97 lines
3 KiB
Markdown
97 lines
3 KiB
Markdown
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Golang Network File Server
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===
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NFSv3 protocol implementation in pure Golang.
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Current Status:
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* Minimally tested
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* Mounts, read-only and read-write support
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Usage
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===
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The most interesting demo is currently in `example/osview`.
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Start the server
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`go run ./example/osview .`.
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The local folder at `.` will be the initial view in the mount. mutations to metadata or contents
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will be stored purely in memory and not written back to the OS. When run, this
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demo will print the port it is listening on.
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The mount can be accessed using a command similar to
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`mount -o port=<n>,mountport=<n> -t nfs localhost:/mount <mountpoint>` (For Mac users)
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or
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`mount -o port=<n>,mountport=<n>,nfsvers=3,noacl,tcp -t nfs localhost:/mount <mountpoint>` (For Linux users)
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API
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===
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The NFS server runs on a `net.Listener` to export a file system to NFS clients.
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Usage is structured similarly to many other golang network servers.
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```golang
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package main
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import (
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"fmt"
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"log"
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"net"
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"github.com/go-git/go-billy/v5/memfs"
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nfs "github.com/willscott/go-nfs"
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nfshelper "github.com/willscott/go-nfs/helpers"
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)
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func main() {
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listener, err := net.Listen("tcp", ":0")
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panicOnErr(err, "starting TCP listener")
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fmt.Printf("Server running at %s\n", listener.Addr())
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mem := memfs.New()
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f, err := mem.Create("hello.txt")
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panicOnErr(err, "creating file")
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_, err = f.Write([]byte("hello world"))
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panicOnErr(err, "writing data")
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f.Close()
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handler := nfshelper.NewNullAuthHandler(mem)
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cacheHelper := nfshelper.NewCachingHandler(handler, 1)
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panicOnErr(nfs.Serve(listener, cacheHelper), "serving nfs")
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}
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func panicOnErr(err error, desc ...interface{}) {
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if err == nil {
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return
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}
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log.Println(desc...)
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log.Panicln(err)
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}
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```
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Notes
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---
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* Ports are typically determined through portmap. The need for running portmap
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(which is the only part that needs a privileged listening port) can be avoided
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through specific mount options. e.g.
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`mount -o port=n,mountport=n -t nfs host:/mount /localmount`
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* This server currently uses [billy](https://github.com/go-git/go-billy/) to
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provide a file system abstraction layer. There are some edges of the NFS protocol
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which do not translate to this abstraction.
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* NFS expects access to an `inode` or equivalent unique identifier to reference
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files in a file system. These are considered opaque identifiers here, which
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means they will not work as expected in cases of hard linking.
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* The billy abstraction layer does not extend to exposing `uid` and `gid`
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ownership of files. If ownership is important to your file system, you
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will need to ensure that the `os.FileInfo` meets additional constraints.
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In particular, the `Sys()` escape hatch is queried by this library, and
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if your file system populates a [`syscall.Stat_t`](https://golang.org/pkg/syscall/#Stat_t)
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concrete struct, the ownership specified in that object will be used.
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* Relevant RFCS:
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[5531 - RPC protocol](https://tools.ietf.org/html/rfc5531),
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[1813 - NFSv3](https://tools.ietf.org/html/rfc1813),
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[1094 - NFS](https://tools.ietf.org/html/rfc1094)
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