Anycast-Wiki

The idea is to setup mirrors of this wiki across dn42, using anycast to provide redundancy and load-balancing. The local webserver is monitored with a simple shell script (below) working in conjuction with ExaBGP, announcing/withdrawing the assigned route if the service is up/down.

Checklist:

• Install gollum.

• Clone the dn42 wiki repo:

  git clone ssh://[email protected]/dn42/wiki /home/wiki.dn42/

• Generate a CSR and send to [email protected]. Wait for a reply containing internal.dn42/wiki.dn42 certificates.

• Start two gollum instances, read-only and editing on 127.0.0.1:

  gollum --css /home/wiki.dn42/custom.css --gollum-path /home/wiki.dn42/public_html/ --host 127.0.0.1  --port 4568 --no-edit```
  
  
  #####gollum-watchdog.sh:
  
  #!/bin/bash
  
  URL=( "http://172.23.0.80" "https://172.23.0.80" )
  
  VALIDATE_KEYWORD='gollum'
  ROUTE='172.23.0.80/28'
  NEXTHOP='172.22.177.72'
  
  INTERVAL=60
  
  ###########################
  
  RUN_STATE=0
  
  check_urls() {
  	for url in "${URL[@]}"; do
  		curl --insecure -L -o - ${url} | egrep -q "${VALIDATE_KEYWORD}" || {
  			return 1
  		}
  	done
  	return 0
  }
  
  while [ 1 ]; do
  	if [ ${RUN_STATE} -eq 0 ]; then
  		check_urls && {
  			RUN_STATE=1
  			echo "announce route ${ROUTE} next-hop ${NEXTHOP}"
  		}
  	else
  		check_urls || {
  			RUN_STATE=0
  			echo "withdraw route ${ROUTE} next-hop ${NEXTHOP}"
  		}
  	fi
  
  	sleep ${INTERVAL}
  
  done
  
  exit 0