spdk-rs crate

spdk-rs crate provides a higher-level bindings and wrappers around SPDK library to enable building safer SPDK-based Rust applications.

Read about SPDK here: https://spdk.io/.

About linking SPDK applications: https://spdk.io/doc/pkgconfig.html.

OpenEBS provides a version of SPDK with a number of patches needed by OpenEBS storage products: https://github.com/openebs/spdk. When a new version of SPDK is released, OpenEBS maintainers port these patches on the new branch. For Mayastor family of products, the branches with OpenEBS patches are named like v24.05.x-mayastor where v24.05 is the tag name of a major SPDK release.

Please note that not every major SPDK release has a branch with OpenEBS patches.

Development enviroment

For developing with spdk-rs, a Rust compiler and an SPDK library must be present on the system. This spdk-rs repo contains a set of scripts that allows to set up this development environment easily.

spdk-rs leverages Nix package manager for that purpose: instead of relying on system's package manager, all the necessary tools and libraries are supplied by Nix.

In order to provide a stable and reproducible build environment, spdk-rs pins the concrete versions of all the required tools and libraries. This is done via a set of Nix package definitions.

Currently, spdk-rs can only be built on Linux.

Nix package manager

In order to make use of this repo's developement scripts, a developer must have a Nix environment installed on the system. One can either install a Nix packager manager on the existing operating system, or install the Nix OS Linux distro which is built on top of the Nix packager manager.

Installing Nix as a packager manager: https://nixos.org/download/

Installing Nix as a Linux distro: https://nixos.org/download/#nixos-iso

Once a Nix environment is ready, the developer can proceed and start spdk-rs Ni x shell.

Nix shell

To start Nix shell, run this command from spdk-rs directory:

nix-shell

Nix package manager will download and install all the necessary tool and libraries, including the Rust compiler and SPDK. Then, it will start a bash session.

When started for the first time, it would take some time to download and build the dependencies. It may take a considerable amount of time, depending on Internet connection speed and CPU power. Next time, Nix will use dependencies previously built and cached.

Nix installs different versions of the same package independently, allowing to have multiple versions of a library on the same system in different shells.

Note: Nix package manager does not install anything on any the system-wide bin or lib directories, instead it creates a virtual environment for each shell instance. All the required libraries and binaries are installed into Nix's own directory. Within the Nix shell, PATH and other variables like LD_LIBRARY_PATH are set up accordingly.

Nix shell arguments

Nix shell for spdk-rs accepts some arguments that allow to alter the development environment. Nix shell arguments are passed by --argstr <value> shell argument, e.g.:

nix-shell --argstr spdk release --argstr rust nightly

The supported parameters are the following:

• spdk <config>:
  • develop: use debug Nix package for SPDK (this is the default);
  • release: use release Nix package for SPDK;
  • none: do not use Nix package for SPDK; see below.
• spdk-path <path>: sets path to SPDK source directory; see below.
• rust <config>
  • stable: use stable Rust Nix package (this is the default);
  • nightly: use nightly Rust Nix package;
  • asan: enable ASAN for Rust; nightly Nix package is forced;
  • none: do not use Nix package for SPDK; see below.

Building spdk-rs

Once the Nix shell is started, spdk-rs can be built the usual Rust way:

cargo build

Example SPDK-based programs from this repo can be built and run with:

cargo build --example hello_world
sudo ./target/debug/examples/hello_world

Note: Generally, SPDK-based program are likely to require root priveleges.

SPDK packages

This repo provides a Nix package definition for SPDK library, configured for spdk-rs needs.

spdk-rs is not designed to work with an arbitrary SPDK version, or arbitrary SPDK configuration. Rather, a specific spdk-rs version is compatible with a specific SPDK commit and configuration. This relationship is established by specifying SPDK commit hash in SPDK Nix package definition: nix/pkgs/libspdk/default.nix. When Nix shell is started, it fetches the version specified in that file (github commit hash).

Nix package definition for SPDK configures and compiles SPDK with options compatible with spdk-rs.

One can select either a debug SPDK package (no optimizations, assertions enabled), or a release package by starting Nix shell with the spdk argument:

nix-shell --argstr spdk debug
or
nix-shell --argstr spdk release

By default, Nix shell starts with debug SPDK.

Note: Installing SPDK via system's package managers like apt is not supported. It may, or may not work.

Custom SPDK

To add new features to, or fix bugs in SPDK itself, SPDK has to be built from source code. To do that, one has to start the Nix shell without SPDK packages, pull and checkout the correct SPDK version, and build it manually. spdk-rs provides helper shell scripts to simplify SPDK compilation.

SPDK must be built with the environment compatible with spdk-rs, and with a compatible configuration. To set up the compatible environment, configure and compile SPDK from within the spdk-rs Nix shell.

