SNMP Notifier

snmp_notifier receives alerts from the Prometheus' Alertmanager and routes them as SNMP traps.

Overview

The SNMP notifier receives alerts and sends them as SNMP traps to any given SNMP poller.

It has been created to handle older monitoring and alerting systems such as Nagios or Centreon.

Prometheus' Alertmanager sends the alerts to the SNMP notifier on its HTTP API. The SNMP notifier then looks for OID in the given alerts' labels. Each trap is sent with a unique ID, which allows, if the alert is updated or once it is resolved, to send additional traps with updated status and data.

Install

There are various ways to install the SNMP notifier:

Precompiled binaries

Precompiled binaries are available in the release section of this repository.

Docker Images

Docker images are available on the Docker Hub.

Compiling the binary

Check out the source code and build it manually:

git clone https://github.com/maxwo/snmp_notifier.git
cd snmp_notifier
make build
./snmp_notifier

Running and configuration

Prometheus' alerts configuration

OID may be added to the alert labels to identify the kind of trap to be sent:

A default OID is specified in the SNMP notifier if none is found in the alert. This can be useful if you want all the alerts to share the same OID.

groups:
- name: service
  rules:

  - alert: ServiceIsDown
    expr: up == 0
    for: 5m
    labels:
      severity: "critical"
      type: "service"
      oid: "1.3.6.1.4.1.123.0.10.1.1.1.5.1"
      environment: "production"
    annotations:
      description: "Service {{ $labels.job }} on {{ $labels.instance }} is down"
      summary: "A service is down."

Alertmanager configuration

The Alertmanager should be configured with the SNMP notifier as alert receiver:

receivers:

- name: 'snmp_notifier'
  webhook_configs:
  - send_resolved: true
    url: http://snmp.notifier.service:9464/alerts

Note that the send_resolved option allows the notifier to update the trap status to normal.

SNMP notifier configuration

Launch the snmp_notifier executable with the help flag to see the available options.

$ ./snmp_notifier --help
usage: snmp_notifier [<flags>]

A tool to relay Prometheus alerts as SNMP traps

Flags:
  -h, --help                     Show context-sensitive help (also try --help-long and --help-man).
      --web.listen-address=:9464
                                 Address to listen on for web interface and telemetry.
      --alert.severity-label="severity"
                                 Label where to find the alert severity.
      --alert.severities="critical,warning,info"
                                 The ordered list of alert severities, from more priority to less priority.
      --alert.default-severity="critical"
                                 The alert severity if none is provided via labels.
      --snmp.version=V2c         SNMP version. V2c and V3 are currently supported.
      --snmp.timeout=5s          SNMP timeout
      --snmp.destination=127.0.0.1:162
                                 SNMP trap server destination.
      --snmp.retries=1           SNMP number of retries
      --snmp.trap-oid-label="oid"
                                 Label where to find the trap OID.
      --snmp.trap-default-oid="1.3.6.1.4.1.98789.0.1"
                                 Trap OID to send if none is found in the alert labels.
      --snmp.trap-description-template=description-template.tpl
                                 SNMP description template.
      --snmp.extra-field-template=4=extra-field-template.tpl ...
                                 SNMP extra field templates, eg. --snmp.extra-field-templates=4=new-field.template.tpl will add the 4th field to the trap, with the given template file. You may add several fields using this flag several times.
      --snmp.community="public"  SNMP community (V2c only). Passing secrets to the command line is not recommended, consider using the SNMP_NOTIFIER_COMMUNITY environment variable instead.
      --snmp.authentication-enabled
                                 Enable SNMP authentication (V3 only).
      --snmp.authentication-protocol=MD5
                                 Protocol for password encryption (V3 only). MD5 and SHA are currently supported.
      --snmp.authentication-username=USERNAME
                                 SNMP authentication username (V3 only). Passing secrets to the command line is not recommended, consider using the SNMP_NOTIFIER_AUTH_USERNAME environment variable instead.
      --snmp.authentication-password=PASSWORD
                                 SNMP authentication password (V3 only). Passing secrets to the command line is not recommended, consider using the SNMP_NOTIFIER_AUTH_PASSWORD environment variable instead.
      --snmp.private-enabled     Enable SNMP encryption (V3 only).
      --snmp.private-protocol=DES
                                 Protocol for SNMP data transmission (V3 only). DES and AES are currently supported.
      --snmp.private-password=SECRET
                                 SNMP private password (V3 only). Passing secrets to the command line is not recommended, consider using the SNMP_NOTIFIER_PRIV_PASSWORD environment variable instead.
      --snmp.security-engine-id=SECURITY_ENGINE_ID
                                 SNMP security engine ID (V3 only).
      --snmp.context-engine-id=CONTEXT_ENGINE_ID
                                 SNMP context engine ID (V3 only).
      --snmp.context-name=CONTEXT_ENGINE_NAME
                                 SNMP context name (V3 only).
      --log.level="info"         Only log messages with the given severity or above. Valid levels: [debug, info, warn, error, fatal]
      --log.format="logger:stderr"
                                 Set the log target and format. Example: "logger:syslog?appname=bob&local=7" or "logger:stdout?json=true"
      --version                  Show application version.

