================== Documenting Ceph ================== The **easiest way** to help the Ceph project is to contribute to the documentation. As the Ceph user base grows and the development pace quickens, an increasing number of people are updating the documentation and adding new information. Even small contributions like fixing spelling errors or clarifying instructions will help the Ceph project immensely. The Ceph documentation source resides in the ``ceph/doc`` directory of the Ceph repository, and Python Sphinx renders the source into HTML and manpages. The http://ceph.com/docs link currently displays the ``master`` branch by default, but you may view documentation for older branches (e.g., ``argonaut``) or future branches (e.g., ``next``) as well as work-in-progress branches by substituting ``master`` with the branch name you prefer. Another way to suggest a documentation correction is to make a pull request. The instructions for making a pull request against the Ceph documentation are in the section :ref:`making_contributions`. If this is your first time making an improvement to the documentation or if you have noticed a small mistake (such as a spelling error or a typo), it will be easier to send an email than to make a pull request. You will be credited for the improvement unless you instruct Ceph Upstream Documentation not to credit you. Location of the Documentation in the Repository =============================================== The Ceph documentation source is in the ``ceph/doc`` directory of the Ceph repository. Python Sphinx renders the source into HTML and manpages. Viewing Old Ceph Documentation ============================== The https://docs.ceph.com link displays the latest release branch by default (for example, if "Quincy" is the most recent release, then by default https://docs.ceph.com displays the documentation for Quincy), but you can view the documentation for older versions of Ceph (for example, ``pacific``) by replacing the version name in the url (for example, ``quincy`` in `https://docs.ceph.com/en/pacific `_) with the branch name you prefer (for example, ``pacific``, to create a URL that reads `https://docs.ceph.com/en/pacific/ `_). .. _making_contributions: Making Contributions ==================== Making a documentation contribution generally involves the same procedural sequence as making a code contribution, except that you must build documentation source instead of compiling program source. The sequence includes the following steps: #. `Get the Source`_ #. `Select a Branch`_ #. `Make a Change`_ #. `Build the Source`_ #. `Commit the Change`_ #. `Push the Change`_ #. `Make a Pull Request`_ #. `Notify Us`_ Get the Source -------------- Ceph documentation lives in the Ceph repository right alongside the Ceph source code under the ``ceph/doc`` directory. For details on github and Ceph, see :ref:`Get Involved`. The most common way to make contributions is to use the `Fork and Pull`_ approach. You must: #. Install git locally. For Debian/Ubuntu, execute: .. prompt:: bash $ sudo apt-get install git For Fedora, execute: .. prompt:: bash $ sudo yum install git For CentOS/RHEL, execute: .. prompt:: bash $ sudo yum install git #. Ensure your ``.gitconfig`` file has your name and email address. : .. code-block:: ini [user] email = {your-email-address} name = {your-name} For example: .. prompt:: bash $ git config --global user.name "John Doe" git config --global user.email johndoe@example.com #. Create a `github`_ account (if you don't have one). #. Fork the Ceph project. See https://github.com/ceph/ceph. #. Clone your fork of the Ceph project to your local host. Ceph organizes documentation into an information architecture primarily by its main components. - **Ceph Storage Cluster:** The Ceph Storage Cluster documentation resides under the ``doc/rados`` directory. - **Ceph Block Device:** The Ceph Block Device documentation resides under the ``doc/rbd`` directory. - **Ceph Object Storage:** The Ceph Object Storage documentation resides under the ``doc/radosgw`` directory. - **Ceph File System:** The Ceph File System documentation resides under the ``doc/cephfs`` directory. - **Installation (Quick):** Quick start documentation resides under the ``doc/start`` directory. - **Installation (Manual):** Manual installation documentation resides under the ``doc/install`` directory. - **Manpage:** Manpage