Difference between revisions of "Funtoo:Metatools/Advanced Usage"

From Funtoo
Jump to navigation Jump to search
Line 17: Line 17:
== Different Approaches ==
== Different Approaches ==


{{c|merge-all-kits}} can be used in a variety of ways. You can use the script to generate your own dynamically-generated kits and meta-repo -- this is the default behavior when you run the script. In this mode, a {{c|meta-repo}} and all automatically-generated kit git repositories are created from scratch. These git repositories will have no remotes, so they will simply exist locally on disk, and they will not have any history shared with the Funtoo project.
{{c|merge-all-kits}} can be used in a variety of ways. If you are an individual developer, you may want to use {{c|merge-all-kits}} in ''developer mode'', which is its default configuration. Developer mode makes it easy to generate a meta-repo and kits that you can test locally.


Another way to use {{c|merge-all-kits}} is with {{c|gitolite}}, which is documented under the [[#Gitolite Setup|Gitolite Setup]] sub-page. Using this configuration, {{c|merge-all-kits}} will write all of its destination git repositories to gitolite.
In developer mode, a {{c|meta-repo}} and all automatically-generated kit git repositories are created from scratch. These git repositories will have no remotes, so they will simply exist locally on disk locally, and they will not have any history shared with the Funtoo project. It you look at the commit history for the kits and meta-repo, you will see that they essentially have no history. When
 
Another way to use {{c|merge-all-kits}} is with {{c|gitolite}} as a remote, which is documented under the [[#Gitolite Setup|Gitolite Setup]] sub-page. Using this configuration, {{c|merge-all-kits}} will write all of its destination git repositories to gitolite. You can then configure other systems to {{c|ego sync}} from gitolite as a source. This can be good in a distributed development environment. This method can also be used to create a meta-repo and kits that ''diverge'' from Funtoo's kit but still connect to its history.
 
Finally, the {{c|merge-all-kits}} script can be run in a production mode, which is very similar to using it with gitolite except that you may be pushing up your destination meta-repo and kits to a public location like GitHub or GitLab.
 
When first starting out with {{c|merge-all-kits}}, you should definitely start with developer mode and see if that meets your needs first.


== Changing Repo Definitions ==
== Changing Repo Definitions ==

Revision as of 23:58, January 21, 2020

Overview

Funtoo Linux uses "merge scripts" to create its kits and update meta-repo. These scripts work by sourcing ebuilds from various overlays, and combining them using special algorithms to yield the kits you use. A meta-repo is also generated, which points to the specific kits generated that are designed to work together.

Required for merge scripts is dev-python/lxml.

The Code

You can find the code that does this on code.funtoo.org, housed at https://code.funtoo.org/bitbucket/projects/CORE/repos/merge-scripts/browse. The script that does all the heavy-lifting is called merge-all-kits. Let's clone it from git, on the machine that will be generating new kits and meta-repo:

user $ git clone https://code.funtoo.org/bitbucket/scm/core/merge-scripts.git

Different Approaches

merge-all-kits can be used in a variety of ways. If you are an individual developer, you may want to use merge-all-kits in developer mode, which is its default configuration. Developer mode makes it easy to generate a meta-repo and kits that you can test locally.

In developer mode, a meta-repo and all automatically-generated kit git repositories are created from scratch. These git repositories will have no remotes, so they will simply exist locally on disk locally, and they will not have any history shared with the Funtoo project. It you look at the commit history for the kits and meta-repo, you will see that they essentially have no history. When

Another way to use merge-all-kits is with gitolite as a remote, which is documented under the Gitolite Setup sub-page. Using this configuration, merge-all-kits will write all of its destination git repositories to gitolite. You can then configure other systems to ego sync from gitolite as a source. This can be good in a distributed development environment. This method can also be used to create a meta-repo and kits that diverge from Funtoo's kit but still connect to its history.

Finally, the merge-all-kits script can be run in a production mode, which is very similar to using it with gitolite except that you may be pushing up your destination meta-repo and kits to a public location like GitHub or GitLab.

When first starting out with merge-all-kits, you should definitely start with developer mode and see if that meets your needs first.