Getting SPDK source code

To get the SPDK source code, determine the branch and/or commit you need, and run the following commands:

git clone git@github.com:openebs/spdk.git
cd spdk
git checkout -t origin/v24.01.x-mayastor
git submodule update --recursive --init

Starting the compatible Nix shell

spdk-rs relies on SPDK_ROOT_DIR environment variable to point to SPDK installation or source code directory.

To begin with custom SPDK compilation, start the shell with SPDK packages disabled, and SPDK source path specified:

nix-shell --argstr spdk none --argstr spdk-path ~/myspdk

--argstr spdk-path <path> will set SPDK_ROOT_DIR to point to the given path. (Please note tha the path is resolved to the real path before assigning the shell var).

Note: If --argstr spdk-path <path> is given, --argstr spdk none is implied:

nix-shell --argstr spdk-path ~/myspdk

Note: However, if --argstr spdk none is given, and --argstr spdk-path <path> is not given, the developer must set SPDK_ROOT_DIR manually.

SPDK helper scripts

spdk-rs provides a helper script to simplify configuring and compiling SPDK, ./build_scripts/build_spdk.sh. The script supports verbose (-v) and dry run (-n) modes. See script's help (--help) for more options.

To configure SPDK, run:

./build_scripts/build_spdk.sh configure

To compile SPDK, run:

./build_scripts/build_spdk.sh make

To check and fix SPDK source code formatting according to SPDK rules, run:

./build_scripts/build_spdk.sh fmt

To clean the SPDK directory with git clean, run:

./build_scripts/build_spdk.sh clean

Rebuild Rust code when SPDK is rebuilt

When Nix shell is started with Nix SPDK packages disabled, Rust build script for spdk-rs will tell Cargo to recompile Rust code every time build_spdk.sh make is invoked.

(./build_spdk.sh make writes to build_logs directory. Rust build script detects modifications of build_logs directory, and rebuilds Rust sources.)

Building SPDK manually

Instead of relying on build_spdk.sh script, one can configure and make SPDK manually:

cd <spdk_path>
AS=nasm ./configure --enable-debug --target-arch=nehalem --without-shared \
    --without-crypto \
    --without-nvme-cuse --without-fuse \
    --with-uring --without-uring-zns \
    --disable-unit-tests --disable-tests \
    --with-fio=$(realpath $(dirname $(which fio))/..)

make -j

Note: Currently, spdk-rs can only link to SPDK built as static libraries.

spdk-rs must be cleaned manually in order to rebuild Rust code after making SPDK.

Checking style

cd <spdk_dir>
./scripts/check_format.sh

Cleaning SPDK build

To clean up the SPDK directory and reset to the initial state:

mkdir ${your_spdk_dir}
make clean
git clean -fdx ./
git submodule foreach --recursive git clean -xfd
git submodule update

Installing SPDK

Currently, SPDK's standard make install script does not make an installation sutiable to be used with spdk-rs. That is, trying to configure (via DESTDIR) and install SPDK in other directory using Makefile is not supported.

To install, run:

./build_scripts/build_spdk.sh install <path>

Rust compiler

To provide a reproducible build environment, Rust compiler is suppiled by Nix. By default, a compatible, verified stable Rust is used when Nix shell starts. One can choose a nightly Rust (although, it is a compatible, verified nightly):

nix-shell --argstr rust nightly

To use Rust provided by the system, e.g. by brough up rustup, run:

nix-shell --argstr rust none

ASAN

One can compile and run Rust code with LLVM Address Sanitizer (ASAN) enabled:

nix-shell --argstr rust asan
cargo build

Note: ASAN forces nightly Rust, and changes output directory.

System Rust

TODO

Appendix A: SPDK versions and configurations

Different versions of SPDK require different configuration option.

Versions < 22.09

./configure --enable-debug --target-arch=nehalem --without-shared \
    --without-isal --with-crypto --with-uring --disable-unit-tests \
    --disable-tests --with-fio=$(which fio | sed s';bin/fio;include;')
make

Versions >= 22.09 and < 24.01

• ISAL is now mandatory
• When upgrading from previous versions, clean the SPDK directory before building (e.g. git clean).
• An AS shell var must be set, either yasm or nasm.
• Zone support for uring must be disabled.
• Crypto must be disabled.

AS=yasm ./configure --enable-debug --target-arch=nehalem --without-shared \
    --without-crypto \
    --with-uring --without-uring-zns \
    --disable-unit-tests --disable-tests \
    --with-fio=$(realpath $(dirname $(which fio))/..)

make

Version >= 24.01

Same as 22.09+ but with the following additionally:

• AS must be nasm now.
• FUSE must be disabled.

AS=nasm ./configure --enable-debug --target-arch=nehalem --without-shared \
    --without-crypto \
    --without-nvme-cuse --without-fuse \
    --with-uring --without-uring-zns \
    --disable-unit-tests --disable-tests \
    --with-fio=$(realpath $(dirname $(which fio))/..)
make