Securing Consul with acl_token

Introduction

In previous steps, we have set up Consul with acl_default_policy=allow so that all operations to the Consul server are allowed. This should be only used for internal testing. For official environments, we must set acl_default_policy=deny while having all operations to the Consul server provide an acl_token in the header.

Now let’s copy our previous state from tag to token for each API:

cd ~/networknt
cp -r light-example-4j/discovery/api_a/tag light-example-4j/discovery/api_a/token
cp -r light-example-4j/discovery/api_b/tag light-example-4j/discovery/api_b/token
cp -r light-example-4j/discovery/api_c/tag light-example-4j/discovery/api_c/token
cp -r light-example-4j/discovery/api_d/tag light-example-4j/discovery/api_d/token

Starting Consul

If your consul server is still running, please stop it and restart it with the following:

docker run -d -p 8400:8400 -p 8500:8500/tcp -p 8600:53/udp -e 'CONSUL_LOCAL_CONFIG={"acl_datacenter":"dc1","acl_default_policy":"deny","acl_down_policy":"extend-cache","acl_master_token":"the_one_ring","bootstrap_expect":1,"datacenter":"dc1","data_dir":"/usr/local/bin/consul.d/data","server":true}' consul agent -server -ui -bind=127.0.0.1 -client=0.0.0.0

The above command will ensure the default policy is to deny access, and configure the master ACL token so that services which have the token can register.

Configuring Consul

Create agent token

curl \
    --request PUT \
    --header "X-Consul-Token: the_one_ring" \
    --data \
'{
  "Name": "Agent Token",
  "Type": "client",
  "Rules": "node \"\" { policy = \"write\" } service \"\" { policy = \"read\" }"
}' http://127.0.0.1:8500/v1/acl/create

And we get the token like this.

{"ID":"67ccac85-36a3-e912-d0b3-bce1194119a0"}

Introduce the token through an API.

curl \
    --request PUT \
    --header "X-Consul-Token: the_one_ring" \
    --data \
'{
  "Token": "67ccac85-36a3-e912-d0b3-bce1194119a0"
}' http://127.0.0.1:8500/v1/agent/token/acl_agent_token

And let’s give anonymous users read permissions.

curl \
    --request PUT \
    --header "X-Consul-Token: the_one_ring" \
    --data \
'{
  "ID": "anonymous",
  "Type": "client",
  "Rules": "node \"\" { policy = \"read\" } service \"\" { policy = \"read\" }"
}' http://127.0.0.1:8500/v1/acl/update

It should return something like this:

{"ID":"anonymous"}

Configuring the Servers

The next step we are going to update consul.yml to add consulToken in order to access the Consul for service registry and discovery.

For each server, go ahead and update secret.yml to add consulToken: the_one_ring. Please be aware that the consul.yml copied from light-4j consul module has the consulToken: the_one_ring already. In case it is not available, you can add the following line into the consul.yml

consulToken: the_one_ring

Starting the servers

Now let’s start four terminals to start servers.

API A

cd ~/networknt/light-example-4j/discovery/api_a/token
mvn clean install -Prelease
java -jar target/aa-1.0.0.jar

API B

cd ~/networknt/light-example-4j/discovery/api_b/token
mvn clean install -Prelease
java -jar target/ab-1.0.0.jar

API C

cd ~/networknt/light-example-4j/discovery/api_c/token
mvn clean install -Prelease
java -jar target/ac-1.0.0.jar

API D

And start the first instance that listen to 7444 as default

cd ~/networknt/light-example-4j/discovery/api_d/token
mvn clean install -Prelease
java -jar target/ad-1.0.0.jar

Now you should be able to see the registered service from the Consul UI.

http://localhost:8500/ui

In this step, we secured our consul access from services so that we can be sure that the services registered on the consul are the valid ones. In the next step, we are going to start services with Docker containers.