source resides under the ``doc/man`` directory. - **Developer:** Developer documentation resides under the ``doc/dev`` directory. - **Images:** If you include images such as JPEG or PNG files, you should store them under the ``doc/images`` directory. Select a Branch --------------- When you make small changes to the documentation, such as fixing typographical errors or clarifying explanations, use the ``main`` branch (default). You should also use the ``main`` branch when making contributions to features that are in the current release. ``main`` is the most commonly used branch. : .. prompt:: bash $ git checkout main When you make changes to documentation that affect an upcoming release, use the ``next`` branch. ``next`` is the second most commonly used branch. : .. prompt:: bash $ git checkout next When you are making substantial contributions such as new features that are not yet in the current release; if your contribution is related to an issue with a tracker ID; or, if you want to see your documentation rendered on the Ceph.com website before it gets merged into the ``main`` branch, you should create a branch. To distinguish branches that include only documentation updates, we prepend them with ``wip-doc`` by convention, following the form ``wip-doc-{your-branch-name}``. If the branch relates to an issue filed in http://tracker.ceph.com/issues, the branch name incorporates the issue number. For example, if a documentation branch is a fix for issue #4000, the branch name should be ``wip-doc-4000`` by convention and the relevant tracker URL will be http://tracker.ceph.com/issues/4000. .. note:: Please do not mingle documentation contributions and source code contributions in a single commit. When you keep documentation commits separate from source code commits, it simplifies the review process. We highly recommend that any pull request that adds a feature or a configuration option should also include a documentation commit that describes the changes. Before you create your branch name, ensure that it doesn't already exist in the local or remote repository. : .. prompt:: bash $ git branch -a | grep wip-doc-{your-branch-name} If it doesn't exist, create your branch: .. prompt:: bash $ git checkout -b wip-doc-{your-branch-name} Make a Change ------------- Modifying a document involves opening a reStructuredText file, changing its contents, and saving the changes. See `Documentation Style Guide`_ for details on syntax requirements. Adding a document involves creating a new reStructuredText file within the ``doc`` directory tree with a ``*.rst`` extension. You must also include a reference to the document: a hyperlink or a table of contents entry. The ``index.rst`` file of a top-level directory usually contains a TOC, where you can add the new file name. All documents must have a title. See `Headings`_ for details. Your new document doesn't get tracked by ``git`` automatically. When you want to add the document to the repository, you must use ``git add {path-to-filename}``. For example, from the top level directory of the repository, adding an ``example.rst`` file to the ``rados`` subdirectory would look like this: .. prompt:: bash $ git add doc/rados/example.rst Deleting a document involves removing it from the repository with ``git rm {path-to-filename}``. For example: .. prompt:: bash $ git rm doc/rados/example.rst You must also remove any reference to a deleted document from other documents. Build the Source ---------------- To build the documentation, navigate to the ``ceph`` repository directory: .. prompt:: bash $ cd ceph .. note:: The directory that contains ``build-doc`` and ``serve-doc`` must be included in the ``PATH`` environment variable in order for these commands to work. To build the documentation on Debian/Ubuntu, Fedora, or CentOS/RHEL, execute: .. prompt:: bash $ admin/build-doc To scan for the reachability of external links, execute: .. prompt:: bash $ admin/build-doc linkcheck Executing ``admin/build-doc`` will create a ``build-doc`` directory under ``ceph``. You may need to create a directory under ``ceph/build-doc`` for output of Javadoc files: .. prompt:: bash $ mkdir -p output/html/api/libcephfs-java/javadoc The build script ``build-doc`` will produce an output of errors and warnings. You MUST fix errors in documents you modified before committing a change, and you SHOULD fix warnings that are