Changing Repo Definitions

Now that you have generated your first meta-repo, let's look at the key file that defines what overlays and repositories are used to create meta-repo, as well as what kit branches exist, and which ones are prime and which are not. You will want to turn your attention to the kit-fixups/modules/fixups/foundations.py file, which can be viewed here on code.funtoo.org]. Let's take a look at various sections of this file:

   foundations.py (python source code) - Top of foundations.py file
#!/usr/bin/python3

from enum import Enum


class KitStabilityRating(Enum):
	PRIME = 0  # Kit is enterprise-quality
	NEAR_PRIME = 1  # Kit is approaching enterprise-quality
	BETA = 2  # Kit is in beta
	ALPHA = 3  # Kit is in alpha
	DEV = 4  # Kit is newly created and in active development
	CURRENT = 10  # Kit follows Gentoo currrent
	DEPRECATED = 11  # Kit is deprecated/retired


def KitRatingString(kit_enum):
	if kit_enum is KitStabilityRating.PRIME:
		return "prime"
	elif kit_enum is KitStabilityRating.NEAR_PRIME:
		return "near-prime"
	elif kit_enum is KitStabilityRating.BETA:
		return "beta"
	elif kit_enum is KitStabilityRating.ALPHA:
		return "alpha"
	elif kit_enum is KitStabilityRating.DEV:
		return "dev"
	elif kit_enum is KitStabilityRating.CURRENT:
		return "current"
	elif kit_enum is KitStabilityRating.DEPRECATED:
		return "deprecated"

At the top of the file, we define an enumeration of the different levels of stability that can exist for a particular kit. Kits marked with a stability rating of KitStabilityRating.PRIME will be tagged in the meta-repo JSON as being a "prime" kit and suitable for production use.

As you scroll down further, you will see some code like this:

   foundations.py (python source code) - foundations.py kit_groups
class KitFoundation:

	kit_groups = {
		'prime': [
			{'name': 'core-kit', 'branch': '1.0-prime', 'source': 'gentoo_prime_protected', 'default': True},
			{'name': 'core-kit', 'branch': '1.1-prime', 'source': 'gentoo_prime_mk3_protected', 'stability': KitStabilityRating.DEPRECATED},
			{'name': 'core-kit', 'branch': '1.2-prime', 'source': 'gentoo_prime_mk4_protected', 'stability': KitStabilityRating.BETA},
			{'name': 'core-hw-kit', 'branch': 'master', 'source': 'funtoo_current', 'default': True},
			{'name': 'security-kit', 'branch': '1.0-prime', 'source': 'gentoo_prime_protected', 'default': True},
			{'name': 'security-kit', 'branch': '1.1-prime', 'source': 'gentoo_prime_mk3_protected', 'stability': KitStabilityRating.DEPRECATED},
			{'name': 'security-kit', 'branch': '1.2-prime', 'source': 'gentoo_prime_mk4_protected', 'stability': KitStabilityRating.BETA},
			{'name': 'xorg-kit', 'branch': '1.17-prime', 'source': 'funtoo_prime_xorg', 'default': False, 'stability': KitStabilityRating.PRIME},
			{'name': 'xorg-kit', 'branch': '1.19-prime', 'source': 'funtoo_mk2_prime', 'default': True, 'stability': KitStabilityRating.PRIME},  # MK2
			{'name': 'gnome-kit', 'branch': '3.20-prime', 'source': 'funtoo_prime_gnome', 'default': True},
			{'name': 'gnome-kit', 'branch': '3.26-prime', 'source': 'funtoo_mk4_prime', 'default': False, 'stability': KitStabilityRating.DEV},
			{'name': 'kde-kit', 'branch': '5.10-prime', 'source': 'funtoo_mk3_prime', 'default': False, 'stability': KitStabilityRating.DEPRECATED},
			{'name': 'kde-kit', 'branch': '5.11-prime', 'source': 'funtoo_prime_kde', 'stability': KitStabilityRating.DEPRECATED},
			{'name': 'kde-kit', 'branch': '5.12-prime', 'source': 'funtoo_prime_kde_late', 'default': True, 'stability': KitStabilityRating.PRIME},
			{'name': 'media-kit', 'branch': '1.0-prime', 'source': 'funtoo_prime_media', 'default': False, 'stability': KitStabilityRating.DEPRECATED},
			{'name': 'media-kit', 'branch': '1.1-prime', 'source': 'funtoo_mk3_prime', 'default': True, 'stability': KitStabilityRating.PRIME},  # MK3
			{'name': 'media-kit', 'branch': '1.2-prime', 'source': 'funtoo_mk4_prime', 'stability': KitStabilityRating.BETA},
			{'name': 'perl-kit', 'branch': '5.24-prime', 'source': 'funtoo_prime_perl', 'default': True},
			{'name': 'perl-kit', 'branch': '5.26-prime', 'source': 'funtoo_mk3_prime', 'default': False, 'stability': KitStabilityRating.DEV},
			{'name': 'python-modules-kit', 'branch': 'master', 'source': 'funtoo_current', 'default': True, 'stability': KitStabilityRating.PRIME},

