		if strings.Contains(diskName, "efidisk") {
@@ -72,6 +79,10 @@ func ParseBlockInfo(raw string) map[string]DiskInfo {
 			Labels:   make(map[string]string),
 		}
 
+		if readOnly {
+			info.Labels["read_only"] = "true"
+		}
+
 		// Detect disk type from path
 		classifyDisk(&info)
 

src/internal/qmmonitor/block_test.go

@@ -130,6 +130,51 @@ func TestHandleJSONPath_NoHostDevice(t *testing.T) {
 	}
 }
 
+func TestParseBlockInfo_ReadOnly(t *testing.T) {
+	raw := `drive-scsi0 (#block100): /dev/zvol/rpool/data/vm-100-disk-0 (raw, read-only)
+`
+	disks := ParseBlockInfo(raw)
+	d := disks["scsi0"]
+	if d.Labels["read_only"] != "true" {
+		t.Errorf("expected read_only=true, got %q", d.Labels["read_only"])
+	}
+}
+
+func TestParseBlockInfo_ReadWrite(t *testing.T) {
+	raw := `drive-scsi0 (#block100): /dev/zvol/rpool/data/vm-100-disk-0 (raw, read-write)
+`
+	disks := ParseBlockInfo(raw)
+	d := disks["scsi0"]
+	if _, ok := d.Labels["read_only"]; ok {
+		t.Error("read_only label should not be set for read-write disks")
+	}
+}
+
+func TestParseBlockInfo_MalformedHeader(t *testing.T) {
+	raw := `drive-scsi0: this is not a valid header
+`
+	disks := ParseBlockInfo(raw)
+	if len(disks) != 0 {
+		t.Fatalf("expected 0 disks for malformed header, got %d", len(disks))
+	}
+}
+
+func TestParseBlockInfo_Empty(t *testing.T) {
+	disks := ParseBlockInfo("")
+	if len(disks) != 0 {
+		t.Fatalf("expected 0 disks for empty input, got %d", len(disks))
+	}
+}
+
+func TestParseBlockInfo_JSONError(t *testing.T) {
+	raw := `drive-scsi0 (#block100): json:{invalid json} (raw, read-write)
+`
+	disks := ParseBlockInfo(raw)
+	if len(disks) != 0 {
+		t.Fatalf("expected 0 disks for invalid JSON path, got %d", len(disks))
+	}
+}
+
 func TestParseBlockInfo_MultiDisk(t *testing.T) {
 	raw := `drive-scsi0 (#block100): /dev/zvol/rpool/data/vm-100-disk-0 (raw, read-write)
     Attached to:      /machine/peripheral/virtioscsi0/virtio-backend

src/internal/qmmonitor/network_test.go

@@ -63,3 +63,27 @@ func TestParseNetworkInfo_Empty(t *testing.T) {
 		t.Fatalf("expected 0 NICs, got %d", len(nics))
 	}
 }
+
+func TestParseNetworkInfo_MalformedLine(t *testing.T) {
+	// Lines without colon-space or without "net" prefix should be skipped
+	raw := "this is garbage\nnotnet0: index=0,type=tap\nno-colon-here\n"
+	nics := ParseNetworkInfo(raw)
+	if len(nics) != 0 {
+		t.Fatalf("expected 0 NICs for malformed input, got %d", len(nics))
+	}
+}
+
+func TestParseNetworkInfo_MissingFields(t *testing.T) {
+	// NIC with minimal fields
+	raw := "net0: index=0"
+	nics := ParseNetworkInfo(raw)
+	if len(nics) != 1 {
+		t.Fatalf("expected 1 NIC, got %d", len(nics))
+	}
+	if nics[0].Queues != 1 {
+		t.Errorf("queues = %d, want 1", nics[0].Queues)
+	}
+	if nics[0].Model != "" {
+		t.Errorf("model = %q, want empty", nics[0].Model)
+	}
+}

src/internal/qmmonitor/qmmonitor.go

@@ -31,7 +31,6 @@ type RealQMMonitor struct {
 
 type deferredProc struct {
 	cmd       *exec.Cmd
-	stdin     io.WriteCloser
 	timestamp time.Time
 }
 
@@ -113,7 +112,7 @@ func (m *RealQMMonitor) deferCloseProcess(cmd *exec.Cmd, stdin io.WriteCloser) {
 	stdin.Close()
 	if m.deferClose {
 		m.mu.Lock()
-		m.deferredProcs = append(m.deferredProcs, deferredProc{cmd: cmd, stdin: stdin, timestamp: time.Now()})
+		m.deferredProcs = append(m.deferredProcs, deferredProc{cmd: cmd, timestamp: time.Now()})
 		m.mu.Unlock()
 		slog.Warn("deferred closing qm monitor process", "pid", cmd.Process.Pid)
 	} else {

src/internal/storage/storage.go

@@ -18,11 +18,6 @@ type StatFS interface {
 	Statfs(path string) (StorageSize, error)
 }
 
-// CommandRunner abstracts command execution for testability.
-type CommandRunner interface {
-	Run(name string, args ...string) (string, error)
-}
-
 // RealStatFS uses the real syscall.
 type RealStatFS struct{}