本文按照官方文档的相关内容整理整理的配置语法以及实现功能

1.prometheus 配置文件主体

# 此片段指定的是prometheus的全局配置， 比如采集间隔，抓取超时时间等.
global:
  # 抓取间隔
  [ scrape_interval: <duration> | default = 1m ]

  # 抓取超时时间
  [ scrape_timeout: <duration> | default = 10s ]

  # 评估规则间隔
  [ evaluation_interval: <duration> | default = 1m ]

  # 外部一些标签设置
  external_labels:
    [ <labelname>: <labelvalue> ... ]

  # File to which PromQL queries are logged.
  # Reloading the configuration will reopen the file.
  [ query_log_file: <string> ]

# 此片段指定报警规则文件， prometheus根据这些规则信息，会推送报警信息到alertmanager中。
rule_files:
  [ - <filepath_glob> ... ]

# 此片段指定抓取配置，prometheus的数据采集通过此片段配置。
scrape_configs:
  [ - <scrape_config> ... ]

# 此片段指定报警配置， 这里主要是指定prometheus将报警规则推送到指定的alertmanager实例地址。
alerting:
  alert_relabel_configs:
    [ - <relabel_config> ... ]
  alertmanagers:
    [ - <alertmanager_config> ... ]

# 指定后端的存储的写入api地址。
remote_write:
  [ - <remote_write> ... ]

# 指定后端的存储的读取api地址。
remote_read:
  [ - <remote_read> ... ]

2.scrape_configs配置详解

一个scrape_config 片段指定一组目标和参数， 目标就是实例，指定采集的端点， 参数描述如何采集这些实例， 配置文件格式如下

# The job name assigned to scraped metrics by default.
job_name: <job_name>

# 抓取间隔,默认继承global值。
[ scrape_interval: <duration> | default = <global_config.scrape_interval> ]

# 抓取超时时间,默认继承global值。
[ scrape_timeout: <duration> | default = <global_config.scrape_timeout> ]

# 抓取路径， 默认是/metrics
[ metrics_path: <path> | default = /metrics ]

# honor_labels controls how Prometheus handles conflicts between labels that are
# already present in scraped data and labels that Prometheus would attach
# server-side ("job" and "instance" labels, manually configured target
# labels, and labels generated by service discovery implementations).
#
# If honor_labels is set to "true", label conflicts are resolved by keeping label
# values from the scraped data and ignoring the conflicting server-side labels.
#
# If honor_labels is set to "false", label conflicts are resolved by renaming
# conflicting labels in the scraped data to "exported_<original-label>" (for
# example "exported_instance", "exported_job") and then attaching server-side
# labels.
#
# Setting honor_labels to "true" is useful for use cases such as federation and
# scraping the Pushgateway, where all labels specified in the target should be
# preserved.
#
# Note that any globally configured "external_labels" are unaffected by this
# setting. In communication with external systems, they are always applied only
# when a time series does not have a given label yet and are ignored otherwise.
[ honor_labels: <boolean> | default = false ]

# honor_timestamps controls whether Prometheus respects the timestamps present
# in scraped data.
#
# If honor_timestamps is set to "true", the timestamps of the metrics exposed
# by the target will be used.
#
# If honor_timestamps is set to "false", the timestamps of the metrics exposed
# by the target will be ignored.
[ honor_timestamps: <boolean> | default = true ]

# 指定采集使用的协议，http或者https。
[ scheme: <scheme> | default = http ]

# 指定url参数。
params:
  [ <string>: [<string>, ...] ]

# 指定认证信息。
basic_auth:
  [ username: <string> ]
  [ password: <secret> ]
  [ password_file: <string> ]

# 指定token的数值， 用户get metrics认证使用
[ bearer_token: <secret> ]

# 指定获取token的文件， 用户get metrics认证使用
[ bearer_token_file: /path/to/bearer/token/file ]

# 指定获取metrics时需要的tls证书
tls_config:
  [ <tls_config> ]

# Optional proxy URL.
[ proxy_url: <string> ]

# List of Azure service discovery configurations.
azure_sd_configs:
  [ - <azure_sd_config> ... ]

# List of Consul service discovery configurations.
consul_sd_configs:
  [ - <consul_sd_config> ... ]

# List of DNS service discovery configurations.
dns_sd_configs:
  [ - <dns_sd_config> ... ]

# List of EC2 service discovery configurations.
ec2_sd_configs:
  [ - <ec2_sd_config> ... ]

# List of OpenStack service discovery configurations.
openstack_sd_configs:
  [ - <openstack_sd_config> ... ]

# List of file service discovery configurations.
file_sd_configs:
  [ - <file_sd_config> ... ]

# List of GCE service discovery configurations.
gce_sd_configs:
  [ - <gce_sd_config> ... ]

# List of Kubernetes service discovery configurations.
kubernetes_sd_configs:
  [ - <kubernetes_sd_config> ... ]

# List of Marathon service discovery configurations.
marathon_sd_configs:
  [ - <marathon_sd_config> ... ]

# List of AirBnB's Nerve service discovery configurations.
nerve_sd_configs:
  [ - <nerve_sd_config> ... ]

# List of Zookeeper Serverset service discovery configurations.
serverset_sd_configs:
  [ - <serverset_sd_config> ... ]

# List of Triton service discovery configurations.
triton_sd_configs:
  [ - <triton_sd_config> ... ]

# 静态指定服务job
static_configs:
  [ - <static_config> ... ]

# 控制采集哪些数据标签，可以删除不必要的标签
relabel_configs:
  [ - <relabel_config> ... ]

# 添加、编辑或修改指标的标签值或标签格式。
metric_relabel_configs:
  [ - <relabel_config> ... ]

# Per-scrape limit on number of scraped samples that will be accepted.
# If more than this number of samples are present after metric relabelling
# the entire scrape will be treated as failed. 0 means no limit.
[ sample_limit: <int> | default = 0 ]

因为部署在kubernetes环境中所以我只在意基于kubernetes_sd_configs的服务发现和static_configs静态文件的发现

2.1 relabel_configs

relable_configss是功能强大的工具，就是Relabel可以在Prometheus采集数据之前，通过Target实例的Metadata信息，动态重新写入Label的值。除此之外，我们还能根据Target实例的Metadata信息选择是否采集或者忽略该Target实例。

relabel_configs

配置格式如下：

# The source labels select values from existing labels. Their content is concatenated
# using the configured separator and matched against the configured regular expression
# for the replace, keep, and drop actions.
[ source_labels: '[' <labelname> [, ...] ']' ]

# 默认分隔符
[ separator: <string> | default = ; ]

# Label to which the resulting value is written in a replace action.
# It is mandatory for replace actions. Regex capture groups are available.
[ target_label: <labelname> ]

# Regular expression against which the extracted value is matched.
[ regex: <regex> | default = (.*) ]

# Modulus to take of the hash of the source label values.
[ modulus: <uint64> ]

# Replacement value against which a regex replace is performed if the
# regular expression matches. Regex capture groups are available.
[ replacement: <string> | default = $1 ]

# Action to perform based on regex matching.
[ action: <relabel_action> | default = replace ]

其中action主要包括:

• replace
• keep
• drop
• hashmod
• labelmap
• labeldrop
• labelkeep

replace：默认，通过regex匹配source_label的值，使用replacement来引用表达式匹配的分组
keep：删除regex与连接不匹配的目标 source_labels
drop：删除regex与连接匹配的目标 source_labels
labeldrop：删除regex匹配的标签
labelkeep：删除regex不匹配的标签
hashmod：设置target_label为modulus连接的哈希值source_labels
labelmap：匹配regex所有标签名称。然后复制匹配标签的值进行分组，replacement分组引用（{2},…）替代

prometheus中的数值都是key:value格式， 其中replace、keep、drop都是对value的操作， labelmap、labeldrop、labelkeep都是对key的操作

replace用法

replace是action的默认值， 通过regex匹配source_label的值，使用replacement来引用表达式匹配的分组

  - action: replace
    regex: ([^:]+)(?::\d+)?;(\d+)
    replacement: $1:$2
    source_labels:
    - __address__
    - __meta_kubernetes_service_annotation_prometheus_io_port
    target_label: __address__

