Using Fabio, the zero-configuration load-balancer

Consul

Fabio uses the Consul Service Catalog to dynamically create routes to backend services.
Fabio determines the routes based on the tags

Start Consul

Using docker containers so we can create a 3-node cluster.
The ports from the master server will be shared so they are accessible from the underlying host.
The Consul UI will be available at http://localhost:8500/ui

docker run -d --name consul0  \
        -p 8300:8300 \
        -p 8301:8301 \
        -p 8301:8301/udp \
        -p 8302:8302 \
        -p 8302:8302/udp \
        -p 8500:8500 \
        -p 8600:8600 \
        -p 8600:8600/udp \
        consul \
        agent -server \
        -client=0.0.0.0 -ui \
        -bootstrap \
        -log-level warn

docker run -d --name consul1 --link consul0 consul \
       agent -server -client=0.0.0.0 -ui \
             -join consul0 -log-level warn

docker run -d --name consul2 --link consul0 consul \
       agent -server -client=0.0.0.0 -ui \
             -join consul0 -log-level warn

Start a backend web service

Hello is a very simple web service that will respond to any request.

docker pull devokun/hello

docker stop hello ; docker rm hello

docker run  -d \
            --name hello \
            \
            -p 6001:6001 \
            -e HTTP_PORT=6001 \
            \
            devokun/hello

curl http://0.0.0.0:6001/

Register the web service with the Consul Service Catalog

##
## Find the Container IP
##

for IDN in $(docker ps --format '{{ .ID }}-{{ .Names }}'); do
  ID=$(echo   "$IDN" | cut -f 1 -d "-")
  NAME=$(echo "$IDN" | cut -f 2 -d "-")
  IP=$(docker inspect ${ID} --format '{{ .NetworkSettings.IPAddress }}')
  echo "${ID} ${IP} ${NAME}"
done

##
## Gotcha
##   Service Address can not be 0.0.0.0
##   The Healthcheck URL must be accessible from the consul service.
##

read -r -d '' REGISTER_SERVICE << EOM
{
  "Name":    "hello",
  "address": "127.0.0.1",
  "port":    6001,
  "tags": ["global", "hello", "urlprefix-hello.gestalts.net/"],
  "checks": [{
     "http":     "http://172.17.0.2:6001/",
     "interval": "5s"
  }]
}
EOM

curl -v -XPUT -d "$REGISTER_SERVICE" http://127.0.0.1:8500/v1/agent/service/register

List Services in Consul

curl http://127.0.0.1:8500/v1/agent/services

curl http://127.0.0.1:8500/v1/agent/services | jq '.hello.ID'

De-Register a Service

SERVICE_ID="hello"
curl -v -XPUT http://127.0.0.1:8500/v1/agent/service/deregister/${SERVICE_ID}

Consule UI

Start Fabio

Admin Portal: http://0.0.0.0:9998/health
Fabio HTTP proxy listening on :9999
Fabio assumes that the consul agent is running on localhost and will connect to it to query the service catalog.

wget https://github.com/fabiolb/fabio/releases/download/v1.5.9/fabio-1.5.9-go1.10.2-linux_amd64

linux_amd64 /usr/local/sbin/fabio

chmod 0755 /usr/local/sbin/fabio

fabio

Fabio UI