Here, we see the beginning of the definition of the KitFoundation class, which contains the kit_groups class variable. This variable, as you can see, defines a bunch of kits -- their name, the branch, a stability value that defines the stability rating of the kit, and other values. Note that if a kit is marked as default, it is assumed to have a kit stability rating of PRIME. You will also see that there is a source key, which defines the group of repositories and overlays that are used to create this kit.

Here are three important things to take away from this part of code: First, this is the official master definition of what kits exist, their stability rating, and what overlays/repositories are used to generate each kit. The next thing to take away from this code is that it is certainly possible to modify these settings for your custom meta-repo so that they are different from the Funtoo defaults.

Here is the third and most important thing about kit_groups -- the order that they are defined determines the order which the merge scripts try to match packages. The merge-scripts/package-sets files will be processed in order that the kits are defined in kit_groups, so core-kit first, security-kit second, etc. Once a catpkg has been added to a kit, it will not be added to any successive kits.

Going Deeper into Foundations.py

Moving right along, you will see a section of the KitFoundation class that looks like this:

   foundations.py (python source code) - foundations.py python_kit_settings
python_kit_settings = {
		#	branch / primary python / alternate python / python mask (if any)
		'master': {
			"primary": "python3_6",
			"alternate": "python2_7",
			"mask": None
		},
		'3.4-prime': {
			"primary": "python3_4",
			"alternate": "python2_7",
			"mask": ">=dev-lang/python-3.5"
		},
		'3.6-prime': {
			"primary": "python3_6",
			"alternate": "python2_7",
			"mask": ">=dev-lang/python-3.7"
		},
		'3.6.3-prime': {
			"primary": "python3_6",
			"alternate": "python2_7",
			"mask": ">=dev-lang/python-3.7"
		}
	}

This section is used to define special settings for python-kit. Specifically, for each branch of python-kit, it defines the primary version of python that we will attempt to use to satisfy python-single USE dependencies, followed by an alternate value to use if the ebuild does not support the first. We can also specify a mask to be injected into each python-kit to mask certain versions of python that should be masked due to lack of support in that kit.

Foundations.py Kit Source Definitons

Next, we have a section that looks like this:

   foundations.py (python source code) - foundations.py kit_source_defs
kit_source_defs = {
		"funtoo_current": [
			{"repo": "flora"},
			{"repo": "faustoo"},
			{"repo": "fusion809"},
			{"repo": "gentoo-staging"}
		],
		"funtoo_mk2_prime": [
			{"repo": "flora", },
			{"repo": "faustoo"},
			{"repo": "fusion809", "src_sha1": "489b46557d306e93e6dc58c11e7c1da52abd34b0", 'date': '31 Aug 2017'},
			{"repo": "gentoo-staging", "src_sha1": '80d2f3782e7f351855664919d679e94a95793a06', 'date': '31 Aug 2017'},
			# add current gentoo-staging to catch any new ebuilds that are not yet in our snapshot above (dev-foo/* match)
			{"repo": "gentoo-staging-underlay"},
		],
		"funtoo_mk3_prime": [
			{"repo": "flora", },
			{"repo": "faustoo", },
			{"repo": "fusion809", "src_sha1": "8733034816d3932486cb593db2dfbfbc7577e28b", 'date': '09 Oct 2017'},
			{"repo": "gentoo-staging", "src_sha1": '2de4b388863ab0dbbd291422aa556c9de646f1ff', 'date': '10 Oct 2017'},
			{"repo": "gentoo-staging-underlay"},
		], ...

