Service discovery with Consul and Registrator and Consul Template (for dev environments)

It is exaple how to generate and keep updated configs (e.g. Nginx) based on information from Consul

Other possible options

• PAProxy and Docker Gen in one container https://github.com/amazeeio/docker-haproxy It works with docker.sock and reading containers tags to generate HAProxy config.
• Docker Gen itself can be used different ways, as an registrator in service discovery or together with Nginx, Logging etc. https://github.com/jwilder/docker-gen https://github.com/jwilder/nginx-proxy

Run consul and Registrator

Run consul server and save its container ID to CONSUL_CONTAINER variable

export CONSUL_CONTAINER=$(docker run -d --name=consul --net=host gliderlabs/consul-server -bootstrap -bind=172.30.0.225)

echo $CONSUL_CONTAINER

Check it is running and here is no registered services in Consul

curl 172.30.0.225:8500/v1/catalog/services ; echo

Run Registrator and save its container ID to REGISTRATOR_CONTAINER variable

export REGISTRATOR_CONTAINER=$(docker run -d --name=registrator --net=host --volume=/var/run/docker.sock:/tmp/docker.sock gliderlabs/registrator:latest consul://localhost:8500)

echo $REGISTRATOR_CONTAINER

Demo

Run 2 containers with Nginx ad 2 containers with Redis.

There are two different SERVICE_TAGS to be able to filter services.

export NGINX_1=$(docker run -d -P -e "SERVICE_TAGS=myenv1111" nginx)
echo $NGINX_1
export REDIS_1=$(docker run -d -P -e "SERVICE_TAGS=myenv1111" redis)
echo $REDIS_1

export NGINX_2=$(docker run -d -P -e "SERVICE_TAGS=myenv2222" nginx)
echo $NGINX_2
export REDIS_2=$(docker run -d -P -e "SERVICE_TAGS=myenv2222" redis)
echo $REDIS_2

All 4 sevices registered in Consul

curl 172.30.0.225:8500/v1/catalog/services ; echo

Try to filter services by tag

curl 54.254.139.197:8500/v1/catalog/service/nginx\?tag=myenv1111 ; echo

Generate and update confix for Nginx or HAProxy with Consul Template based on data from Consule

Run Consul Template and save its container ID to CONSUL_TEMPLATE variable. Mount template for config inside the container and run consul-template to pull data from Consul and regenerate config after any update.

export CONSUL_TEMPLATE=$(docker run -d --rm -v "$(pwd):/tmp/config" hashicorp/consul-template:alpine consul-template -template "/tmp/config/config.ctmpl:/tmp/config/config.txt" -consul-addr=172.30.0.225:8500)

Check generated file

cat config.txt

Run one more set of containers.

export NGINX_3=$(docker run -d -P -e "SERVICE_TAGS=myenv3333" nginx)
echo $NGINX_3

export REDIS_3=$(docker run -d -P -e "SERVICE_TAGS=myenv3333" redis)
echo $REDIS_3

config.txt will be updated automatically.

cat config.txt

Clean you environment

docker stop $CONSUL_TEMPLATE
docker rm $CONSUL_TEMPLATE

docker stop $NGINX_1 $NGINX_2 $NGINX_3
docker rm $NGINX_1 $NGINX_2 $NGINX_3

docker stop $REDIS_1 $REDIS_2 $REDIS_3
docker rm $REDIS_1 $REDIS_2 $REDIS_3

docker stop $REGISTRATOR_CONTAINER
docker rm $REGISTRATOR_CONTAINER

docker stop $CONSUL_CONTAINER
docker rm $CONSUL_CONTAINER