nfs-server-alpine
A handy NFS Server image comprising of Alpine Linux v3.5.0 and NFS v4 only, over TCP on port 2049.
Overview
The image comprises of;
- Alpine Linux v3.5.0. Alpine Linux is a security-oriented, lightweight Linux distribution based on musl libc (v1.1.15) and BusyBox.
- NFS v4 only, over TCP on port 2049.
When run, this container will make whatever directory is specified by the environment variable SHARED_DIRECTORY available to NFS v4 clients.
docker run -d --name nfs --privileged -v /some/where/fileshare:/nfsshare -e SHARED_DIRECTORY=/nfsshare itsthenetwork/nfs-server-alpine:latest
Add --net=host or -p 2049:2049 to make the shares externally accessible via the host networking stack. This isn't necessary if using Rancher or linking containers in some other way.
Due to the fsid=0 parameter set in the /etc/exports file, there's no need to specify the folder name when mounting from a client. For example, this works fine even though the folder being mounted and shared is /nfsshare:
sudo mount -v 10.11.12.101:/ /some/where/here
To be a little more explicit:
sudo mount -v -o vers=4,loud 10.11.12.101:/ /some/where/here
To unmount:
sudo umount /some/where/here
The exports file contains these parameters:
*(rw,fsid=0,async,no_subtree_check,no_auth_nlm,insecure,no_root_squash)
Note that the showmount command won't work against the server as rpcbind isn't running.
RancherOS
You may need to do this to get things working;
sudo ros service enable kernel-headers
sudo ros service up kernel-headers
RancherOS also uses overlayfs for Docker so please read the next section.
OverlayFS
OverlayFS does not support NFS export so please volume mount into your NFS container from an alternative (hopefully one is available).
On RancherOS the /home, /media and /mnt file systems are good choices as these are ext4.
Other OS's
You may need to ensure the nfs and nfsd kernel modules are loaded by running modprobe nfs nfsd.
Mounting Within a Container
The container requires the SYS_ADMIN capability, or, less securely, to be run in privileged mode.
What Good Looks Like
A successful server start should produce log output like this:
Starting Confd population of files...
confd 0.12.0-dev
2017-05-17T09:24:57Z ffcbba1623e6 /usr/bin/confd[13]: INFO Backend set to env
2017-05-17T09:24:57Z ffcbba1623e6 /usr/bin/confd[13]: INFO Starting confd
2017-05-17T09:24:57Z ffcbba1623e6 /usr/bin/confd[13]: INFO Backend nodes set to
2017-05-17T09:24:57Z ffcbba1623e6 /usr/bin/confd[13]: INFO /etc/exports has md5sum 4f1bb7b2412ce5952ecb5ec22d8ed99d should be 92cc8fa446eef0e167648be03aba09e5
2017-05-17T09:24:57Z ffcbba1623e6 /usr/bin/confd[13]: INFO Target config /etc/exports out of sync
2017-05-17T09:24:57Z ffcbba1623e6 /usr/bin/confd[13]: INFO Target config /etc/exports has been updated
Displaying /etc/exports contents...
/nfsshare *(rw,fsid=0,async,no_subtree_check,no_auth_nlm,insecure,no_root_squash)
Starting NFS in the background...
rpc.nfsd: knfsd is currently down
rpc.nfsd: Writing version string to kernel: -2 -3 +4
rpc.nfsd: Created AF_INET TCP socket.
rpc.nfsd: Created AF_INET6 TCP socket.
Exporting File System...
exporting *:/nfsshare
Starting Mountd in the background...
Dockerfile
The Dockerfile used to create this image is copied to the root of the file system on build.