SNMP Exporter

The SNMP Exporter enables Prometheus to collect metrics from SNMP-enabled devices, specifically monitoring the Synology DS925+ NAS that provides storage for the cluster.

Overview

Namespace: default
Image: prom/snmp-exporter:v0.30.0
Deployment: Managed by ArgoCD as part of kube-prometheus-stack
Target Device: Synology DS925+ NAS (10.0.1.204)

Version Update (2026-01-11)

Upgraded from v0.26.0 to v0.30.0 to address 2 CRITICAL and 6 HIGH vulnerabilities.

Breaking Change: The /health endpoint was removed in v0.30.0. Liveness and readiness probes now use / instead.

Purpose

The SNMP Exporter provides comprehensive NAS monitoring by collecting:

Disk health and temperature
Volume capacity and usage
RAID status and health
System resource utilization
Network interface statistics
iSCSI target statistics
Fan speeds and system temperatures

Architecture

Components

Init Container (config-processor):

Processes SNMP configuration template
Injects credentials from Kubernetes secrets
Generates final configuration file
Uses busybox:1.36

Main Container (snmp-exporter):

Prometheus SNMP Exporter
Exposes HTTP endpoint for metric scraping
Queries NAS via SNMPv3
Translates SNMP OIDs to Prometheus metrics

SNMPv3 Configuration

Authentication

The exporter uses SNMPv3 with authentication and privacy for secure monitoring:

Security Level: authPriv

Authentication:

Protocol: SHA (configurable)
Username: Stored in secret
Password: Stored in secret

Privacy (Encryption):

Protocol: AES (configurable)
Password: Stored in secret

Why SNMPv3?

Encrypted communication with NAS
Authentication prevents unauthorized access
Privacy ensures data confidentiality
Industry best practice for SNMP monitoring

Credentials Management

Secret: snmp-exporter-credentials

Location: manifests/base/kube-prometheus-stack/snmp-exporter-secret.yaml (git-crypt encrypted)

Fields:

snmp-username: <username>
snmp-auth-password: <authentication password>
snmp-priv-password: <privacy password>
snmp-auth-protocol: SHA  # or MD5
snmp-priv-protocol: AES  # or DES

Apply Secret:

kubectl apply -f manifests/base/kube-prometheus-stack/snmp-exporter-secret.yaml

Deployment Configuration

Deployment Manifest

Location: manifests/base/kube-prometheus-stack/snmp-exporter-deployment.yaml

Key Features:

Init container for credential injection
Environment variable substitution
Health checks (liveness and readiness probes)
Resource limits appropriate for Pi cluster

Resource Limits:

resources:
  requests:
    cpu: 50m
    memory: 64Mi
  limits:
    cpu: 100m
    memory: 128Mi

Service Configuration

Endpoint: snmp-exporter.default:9116

apiVersion: v1
kind: Service
metadata:
  name: snmp-exporter
  namespace: default
spec:
  type: ClusterIP
  ports:
  - port: 9116
    targetPort: 9116

ConfigMap

Location: manifests/base/kube-prometheus-stack/snmp-exporter-configmap.yaml

Contains SNMP module configuration including:

OID mappings
Metric translations
Walk configurations
Synology-specific MIBs

Prometheus Integration

Scrape Configuration

Prometheus scrapes SNMP metrics via the exporter:

scrape_configs:
- job_name: 'snmp-nas'
  static_configs:
    - targets:
      - 10.0.1.204  # Synology NAS
  metrics_path: /snmp
  params:
    module: [synology]  # Use synology SNMP module
  relabel_configs:
    - source_labels: [__address__]
      target_label: __param_target
    - source_labels: [__param_target]
      target_label: instance
    - target_label: __address__
      replacement: snmp-exporter.default:9116

How It Works:

Prometheus sends scrape request to snmp-exporter
snmp-exporter queries NAS via SNMP
snmp-exporter translates SNMP data to Prometheus metrics
Prometheus stores the metrics

Collected Metrics

Storage Metrics

Disk Health:

diskTable - Disk status and health
diskTemperature - Drive temperatures
diskModel - Drive model information

Volume Metrics:

volumeTable - Volume status
volumeSize - Total capacity
volumeFreeSize - Available space
volumePercentUsed - Usage percentage

RAID Status:

raidTable - RAID array status
raidFreeSize - Available RAID capacity
raidStatus - Health status