This section contains definitions of various overlay stacks, called "kit sources". Kit sources are a combination of overlays, arranged in a python list ([ ]). A kit source serves as a unified collection of source catpkgs for a particular kit. Each kit can have one kit source. Kit sources may be shared among kits for consistency purposes, and to avoid duplication and to help organization. Note that this is where we specify branch or SHA1 that is used for each overlay. If no SHA1 is specified, the merge scripts will use the top commit of master as the source for that overlay (ie. the overlay will track upstream.)

   Note

A "catpkg" is a category/package combination, like sys-apps/portage, with no version information. When we match catpkgs, we look for a cat/pkg directory in the overlay, and if we find a match, we grab the full contents of the catpkg directory from the overlay, and ignore any other occurrence of the same catpkg in other overlays. When we talk of "package-set" rules below, we are referring to text files that define what catpkgs go into what kits. We can specify catpkgs literally or use patterns and other approaches to select catpkgs destined for a particular kit. The merge scripts uses these package-set rules files to define what goes in each kit. But where they search for each catpkg is defined in foundations.py, above.

Currently, package-set rules (see note above) are applied in the same order that the overlay appears in the kit_source_defs list -- so for "funtoo_current", package-set rules -- an attempt to match catpkg patterns for a kit -- will be applied to flora first, then faustoo, then fusion809, etc, with gentoo-staging searched last. In theory, this would allow any "upper" overlay to override catpkgs in later-appearing overlays. However, this is not the case, because the "upper" overlays are generally "locked down" so that they are only allowed to provide a particular set of catpkgs, or are allowed to provide any catpkg as long as it doesn't appear in Gentoo, for example. So in actual practice, gentoo-staging is set up to have the higher priority, even though it is searched for matches later. Also notice that newer kit source definitions now have a "bottom" gentoo-staging-underlay definition that has a special purpose -- to allow us to grab new Gentoo catpkgs that aren't in our snapshotted gentoo-staging repository yet. This works because gentoo-staging-underlay tracks upstream master, while gentoo-staging is locked to a particular point in the past. This way we get brand-new gentoo catpkgs, but existing gentoo catpkgs stay locked to a particular point in time.

Completing the Deep Dive

Our deep dive into the functionality of foundations.py is almost complete -- just one more part to go! You will notice the following code at the end of the file:

   foundations.py (python source code) - foundations.py overlay definitions
@property
	def overlays(self):
		return {
			# use gentoo-staging-2017 dirname to avoid conflicts with ports-2012 generation
			"gentoo-staging": {"url": self.config.gentoo_staging, "dirname": "gentoo-staging-2017"},
			"gentoo-staging-underlay": {"url": self.config.gentoo_staging, "dirname": "gentoo-staging-2017-underlay"},
			"faustoo": {"url": "https://github.com/fmoro/faustoo.git", "eclasses": [
				"waf",
				"googlecode"
			],
			            # SKIP any catpkgs that also exist in gentoo-staging (like nvidia-drivers). All others will be copied.
			            "filter": ["gentoo-staging"],
			            # well, I lied. There are some catpkgs that exist in gentoo-staging that we DO want to copy. These are the
			            # ones we will copy. We need to specify each one. This list may change over time as faustoo/gentoo gets stale.
			            "force": [
				            "dev-java/maven-bin",
				            "dev-java/sun-java3d-bin",
				            "dev-php/pecl-mongo",
				            "dev-php/pecl-mongodb",
				            "dev-python/mongoengine",
				            "dev-python/pymongo",
				            "dev-util/idea-community",
				            "dev-util/webstorm",
				            "x11-wm/blackbox"
			            ]
			            },
			"fusion809": {"url": "https://github.com/fusion809/fusion809-overlay.git", "select": [
				"app-editors/atom-bin",
				"app-editors/notepadqq",
				"app-editors/bluefish",
				"app-editors/textadept",
				"app-editors/scite",
				"app-editors/gvim",
				"app-editors/vim",
				"app-editors/vim-core",
				"app-editors/sublime-text"
			]
			              },  # FL-3633, FL-3663, FL-3776
			"plex": {"url": "https://github.com/Ghent/funtoo-plex.git", "select": [
				"media-tv/plex-media-server",
			],
			         },
			# damex's deadbeef (music player like foobar2000) overlay
			"deadbeef": {"url": "https://github.com/damex/deadbeef-overlay.git", "copyfiles": {
				"profiles/package.mask": "profiles/package.mask/deadbeef.mask"
			},
			             },
			# damex's wmfs (window manager from scratch) overlay
			"wmfs": {"url": "https://github.com/damex/wmfs-overlay.git", "copyfiles": {
				"profiles/package.mask": "profiles/package.mask/wmfs.mask"
			},
			         },
			"flora": {"url": self.config.flora, "copyfiles": {
				"licenses/renoise-EULA": "licenses/renoise-EULA"
			},
			          },
		}

