Prometheus poller_exporter

Blackbox service poller for Prometheus. It is intended to provide a detailed metrics endpoint, and also a usable HTTP interface for inspecting the state of a given hosts metrics.

Getting Started

A prebuilt docker container is hosted on Github Packages:

docker run -it -p 9115:9115 -v /myconfig.yml:/poller_exporter.yml ghcr.io/wrouesnel/poller_exporter

Or you can build your own:

docker build -t poller_exporter .
docker run -p 9115:9115 -v /myconfig.yml:/poller_exporter.yml

Documentation on configuration options can be found in the complete parameters example file poller_exporter.complete.yml.

Web UI

The web UI will provide basic information about the configured pollers - this provides a degree of self-describing functionality.

For production deployments use a tagged release, or better, the full hash. The docker containers default logging to JSON mode.

Configuration

This tool is intended to be deployed on all servers in your environment, and its configuration provised via a tool such as Ansible or a Kubernetes ConfigMap.

There are several types of checker, which internally simply represent logic layers of each previous checker. Checkers are configured against hosts.

Host Config

Hosts are DNS names (or IPs) which should be polled and have a series of basic_checks, challenge_response_checks and http_checks.

Each host by default is also ICMP ping checked, but this can be disabled in cases where ICMP connectivity is not available or poller_exporter is running without permissions to send ICMP.

Service Config

Important: when configuring services, the name parameter is vital. Services are uniquely identified to Prometheus by hostname, name, protocol and port. If you register multiple services with the same name, then their metrics will collide. This is detected by the exporter automatically but does lead to weird looking errors.

Basic Check

Basic checks simply check for open ports, and optionally validates TLS certificates.

Challenge Response Checks

Challenge-Response checks send a configured byte-sequence to the TCP port and check for a response - either a literal string or a byte-regex. This can be used to check for example if OpenSSH is running by looking for the header.

• response looks for a literal response starting from the start of the line.
• response_re matches a regex anywhere along the line if not supplied with anchor expressions. In general this is more useful.

It is not recommended to use this for HTTP, which is implemented as its own checker due to occurrence and complexity.

HTTP Checks

HTTP checker is an enhanced form of challenge-response checker which challenges with an HTTP request. The given HTTP verb and url is used. I

Important url is not used to resolve the IP of the HTTP server - it is solely used for the Host: header and query path.

The HTTP check can be configured to parse a range of success_status codes which can be specified as a string-like 200-299,301,401.

Important Metrics for HTTP responses come with some caveats. They are accurate and specific only if "no_redirects" is used

Configuration Advice

The optimal configuration is a full mesh of related servers behind a network segment - i.e. within a cluster of servers it is best for each server to poll every other server to rapidly find connectivity issues.

Hacking

To get started with the repository run go run mage.go autogen to configure your repositories build hooks.

To build a binary for your current platform run go run mage.go binary