System Metrics

CPU and Memory:

systemCPU - CPU utilization
memorySize - Total memory
memoryAvailable - Free memory

Temperature:

systemTemperature - System temperature
cpuFanStatus - Fan status and speed
systemFanStatus - Chassis fan status

Network Metrics

Interface Statistics:

ifInOctets - Incoming bytes
ifOutOctets - Outgoing bytes
ifInErrors - Receive errors
ifOutErrors - Transmit errors
ifSpeed - Link speed

iSCSI Metrics

Target Statistics:

iscsiTargetTable - iSCSI target status
iscsiLUNTable - LUN status and usage
iscsiSessionTable - Active sessions

Grafana Dashboards

Synology NAS Dashboard

Location: Synology_Dashboard2.json

Panels Include:

Storage capacity overview
Disk health and temperature
RAID status
Network throughput
System resource usage
iSCSI performance
Temperature trends

Import Dashboard:

Access Grafana UI
Navigate to Dashboards → Import
Upload Synology_Dashboard2.json
Select Prometheus datasource
Import

Common Queries

Volume Usage:

(volumeSize - volumeFreeSize) / volumeSize * 100

Disk Temperature:

diskTemperature{disk="Disk 1"}

Network Throughput:

rate(ifInOctets{ifDescr="eth0"}[5m]) * 8

iSCSI LUN Usage:

iscsiLUNUsed / iscsiLUNSize * 100

Accessing the Exporter

Metrics Endpoint

Port Forward:

kubectl port-forward -n default svc/snmp-exporter 9116:9116

Query Metrics Directly:

curl http://localhost:9116/snmp?target=10.0.1.204&module=synology

Health Check:

curl http://localhost:9116/health

Testing SNMP Connectivity

From within cluster:

kubectl exec -n default deployment/snmp-exporter -- \
  wget -qO- http://localhost:9116/snmp?target=10.0.1.204&module=synology | head -50

Troubleshooting

Check Pod Status

# View pod
kubectl get pods -n default | grep snmp-exporter

# Check logs (init container)
kubectl logs -n default deployment/snmp-exporter -c config-processor

# Check logs (main container)
kubectl logs -n default deployment/snmp-exporter -c snmp-exporter

Common Issues

No Metrics Returned

Symptoms:

Empty metrics output
SNMP exporter returns errors

Diagnosis:

# Check exporter logs
kubectl logs -n default deployment/snmp-exporter

# Test SNMP connection from pod
kubectl exec -n default deployment/snmp-exporter -- \
  snmpwalk -v3 -l authPriv -u <username> -a SHA -A <auth-pass> \
  -x AES -X <priv-pass> 10.0.1.204 system

Common Causes:

SNMP not enabled on Synology NAS
Incorrect credentials
Firewall blocking SNMP (UDP 161)
Wrong security level configuration

Solution:

Verify SNMP enabled in DSM (Control Panel → Terminal & SNMP → SNMP)
Check SNMPv3 user configured in DSM
Verify credentials in secret match DSM
Test network connectivity to NAS

Authentication Failures

Symptoms:

Logs show "authentication failure"
"Unknown user name" errors

Solution:

Verify SNMPv3 user exists in Synology DSM
Check username in secret: kubectl get secret snmp-exporter-credentials -o yaml
Ensure auth/priv protocols match DSM configuration
Recreate secret if credentials changed

Missing Specific Metrics

Symptoms:

Some metrics present, others missing
Incomplete disk or volume data

Common Causes:

OID not in walk configuration
Synology model differences
Firmware version changes

Solution:

Check ConfigMap for OID definitions
Use snmpwalk to discover available OIDs
Update ConfigMap with new OIDs if needed
Restart deployment after ConfigMap changes

Configuration Changes

Update SNMP Module:

Edit manifests/base/kube-prometheus-stack/snmp-exporter-configmap.yaml
Commit and push changes
ArgoCD will sync automatically
Pod will restart with new configuration

Update Credentials:

Edit secret file (git-crypt encrypted)
Apply updated secret: kubectl apply -f snmp-exporter-secret.yaml
Restart deployment: kubectl rollout restart deployment/snmp-exporter -n default

Synology NAS Configuration

Enable SNMP on Synology DSM

Log in to DSM (https://10.0.1.204:5001)
Go to Control Panel → Terminal & SNMP
Click SNMP tab
Enable SNMPv3 service
Create SNMPv3 user:
- Username: (configure as needed)
- Auth protocol: SHA
- Auth password: (set strong password)
- Priv protocol: AES
- Priv password: (set strong password)
Apply settings

