Transfer symfony logfiles with filebeat to graylog in local docker-environment
Graylog seems to be running on http://127.0.0.1:9000/api which is in the container. You might want to run it as http://graylog:9000/api or as http://0.0.0.0:9000/api
Accessing the other images from within any of the other images will have be done with the same name as the service name, as defined in the docker-compose.yml files. The url to the graylog-elasticsearch would be something like: http://graylog-elasticsearch/.... if you would post to localhost it would stay inside its own image.
Hope this will help you along in finding the solution.