This section of foundations.py declares the names for the actual overlays themselves, where we can clone them from, and also helps us answer the question of which overlay has priority over another. In the case of the fusion809 overlay, for example, we will only grab a select set of catpkgs, specified in the select list. Whereas in the faustoo overlay, we will force the merge scripts to grab updates the the catpkgs listed in the force list, but skip any catpkgs in faustoo that also appear in our gentoo-staging snapshot. All these special rules define exceptions to the normal processing logic of the merge scripts, which will look for catpkg matches in the first overlay listed in the kit source definition, before proceeding to the second, etc.

Wrapping Up Foundations.py

We certainly have a lot of levers we can use to control what gets included in a particular kit. Using foundations.py, we can add or remove overlays we want to use, and we can also alter the order they are scanned by the merge scripts. We can control what snapshots are used, and vary this on a per-kit basis. And in the overlay definitions, we can also create exceptions to the normal processing order, to effectively prioritize gentoo catpkgs over overlay catpkgs, even if the overlays are processed first. Or we can limit the scope of what catpkgs we scan a particular overlay for, or force certain catpkgs to be copied from a particular overlay if we know we want those particular ones.

All that is left to cover are the package-set rules, which define which catpkgs go into each kit, and kit-fixups, which allow us to have Funtoo overrides for any catpkgs we want. We'll cover those topics next.

Package Sets

Package sets define which catpkgs go in which kits. The package set files are located at kit-fixups/package-sets. They can either consist of a single file named (kit)-packages or a directory with the same name. In the case of a directory, all of the files inside the directory are concatenated and used as a package set.

Package Set Format

Package sets are a text-based format that consist of one catpkg entry per line. Let's look at the various types of package sets entries:

Entry typeExampleExplanation
literalsys-apps/portageSpecify a single catpkg by exact name.
literal with movesys-apps/oldpkg -> sys-foo/newpkgSpecify a catpkg by exact name, but copy it over as a new name.
category wildcardsys-apps/*Specify all packages that appear in a particular category.
category wildcard with exceptionssys-apps/* -sys-apps/foo -sys-apps/barSpecify all packages that appear in a particular category, with some exceptions.
regexsys-.*/foo.*Specify all catpkgs that match a particular regex.
dependencies in category@depsincat@:x11-base/xorg-x11:media-fontsIn this example, anything in the media-fonts category that has dependencies upon x11-base/xorg-x11.
maintainer@maintainer@:dev-lang:ml@gentoo.orgIn this example, all dev-lang packages that have a maintainer of ml@gentoo.org.
has eclass@has_eclass@:kde5In this example, all catpkgs that use an eclass of kde5.eclass.
category has eclass@cat_has_eclass@:x11-apps:xorg-2In this example, all catpkgs in the x11-apps category that use an eclass of xorg-2.eclass.
   Important

It is possible to blacklist certain catpkgs for inclusion in particular kit by creating a "skip" list at kit-fixups/package-sets/mykitnamehere-packages-skip. This file can contain individual catpkgs, one per line, that should not be included in the package-set, even if they match any rules above. Note that you must use literal catpkgs in the skip list -- no patterns or other special matches are supported.

Inline Package Moves

   Note

The "literal with move" option is a new feature, described below.

The "literal with move" package set syntax described above is one way to tell the merge scripts to copy a catpkg from a source location but give it a new catpkg name, and they are specified directly in the package-set files.

If the old package name is found, it will be copied over as the new name. If the old name is not found, but the new name is found, the new name will be copied over as the new name. So either the old name or the new name, if found, will be copied over.

Move-Maps

You can also specify package moves by creating a file called kit-fixups/move-maps/kitname containing the same "literal with move" syntax. Global move maps can be placed in kit-fixups/move-maps/global. Also note that kit-fixups/move-maps/nokit or kit-fixups/move-maps/global is the only way to perform funtoo package moves for nokit. I recommend using the "global" method since it will still automatically work if someone else moves your package into a kit.

This move-maps functionality works similarly to package-moves that appear within a kit package-set, except that these moves do not automatically add either specified catpkg to the kit. So there must be something in the package-set that matches the old package name. After the old package is matched, additional logic looks at the move-maps and see if the match is in a move-map that tells us to copy it over as the "new" name. The old package will be copied over as the new name.

If you need to just rename a single package in a kit, it's fine to use the inline method. For more capability, move-maps/ are your friend. They're more powerful because a move-map specified with move-maps/ will also apply to any special wildcard package-set matches via @regex@, etc, whereas the inline method is limited by design. Also, the out-of-band method allows you to perform package moves on catpkgs in nokit.

   Important

Package moves give you the ability to rename catpkgs as they appear in kits. We still need to add functionality to provide this data to Portage so that it can update any package database entries for packages installed under the old name. This part is not done yet, so this is considered a testing-only feature for the time being and should only be used on local kit-fixups overlays for testing, not in our official kit-fixups repo yet.

Package Sets -- Putting It All Together

Here are some important facts about package sets:

  1. Package set matches are executed in a particular order, and this order is defined by the order of kits in kit_groups in foundations.py.
  2. Once a catpkg is matched during processing of a kit, that catpkg is assigned to that kit, and cannot appear in another kit.
  3. If a catpkg is included in a particular branch of a kit, then that catpkg will appear in all branches of that kit, assuming it is available.
  4. Each kit and branch defined in kit_groups specifies a "source" -- an entry in kit_source_defs which in turn defines a stack of repositories/overlays and associated SHA1 commits to use as sources for catpkgs.

So, here's how the package set processing would begin. If we look at kit_groups in foundations.py, we see that core-kit 1.0-prime is listed first. So we will look for catpkg matches for core-kit 1.0-prime using the kit-fixups/package-sets/core-kit-packages package set directory. We will apply these match rules against the gentoo_prime_protected kit source definition, and we will look for matches in each repository in the order listed in the kit_source_defs entry. The first match we find will be used as the source catpkg. But remember that we have specific rules in place, defined in the overlays property, that effectively gives gentoo-staging priority for most of the catpkgs.

After this is done, we will then process core-kit 1.2-prime, since 1.1-prime is deprecated and will be skipped, and then continue to core-hw-kit, and continue to work down the kit_groups list. This process will build up a set of catpkgs that will appear in each kit.

Kit Fixups

And finally, we have saved a very key part of the kit generation process for last. The kit-fixups repository is so named because it contains fixups, which are forked Funtoo catpkgs that are used to override catpkgs that appear in the upstream overlays and repositories. They have a special structure. We will look at the structure of the core-kit fixup directory, although others will follow the same model:

CatPkg PathDescription
kit-fixups/core-kit/global/sys-apps/portageDue to the global directory, this catpkg will always be used when a package set specifies a match for sys-apps/portage, for all branches of core-kit.
kit-fixups/core-kit/curated/sys-apps/portageDue to the curated directory, this catpkg will always be used when a package set specifies a match for sys-apps/portage, for all branches of core-kit except a master branch.
kit-fixups/core-kit/1.2-prime/sys-apps/portageDue to the 1.2-prime directory, this catpkg will always be used when a package set specifies a match for sys-apps/portage, for the 1.2-prime branch of core-kit only.

