In-memory storage backend for testing and development.

This backend stores all files in memory using an Agent. It's useful for:

• Testing without external dependencies (no S3-compatible service needed)
• Development and experimentation
• As a reference implementation for custom backends

Usage

{:ok, ref} = Sftpd.start_server(
  port: 2222,
  backend: Sftpd.Backends.Memory,
  backend_opts: [],
  auth: {:passwords, [{"user", "pass"}]},
  system_dir: "path/to/ssh_keys"
)

State Structure

The backend maintains a map of paths to file data:

%{
  "path/to/file.txt" => %{content: "...", mtime: ~N[...]},
  "path/to/dir/.keep" => %{content: "", mtime: ~N[...]}
}

Directories are represented by .keep marker files (like S3).

Examples

iex> {:ok, state} = Sftpd.Backends.Memory.init(
...>   files: %{"hello.txt" => %{content: "hi", mtime: ~N[2024-01-01 00:00:00]}}
...> )
iex> Sftpd.Backends.Memory.list_dir(~c"/", state)
{:ok, [~c".", ~c"..", ~c"hello.txt"]}

iex> {:ok, state} = Sftpd.Backends.Memory.init([])
iex> :ok = Sftpd.Backends.Memory.write_file(~c"/notes.txt", "hello", state)
iex> Sftpd.Backends.Memory.read_file(~c"/notes.txt", state)
{:ok, "hello"}

See the Backends and Custom Backends extras in HexDocs for how this backend fits into the wider package model.