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healthchecker forBIRD-anycasted services

⚠️NOTE: this version of birdwatcher is designed to work with BIRD version 2 and up. If you want to use birdwatcher with BIRD 1.x, refer to thebird1 branch.

This project is heavily influenced byanycast-healthchecker. If you want to know more about use cases of birdwatcher, please read their excellent documention about anycasted services and how a healthchecker can contribute to a more stable service availability.

In a nutshell: birdwatcher periodically checks a specific service and tells BIRD which prefixes to announce or to withdraw when the service appears to be up or down respectively.

When I found out about anycast-healthchecker (sadly only recently onHaproxyConf 2019), I figured this would solve the missing link between BIRD and whatever anycasted services I have running (mostly haproxy though). Currently however in anycast-healthchecker, it is not possible to specify multiple prefixes to a service. Some machines in these kind of setups are announcingmany/32 and/128 prefixes and I ended up specifiying so many services (one per prefix) that python crashed giving me atoo many open files error. At first I tried to patch anycast-healthchecker but ended up writing something similar, hence birdwatcher.

It is written in Go because I like it and running multiple threads is easy.

The notation oftimeout for services changed from int (for number of seconds) to the formattime.ParseDuration uses, such as "300ms", "-1.5h" or "2h45m".

For example:10 should become"10s" in your config files.

This simple example configures a single service, runshaproxy_check.sh every second and manages 2 prefixes based on the exit code of the script:

[services]  [services."foo"]command ="/usr/bin/haproxy_check.sh"prefixes = ["192.168.0.0/24","fc00::/7"]

Sample output in/etc/bird/birdwatcher.conf ifhaproxy_check.sh checks out would be:

# DO NOT EDIT MANUALLYfunction match_route() -> bool{return net ~ [192.168.0.0/24,fc00::/7];}

As soon as birdwatcher finds out haproxy is down, it will change the content in/etc/bird/birdwatcher.conf to:

# DO NOT EDIT MANUALLYfunction match_route() -> bool{return false;}

and reconfigures BIRD by givenreloadcommand. Obviously, if you have multiple services being checked by birdwatcher, only the prefixes of that particular service would be removed from the list inmatch_route.

Integration in BIRD is a matter of including/etc/bird/birdwatcher.conf (or whatever you configured atconfigfile) in the configuration for BIRD and use it in a protocol like this:

protocol bgp my_bgp_proto {  local as 12345;  neighbor 1.2.3.4 as 23435;  ...  ipv4 {    ...    export where match_route();  }  ...  ipv6 {    ...    export where match_route();  }}

Configuration section for global options.

Each service under this section can have the following settings:

Configuration for the prometheus exporter