Also, it is recommended to use the following environment variables to set the SNMP secrets:

Environment variable	Configuration	Default
SNMP_NOTIFIER_COMMUNITY	SNMP community for SNMP v2c	public
SNMP_NOTIFIER_AUTH_USERNAME	SNMP authentication username for SNMP v3
SNMP_NOTIFIER_AUTH_PASSWORD	SNMP authentication password for SNMP v3
SNMP_NOTIFIER_PRIV_PASSWORD	SNMP private (or server) password for SNMP v3

Any Go template directive may be used in the snmp.trap-description-template file.

Examples

Simple Usage

Here are 2 example traps received with the default configuration. It includes 2 firing alerts sharing the same OID, and 1 resolved alert.

Traps include 3 fields:

a trap unique ID;
the alert/trap status;
a description of the alerts.

$ snmptrapd -m ALL -m +SNMP-NOTIFIER-MIB -f -Of -Lo -c scripts/snmptrapd.conf
 Agent Address: 0.0.0.0
 Agent Hostname: localhost
 Date: 1 - 0 - 0 - 1 - 1 - 1970
 Enterprise OID: .
 Trap Type: Cold Start
 Trap Sub-Type: 0
 Community/Infosec Context: TRAP2, SNMP v3, user snmp_user_v3, context
 Uptime: 0
 Description: Cold Start
 PDU Attribute/Value Pair Array:
.iso.org.dod.internet.mgmt.mib-2.system.sysUpTime.sysUpTimeInstance = Timeticks: (17131100) 1 day, 23:35:11.00
.iso.org.dod.internet.snmpV2.snmpModules.snmpMIB.snmpMIBObjects.snmpTrap.snmpTrapOID.0 = OID: .iso.org.dod.internet.private.enterprises.snmpNotifier.prometheusAlerts.defaultAlert
.iso.org.dod.internet.private.enterprises.snmpNotifier.prometheusAlerts.defaultAlert.1 = STRING: "1.3.6.1.4.1.98789.0.1[environment=production,label=test]"
.iso.org.dod.internet.private.enterprises.snmpNotifier.prometheusAlerts.defaultAlert.2 = STRING: "critical"
.iso.org.dod.internet.private.enterprises.snmpNotifier.prometheusAlerts.defaultAlert.3 = STRING: "Status: critical
- Alert: TestAlert
  Summary: this is the summary
  Description: this is the description on job1

Status: warning
- Alert: TestAlert
  Summary: this is the random summary
  Description: This is the description of alert 1"
 --------------
 Agent Address: 0.0.0.0
 Agent Hostname: localhost
 Date: 1 - 0 - 0 - 1 - 1 - 1970
 Enterprise OID: .
 Trap Type: Cold Start
 Trap Sub-Type: 0
 Community/Infosec Context: TRAP2, SNMP v3, user snmp_user_v3, context
 Uptime: 0
 Description: Cold Start
 PDU Attribute/Value Pair Array:
.iso.org.dod.internet.mgmt.mib-2.system.sysUpTime.sysUpTimeInstance = Timeticks: (17129200) 1 day, 23:34:52.00
.iso.org.dod.internet.snmpV2.snmpModules.snmpMIB.snmpMIBObjects.snmpTrap.snmpTrapOID.0 = OID: .iso.org.dod.internet.private.enterprises.1234.0.10.1.1.1.1.1
.iso.org.dod.internet.private.enterprises.1234.0.10.1.1.1.1.1.1 = STRING: "1.3.6.1.4.1.1234.0.10.1.1.1.1.1[environment=production,label=test]"
.iso.org.dod.internet.private.enterprises.1234.0.10.1.1.1.1.1.2 = STRING: "info"
.iso.org.dod.internet.private.enterprises.1234.0.10.1.1.1.1.1.3 = STRING: "Status: OK"
 --------------

With extra fields

You may add additional fields thanks to the --snmp.extra-field-template arguments.

For instance, the template {{ len .Alerts }} alerts are firing. given in the --snmp.extra-field-template=4=alert-count.tpl argument will produce:

$ snmptrapd -m ALL -m +SNMP-NOTIFIER-MIB -f -Of -Lo -c scripts/snmptrapd.conf
 Agent Address: 0.0.0.0
 Agent Hostname: localhost
 Date: 1 - 0 - 0 - 1 - 1 - 1970
 Enterprise OID: .
 Trap Type: Cold Start
 Trap Sub-Type: 0
 Community/Infosec Context: TRAP2, SNMP v2c, community public
 Uptime: 0
 Description: Cold Start
 PDU Attribute/Value Pair Array:
.iso.org.dod.internet.mgmt.mib-2.system.sysUpTime.sysUpTimeInstance = Timeticks: (2665700) 7:24:17.00
.iso.org.dod.internet.snmpV2.snmpModules.snmpMIB.snmpMIBObjects.snmpTrap.snmpTrapOID.0 = OID: .iso.org.dod.internet.private.enterprises.98789.0.1
.iso.org.dod.internet.private.enterprises.98789.0.1.1 = STRING: "1.3.6.1.4.1.98789.0.1[environment=production,label=test]"
.iso.org.dod.internet.private.enterprises.98789.0.1.2 = STRING: "critical"
.iso.org.dod.internet.private.enterprises.98789.0.1.3 = STRING: "Status: critical
- Alert: TestAlert
  Summary: This is the summary
  Description: This is the description on job1

Status: warning
- Alert: TestAlert
  Summary: This is the random summary
  Description: This is the description of alert 1"
.iso.org.dod.internet.private.enterprises.98789.0.1.4 = STRING: "2 alerts are firing."
--------------

Contributing

Issues, feedback, PR welcome.

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