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Documentation Grafana Alloy Reference Components prometheus prometheus.scrape

prometheus.scrape

prometheus.scrape configures a Prometheus scraping job for a given set of targets. The scraped metrics are forwarded to the list of receivers passed in forward_to.

Multiple prometheus.scrape components can be specified by giving them different labels.

Usage

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prometheus.scrape "LABEL" {
  targets    = TARGET_LIST
  forward_to = RECEIVER_LIST
}

Arguments

The component configures and starts a new scrape job to scrape all the input targets. The list of arguments that can be used to configure the block is presented below.

The scrape job name defaults to the component’s unique identifier.

Any omitted fields take on their default values. In case that conflicting attributes are being passed (e.g. defining both a BearerToken and BearerTokenFile or configuring both Basic Authorization and OAuth2 at the same time), the component reports an error.

The following arguments are supported:

At most, one of the following can be provided:

• bearer_token argument.
• bearer_token_file argument.
• basic_auth block.
• authorization block.
• oauth2 block.

scrape_protocols controls the preferred order of protocols to negotiate during a scrape. The following values are supported:

• OpenMetricsText1.0.0
• OpenMetricsText0.0.1
• PrometheusProto
• PrometheusText0.0.4

If you were using the now deprecated enable_protobuf_negotiation argument, switch to using scrape_protocols = ["PrometheusProto", "OpenMetricsText1.0.0", "OpenMetricsText0.0.1", "PrometheusText0.0.4"] instead.

no_proxy can contain IPs, CIDR notations, and domain names. IP and domain names can contain port numbers. proxy_url must be configured if no_proxy is configured.

proxy_from_environment uses the environment variables HTTP_PROXY, HTTPS_PROXY and NO_PROXY (or the lowercase versions thereof). Requests use the proxy from the environment variable matching their scheme, unless excluded by NO_PROXY. proxy_url and no_proxy must not be configured if proxy_from_environment is configured.

proxy_connect_header should only be configured if proxy_url or proxy_from_environment are configured.

track_timestamps_staleness controls whether Prometheus tracks staleness of metrics with an explicit timestamp present in scraped data.

• An “explicit timestamp” is an optional timestamp in the Prometheus metrics exposition format. For example, this sample has a timestamp of 1395066363000:
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  http_requests_total{method="post",code="200"} 1027 1395066363000

• If track_timestamps_staleness is set to true, a staleness marker will be inserted when a metric is no longer present or the target is down.
• A “staleness marker” is just a sample with a specific NaN value which is reserved for internal use by Prometheus.
• It is recommended to set track_timestamps_staleness to true if the database where metrics are written to has enabled out of order ingestion.
• If track_timestamps_staleness is set to false, samples with explicit timestamps will only be labeled as stale after a certain time period, which in Prometheus is 5 minutes by default.

Blocks

The following blocks are supported inside the definition of prometheus.scrape:

The > symbol indicates deeper levels of nesting. For example, oauth2 > tls_config refers to a tls_config block defined inside an oauth2 block.

basic_auth block

password and password_file are mutually exclusive, and only one can be provided inside a basic_auth block.

authorization block

credential and credentials_file are mutually exclusive, and only one can be provided inside an authorization block.

oauth2 block

client_secret and client_secret_file are mutually exclusive, and only one can be provided inside an oauth2 block.

The oauth2 block may also contain a separate tls_config sub-block.

no_proxy can contain IPs, CIDR notations, and domain names. IP and domain names can contain port numbers. proxy_url must be configured if no_proxy is configured.

proxy_from_environment uses the environment variables HTTP_PROXY, HTTPS_PROXY and NO_PROXY (or the lowercase versions thereof). Requests use the proxy from the environment variable matching their scheme, unless excluded by NO_PROXY. proxy_url and no_proxy must not be configured if proxy_from_environment is configured.

proxy_connect_header should only be configured if proxy_url or proxy_from_environment are configured.

tls_config block

The following pairs of arguments are mutually exclusive and can’t both be set simultaneously:

• ca_pem and ca_file
• cert_pem and cert_file
• key_pem and key_file

When configuring client authentication, both the client certificate (using cert_pem or cert_file) and the client key (using key_pem or key_file) must be provided.

When min_version is not provided, the minimum acceptable TLS version is inherited from Go’s default minimum version, TLS 1.2. If min_version is provided, it must be set to one of the following strings:

• "TLS10" (TLS 1.0)
• "TLS11" (TLS 1.1)
• "TLS12" (TLS 1.2)
• "TLS13" (TLS 1.3)

clustering block

When Alloy is using clustering, and enabled is set to true, then this prometheus.scrape component instance opts-in to participating in the cluster to distribute scrape load between all cluster nodes.

Clustering assumes that all cluster nodes are running with the same configuration file, have access to the same service discovery APIs and that all prometheus.scrape components that have opted-in to using clustering, over the course of a scrape interval, are converging on the same target set from upstream components in their targets argument.

All prometheus.scrape components instances opting in to clustering use target labels and a consistent hashing algorithm to determine ownership for each of the targets between the cluster peers. Then, each peer only scrapes the subset of targets that it is responsible for, so that the scrape load is distributed. When a node joins or leaves the cluster, every peer recalculates ownership and continues scraping with the new target set. This performs better than hashmod sharding where all nodes have to be re-distributed, as only 1/N of the targets ownership is transferred, but is eventually consistent (rather than fully consistent like hashmod sharding is).