上面的列子中address的值为$1:$2， 其中 $1 是正则表达式([^:]+)(?::\d+)?从address中获取， $2是正则表达式(\d+)从(\d+)中获取， 最后的address的数值为192.168.1.1:9100

keep用法

relabel_configs:
  - source_labels: [__meta_kubernetes_service_annotation_prometheus_io_probe]
    action: keep
    regex: true

上面的例子只要匹配__meta_kubernetes_service_annotation_prometheus_io_probe=true数据就保留， 反正source_labels中的值没有匹配regex中的值就丢弃

drop用法

drop 的使用和keep刚好相反， 还是使用keep的例子:

relabel_configs:
  - source_labels: [__meta_kubernetes_service_annotation_prometheus_io_probe]
    action: keep
    regex: true

上面的例子只要__meta_kubernetes_service_annotation_prometheus_io_probe这个标签的值为true就丢弃， 反之如果__meta_kubernetes_service_annotation_prometheus_io_probe!=true的数据就保留

labelmap用法

labelmap的用法和上面说到replace、keep、drop不同， labelmap匹配的是标签名称， 而replace、keep、drop匹配的是value

relabel_configs:
  - action: labelmap
    regex: __meta_kubernetes_service_label_(.+)

上面例子中只要匹配到正则表达式__meta_kubernetes_service_label_(.+)的标签， 就将标签重写为(.+)中的内容， 效果如下：

原标签： __meta_kubernetes_service_label_test=111 
重写后： test=111

hashmod用法

待续

2.1.6 labeldrop用法

使用labeldrop则可以对Target标签进行过滤，删除符合过滤条件的标签，例如：

relabel_configs:
  - action: labeldrop
    regex: __meta_kubernetes_service_label_(.+)

该配置会使用regex匹配当前target中的所有标签， 删除符合规则的标签， 反之保留不符合规则的

labelkeep用法

使用labelkeep则可以对Target标签进行过滤，仅保留符合过滤条件的标签，例如：

relabel_configs:
  - action: labelkeep
    regex: __meta_kubernetes_service_label_(.+)

该配置会使用regex匹配当前target中的所有标签， 保留符合规则的标签， 反之不符合的移除

2.2 metric_relabel_configs

上面我们说到relabel_config是获取metrics之前对标签的重写， 对应的metric_relabel_configs是对获取metrics之后对标签的操作， metric_relabel_configs能够确定我们保存哪些指标，删除哪些指标，以及这些指标将是什么样子。

metric_relabel_configs的配置和relabel_config的配置基本相同， 如果需要配置相关参数请参考2.scrape_configs

2.2 static_configs

主要用途为指定exporter获取metrics数据的目标， 可以指定prometheus、 mysql、 nginx等目标

    scrape_configs:
    - job_name: prometheus
      static_configs:
      - targets:
        - localhost:9090

此规则主要是用于抓取prometheus自己数据的配置， targets列表中的为prometheus 获取metrics的地址和端口， 因为没有指定metrics_path所以使用默认的/metrics中获取数据，

简单理解就是， prometheus访问 http://localhost:9090/metrics 获取监控数据

还可以配置指定exporter中的目的地址， 如获取node_exporter的数据

scrape_configs: 
- job_name: node 
  static_configs: 
  - targets: 
    - 10.40.58.153:9100 
    - 10.40.61.116:9100 
    - 10.40.58.154:9100 

简单理解为分别访问 http://10.40.58.153:9100/metrics http://10.40.58.154:9100/metrics http://10.40.61.116:9100/metrics 获取metrics数据

