CassFS is a fuse filesystem that uses Cassandra as the storage engine. It has a concept of owners and environments to support multi-tenency. The idea is based on the concept of the Valhalla filesystem created by Pantheon. Except that they use a webdav mounted filesystem, and a lot on the server side. CassFS interacts directly with Cassandra.
All of the normal rules apply when talking about any new filesystem.
- Do not keep important data on it, you will likely lose any data at this point
- The schema and data structures are not stable, so breaking changes will likely occur
- There is no guarantee or warranty for stability or safety in using this software
To be able to run something like drupal or wordpress in a container without having to set up a distributed file system. If you need to support running a database or some other persistent datastore with large files, this is not intended for that use. The blog from Pantheon does a very good job describing the type of behaviour that this is suited for. It is best for smaller files, more reads than writes, and when there are writes they are of the entire file.
This is how I have been testing it, running an apache/php container and drupal from the file system.
Start it with
To stop it run
fusermout -u <moutnpoint>
The options are:
-debug Turn on debugging -entry_ttl float fuse entry cache TTL. (default 1) -environment string Environment to mount (default "prod") -keyspace string Keyspace to use for the filesystem (default "cassfs") -mount string Mount directory (default "./") -negative_ttl float fuse negative entry cache TTL. (default 1) -owner int ID of the FS owner (default 1) -server string Cassandra server to connect to (default "localhost")
Example Usage with Local Caching
go-fuse, one of the required modules includes a unionfs example. This will locally cache files, using both should provide a significant performance boost for sites with enough traffic where the cache would be able to serve files.
In my testing on CentOS, you need to be sure to run this to allow docker to be able to read from a fuse mount
setsebool virt_use_fusefs true
Requires Go 1.6
# Glide - Update a project's dependencies glide update # Build binary for OS X make osx #Build binary for Linux make linux
Local Test Env
docker-compose up -d make linux docker-compose exec cassandra cqlsh -f /opt/cassfs.cql ./cassfs -mount /opt -keyspace cassfs
This is still very early on, so there are surely many thing that I have not even thought of. This list is really too long to get right on the first pass, but here are a few of the things. 1. Testing 2. Caching? 3. docker/kubernetes integration 4. Mount script 5. More robust options handling (Environment variables)