3.5 static_configs采集配置源码解读

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福大大架构师每日一题 2024-07-09 11:37:37 ©著作权

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本节重点介绍 :

采集段静态配置的解释
static_configs解析相关源码解读

采集段的解释

采集段是以job为单位配置的

# 采集配置段
scrape_configs:
  # The job name is added as a label `job=<job_name>` to any timeseries scraped from this config.
  - job_name: 'prometheus'

    # metrics_path defaults to '/metrics'
    # scheme defaults to 'http'.

    static_configs:
    - targets: ['localhost:9090']

target页面上可以看到相关的job
采集段中有很多配置项目，在页面上观察配置文件可以看到补全的信息

- job_name: prometheus
  # true代表使用原始数据的时间戳，false代表使用prometheus采集器的时间戳
  honor_timestamps: true
  # 多久执行一次采集，就是这个job 多久执行一次
  scrape_interval: 15s
  # 采集的超时
  scrape_timeout: 15s
  # 就是采集target的 metric暴露 http path，默认是/metrics ,比如探针型的就是/probe
  metrics_path: /metrics
  # 采集目标的协议 是否是https
  scheme: http
  # 是否跟踪 redirect 
  follow_redirects: true
  static_configs:
  - targets:
    - localhost:9090

查看源码

D:\go_path\src\github.com\prometheus\prometheus\config\config.go +380
可以看到全量的配置项

type ScrapeConfig struct {
	// The job name to which the job label is set by default.
	JobName string `yaml:"job_name"`
	// Indicator whether the scraped metrics should remain unmodified.
	HonorLabels bool `yaml:"honor_labels,omitempty"`
	// Indicator whether the scraped timestamps should be respected.
	HonorTimestamps bool `yaml:"honor_timestamps"`
	// A set of query parameters with which the target is scraped.
	Params url.Values `yaml:"params,omitempty"`
	// How frequently to scrape the targets of this scrape config.
	ScrapeInterval model.Duration `yaml:"scrape_interval,omitempty"`
	// The timeout for scraping targets of this config.
	ScrapeTimeout model.Duration `yaml:"scrape_timeout,omitempty"`
	// The HTTP resource path on which to fetch metrics from targets.
	MetricsPath string `yaml:"metrics_path,omitempty"`
	// The URL scheme with which to fetch metrics from targets.
	Scheme string `yaml:"scheme,omitempty"`
	// An uncompressed response body larger than this many bytes will cause the
	// scrape to fail. 0 means no limit.
	BodySizeLimit units.Base2Bytes `yaml:"body_size_limit,omitempty"`
	// More than this many samples post metric-relabeling will cause the scrape to
	// fail.
	SampleLimit uint `yaml:"sample_limit,omitempty"`
	// More than this many targets after the target relabeling will cause the
	// scrapes to fail.
	TargetLimit uint `yaml:"target_limit,omitempty"`
	// More than this many labels post metric-relabeling will cause the scrape to
	// fail.
	LabelLimit uint `yaml:"label_limit,omitempty"`
	// More than this label name length post metric-relabeling will cause the
	// scrape to fail.
	LabelNameLengthLimit uint `yaml:"label_name_length_limit,omitempty"`
	// More than this label value length post metric-relabeling will cause the
	// scrape to fail.
	LabelValueLengthLimit uint `yaml:"label_value_length_limit,omitempty"`

	// We cannot do proper Go type embedding below as the parser will then parse
	// values arbitrarily into the overflow maps of further-down types.

	ServiceDiscoveryConfigs discovery.Configs       `yaml:"-"`
	HTTPClientConfig        config.HTTPClientConfig `yaml:",inline"`

	// List of target relabel configurations.
	RelabelConfigs []*relabel.Config `yaml:"relabel_configs,omitempty"`
	// List of metric relabel configurations.
	MetricRelabelConfigs []*relabel.Config `yaml:"metric_relabel_configs,omitempty"`
}

static_configs 段代表静态配置采集的端点
为何在上述ScrapeConfig配置段中没有找到 static_configs配置项，这又是怎么回事呢

源码搜索思路

在prometheus 源码目录搜索 static_configs
发现在文件 D:\go_path\src\github.com\prometheus\prometheus\discovery\registry.go中有

3.5 static_configs采集配置源码解读_服务发现

看到这里在registry.go中的init 函数会在包自动导入的时候注册static_configs 到configFields中
所有服务发现都会在各自包中的init方法自动注册自己

追查 configFields是干什么用的

D:\go_path\src\github.com\prometheus\prometheus\config\config.go
ScrapeConfig实现了 yaml的Unmarshaler接口中的UnmarshalYAML方法
所以在yaml解析的时候 ScrapeConfig字段时会调用这个UnmarshalYAML方法

func (c *ScrapeConfig) UnmarshalYAML(unmarshal func(interface{}) error) error {
	*c = DefaultScrapeConfig
	if err := discovery.UnmarshalYAMLWithInlineConfigs(c, unmarshal); err != nil {
		return err
	}