2.3 kubernetes_sd_configs

kubernetes的服务发现可以刮取以下几种数据

• node
• service
• pod
• endpoints
• ingress

通过指定kubernetes_sd_config的模式为endpoints，Prometheus会自动从Kubernetes中发现到所有的endpoints节点并作为当前Job监控的Target实例。如下所示，

kubernetes_sd_configs:   
- role: endpoints

配置实例一

该配置是使用kubernetes的发现机制发现kube-apiservers

scrape_configs:
- bearer_token_file: /var/run/secrets/kubernetes.io/serviceaccount/token
  job_name: kubernetes-apiservers 
  kubernetes_sd_configs:   
  - role: endpoints
  relabel_configs:
  - action: keep
    regex: default;kubernetes;https
    source_labels:
    - __meta_kubernetes_namespace
    - __meta_kubernetes_service_name
    - __meta_kubernetes_endpoint_port_name
  scheme: https
  tls_config:
    ca_file: /var/run/secrets/kubernetes.io/serviceaccount/ca.crt
    insecure_skip_verify: true

上面的刮取配置定义了如下信息：

• job名称为kubernetes-apiservers(job-name: kubernetes-apiservers)
• 获取kubernetes中endpoints的相关信息(role: endpoints)
• 使用https的方式获取信息(scheme: https)
• target的需要满足default名称空间下service名字为kubernetes，并且端口为https
  • __meta_kubernetes_namespace=～default
  • __meta_kubernetes_service_name=～kubernetes
  • __meta_kubernetes_endpoint_port_name=～=https

配置实例二

该配置是自动发现kubernetes中的endpoints

- job_name: 'kubernetes-service-endpoints'

kubernetes_sd_configs:
  - role: endpoints

relabel_configs:
  - source_labels: [__meta_kubernetes_service_annotation_prometheus_io_scrape]
    action: keep
    regex: true
    
  - source_labels: [__meta_kubernetes_service_annotation_prometheus_io_scheme]
    action: replace
    target_label: __scheme__
    regex: (https?)
  - source_labels: [__meta_kubernetes_service_annotation_prometheus_io_path]
    action: replace
    target_label: __metrics_path__
    regex: (.+)
  - source_labels: [__address__, __meta_kubernetes_service_annotation_prometheus_io_port]
    action: replace
    target_label: __address__
    regex: ([^:]+)(?::\d+)?;(\d+)
    replacement: $1:$2
    
  - action: labelmap
    regex: __meta_kubernetes_service_label_(.+)
    
  - source_labels: [__meta_kubernetes_namespace]
    action: replace
    target_label: kubernetes_namespace
  - source_labels: [__meta_kubernetes_service_name]
    action: replace
    target_label: kubernetes_name
  - source_labels: [__meta_kubernetes_pod_node_name]
    action: replace
    target_label: kubernetes_node

可以看到relable_configs中的规则很多， 具体的内容如下

• job名称为kubernetes-service-endpoints(job-name: kubernetes-service-endpoints)
• 获取kubernetes中endpoints的相关信息(role: endpoints)
• 使用http的方式获取信息(没有配置使用默认配置http)
• relabel配置部分：

  • annotations中必须存在prometheus.io/scrape: "true"配置才会被promethues发现

  • __scheme__的值为__meta_kubernetes_service_annotation_prometheus_io_scheme的value， 需要满足正则表达式(https?)

  • __metrics_path__的值为__meta_kubernetes_service_annotation_prometheus_io_path的value， 满足正则表达式(.+)

  • __address__的value替换为IP:port的方式

  • kubernetes_namespace的value replace为__meta_kubernetes_namespace的value

  • kubernetes_name的value replace为__meta_kubernetes_service_name的value

  • kubernetes_node的value replace为__meta_kubernetes_pod_node_name的value

获取的metrics的信息如下：

up{app="prometheus",app_kubernetes_io_managed_by="Helm",chart="prometheus-11.3.0",component="node-exporter",heritage="Helm",instance="10.40.61.116:9100",job="kubernetes-service-endpoints",kubernetes_name="prometheus-node-exporter",kubernetes_namespace="devops",kubernetes_node="py-modelo2o08cn-p005.pek3.example.com",release="prometheus"}