related to syntax you modified. .. important:: You must validate ALL HYPERLINKS. If a hyperlink is broken, it automatically breaks the build! Once you build the documentation set, you may start an HTTP server at ``http://localhost:8080/`` to view it: .. prompt:: bash $ admin/serve-doc You can also navigate to ``build-doc/output`` to inspect the built documents. There should be an ``html`` directory and a ``man`` directory containing documentation in HTML and manpage formats respectively. Build the Source (First Time) ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Ceph uses Python Sphinx, which is generally distribution agnostic. The first time you build Ceph documentation, it will generate a doxygen XML tree, which is a bit time consuming. Python Sphinx does have some dependencies that vary across distributions. The first time you build the documentation, the script will notify you if you do not have the dependencies installed. To run Sphinx and build documentation successfully, the following packages are required: .. raw:: html

Debian/Ubuntu

- gcc - python3-dev - python3-pip - python3-sphinx - pytnon3-venv - libxml2-dev - libxslt1-dev - doxygen - graphviz - ant - ditaa .. raw:: html

Fedora

- gcc - python-devel - python-pip - python-docutils - python-jinja2 - python-pygments - python-sphinx - libxml2-devel - libxslt1-devel - doxygen - graphviz - ant - ditaa .. raw:: html

CentOS/RHEL

- gcc - python-devel - python-pip - python-docutils - python-jinja2 - python-pygments - python-sphinx - libxml2-dev - libxslt1-dev - doxygen - graphviz - ant .. raw:: html
Install each dependency that is not installed on your host. For Debian/Ubuntu distributions, execute the following: .. prompt:: bash $ sudo apt-get install gcc python-dev python-pip libxml2-dev libxslt-dev doxygen graphviz ant ditaa sudo apt-get install python-sphinx For Fedora distributions, execute the following: .. prompt:: bash $ sudo yum install gcc python-devel python-pip libxml2-devel libxslt-devel doxygen graphviz ant sudo pip install html2text sudo yum install python-jinja2 python-pygments python-docutils python-sphinx sudo yum install jericho-html ditaa For CentOS/RHEL distributions, it is recommended to have ``epel`` (Extra Packages for Enterprise Linux) repository as it provides some extra packages which are not available in the default repository. To install ``epel``, execute the following: .. prompt:: bash $ sudo yum install -y https://dl.fedoraproject.org/pub/epel/epel-release-latest-7.noarch.rpm For CentOS/RHEL distributions, execute the following: .. prompt:: bash $ sudo yum install gcc python-devel python-pip libxml2-devel libxslt-devel doxygen graphviz ant sudo pip install html2text For CentOS/RHEL distributions, the remaining python packages are not available in the default and ``epel`` repositories. So, use http://rpmfind.net/ to find the packages. Then, download them from a mirror and install them. For example: .. prompt:: bash $ wget http://rpmfind.net/linux/centos/7/os/x86_64/Packages/python-jinja2-2.7.2-2.el7.noarch.rpm sudo yum install python-jinja2-2.7.2-2.el7.noarch.rpm wget http://rpmfind.net/linux/centos/7/os/x86_64/Packages/python-pygments-1.4-9.el7.noarch.rpm sudo yum install python-pygments-1.4-9.el7.noarch.rpm wget http://rpmfind.net/linux/centos/7/os/x86_64/Packages/python-docutils-0.11-0.2.20130715svn7687.el7.noarch.rpm sudo yum install python-docutils-0.11-0.2.20130715svn7687.el7.noarch.rpm wget http://rpmfind.net/linux/centos/7/os/x86_64/Packages/python-sphinx-1.1.3-11.el7.noarch.rpm sudo yum install python-sphinx-1.1.3-11.el7.noarch.rpm Ceph documentation makes extensive use of `ditaa`_, which is not presently built for CentOS/RHEL7. You must install ``ditaa`` if you are making changes to ``ditaa`` diagrams so that you can verify that they render properly before you commit new or modified ``ditaa`` diagrams. You may retrieve compatible required packages for CentOS/RHEL distributions and install them manually. To run ``ditaa`` on CentOS/RHEL7, following dependencies are required: - jericho-html - jai-imageio-core - batik Use http://rpmfind.net/ to find compatible ``ditaa`` and the dependencies. Then, download them from a mirror and install them. For example: .. prompt:: bash $ wget http://rpmfind.net/linux/fedora/linux/releases/22/Everything/x86_64/os/Packages/j/jericho-html-3.3-4.fc22.noarch.rpm sudo yum install