Relabel job_name as a meta label (prometheus-operator#3828)

* Relabel job_name as a meta label

Keeping job_name as a meta label (__meta_prometheus_job_name) allows
users to keep it after further relabeling, e.g. for debugging purposes.

* Fix tests (add __meta_prometheus_job_name relabeling)

* Rename __meta_prometheus_job_name -> __tmp_prometheus_job_name

* Initialize relabelings with job -> __tmp_prometheus_job_name replacement

* Refactor relabelings initialization & docs

* auto-generated files

* auto-generated api.md

Documentation/api.md

@@ -289,7 +289,7 @@ Endpoint defines a scrapeable endpoint serving Prometheus metrics.
 | honorTimestamps | HonorTimestamps controls whether Prometheus respects the timestamps present in scraped data. | *bool | false |
 | basicAuth | BasicAuth allow an endpoint to authenticate over basic authentication More info: https://prometheus.io/docs/operating/configuration/#endpoints | *[BasicAuth](#basicauth) | false |
 | metricRelabelings | MetricRelabelConfigs to apply to samples before ingestion. | []*[RelabelConfig](#relabelconfig) | false |
-| relabelings | RelabelConfigs to apply to samples before scraping. More info: https://prometheus.io/docs/prometheus/latest/configuration/configuration/#relabel_config | []*[RelabelConfig](#relabelconfig) | false |
+| relabelings | RelabelConfigs to apply to samples before scraping. Prometheus Operator automatically adds relabelings for a few standard Kubernetes fields and replaces original scrape job name with __tmp_prometheus_job_name. More info: https://prometheus.io/docs/prometheus/latest/configuration/configuration/#relabel_config | []*[RelabelConfig](#relabelconfig) | false |
 | proxyUrl | ProxyURL eg http://proxyserver:2195 Directs scrapes to proxy through this endpoint. | *string | false |
 
 [Back to TOC](#table-of-contents)
@@ -335,7 +335,7 @@ PodMetricsEndpoint defines a scrapeable endpoint of a Kubernetes Pod serving Pro
 | honorTimestamps | HonorTimestamps controls whether Prometheus respects the timestamps present in scraped data. | *bool | false |
 | basicAuth | BasicAuth allow an endpoint to authenticate over basic authentication. More info: https://prometheus.io/docs/operating/configuration/#endpoint | *[BasicAuth](#basicauth) | false |
 | metricRelabelings | MetricRelabelConfigs to apply to samples before ingestion. | []*[RelabelConfig](#relabelconfig) | false |
-| relabelings | RelabelConfigs to apply to samples before ingestion. More info: https://prometheus.io/docs/prometheus/latest/configuration/configuration/#relabel_config | []*[RelabelConfig](#relabelconfig) | false |
+| relabelings | RelabelConfigs to apply to samples before scraping. Prometheus Operator automatically adds relabelings for a few standard Kubernetes fields and replaces original scrape job name with __tmp_prometheus_job_name. More info: https://prometheus.io/docs/prometheus/latest/configuration/configuration/#relabel_config | []*[RelabelConfig](#relabelconfig) | false |
 | proxyUrl | ProxyURL eg http://proxyserver:2195 Directs scrapes to proxy through this endpoint. | *string | false |
 
 [Back to TOC](#table-of-contents)

bundle.yaml

@@ -5247,7 +5247,7 @@ spec:
                       description: ProxyURL eg http://proxyserver:2195 Directs scrapes to proxy through this endpoint.
                       type: string
                     relabelings:
-                      description: 'RelabelConfigs to apply to samples before ingestion. More info: https://prometheus.io/docs/prometheus/latest/configuration/configuration/#relabel_config'
+                      description: 'RelabelConfigs to apply to samples before scraping. Prometheus Operator automatically adds relabelings for a few standard Kubernetes fields and replaces original scrape job name with __tmp_prometheus_job_name. More info: https://prometheus.io/docs/prometheus/latest/configuration/configuration/#relabel_config'
                       items:
                         description: 'RelabelConfig allows dynamic rewriting of the label set, being applied to samples before ingestion. It defines `<metric_relabel_configs>`-section of Prometheus configuration. More info: https://prometheus.io/docs/prometheus/latest/configuration/configuration/#metric_relabel_configs'
                         properties:
@@ -10474,7 +10474,7 @@ spec:
                       description: ProxyURL eg http://proxyserver:2195 Directs scrapes to proxy through this endpoint.
                       type: string
                     relabelings:
-                      description: 'RelabelConfigs to apply to samples before scraping. More info: https://prometheus.io/docs/prometheus/latest/configuration/configuration/#relabel_config'
+                      description: 'RelabelConfigs to apply to samples before scraping. Prometheus Operator automatically adds relabelings for a few standard Kubernetes fields and replaces original scrape job name with __tmp_prometheus_job_name. More info: https://prometheus.io/docs/prometheus/latest/configuration/configuration/#relabel_config'
                       items:
                         description: 'RelabelConfig allows dynamic rewriting of the label set, being applied to samples before ingestion. It defines `<metric_relabel_configs>`-section of Prometheus configuration. More info: https://prometheus.io/docs/prometheus/latest/configuration/configuration/#metric_relabel_configs'
                         properties:

example/prometheus-operator-crd/monitoring.coreos.com_podmonitors.yaml

@@ -160,7 +160,7 @@ spec:
                       description: ProxyURL eg http://proxyserver:2195 Directs scrapes to proxy through this endpoint.
                       type: string
                     relabelings:
-                      description: 'RelabelConfigs to apply to samples before ingestion. More info: https://prometheus.io/docs/prometheus/latest/configuration/configuration/#relabel_config'
+                      description: 'RelabelConfigs to apply to samples before scraping. Prometheus Operator automatically adds relabelings for a few standard Kubernetes fields and replaces original scrape job name with __tmp_prometheus_job_name. More info: https://prometheus.io/docs/prometheus/latest/configuration/configuration/#relabel_config'
                       items:
                         description: 'RelabelConfig allows dynamic rewriting of the label set, being applied to samples before ingestion. It defines `<metric_relabel_configs>`-section of Prometheus configuration. More info: https://prometheus.io/docs/prometheus/latest/configuration/configuration/#metric_relabel_configs'
                         properties:

example/prometheus-operator-crd/monitoring.coreos.com_servicemonitors.yaml

@@ -148,7 +148,7 @@ spec:
                       description: ProxyURL eg http://proxyserver:2195 Directs scrapes to proxy through this endpoint.
                       type: string
                     relabelings:
-                      description: 'RelabelConfigs to apply to samples before scraping. More info: https://prometheus.io/docs/prometheus/latest/configuration/configuration/#relabel_config'
+                      description: 'RelabelConfigs to apply to samples before scraping. Prometheus Operator automatically adds relabelings for a few standard Kubernetes fields and replaces original scrape job name with __tmp_prometheus_job_name. More info: https://prometheus.io/docs/prometheus/latest/configuration/configuration/#relabel_config'
                       items:
                         description: 'RelabelConfig allows dynamic rewriting of the label set, being applied to samples before ingestion. It defines `<metric_relabel_configs>`-section of Prometheus configuration. More info: https://prometheus.io/docs/prometheus/latest/configuration/configuration/#metric_relabel_configs'
                         properties: