Docker_Tech_Notes.md

Volumes and Mongo Data in Docker

We are using a Docker-managed volume for storing Mongo data (see https://docs.docker.com/storage/volumes/) to avoid issues with mounting external file directories, especially in Windows and OSX, see https://docs.docker.com/samples/library/mongo/#where-to-store-data.

The Docker volumes are named using the parent directory of the docker-compose file and the volume name used in the docker-compose file, i.e. DIRNAME_VOLUMENAME. Volumes are never deleted unless you explicitly tell Docker to do so.

Useful Docker Commands

• docker volume ls //list all volumes
• docker volume prune //remove unused volumes
• docker image prune //remove unused images
• docker container prune //remove unused containers
• docker exec -it [container_name] bash //login to container
• docker cp [local_file] [container_name]:[container_file] //copy file into container
• docker images //list images
• docker exec [container_name] sh -c 'exec mongodump -d [database_name] --archive' > /some/path/on/your/host/all-collections.archive //backup Mongo data
• docker run --rm --volumes-from [container_name] -v [local_dir]:/backup ubuntu tar cvf /backup/backup.tar /[volume_name] //backup Docker volume
• docker run --rm --volumes-from [container_name] -v [local_dir]:/backup ubuntu bash -c "cd /[volume_name] && tar xvf /backup/backup.tar --strip 1" //restore volume backup

Production Mongo Considerations

Most of these notes are from here: https://docs.mongodb.com/manual/administration/production-notes/

To get Mongo configuration in Mongo console (mongo): db.runCommand( { serverStatus: 1 } )

How to configure Mongo in Docker: https://docs.docker.com/samples/library/mongo/#configuration

• Make sure httpd interface is disabled - https://docs.mongodb.com/manual/administration/production-notes/#disable-http-interface
• Add access control
• Use XFS filesystem - https://docs.mongodb.com/manual/administration/production-notes/#kernel-and-file-systems
• Adjust cache. Looks like Mongo on upload has 1.5 for cache. - https://docs.mongodb.com/manual/administration/production-notes/#id3
  • If you run mongod in a container (e.g. lxc, cgroups, Docker, etc.) that does not have access to all of the RAM available in a system, you must set storage.wiredTiger.engineConfig.cacheSizeGB to a value less than the amount of RAM available in the container. The exact amount depends on the other processes running in the container.
• Add montoring - https://docs.mongodb.com/manual/administration/free-monitoring/, https://www.mongodb.com/blog/post/introducing-free-cloud-monitoring-for-mongodb
• Noop scheduler when using VM - https://docs.mongodb.com/manual/administration/production-notes/#scheduling
• Use Enhanced Networking for EC2 - https://docs.mongodb.com/manual/administration/production-notes/#aws-ec2
• Adjust VMWare settings for Pathology-hosted - https://docs.mongodb.com/manual/administration/production-notes/#vmware
• Make backups - https://docs.mongodb.com/manual/core/backups/