This exporter is the recommended way to expose SNMP data in a format which Prometheus can ingest. （这个exporter是以prometheus公开推荐的方式获取数据的）
To simply get started, it's recommended to use the if_mib module with
switches, access points, or routers using the public_v2 auth module,
which should be a read-only access community on the target device.
Note, community strings in SNMP are not considered secrets, as they are sent unencrypted in SNMP v1 and v2c. For secure access, SNMP v3 is required.
（概念）
While SNMP uses a hierarchical data structure and Prometheus uses an
n-dimensional matrix, the two systems map perfectly, and without the need
to walk through data by hand. snmp_exporter maps the data for you.
（虽然snmp是层次结构的，而prometheus是N维矩阵，但是两者是可以完美衔接的。）
Prometheus is able to map SNMP index instances to labels. For example, the ifEntry specifies an INDEX of ifIndex. This becomes the ifIndex label in Prometheus.
If an SNMP entry has multiple index values, each value is mapped to a separate Prometheus label.
SNMP is structured in OID trees, described by MIBs. OID subtrees have the same
order across different locations in the tree. The order under
1.3.6.1.2.1.2.2.1.1 (ifIndex) is the same as in 1.3.6.1.2.1.2.2.1.2
(ifDescr), 1.3.6.1.2.1.31.1.1.1.10 (ifHCOutOctets), etc. The numbers are
OIDs, the names in parentheses are the names from a MIB, in this case
IF-MIB.
（映射）
Given a device with an interface at number 2, a partial snmpwalk return looks
like:
1.3.6.1.2.1.2.2.1.1.2 = INTEGER: 2 # ifIndex for '2' is literally just '2'
1.3.6.1.2.1.2.2.1.2.2 = STRING: "eth0" # ifDescr
1.3.6.1.2.1.31.1.1.1.1.2 = STRING: "eth0" # IfName
1.3.6.1.2.1.31.1.1.1.10.2 = INTEGER: 1000 # ifHCOutOctets, 1000 bytes
1.3.6.1.2.1.31.1.1.1.18.2 = STRING: "" # ifAlias
snmp_exporter combines all of this data into:
ifHCOutOctets{ifAlias="",ifDescr="eth0",ifIndex="2",ifName="eth0"} 1000
（缩放）
A single instance of snmp_exporter can be run for thousands of devices.
（用法）
（安装）
Binaries can be downloaded from the Github releases page and need no special installation.
We also provide a sample systemd unit file.
（运行）
Start snmp_exporter as a daemon or from CLI:
./snmp_exporterVisit http://localhost:9116/snmp?target=192.0.0.8 where 192.0.0.8 is the IP or
FQDN of the SNMP device to get metrics from. Note that this will use the default transport (udp),
default port (161), default auth (public_v2) and default module (if_mib). The auth and module
must be defined in the snmp.yml file.
For example, if you have an auth named my_secure_v3 for walking ddwrt, the URL would look like
http://localhost:9116/snmp?auth=my_secure_v3&module=ddwrt&target=192.0.0.8.
To configure a different transport and/or port, use the syntax [transport://]host[:port].
For example, to scrape a device using tcp on port 1161, the URL would look like
http://localhost:9116/snmp?auth=my_secure_v3&module=ddwrt&target=tcp%3A%2F%2F192.0.0.8%3A1161.
Note that URL encoding should be used for target due
to the : and / characters. Prometheus encodes query parameters automatically and manual encoding
is not necessary within the Prometheus configuration file.
Metrics concerning the operation of the exporter itself are available at the endpoint http://localhost:9116/metrics.
It is possible to supply an optional snmp_context parameter in the URL, like this:
http://localhost:9116/snmp?auth=my_secure_v3&module=ddwrt&target=192.0.0.8&snmp_context=vrf-mgmt
The snmp_context parameter in the URL would override the context_name parameter in the snmp.yml file.
The multi-module functionality allows you to specify multiple modules, enabling the retrieval of information from several modules in a single scrape.
The concurrency can be specified using the snmp-exporter option --snmp.module-concurrency (the default is 1).
Note: This implementation does not perform any de-duplication of walks between different modules.