If Alloy is not running in clustered mode, then the block is a no-op and prometheus.scrape scrapes every target it receives in its arguments.

Exported fields

prometheus.scrape does not export any fields that can be referenced by other components.

Component health

prometheus.scrape is only reported as unhealthy if given an invalid configuration.

Debug information

prometheus.scrape reports the status of the last scrape for each configured scrape job on the component’s debug endpoint.

Debug metrics

• prometheus_fanout_latency (histogram): Write latency for sending to direct and indirect components.
• prometheus_scrape_targets_gauge (gauge): Number of targets this component is configured to scrape.
• prometheus_forwarded_samples_total (counter): Total number of samples sent to downstream components.

Scraping behavior

The prometheus.scrape component borrows the scraping behavior of Prometheus. Prometheus, and by extent this component, uses a pull model for scraping metrics from a given set of targets. Each scrape target is defined as a set of key-value pairs called labels. The set of targets can either be static, or dynamically provided periodically by a service discovery component such as discovery.kubernetes. The special label __address__ must always be present and corresponds to the <host>:<port> that is used for the scrape request.

By default, the scrape job tries to scrape all available targets’ /metrics endpoints using HTTP, with a scrape interval of 1 minute and scrape timeout of 10 seconds. The metrics path, protocol scheme, scrape interval and timeout, query parameters, as well as any other settings can be configured using the component’s arguments.

If a target is hosted at the in-memory traffic address specified by the run command, prometheus.scrape will scrape the metrics in-memory, bypassing the network.

The scrape job expects the metrics exposed by the endpoint to follow the OpenMetrics format. All metrics are then propagated to each receiver listed in the component’s forward_to argument.

Labels coming from targets, that start with a double underscore __ are treated as internal, and are removed prior to scraping.

The prometheus.scrape component regards a scrape as successful if it responded with an HTTP 200 OK status code and returned a body of valid metrics.

If the scrape request fails, the component’s debug UI section contains more detailed information about the failure, the last successful scrape, as well as the labels last used for scraping.

The following labels are automatically injected to the scraped time series and can help pin down a scrape target.

Similarly, these metrics that record the behavior of the scrape targets are also automatically available.

The up metric is particularly useful for monitoring and alerting on the health of a scrape job. It is set to 0 in case anything goes wrong with the scrape target, either because it is not reachable, because the connection times out while scraping, or because the samples from the target could not be processed. When the target is behaving normally, the up metric is set to 1.

To enable scraping of Prometheus’ native histograms over gRPC, the scrape_protocols should specify PrometheusProto as the first protocol to negotiate, for example:

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prometheus.scrape "prometheus" {
  ...
  scrape_protocols = ["PrometheusProto", "OpenMetricsText1.0.0", "OpenMetricsText0.0.1", "PrometheusText0.0.4"]
}

Thescrape_classic_histograms argument controls whether the component should also scrape the ‘classic’ histogram equivalent of a native histogram, if it is present.

Example

Set up scrape jobs for blackbox exporter targets

The following example sets up the scrape job with certain attributes (scrape endpoint, scrape interval, query parameters) and lets it scrape two instances of the blackbox exporter. The exposed metrics are sent over to the provided list of receivers, as defined by other components.

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prometheus.scrape "blackbox_scraper" {
  targets = [
    {"__address__" = "blackbox-exporter:9115", "instance" = "one"},
    {"__address__" = "blackbox-exporter:9116", "instance" = "two"},
  ]

  forward_to = [prometheus.remote_write.grafanacloud.receiver, prometheus.remote_write.onprem.receiver]

  scrape_interval = "10s"
  params          = { "target" = ["grafana.com"], "module" = ["http_2xx"] }
  metrics_path    = "/probe"
}

Here are the endpoints that are being scraped every 10 seconds:

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http://blackbox-exporter:9115/probe?target=grafana.com&module=http_2xx
http://blackbox-exporter:9116/probe?target=grafana.com&module=http_2xx

Authentication with the Kubernetes API server

The following example shows you how to authenticate with the Kubernetes API server.

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prometheus.scrape "kubelet" {
        scheme = "https"
        tls_config {
            server_name = "kubernetes"
            ca_file = "/var/run/secrets/kubernetes.io/serviceaccount/ca.crt"
            insecure_skip_verify = false
        }
        bearer_token_file = "/var/run/secrets/kubernetes.io/serviceaccount/token"
}

Technical details

prometheus.scrape supports gzip compression.

The following special labels can change the behavior of prometheus.scrape:

• __address__ is the name of the label that holds the <host>:<port> address of a scrape target.
• __metrics_path__ is the name of the label that holds the path on which to scrape a target.
• __scheme__ is the name of the label that holds the scheme (http,https) on which to scrape a target.
• __scrape_interval__ is the name of the label that holds the scrape interval used to scrape a target.
• __scrape_timeout__ is the name of the label that holds the scrape timeout used to scrape a target.
• __param_<name> is a prefix for labels that provide URL parameters <name> used to scrape a target.

Special labels added after a scrape

• __name__ is the label name indicating the metric name of a timeseries.
• job is the label name indicating the job from which a timeseries was scraped.
• instance is the label name used for the instance label.

Compatible components

prometheus.scrape can accept arguments from the following components:

• Components that export Targets
• Components that export Prometheus MetricsReceiver