Developer Documentation

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Introduction

Please coordinate your efforts with us before starting any development. It is important to have a common view of the problem and the corresponding solution – just to avoid duplicated or unnecessary efforts.

We will only include software which matches our quality criteria. The source code repository is read only. To include some code, send it as patch (git diff) to the pve-devel mailing list. We will review your code and commit after a successful review (and possible corrections/additions).

Mailing List

This is the primary communication channel for developers, discussing new features and implementation details. If you are a developer and you want to develop additional features, this is the place to start.

PVE Development List: https://lists.proxmox.com/cgi-bin/mailman/listinfo/pve-devel

Archive: https://lists.proxmox.com/pipermail/pve-devel/

Access to Code Repository (git)

https://git.proxmox.com

Build instructions

You could find build instructions here :

https://git.proxmox.com/?p=pve-common.git;a=blob_plain;f=README.dev;hb=HEAD

Development Package Repository

Some packages required for development can only be found in the devel repository. This is a cross project repository and may be used for all Proxmox Projects.

Add the following to the /etc/apt/sources.list file:

For Proxmox VE 8.x based on Debian 12 Bookworm

 deb http://download.proxmox.com/debian/devel/ bookworm main

For Proxmox VE 7.x based on Debian 11 Bullseye

 deb http://download.proxmox.com/debian/devel/ bullseye main

For Proxmox VE 6.x based on Debian 10 Buster

 deb http://download.proxmox.com/debian/devel/ buster main

Checking out a git repository

To clone a repository run 'git clone' with the repository name prefixed with the common URL: git://git.proxmox.com/git/ 

# git clone git://git.proxmox.com/git/pve-manager.git

To update an already cloned project to the current version use: 

# git pull

Working on the code

Coding guidelines

The codebase mostly contains Perl and rust code for the backend, JavaScript for the user interface, and C for the Proxmox Cluster Filesystem and upstream projects like the Linux kernel or QEMU. The documentation for Proxmox VE is written in AsciiDoc, using the python implementation.

Perl

For Perl, we recommend having a look at our perl style guide.

Rust

For our Rust code we use rustfmt (e.g., through cargo fmt) with default settings.

Compiler warnings must be avoided. Additionally, one might check lints reported by cargo clippy, but we do not accept mass fixing of those all over the place, such fixes are not always productive and can introduce actual subtle (logical) errors.

JavaScript

For JavaScript, we use eslint as separate package to check basic code standards. New contribution must not ensure that eslint doesn't output any warning or error. Check out Javascript Style Guide

We use the ExtJS framework for the web UI Components, its API documentation can be found at https://docs.sencha.com/extjs/7.0.0/.

Documentation

Avoid overly long line. Use line-length from context, which is 80 character columns most of the time, try to stay below 100 as maximum.

Adhere to our Technical Writing Style Guide.

Using git

If you are not familiar with git it could be worth to take a look at this interactive tutorial: https://try.github.io and read a brief introduction chapter from the official git documentation: https://git-scm.com/docs/gittutorial to gain basic knowledge on it.

First, configure your real name and email address for git, if not done already: 

$ git config --global user.name "John Doe"
$ git config --global user.email john@example.com

This will be used to sign off commits as your work.

It is recommended to start a feature branch before working on the code locally: 

# git checkout -f -b my_branch master

After this you can start working on your improvements. You'll be able to compare your changes to the current PVE master branch easily with 

# git diff master..my_branch

Commits and Commit Messages

Then, make your commit (try to make small, but self-contained, commits) and include a sign-off line (-s).

In general, commit messages should be written with the following style guide in mind:

  • Write your commit message in the imperative: "Fix bug" and not "Fixed bug" or "Fixes bug."
    This convention matches up with commit messages generated by commands like git merge and git revert.
  • Avoid using "we", as for readers it's unclear who is meant.
  • Make sure the line-length (text-width, column count) of the commit's message is not longer than 72 characters.
Note, HTTPS links and git trailers (e.g., Signed-off-by:, Reviewed-by: or Fixes:) are an exception and must not be split over multiple lines.
  • If the commit fixes a bug start with that information in this form: fix #1234: summary here
    If it implements a feature tracked on Bugzilla you can also use: close #1234: summary here albeit fix #1234: is more commonly used and also fine
  • Try to add a tag prefix to denote the subsystem you're (mainly) changing, if an obvious choice exists.
    • For example, if you changed the QEMU UI component in pve-manager, a possible tag could be ui: qemu: rest of summary here
    • Don't add tags for things that are already clear from context, for example, adding a qemu tag for a patch in the qemu-server repository has no use.
    • But, do not just paste the affected files, including (parts of the) path and maybe even the file ending, as tag! That has no use (already contained in diff stat) and just makes it harder to read.
  • Commit messages are made for humans and thus should focus on a short summary of core semantic changes.
    • Ideally, the subject is worded such, that it can be copied directly into the debian/changelog, which is consumed by end users.
    • Most of the time it's best to avoid mentioning implementations details, like for example specific function or type names in verbatim as written in the programming language.
    An exception can be changes, that do not have any visible (semantic) effect for users, like pure refactoring (movement of code without changing its logic) or preparations, especially if they happen in pure library repos/crates. But even there one often benefits from a higher-level human-readable overview too.