Remember that kit-fixups is designed so that a fixup will always override any upstream packages. This makes it easy to keep track of Funtoo-maintained core packages. And also note that the flora repository should be used for "bonus" packages while kit-fixups should focus more on forks of critical system packages and bug fixes for Funtoo. This way, we can keep contributed ebuilds separate from core operating system ebuilds and associated bug fixes for upstream issues.

Developer Q&A

This section contains various tasks that a developer may need to perform, and what steps should be taken to perform each of these steps.

I want to move a catpkg sys-apps/blah from core-kit to foobar-kit.
To do this, first we'll note that core-kit comes before foobar-kit in kit_groups. This means that core-kit's package set rules will run first. So we will want to make sure that sys-apps/blah does not match any rules in the core-kit package-set. This can be done by possibly removing a package-set rule, or using a wildcard with exclusion like sys-apps/* -sys-apps/blah. If this doesn't work, a file can be created called core-kit-packages-skip which contains exclusions, and sys-apps/blah can be added to a line in this file. Then, you will want to make sure that sys-apps/blah does match a package set rule for foobar-kit.
I want to move a catpkg sys-apps/blah from foobar-kit to core-kit.
To do this, first we'll note that foobar-kit comes after core-kit in kit-groups, so core-kit's package set rules will run first. We can thus simply add something that will match 'sys-apps/blah' to core-kit's package-set rules. Once sys-apps/blah is included in core-kit, it will not be available for inclusion in foobar-kit, even if it has an identical rule, or a rule like 'sys-apps/*'. However, note that it is good practice to clean up any rules in foobar-kit that you know are no longer matching any catpkgs.
   Note

The above two approaches can be used to move catpkgs between kits transparently to the end-user. In the next ego sync, the catpkg will atomically move from one kit to another and no re-emerging will be required, even if the user had emerged the package from the 'old' kit location.

I want to contribute a cool package to Funtoo.
To do this, you will want to open a pull request against flora. Flora is used for all 'bonus' community-contributed ebuilds.
I want to fix a bug in a particular ebuild.
To do this, first find out where the ebuild is coming from. A good way to do this is to type ls -d /var/git/meta-repo/kits/*/sys-apps/foobar, which will show you what kit it is in. Running emerge -s sys-apps/foobar will also display this information. For research purposes, it is often useful to find where the original catpkg was sourced from. You can consult https://ports.funtoo.org/packages.xml which contains a list of all catpkgs and their source repository. After doing some initial research and seeing what's wrong, you might have a fix for the ebuild. Generally, the best way to fix the ebuild is to fork kit-fixups and create an appropriate fixup for the ebuild if none exists, and simply improve our fixup if one exists already. Then you can create a code.funtoo.org pull request, or open a bug on bugs.funtoo.org, or both. Remember that fixup catpkgs will totally replace all upstream ebuilds, so you may need to include multiple versions of the ebuild, even ones that don't need a fix, if they are still needed for certain packages.
   Note

If you want to fix a bug in an ebuild and you find that the ebuild comes from flora, you will want to fork flora and submit a pull request against flora instead.

I want to make a particular branch of a kit the default kit.
To do this, you will modify kit_groups and set the kit you want to be default to have 'default' : True or 'stability' : KitStabilityRating.PRIME, or both. Only one kit branch can be set as default.
I don't want to generate a particular branch of a kit.
To prevent a branch of a kit from being generated, set its stability to KitStabilityRating.DEPRECATED in kit_groups.
I want to generate a new kit branch that uses much newer ebuilds from Gentoo or from an upstream repo.
First, define a new entry in kit_source_defs that contains the collection of overlays and repos you want to use as sources. Specify the SHA1 commits you want to use for each repo (or don't specify one to use master.) Then, you will want to add a new kit definition to kit_groups, in the "prime" section.
I want to include a package in Funtoo, but move it to a new name.
To do this, use the "literal with package move" format in the package set (see section on #Package Moves, above). You can also use files in kit_fixups/move-maps/kitname or kit_fixups/move-maps/global (info in a note below the Package Set syntax section.).
   Important

Be sure to stop by #funtoo-dev on irc.freenode.net if you need further assistance! We are here to help.