See the source repository for most up to date description.
Redundancy Group Announcement Protocol
Design notes: https://gist.github.com/Snawoot/39282757e5f7db40632e5e01280b683f
RGAP allows one group of hosts to be aware about IP addresses of other group of hosts.
It is useful to inform load balancers about ever-changing IP addresses of worker server.
Announcements are propagated via short HMAC-signed UDP messages, using unicast or multicast.
This implementation defines two primary parts: agent and listener.
Agent periodically sends unicast or broadcast UDP message to announce it's presense in particular redundancy group.
Listener accepts announces, verifies them and maintains the list of active IP addresses for each redundancy group. At the same time it exposes current list of IP addresses through its output plugins.
RGAP_ADDRESS=127.1.2.3 RGAP_PSK=8f1302643b0809279794c5cc47f236561d7442b85d748bd7d1a58adfbe9ff431 rgap agent -g 1000 -i 5s
where RGAP_ADDRESS is actual IP address which node exposes to redundancy group.
rgap listener -c /etc/rgap.yaml
Configuration example:
listen:
- 239.82.71.65:8271
- 127.0.0.1:8282
groups:
- id: 1000
psk: 8f1302643b0809279794c5cc47f236561d7442b85d748bd7d1a58adfbe9ff431
expire: 15s
clock_skew: 10s
readiness_delay: 15s
outputs:
- kind: noop
spec:
- kind: log
spec:
interval: 1s
- kind: hostsfile
spec:
interval: 5s
filename: hosts
mappings:
- group: 1000
hostname: worker
fallback_addresses:
- 1.2.3.4
- 5.6.7.8
prepend_lines:
- "# Auto-generated hosts file"
- "# Do not edit manually, changes will be overwritten by RGAP"
append_lines:
- "# End of auto-generated file"
- kind: dns
spec:
bind_address: :8253
mappings:
worker.example.com:
group: 1000
fallback_addresses:
- 1.2.3.4
- 5.6.7.8
worker.example.org:
group: 1000
fallback_addresses:
- 1.2.3.4
- 5.6.7.8
rgap genpsk
See rgap help for details of command line interface.
docker pull yarmak/rgap