There are two ways to specify multiple modules. You can either separate them with a comma or define multiple params_module. The URLs would look like this:
For comma separation:
http://localhost:9116/snmp?module=if_mib,arista_sw&target=192.0.0.8
For multiple params_module:
http://localhost:9116/snmp?module=if_mib&module=arista_sw&target=192.0.0.8
Prometheus Example:
- job_name: 'my'
params:
module:
- if_mib
- synology
- ucd_la_table（配置）
The default configuration file name is snmp.yml and should not be edited
by hand. If you need to change it, see
Generating configuration.
The default snmp.yml file covers a variety of common hardware walking them
using SNMP v2 GETBULK.
The --config.file parameter can be used multiple times to load more than one file.
It also supports glob filename matching, e.g. snmp*.yml.
The --config.expand-environment-variables parameter allows passing environment variables into some fields of the configuration file. The username, password & priv_password fields in the auths section are supported. Defaults to disabled.
Duplicate module or auth entries are treated as invalid and can not be loaded.
（Prometheus配置）
The URL params target, auth, and module can be controlled through relabelling.
Example config:
scrape_configs:
- job_name: 'snmp'
static_configs:
- targets:
- 192.168.1.2 # SNMP device.
- switch.local # SNMP device.
- tcp://192.168.1.3:1161 # SNMP device using TCP transport and custom port.
metrics_path: /snmp
params:
auth: [public_v2]
module: [if_mib]
relabel_configs:
- source_labels: [__address__]
target_label: __param_target
- source_labels: [__param_target]
target_label: instance
- target_label: __address__
replacement: 127.0.0.1:9116 # The SNMP exporter's real hostname:port.
# Global exporter-level metrics
- job_name: 'snmp_exporter'
static_configs:
- targets: ['localhost:9116']You could pass username, password & priv_password via environment variables of your choice in below format.
If the variables exist in the environment, they are resolved on the fly otherwise the string in the config file is passed as-is.
This requires the --config.expand-environment-variables flag be set.
auths:
example_with_envs:
community: mysecret
security_level: SomethingReadOnly
username: ${ARISTA_USERNAME}
password: ${ARISTA_PASSWORD}
auth_protocol: SHA256
priv_protocol: AES
priv_password: ${ARISTA_PRIV_PASSWORD}Similarly to blackbox_exporter,
snmp_exporter is meant to run on a few central machines and can be thought of
like a "Prometheus proxy".
The SNMP Exporter supports TLS and basic authentication. This enables better control of the various HTTP endpoints.
To use TLS and/or basic authentication, you need to pass a configuration file
using the --web.config.file parameter. The format of the file is described
in the exporter-toolkit repository.
Note that the TLS and basic authentication settings affect all HTTP endpoints: /metrics for scraping, /snmp for scraping SNMP devices, and the web UI.
Most use cases should be covered by our default configuration. If you need to generate your own configuration from MIBs, you can use the generator.
Use the generator if you need to customize which objects are walked or use non-public MIBs.
（大规模计数值处理）
In order to provide accurate counters for large Counter64 values, the exporter will automatically wrap the value every 2^53 to avoid 64-bit float rounding. Prometheus handles this gracefully for you and you will not notice any negative effects.
If you need to disable this feature for non-Prometheus systems, use the
command line flag --no-snmp.wrap-large-counters.
（马上开启运行）
It can be opaque to get started with all this, but in our own experience,
snmp_exporter is honestly the best way to interact with SNMP. To make it
easier for others, please consider contributing back your configurations to
us.
（刚开始接触这一切可能会有些困难，但根据我们的实际经验来看，“snmp_exporter”确实是与 SNMP 进行交互的最佳方式。为了方便其他人使用，建议您将您的配置信息回馈给我们。）
snmp.yml config should be accompanied by generator config.
For your dashboard, alerts, and recording rules, please consider
contributing them to https://github.com/prometheus/snmp_exporter/tree/main/snmp-mixin.
（‘snmp.yml’配置文件应与生成器配置文件一同提供。对于您的仪表板、警报和记录规则，请考虑将其贡献出来。）