Stackdriver Prometheus sidecar

IMPORTANT: The Stackdriver Prometheus sidecar is in maintenance mode and will not receive any new feature updates. Please review the recommendations in the Google Cloud documentation before proceeding with any new deployments.

This repository contains a sidecar for the Prometheus server that can send metrics to Stackdriver. This is based on this design.

Custom metrics are a chargeable feature of Stackdriver Monitoring and there could be costs for your custom metrics. For more information on pricing, see Stackdriver Pricing.

The sidecar batches up to 200 timeseries per request (200 is the limit imposed by the Google Cloud Monitoring API).

Installation

To install the sidecar on a local machine run:

go get github.com/Stackdriver/stackdriver-prometheus-sidecar/...

Deployment

The sidecar is deployed next to an already running Prometheus server. It can stream sample data into Stackdriver that is associated with a Kubernetes target in Prometheus.

The following information must be provided:

• GCP_PROJECT: The ID of the GCP project the data is written to.
• WAL_DIR: the ./wal directory within Prometheus's data directory.
• API_ADDRESS: Prometheus's API address, typically 127.0.0.1:9090 like the default
• REGION: a valid GCP or AWS region with which the Stackdriver monitored resources are associated. Maps to the resource's location label (sometimes also called region).
• CLUSTER: a custom name for the monitored Kubernetes cluster. Maps to the monitored resource's cluster_name label.

stackdriver-prometheus-sidecar \
  --stackdriver.project-id=${GCP_PROJECT} \
  --prometheus.wal-directory=${WAL_DIR} \
  --prometheus.api-address=${API_ADDRESS} \
  --stackdriver.kubernetes.location=${REGION} \
  --stackdriver.kubernetes.cluster-name=${CLUSTER}

The sidecar requires write access to the directory to store its progress between restarts.

If your Prometheus server itself is running inside of Kubernetes, the example Kubernetes setup can be used as a reference for setup.

Configuration

The majority of configuration options for the sidecar are set through flags. To see all available flags, run:

stackdriver-prometheus-sidecar --help

Filters

The --include flag allows to provide filters which all series have to pass before being sent to Stackdriver. Filters use the same syntax as Prometheus instant vector selectors, e.g.:

stackdriver-prometheus-sidecar --include='{__name__!~"cadvisor_.+",job="k8s"}' ...

This drops all series which do not have a job label k8s and all metrics that have a name starting with cadvisor_.

For equality filter on metric name you can use the simpler notation, e.g., --include='metric_name{label="foo"}'.

The flag may be repeated to provide several sets of filters, in which case the metric will be forwarded if it matches at least one of them. Please note that inclusion filters only apply to Prometheus metrics proxied directly, and do not apply to aggregated counters.

File

The sidecar can also be provided with a configuration file. It allows to define static metric renames and to overwrite metric metadata which is usually provided by Prometheus. A configuration file should not be required for the majority of users.

metric_renames:
  - from: original_metric_name
    to: new_metric_name
# - ...

static_metadata:
  - metric: some_metric_name
    type: counter # or gauge/histogram
    value_type: double # or int64
    help: an arbitrary help string
# - ...

• All static_metadata entries must have type specified. This specifies the Stackdriver metric type and overrides the metric type chosen by the Prometheus client.
• If value_type is specified, it will override the default value type for counters and gauges. All Prometheus metrics have a default type of double.

Dealing with recording rules

The default Prometheus naming format for recording rules is level:metric:operations, e.g., instance:requests_total:sum, but colons are not allowed in Stackdriver metric descriptor names. To forward a recorded Prometheus metric to Stackdriver, you must use the metric_renames feature to replace the colon characters:

metric_renames:
  - from: instance:requests_total:sum
    to: recorded_instance_requests_total_sum

Additionally, the sidecar assumes that any recorded metrics are gauges. If this is not the case (e.g., for a Prometheus counter metric) you will need to specify that in static_metadata:

static_metadata:
  - metric: recorded_instance_requests_total_sum
    type: counter
    value_type: int64
    help: an arbitrary help string

Warning: recorded metrics must have minimally an "instance" and "job" label, otherwise they will not be forwarded.

Counter Aggregator

Counter Aggregator is an advanced feature of the sidecar that can be used to export a sum of multiple Prometheus counters to Stackdriver as a single CUMULATIVE metric.

You might find this useful if you have counter metrics in Prometheus with high cardinality labels (or perhaps just counters exported by a large number of targets) which makes exporting all of them to Stackdriver directly too expensive, however you would like to have a cumulative metric that has the sum of those counters.

Aggregated counters are configured in the aggregated_counters block of the configuration file. For example:

aggregated_counters:
  - metric: network_transmit_bytes
    help: total number of bytes sent over eth0
    filters:
     - 'node_network_transmit_bytes_total{device="eth0"}'
     - 'node_network_transmit_bytes{device="eth0"}'

In this example, the sidecar will export a new counter network_transmit_bytes, which will correspond to the total number of bytes transmitted over 'eth0' interface across all machines monitored by Prometheus. Counter Aggregator keeps track of all counters matching the filters and correctly handles counter resets. Like all internal metrics exported by the sidecar, the aggregated counter is exported using OpenCensus and will be available in Stackdriver as a custom metric (custom.googleapis.com/opencensus/network_transmit_bytes).

A list of Prometheus instant vector selectors is expected in the filters field. A time series needs to match any of the specified selectors to be included in the aggregated counter.

Counter aggregator and inclusion filters

Please note that by default metrics that match one of aggregated counter filters will still be exported to Stackdriver unless you have inclusion filters configured that prevent those metrics from being exported (see --include). Using --include to prevent a metric from being exported to Stackdriver does not prevent the metric from being covered by aggregated counters.

When using Counter Aggregator you would usually want to configure a restrictive inclusion filter to avoid raw metrics from being exported to Stackdriver.

Compatibility

The matrix below lists the versions of Prometheus Server and other dependencies that have been qualified to work with releases of stackdriver-prometheus-sidecar. If the matrix does not list whether they are compatible, please assume they are not verified yet but can be compatible. Feel free to contribute to the matrix if you have run the end-to-end test between a version of stackdriver-prometheus-sidecar and Prometheus server.

Alternatives

Google develops stackdriver-prometheus primarily for Stackdriver users and gives support to Stackdriver users. We designed the user experience to meet the expectations of Prometheus users and to make it easy to run with Prometheus server. stackdriver-prometheus is intended to monitor all your applications, Kubernetes and beyond.

Google develops prometheus-to-sd primarily for Google Kubernetes Engine to collect metrics from system services in order to support Kubernetes users. We designed the tool to be lean when deployed as a sidecar in your pod. It's intended to support only the metrics the Kubernetes team at Google needs; you can use it to monitor your applications, but the user experience could be rough.

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