Spring boot app fail to link consul in docker - docker

Question

I am trying to use Consul as discovery service, and another two spring boot app to register with Consul; and put them into docker;
following are my codes:
app:
server:
port: 3333
spring:
application:
name: adder
cloud:
consul:
host: consul
port: 8500
discovery:
preferIpAddress: true
healthCheckPath: /health
healthCheckInterval: 15s
instanceId: ${spring.application.name}:${spring.application.instance_id:${server.port}}
2 docker-compose.yml
consul1:
image: "progrium/consul:latest"
container_name: "consul1"
hostname: "consul1"
command: "-server -bootstrap -ui-dir /ui"
adder:
image: wsy/adder
ports:
- "3333:3333"
links:
- consul1
environment:
WAIT_FOR_HOSTS: consul1:8500
There is another similar question Cannot link Consul and Spring Boot app in Docker;
the answer suggests, the app should wait for consul to fully work by using depends_on, which I tried, but didn't work;
the error message is as following:
adder_1 | com.ecwid.consul.transport.TransportException: java.net.ConnectException: Connection refused
adder_1 | at com.ecwid.consul.transport.AbstractHttpTransport.executeRequest(AbstractHttpTransport.java:80) ~[consul-api-1.1.8.jar!/:na]
adder_1 | at com.ecwid.consul.transport.AbstractHttpTransport.makeGetRequest(AbstractHttpTransport.java:39) ~[consul-api-1.1.8.jar!/:na]
besides spring boot application.yml and docker-compose.yml, following is App's Dockerfile
FROM java:8
VOLUME /tmp
ADD adder-0.0.1-SNAPSHOT.jar app.jar
RUN bash -c 'touch /app.jar'
ADD start.sh start.sh
RUN bash -c 'chmod +x /start.sh'
EXPOSE 3333
ENTRYPOINT ["/start.sh", " java -Djava.security.egd=file:/dev/./urandom -jar /app.jar"]
and the start.sh
#!/bin/bash
set -e
wait_single_host() {
local host=$1
shift
local port=$1
shift
echo "waiting for TCP connection to $host:$port..."
while ! nc ${host} ${port} > /dev/null 2>&1 < /dev/null
do
echo "TCP connection [$host] not ready, will try again..."
sleep 1
done
echo "TCP connection ready. Executing command [$host] now..."
}
wait_all_hosts() {
if [ ! -z "$WAIT_FOR_HOSTS" ]; then
local separator=':'
for _HOST in $WAIT_FOR_HOSTS ; do
IFS="${separator}" read -ra _HOST_PARTS <<< "$_HOST"
wait_single_host "${_HOST_PARTS[0]}" "${_HOST_PARTS[1]}"
done
else
echo "IMPORTANT : Waiting for nothing because no $WAIT_FOR_HOSTS env var defined !!!"
fi
}
wait_all_hosts
exec $1

Answer 1

I can infer that your Consul configuration is located in your application.yml instead of bootstrap.yml, that's the problem.
According to this answer, bootstrap.yml is loaded before application.yml and Consul client has to check its configuration before the application itself and therefore look at the bootstrap.yml.
Example of a working bootstrap.yml :
spring:
cloud:
consul:
host: consul
port: 8500
discovery:
prefer-ip-address: true
Run Consul server and do not forget the name option to match with your configuration:
docker run -d -p 8500:8500 --name=consul progrium/consul -server -bootstrap
Consul server is now running, run your application image (builded previously with your artifact) and link it to the Consul container:
docker run -d -name=my-consul-client-app --link consul:consul acme/spring-app

Answer 2

Your problem is that depends_on does only control the startup order of your services. You have to wait until the consul servers are up and running before starting your spring app. You can do this with this script:
#!/bin/bash
set -e
default_host="database"
default_port="3306"
host="${2:-$default_host}"
port="${3:-$default_port}"
echo "waiting for TCP connection to $host:$port..."
while ! (echo >/dev/tcp/$host/$port) &>/dev/null
do
sleep 1
done
echo "TCP connection ready. Executing command [$1] now..."
exec $1
Usage in you docker file:
COPY wait.sh /wait.sh
RUN chmod +x /wait.sh
CMD ["/wait.sh", "java -jar yourApp-jar" , "consulURL" , "ConsulPort" ]

Answer 3

I just want to clarify that, at last I still don't have a solution, and can't understand the situation here; I tried the suggestion from Ohmen, in APP container, I am able to ping consul1; But the APP still fails to connect consul;
If I only start the consul by following command:
docker-compose -f docker-compose-discovery.yml up discovery
Then I can run the APP directly(through Main), and it is able to connect with spring.cloud.consul.host: discovery;
But if I try to run APP in docker container, like following:
docker run --name adder --link discovery-consul:discovery wsy/adder
It fails again with connection refused;
I am very new to docker & docker-compose; I thought it would be a good example to start, but it seems not that easy for me;