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Driver development

There are two main ways to have an openstorage driver, one is by vendoring openstorage with your repo, and the other is to include your driver in this repo.

Both models have their positives and negatives. By vendoring openstorage you can include the api and the server on your repo, but are responsible for updating the library. By including it in openstorage, it will be part of the openstorage library and the community and you will try to keep it up to date.

Creating a volume driver

Adding a driver is fairly straightforward:

  1. Add your driver decleration in volumes/drivers.go
  2. Add your driver mydriver implementation in the volumes/drivers/mydriver directory. The driver must implement the VolumeDriver interface specified in volumes/volume.go. This interface is an implementation of the specification available at api.openstorage.org.
  3. You're driver must be a File Volume driver or a Block Volume driver. A File Volume driver will not implement a few low level primatives, such as Format, Attach and Detach.

Here is an example of drivers.go:

// To add a provider to openstorage, declare the provider here.
package drivers

import (
    "github.com/libopenstorage/openstorage/volume/drivers/aws"
    "github.com/libopenstorage/openstorage/volume/drivers/btrfs"
    "github.com/libopenstorage/openstorage/volume/drivers/nfs"
    "github.com/libopenstorage/openstorage/volume"
)           
            
type Driver struct {
    providerType volume.ProviderType
    name         string
}       
            
var (       
    providers = []Driver{
        // AWS provider. This provisions storage from EBS.
        {providerType: volume.Block,
            name: aws.Name},
        // NFS provider. This provisions storage from an NFS server.
        {providerType: volume.File,
            name: nfs.Name},
        // BTRFS provider. This provisions storage from local btrfs fs.
        {providerType: volume.File,
            name: btrfs.Name},
    }
)

That's pretty much it. At this point, when you start the OSD, your driver will be loaded.

Building a Docker image

OSD can run inside of Docker:

make docker-build-osd

This builds a Docker image called openstorage/osd. You can then run the image:

make launch

OSD on the Docker registry

Pre-built Docker images of the OSD are available at https://hub.docker.com/r/openstorage/osd/

Using openstorage with systemd

[Unit]
Description=Open Storage

[Service]
CPUQuota=200%
MemoryLimit=1536M
ExecStart=/usr/local/bin/osd
Restart=on-failure

[Install]
WantedBy=multi-user.target