jericho-html-3.3-4.fc22.noarch.rpm wget http://rpmfind.net/linux/centos/7/os/x86_64/Packages/jai-imageio-core-1.2-0.14.20100217cvs.el7.noarch.rpm sudo yum install jai-imageio-core-1.2-0.14.20100217cvs.el7.noarch.rpm wget http://rpmfind.net/linux/centos/7/os/x86_64/Packages/batik-1.8-0.12.svn1230816.el7.noarch.rpm sudo yum install batik-1.8-0.12.svn1230816.el7.noarch.rpm wget http://rpmfind.net/linux/fedora/linux/releases/22/Everything/x86_64/os/Packages/d/ditaa-0.9-13.r74.fc21.noarch.rpm sudo yum install ditaa-0.9-13.r74.fc21.noarch.rpm Once you have installed all these packages, build the documentation by following the steps given in `Build the Source`_. Commit the Change ----------------- Ceph documentation commits are simple, but follow a strict convention: - A commit SHOULD have 1 file per commit (it simplifies rollback). You MAY commit multiple files with related changes. Unrelated changes SHOULD NOT be put into the same commit. - A commit MUST have a comment. - A commit comment MUST be prepended with ``doc:``. (strict) - The comment summary MUST be one line only. (strict) - Additional comments MAY follow a blank line after the summary, but should be terse. - A commit MAY include ``Fixes: #{bug number}``. - Commits MUST include ``Signed-off-by: Firstname Lastname ``. (strict) .. tip:: Follow the foregoing convention particularly where it says ``(strict)`` or you will be asked to modify your commit to comply with this convention. The following is a common commit comment (preferred):: doc: Fixes a spelling error and a broken hyperlink. Signed-off-by: John Doe The following comment includes a reference to a bug. :: doc: Fixes a spelling error and a broken hyperlink. Fixes: #1234 Signed-off-by: John Doe The following comment includes a terse sentence following the comment summary. There is a carriage return between the summary line and the description:: doc: Added mon setting to monitor config reference Describes 'mon setting', which is a new setting added to config_opts.h. Signed-off-by: John Doe To commit changes, execute the following: .. prompt:: bash $ git commit -a An easy way to manage your documentation commits is to use visual tools for ``git``. For example, ``gitk`` provides a graphical interface for viewing the repository history, and ``git-gui`` provides a graphical interface for viewing your uncommitted changes, staging them for commit, committing the changes and pushing them to your forked Ceph repository. For Debian/Ubuntu, execute: .. prompt:: bash $ sudo apt-get install gitk git-gui For Fedora/CentOS/RHEL, execute: .. prompt:: bash $ sudo yum install gitk git-gui Then, execute: .. prompt:: bash $ cd {git-ceph-repo-path} gitk Finally, select **File->Start git gui** to activate the graphical user interface. Push the Change --------------- Once you have one or more commits, you must push them from the local copy of the repository to ``github``. A graphical tool like ``git-gui`` provides a user interface for pushing to the repository. If you created a branch previously: .. prompt:: bash $ git push origin wip-doc-{your-branch-name} Otherwise: .. prompt:: bash $ git push Make a Pull Request ------------------- As noted earlier, you can make documentation contributions using the `Fork and Pull`_ approach. Notify Us --------- After you make a pull request, please email ceph-docs@redhat.com. Documentation Style Guide ========================= One objective of the Ceph documentation project is to ensure the readability of the documentation in both native restructuredText format and its rendered formats such as HTML. Navigate to your Ceph repository and view a document in its native format. You may notice that it is generally as legible in a terminal as it is in its rendered HTML format. Additionally, you may also notice that diagrams in ``ditaa`` format also render reasonably well in text mode. : .. prompt:: bash $ less doc/architecture.rst Review the following style guides to maintain this consistency. Headings -------- #. **Document Titles:** Document titles use the ``=`` character overline and underline with a leading and trailing space on the title text line. See `Document Title`_ for details. #. **Section Titles:** Section tiles use the ``=`` character underline with no leading or trailing spaces for text. Two carriage returns should precede a section title (unless an inline reference precedes it). See `Sections`_ for