Deployment on AWS Elastic Beanstalk with Docker fails

Question

I'm developing a web application with Play framework and I'm running it on AWS Elastic Beanstalk using a single docker container and a load balancer. Normally, everything is running fine, but when I rebuild the whole environment I get the following error:

Command failed on instance. Return code: 6 Output: (TRUNCATED)... in /etc/nginx/sites-enabled/elasticbeanstalk-nginx-docker-proxy.conf:11 nginx: [emerg] host not found in upstream "docker" in /etc/nginx/sites-enabled/elasticbeanstalk-nginx-docker-proxy.conf:24 nginx: configuration file /etc/nginx/nginx.conf test failed.

When I log into the EC2 I can see that no docker image is running and therefore the Nginx server cannot start. I cannot see any other error in the logs (or maybe I don't know where to look). The strange thing is that the same version worked fine before rebuilding the environment.

I'm using the following Dockerfile for the deployment:

FROM java
COPY <app_folder> /opt/<app_name>
WORKDIR /opt/<app_name>
CMD [ "/opt/<app_name>/bin/<app_name>", "-mem", "512", "-J-server" ]
EXPOSE 9000

Any ideas what the problem could be or where to check for more details?

Answer 1

I had this same problem. elasticbeanstalk-nginx-docker-proxy.conf is referring to proxy_pass http://docker but the definition of that is missing. You need to add something like

    # List of application servers
    upstream docker {
        server 127.0.0.1:8080;  # your app
    }

(Make sure it's outside of the server directive.)