By default, the container logs are stored in /var/log/docker/yyyyMMdd.log inside this logging container. The data is buffered, so you may also see buffer files like /var/log/docker/20141114.b507c71e6fe540eab.log where "b507c71e6fe540eab" is a hash identifier. You can mount that container volume back to host. Also, by modifying fluent.conf and rebuilding the Docker image, you can stream up your logs to Elasticsearch, Amazon S3, MongoDB, Treasure Data, etc.docker-fluentd uses Fluentd inside to tail log files that are mounted on /var/lib/docker/containers/<CONTAINER_ID>/<CONTAINER_ID>-json.log. It uses the tail input plugin to tail JSON-formatted log files that each Docker container emits.