details. #. **Subsection Titles:** Subsection titles use the ``_`` character underline with no leading or trailing spaces for text. Two carriage returns should precede a subsection title (unless an inline reference precedes it). Text Body --------- As a general rule, we prefer text to wrap at column 80 so that it is legible in a command line interface without leading or trailing white space. Where possible, we prefer to maintain this convention with text, lists, literal text (exceptions allowed), tables, and ``ditaa`` graphics. #. **Paragraphs**: Paragraphs have a leading and a trailing carriage return, and should be 80 characters wide or less so that the documentation can be read in native format in a command line terminal. #. **Literal Text:** To create an example of literal text (e.g., command line usage), terminate the preceding paragraph with ``::`` or enter a carriage return to create an empty line after the preceding paragraph; then, enter ``::`` on a separate line followed by another empty line. Then, begin the literal text with tab indentation (preferred) or space indentation of 3 characters. #. **Indented Text:** Indented text such as bullet points (e.g., ``- some text``) may span multiple lines. The text of subsequent lines should begin at the same character position as the text of the indented text (less numbers, bullets, etc.). Indented text may include literal text examples. Whereas, text indentation should be done with spaces, literal text examples should be indented with tabs. This convention enables you to add an additional indented paragraph following a literal example by leaving a blank line and beginning the subsequent paragraph with space indentation. #. **Numbered Lists:** Numbered lists should use autonumbering by starting a numbered indent with ``#.`` instead of the actual number so that numbered paragraphs can be repositioned without requiring manual renumbering. #. **Code Examples:** Ceph supports the use of the ``.. code-block::`` role, so that you can add highlighting to source examples. This is preferred for source code. However, use of this tag will cause autonumbering to restart at 1 if it is used as an example within a numbered list. See `Showing code examples`_ for details. Paragraph Level Markup ---------------------- The Ceph project uses `paragraph level markup`_ to highlight points. #. **Tip:** Use the ``.. tip::`` directive to provide additional information that assists the reader or steers the reader away from trouble. #. **Note**: Use the ``.. note::`` directive to highlight an important point. #. **Important:** Use the ``.. important::`` directive to highlight important requirements or caveats (e.g., anything that could lead to data loss). Use this directive sparingly, because it renders in red. #. **Version Added:** Use the ``.. versionadded::`` directive for new features or configuration settings so that users know the minimum release for using a feature. #. **Version Changed:** Use the ``.. versionchanged::`` directive for changes in usage or configuration settings. #. **Deprecated:** Use the ``.. deprecated::`` directive when CLI usage, a feature or a configuration setting is no longer preferred or will be discontinued. #. **Topic:** Use the ``.. topic::`` directive to encapsulate text that is outside the main flow of the document. See the `topic directive`_ for additional details. Table of Contents (TOC) and Hyperlinks --------------------------------------- The documents in the Ceph documentation suite follow certain conventions that are explained in this section. Every document (every ``.rst`` file) in the Sphinx-controlled Ceph documentation suite must be linked either (1) from another document in the documentation suite or (2) from a table of contents (TOC). If any document in the documentation suite is not linked in this way, the ``build-doc`` script generates warnings when it tries to build the documentation. The Ceph project uses the ``.. toctree::`` directive. See `The TOC tree`_ for details. When rendering a table of contents (TOC), specify the ``:maxdepth:`` parameter so that the rendered TOC is not too long. Use the ``:ref:`` syntax where a link target contains a specific unique identifier (for example, ``.. _unique-target-id:``). A link to the section designated by ``.. _unique-target-id:`` looks like this: ``:ref:`unique-target-id```. If this convention is