gojekfarm / patroni-exporter

Prometheus exporter of Patroni API metrics

patroni-exporter

Provides Patroni related metrics for Prometheus.

This exporter scrapes Patroni API (https://github.com/zalando/patroni) and transforms the obtained information into Prometheus-scrapable (https://prometheus.io/) format.

Configuration can by environment variables or commandline arguments. If both is available the value of the commandline argument is taken. The following configuration parameters are available:

• port: PATRONI_EXPORTER_PORT, -p, --port specifies the port it should listen at
• bind: PATRONI_EXPORTER_BIND, -b, --bind specifies the address to bind to
• patroni url: PATRONI_EXPORTER_URL, -u, --patroni-url specifies the full to path the patroni API endpoint
• debug: PATRONI_EXPORTER_DEBUG, -d, --debug enables debug output
• timeout: PATRONI_EXPORTER_TIMEOUT, -t, --timeout configures the timeout for patroni API
• address family: PATRONI_EXPORTER_ADDRESS_FAMILY, -a, --address-family chooses which adress family to use. Either ipv4 (AF_INET) or ipv6 (AF_INET6). If listening on both ipv6 and ipv4 is required, AF_INET6 and a bind to '' or '::' must be used (the unfortunate side-effect is that it listens on all interfaces)
• requests verify: PATRONI_EXPORTER_REQUEST_VERIFY, --requests-verify Accepts true|false, in which case it controls whether Python's requests library verifies the server's TLS certificate. It also accepts a path to a CA bundle to use. Defaults to true

This service also responds on the /health endpoint and can be monitored this way.

The /metrics endpoint is designated for the prometheus scraping.

The default 9547 port has been reserved on https://github.com/prometheus/prometheus/wiki/Default-port-allocations

Requires python >= 3.6 because of the usage of f-strings and type hints.

Docker

There is a simple Dockerfile which allows you to run patroni-exporter in the Docker container. Usage example:

1. Build patroni-exporter docker image.

docker build -t patroni_exporter .

2. Run Docker container. Don't forget to pass required commandline arguments at the end of the run command.

docker run -d -ti patroni_exporter --port some_port --patroni-url http://some_host_fqdn:some_port/patroni --timeout 5 --debug

Known issues/limitations/workarounds

• due to how Patroni replicas respond with their information, but, when compared to primary, use HTTP code 503 (Service Unavailable) to avoid being registered as write-capable endpoints on load balancers, the exporter will attempt proper parsing when the response is a JSON with key-value {"role": "replica"}