# Ceph - a scalable distributed storage system

Please see https://ceph.com/ for current info.


## Contributing Code

Most of Ceph is dual licensed under the LGPL version 2.1 or 3.0.  Some
miscellaneous code is under a BSD-style license or is public domain.
The documentation is licensed under Creative Commons
Attribution Share Alike 3.0 (CC-BY-SA-3.0).  There are a handful of headers
included here that are licensed under the GPL.  Please see the file
COPYING for a full inventory of licenses by file.

Code contributions must include a valid "Signed-off-by" acknowledging
the license for the modified or contributed file.  Please see the file
SubmittingPatches.rst for details on what that means and on how to
generate and submit patches.

We do not require assignment of copyright to contribute code; code is
contributed under the terms of the applicable license.


## Checking out the source

Clone the ceph/ceph repository from github by running the following command on
a system that has git installed:

	git clone git@github.com:ceph/ceph

Alternatively, if you are not a github user, you should run the following
command on a system that has git installed:

	git clone https://github.com/ceph/ceph.git

When the ceph/ceph repository has been cloned to your system, run the following
command to check out the git submodules associated with the ceph/ceph
repository: 

	git submodule update --init --recursive


## Build Prerequisites

*section last updated 27 Jul 2023*

Make sure that ``curl`` is installed. The Debian and Ubuntu ``apt`` command is
provided here, but if you use a system with a different package manager, then
you must use whatever command is the proper counterpart of this one:

    apt install curl

Install Debian or RPM package dependencies by running the following command:

	./install-deps.sh

Install the ``python3-routes`` package:

    apt install python3-routes


## Building Ceph

These instructions are meant for developers who are compiling the code for
development and testing. To build binaries that are suitable for installation
we recommend that you build .deb or .rpm packages, or refer to ``ceph.spec.in``
or ``debian/rules`` to see which configuration options are specified for
production builds.

Build instructions:

	./do_cmake.sh
	cd build
	ninja

``do_cmake.sh`` defaults to creating a debug build of Ceph that can be up to 5x
slower with some workloads. Pass ``-DCMAKE_BUILD_TYPE=RelWithDebInfo`` to
``do_cmake.sh`` to create a non-debug release.

The number of jobs used by `ninja` is derived from the number of CPU cores of
the building host if unspecified. Use the `-j` option to limit the job number
if the build jobs are running out of memory. On average, each job takes around
2.5GiB memory.

This assumes that you make your build directory a subdirectory of the ceph.git
checkout. If you put it elsewhere, just point `CEPH_GIT_DIR` to the correct
path to the checkout. Additional CMake args can be specified by setting ARGS
before invoking ``do_cmake.sh``. See [cmake options](#cmake-options)
for more details. For example:

    ARGS="-DCMAKE_C_COMPILER=gcc-7" ./do_cmake.sh

To build only certain targets use:

	ninja [target name]

To install:

	ninja install
 
### CMake Options

If you run the `cmake` command by hand, there are many options you can
set with "-D". For example, the option to build the RADOS Gateway is
defaulted to ON. To build without the RADOS Gateway:

	cmake -DWITH_RADOSGW=OFF [path to top-level ceph directory]

Another example below is building with debugging and alternate locations 
for a couple of external dependencies:

	cmake -DLEVELDB_PREFIX="/opt/hyperleveldb" \
	-DCMAKE_INSTALL_PREFIX=/opt/ceph -DCMAKE_C_FLAGS="-Og -g3 -gdwarf-4" \
	..

Ceph has several bundled dependencies such as Boost, RocksDB and Arrow. By
default, cmake will build these bundled dependencies from source instead of
using libraries that are already installed on the system. You can opt-in to
using these system libraries, provided they meet the minimum version required
by Ceph, with cmake options like `WITH_SYSTEM_BOOST`:

	cmake -DWITH_SYSTEM_BOOST=ON [...]

To view an exhaustive list of -D options, you can invoke `cmake` with:

	cmake -LH

If you often pipe `ninja` to `less` and would like to maintain the
diagnostic colors for errors and warnings (and if your compiler
supports it), you can invoke `cmake` with:

	cmake -DDIAGNOSTICS_COLOR=always ...

Then you'll get the diagnostic colors when you execute:

	ninja | less -R

Other available values for 'DIAGNOSTICS_COLOR' are 'auto' (default) and
'never'.


## Building a source tarball

To build a complete source tarball with everything needed to build from
source and/or build a (deb or rpm) package, run

	./make-dist

This will create a tarball like ceph-$version.tar.bz2 from git.
(Ensure that any changes you want to include in your working directory
are committed to git.)


## Running a test cluster

To run a functional test cluster,

	cd build
	ninja vstart        # builds just enough to run vstart
	../src/vstart.sh --debug --new -x --localhost --bluestore
	./bin/ceph -s

Almost all of the usual commands are available in the bin/ directory.
For example,

	./bin/rados -p rbd bench 30 write
	./bin/rbd create foo --size 1000

To shut down the test cluster,

	../src/stop.sh

To start or stop individual daemons, the sysvinit script can be used:

	./bin/init-ceph restart osd.0
	./bin/init-ceph stop


## Running unit tests

To build and run all tests (in parallel using all processors), use `ctest`:

	cd build
	ninja
	ctest -j$(nproc)

(Note: Many targets built from src/test are not run using `ctest`.
Targets starting with "unittest" are run in `ninja check` and thus can
be run with `ctest`. Targets starting with "ceph_test" can not, and should
be run by hand.)

When failures occur, look in build/Testing/Temporary for logs.

To build and run all tests and their dependencies without other
unnecessary targets in Ceph:

	cd build
	ninja check -j$(nproc)

To run an individual test manually, run `ctest` with -R (regex matching):

	ctest -R [regex matching test name(s)]

(Note: `ctest` does not build the test it's running or the dependencies needed
to run it)

To run an individual test manually and see all the tests output, run
`ctest` with the -V (verbose) flag:

	ctest -V -R [regex matching test name(s)]

To run tests manually and run the jobs in parallel, run `ctest` with 
the `-j` flag:

	ctest -j [number of jobs]

There are many other flags you can give `ctest` for better control
over manual test execution. To view these options run:

	man ctest


## Building the Documentation

### Prerequisites

The list of package dependencies for building the documentation can be
found in `doc_deps.deb.txt`:

	sudo apt-get install `cat doc_deps.deb.txt`

### Building the Documentation

To build the documentation, ensure that you are in the top-level
`/ceph` directory, and execute the build script. For example:

	admin/build-doc

## Reporting Issues

To report an issue and view existing issues, please visit https://tracker.ceph.com/projects/ceph.