followed, the links within the ``.rst`` source files will work even if the source files are moved within the ``ceph/doc`` directory. See `Cross referencing arbitrary locations`_ for details. .. _start_external_hyperlink_example: External Hyperlink Example ~~~~~~~~~~~~~~~~~~~~~~~~~~ It is also possible to create a link to a section of the documentation and to have custom text appear in the body of the link. This is useful when it is more important to preserve the text of the sentence containing the link than it is to refer explicitly to the title of the section being linked to. For example, RST that links to the Sphinx Python Document Generator homepage and generates a sentence reading "Click here to learn more about Python Sphinx." looks like this: :: ``Click `here `_ to learn more about Python Sphinx.`` And here it is, rendered: Click `here `_ to learn more about Python Sphinx. Pay special attention to the underscore after the backtick. If you forget to include it and this is your first day working with RST, there's a chance that you'll spend all day wondering what went wrong without realizing that you omitted that underscore. Also, pay special attention to the space between the substitution text (in this case, "here") and the less-than bracket that sets the explicit link apart from the substition text. The link will not render properly without this space. Linking Customs ~~~~~~~~~~~~~~~ By a custom established when Ceph was still being developed by Inktank, contributors to the documentation of the Ceph project preferred to use the convention of putting ``.. _Link Text: ../path`` links at the bottom of the document and linking to them using references of the form ``:ref:`path```. This convention was preferred because it made the documents more readable in a command line interface. As of 2023, though, we have no preference for one over the other. Use whichever convention makes the text easier to read. Quirks of ReStructured Text --------------------------- External Links ~~~~~~~~~~~~~~ .. _external_link_with_inline_text: This is the formula for links to addresses external to the Ceph documentation: :: `inline text `_ .. note:: Do not fail to include the space between the inline text and the less-than sign. Do not fail to include the underscore after the final backtick. To link to addresses that are external to the Ceph documentation, include a space between the inline text and the angle bracket that precedes the external address. This is precisely the opposite of :ref:`the convention for inline text that links to a location inside the Ceph documentation`. If this seems inconsistent and confusing to you, then you're right. It is inconsistent and confusing. See also ":ref:`External Hyperlink Example`". Internal Links ~~~~~~~~~~~~~~ To link to a section in the Ceph documentation, you must (1) define a target link before the section and then (2) link to that target from another location in the documentation. Here are the formulas for targets and links to those targets: Target:: .. _target: Title of Targeted Section ========================= Lorem ipsum... Link to target:: :ref:`target` .. _internal_link_with_inline_text: Link to target with inline text:: :ref:`inline text` .. note:: There is no space between "inline text" and the angle bracket that immediately follows it. This is precisely the opposite of :ref:`the convention for inline text that links to a location outside of the Ceph documentation`. If this seems inconsistent and confusing to you, then you're right. It is inconsistent and confusing. .. _Python Sphinx: https://www.sphinx-doc.org .. _restructuredText: http://docutils.sourceforge.net/rst.html .. _Fork and Pull: https://help.github.com/articles/using-pull-requests .. _github: http://github.com .. _ditaa: http://ditaa.sourceforge.net/ .. _Document Title: http://docutils.sourceforge.net/docs/user/rst/quickstart.html#document-title-subtitle .. _Sections: http://docutils.sourceforge.net/docs/user/rst/quickstart.html#sections .. _Cross referencing arbitrary locations: http://www.sphinx-doc.org/en/master/usage/restructuredtext/roles.html#role-ref .. _The TOC tree: http://sphinx-doc.org/markup/toctree.html .. _Showing code examples: http://sphinx-doc.org/markup/code.html .. _paragraph level markup: http://sphinx-doc.org/markup/para.html .. _topic directive: http://docutils.sourceforge.net/docs/ref/rst/directives.html#topic