Firewall Configuration

Ensure Synology firewall allows SNMP from Kubernetes nodes:

Control Panel → Security → Firewall
Edit rules to allow UDP port 161 from cluster network
Recommended: Restrict to cluster subnet (10.0.10.0/24)

Alerting

Recommended Alerts

Disk Temperature:

- alert: DiskHighTemperature
  expr: diskTemperature > 50
  for: 10m
  annotations:
    summary: "Disk {{ $labels.disk }} temperature high"

Volume Nearly Full:

- alert: VolumeHighUsage
  expr: (volumeSize - volumeFreeSize) / volumeSize * 100 > 85
  for: 5m
  annotations:
    summary: "Volume {{ $labels.volumeDescr }} is {{ $value }}% full"

RAID Degraded:

- alert: RAIDDegraded
  expr: raidStatus != 1
  for: 1m
  annotations:
    summary: "RAID array {{ $labels.raidName }} is degraded"

Updates and Maintenance

Updating SNMP Exporter

To update to a newer version:

Update image version in deployment manifest
Check release notes
Test in non-production environment
Commit and push
ArgoCD deploys automatically

Example:

image: prom/snmp-exporter:v0.27.0  # Update from v0.26.0

MIB Updates

If Synology releases firmware updates with new MIBs:

Download updated MIB files from Synology
Generate new SNMP exporter configuration
Update ConfigMap with new OIDs
Test metrics collection
Commit changes

Performance Considerations

Scrape Interval

Current: 30s (standard Prometheus default)

Considerations:

SNMP queries are lightweight
30s provides good resolution for storage metrics
Can be reduced to 15s for more frequent updates
Increase if NAS load becomes a concern

Resource Usage

Typical:

CPU: ~20-30m
Memory: ~40-50Mi
Network: Minimal (SNMP queries are small)

Limits:

Set conservatively for Pi cluster
Monitor actual usage and adjust if needed

Migration History

Date: December 2025

SNMP exporter was added to provide comprehensive NAS monitoring:

Changes:

Deployed SNMP exporter for Synology DS925+
Configured SNMPv3 with authentication and privacy
Added comprehensive OID mappings for storage, system, network, and iSCSI metrics
Created Grafana dashboard for NAS visualization
Integrated with existing Prometheus stack
Implemented secure credential management

Overview​

Purpose​

Architecture​

Components​

SNMPv3 Configuration​

Authentication​

Credentials Management​

Deployment Configuration​

Deployment Manifest​

Service Configuration​

ConfigMap​

Prometheus Integration​

Scrape Configuration​

Collected Metrics​

Storage Metrics​

System Metrics​

Network Metrics​

iSCSI Metrics​

Grafana Dashboards​

Synology NAS Dashboard​

Common Queries​

Accessing the Exporter​

Metrics Endpoint​

Testing SNMP Connectivity​

Troubleshooting​

Check Pod Status​

Common Issues​

No Metrics Returned​

Authentication Failures​

Missing Specific Metrics​

Configuration Changes​

Synology NAS Configuration​

Enable SNMP on Synology DSM​

Firewall Configuration​

Alerting​

Recommended Alerts​

Updates and Maintenance​

Updating SNMP Exporter​

MIB Updates​

Performance Considerations​

Scrape Interval​

Resource Usage​

Migration History​

Related Documentation​

References​

Overview

Purpose

Architecture

Components

SNMPv3 Configuration

Authentication

Credentials Management

Deployment Configuration

Deployment Manifest

Service Configuration

ConfigMap

Prometheus Integration

Scrape Configuration

Collected Metrics

Storage Metrics

System Metrics

Network Metrics

iSCSI Metrics

Grafana Dashboards

Synology NAS Dashboard

Common Queries

Accessing the Exporter

Metrics Endpoint

Testing SNMP Connectivity

Troubleshooting

Check Pod Status

Common Issues

No Metrics Returned

Authentication Failures

Missing Specific Metrics

Configuration Changes

Synology NAS Configuration

Enable SNMP on Synology DSM

Firewall Configuration

Alerting

Recommended Alerts

Updates and Maintenance

Updating SNMP Exporter

MIB Updates

Performance Considerations

Scrape Interval

Resource Usage

Migration History

Related Documentation

References