You can always edit the commit message of the most recent commit using amend: 

# git commit --amend

If you work on a series you can use the git rebase command to re-order, drop, squash/fixup and edit both the whole commit or just rewording its message: 

git rebase -i --autosquash --autostash origin/master

The autostash is not required, but convenient if there are still pending changes, it will stash before rebase starts and apply again after rebase is done. The autosquash is also not required, but very convenient to auto squash fixups (git commit --fixup=<ref>) made for older commits in a development series


The following command will take all changes of tracked files and add it to the commit: 

# git commit -s -a

New files won't get added automatically. To do that, or to just add some changed files to a commit, use 

# git add newfile1.pl file2.pl

You can always look at what will get into commit with: 

# git diff --staged

Preparing Patches

Yellowpin.svg Note: Note that we need a valid CLA to include your changes

Since we have several projects in our git repository and only one development mailing list, we ask you to clarify which repository your patches are meant for by specifying it in the subject prefix. Since some names are long it's fine if you shorten them (eg. remove the 'pve-' prefix).

Creating the raw patch series, for instance for the pve-container package: 

# rm -rf my-patches/       # to clean left-overs
# git format-patch -o my-patches/ --subject-prefix="PATCH container" master..my_branch --cover-letter

Explain in the cover letter the aim of your patches: 

edit my-patches/0000-cover-letter.patch

Sending patches: 

# git send-email --to=pve-devel@lists.proxmox.com  my-patches/00*.patch
# rm -rf my-patches/       # to clean left-overs

If you wish to write comments for individual patches, you can do that either in the cover-letter, or in the patch's commit summary section (between the line consisting of 3 consecutive dashes ending your commit message and before the list of files with their change-counts.

Example: 

From 12345abcde Mon Sep 12 00:00:00 2001
From: Git Committer <some email address>
Date: Fri, 7 Oct 2016 08:30:17 +0200
Subject: [PATCH v2 container 1/2] Fix #1013: this and that

Here is your commit message.
It explains the bugfix and ends after this line.

Signed-off-by: Firstname Lastname <firstname@lastname.email>
---

 ***HERE*** you can write your comments.
 If this is a new version of an old patch, explain your changes here,
 for example:
 
 changes since v1:
 * fixed an error in the new regex
 * reworked algorithm to be O(n)
 
 src/PVE/Tools.pm | 2 +-

diff --git a/src/PVE/Tools.pm b/src/PVE/Tools.pm
(...)

If you want to send several related patches for one feature but different repositories, you can first iterate over all involved repositories, save the patches into one directory and then do a single git send-email over all generated patches. For example, lets go to a few repos and format the most recent commit as patch to /tmp/patchq, then send it: 

# cd pve-manager; git format-patch -s -o /tmp/patchq -1 
# cd ../pve-guest-common; git format-patch -s -o /tmp/patchq -1 
# cd ../pve-docs; git format-patch -s -o /tmp/patchq -1 
# git send-email --compose --to=pve-devel@lists.proxmox.com /tmp/patchq/*

Using "start-number" and the like can improve this further, but it's a good start.

Versioned Patches

If an updated version of your patch series is called for, it should be sent as a new series rather than as reply to the old series. Always send the whole series with all patches showing the same version.

Please mark your versions in your subject prefix with a small 'v' followed by the version number, git can do this for you using the -vX command line option. For example: 

# git format-patch -o my-patches/ --subject-prefix="PATCH container" -v2 master..my_branch

Please list all the changes to the previous versions in the commit summary section as shown in the above example.

For patches with no changes to the previous version, you should mention that there were no changes in the summary section, like no changes since last version

If your series has a cover letter, also summarize all changes in it as well.

Reviewing patches

After reviewing patches which affect a subsystem you maintain, you can notify committers that you reviewed the patch and are OK with the changes by using: 

Acked-by: Full Name <email address>

Convenience Settings

For convenience, you can store the pve-devel email address and the repository's default subject prefixes in your repository clones' configurations as follows: 

$ git config --local sendemail.to pve-devel@lists.proxmox.com
$ git config --local format.subjectprefix 'PATCH container'
$ git config --local format.signoff true

Now the commands to create and send patches become: 

# git format-patch -o my-patches/ master..my_branch
# git send-email --compose my-patches/00*.patch

Sending Patches

Always use git send-email to send out patches, otherwise the indentation and formatting will get mangled, and the patch cannot be applied anymore.

Tutorial

See https://git-send-email.io/ for an interactive tutorial to setup git send-email.

Using Authenticated SMTP Server

git send-email can be instructed to use a specific SMTP server for sending, the following shows an anonymized config section example: 

[sendemail]
        smtpencryption=tls
        smtpserver=webmail.example.com
        smtpserverport=587
        smtpuser=j.smith@example.com
        smtpsslcertpath=
        confirm = always

Add this to your global user ~/.gitconfig or to the per project .git/config. git send-email will then use these settings by default and ask you for the password on sending.

Example

To send the last two commits for a Proxmox VE project to the Proxmox VE development list you could then execute: 

 git send-email --to="pve-devel@lists.proxmox.com" -2

If you're not used to git send-email it can be a good test to first send the patches to an email address of yourself, that allows to ensure all details and commands are correct.

Bugtracker (bugzilla)

https://bugzilla.proxmox.com

Software License and Copyright

We only include code licensed under the respective repo's license, visible under debian/copyright. For most of our projects, or if in doubt, this is the GNU Affero General Public License, version 3 http://www.gnu.org/licenses/agpl-3.0.html.

Additionally, we require that contributors send us a contributor license agreement form by email to office@proxmox.com. This agreement establishes a relationship between us and the contributor, gives details on what it means when the contributor grants permission for their work to be included in a project, and enables us to be better stewards of these projects.

With the contributor agreement chosen by Proxmox, the Harmony CLA, the contributor gives Proxmox a license to use their contributions. The contributor continues to own the copyright in the contribution, with full rights to re-use, re-distribute, and continue modifying the contributed code, allowing them to also share that contribution with other projects.

We've tried to keep the agreement as simple and comprehensible as possible. It comes in two flavors:

If you are making a contribution that is not your work (for example, a patch or library written by someone else), please contact office@proxmox.com for guidance on whether any additional steps are needed.

See Also

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