config/config.go
func (c *ScrapeConfig) UnmarshalYAML(unmarshal func(interface{}) error) error {
	*c = DefaultScrapeConfig
	type plain ScrapeConfig
	err := unmarshal((*plain)(c))
	if err != nil {
		return err
	}
	if len(c.JobName) == 0 {
		return errors.New("job_name is empty")
	}

	// The UnmarshalYAML method of HTTPClientConfig is not being called because it's not a pointer.
	// We cannot make it a pointer as the parser panics for inlined pointer structs.
	// Thus we just do its validation here.
	if err := c.HTTPClientConfig.Validate(); err != nil {
		return err
	}

	// The UnmarshalYAML method of ServiceDiscoveryConfig is not being called because it's not a pointer.
	// We cannot make it a pointer as the parser panics for inlined pointer structs.
	// Thus we just do its validation here.
	if err := c.ServiceDiscoveryConfig.Validate(); err != nil {
		return err
	}

	// Check for users putting URLs in target groups.
	if len(c.RelabelConfigs) == 0 {
		for _, tg := range c.ServiceDiscoveryConfig.StaticConfigs {
			for _, t := range tg.Targets {
				if err := CheckTargetAddress(t[model.AddressLabel]); err != nil {
					return err
				}
			}
		}
	}

	for _, rlcfg := range c.RelabelConfigs {
		if rlcfg == nil {
			return errors.New("empty or null target relabeling rule in scrape config")
		}
	}
	for _, rlcfg := range c.MetricRelabelConfigs {
		if rlcfg == nil {
			return errors.New("empty or null metric relabeling rule in scrape config")
		}
	}

	// Add index to the static config target groups for unique identification
	// within scrape pool.
	for i, tg := range c.ServiceDiscoveryConfig.StaticConfigs {
		tg.Source = fmt.Sprintf("%d", i)
	}

	return nil
}
func (c *ScrapeConfig) UnmarshalYAML(unmarshal func(interface{}) error) error {
	*c = DefaultScrapeConfig
	type plain ScrapeConfig
	err := unmarshal((*plain)(c))
	if err != nil {
		return err
	}
	if len(c.JobName) == 0 {
		return errors.New("job_name is empty")
	}

	// The UnmarshalYAML method of HTTPClientConfig is not being called because it's not a pointer.
	// We cannot make it a pointer as the parser panics for inlined pointer structs.
	// Thus we just do its validation here.
	if err := c.HTTPClientConfig.Validate(); err != nil {
		return err
	}

	// The UnmarshalYAML method of ServiceDiscoveryConfig is not being called because it's not a pointer.
	// We cannot make it a pointer as the parser panics for inlined pointer structs.
	// Thus we just do its validation here.
	if err := c.ServiceDiscoveryConfig.Validate(); err != nil {
		return err
	}

	// Check for users putting URLs in target groups.
	if len(c.RelabelConfigs) == 0 {
		for _, tg := range c.ServiceDiscoveryConfig.StaticConfigs {
			for _, t := range tg.Targets {
				if err := CheckTargetAddress(t[model.AddressLabel]); err != nil {
					return err
				}
			}
		}
	}

	for _, rlcfg := range c.RelabelConfigs {
		if rlcfg == nil {
			return errors.New("empty or null target relabeling rule in scrape config")
		}
	}
	for _, rlcfg := range c.MetricRelabelConfigs {
		if rlcfg == nil {
			return errors.New("empty or null metric relabeling rule in scrape config")
		}
	}

	// Add index to the static config target groups for unique identification
	// within scrape pool.
	for i, tg := range c.ServiceDiscoveryConfig.StaticConfigs {
		tg.Source = fmt.Sprintf("%d", i)
	}

	return nil
}
// UnmarshalYAML implements the yaml.Unmarshaler interface.