name: guix description: Expert knowledge for GNU Guix package and service development. Use when creating or modifying Guix packages, system services, home services, or working with a Guix repository checkout. Handles package definitions, build systems, service types, configuration records, and development workflows.

GNU Guix Development Expert

This skill provides comprehensive guidance for working with GNU Guix, including package definitions, system and home services, and development workflows using a Guix repository checkout.

When to Use This Skill

Creating new Guix package definitions
Updating existing packages to new versions
Defining system services (gnu/services)
Creating home services (gnu/home/services)
Working with Guix from a repository checkout
Debugging package build failures
Understanding build systems and their options
Converting packages between old and new styles

Package Definition Patterns

Standard Package Structure

Every Guix package follows this basic structure:

(define-module (gnu packages category)
  #:use-module (guix packages)
  #:use-module (guix download)
  #:use-module (guix git-download)
  #:use-module (guix build-system gnu)
  #:use-module ((guix licenses) #:prefix license:)
  #:use-module (gnu packages base)
  #:export (package-name))

(define-public package-name
  (package
    (name "package-name")           ; lowercase, dash-separated
    (version "1.0.0")
    (source (origin ...))           ; where to get source
    (build-system gnu-build-system) ; how to build it
    (inputs (list pkg1 pkg2))       ; runtime dependencies
    (native-inputs (list tool1))    ; build-time only tools
    (propagated-inputs (list lib))  ; runtime deps for users
    (arguments (list ...))          ; build system arguments
    (synopsis "One-line description")
    (description "Detailed description in Texinfo format")
    (home-page "https://example.com")
    (license license:gpl3+)))

Module Definition

Naming Convention:

System packages: (gnu packages CATEGORY) → gnu/packages/CATEGORY.scm
One package per module or related packages grouped together
Always use lowercase with dashes

Required Imports:

(define-module (gnu packages mypackage)
  #:use-module (guix packages)
  #:use-module (guix download)           ; for url-fetch
  #:use-module (guix git-download)       ; for git-fetch
  #:use-module (guix build-system gnu)   ; or other build system
  #:use-module ((guix licenses) #:prefix license:)
  #:use-module (gnu packages base)       ; for common deps
  #:export (mypackage))

Source Origins

URL Fetch (tarballs, releases):

(source (origin
          (method url-fetch)
          (uri (string-append "https://example.com/package-" version ".tar.gz"))
          (sha256
           (base32 "0ssi1wpaf7plaswqqjwigppsg5fyh99vdlb9kzl7c9lng89ndq1i"))
          (patches (search-patches "package-fix-build.patch"))
          (snippet
           #~(begin
               (use-modules (guix build utils))
               (delete-file-recursively "bundled-lib")))))

Git Fetch (from repository):

(source (origin
          (method git-fetch)
          (uri (git-reference
                (url "https://github.com/example/repo")
                (commit (string-append "v" version))))
          (file-name (git-file-name name version))
          (sha256
           (base32 "..."))))

Getting Source Hash:

# Download and get hash
guix download https://example.com/package-1.0.tar.gz

# Hash local file
guix hash file.tar.gz

Dependency Management

Three Types of Inputs:

inputs - Runtime dependencies (libraries, programs needed when running)
```
(inputs (list libffi glib ncurses))
```
native-inputs - Build-time tools (compilers, pkg-config, test frameworks)
```
(native-inputs (list pkg-config autoconf automake check))
```
propagated-inputs - Transitive dependencies (headers, libs in public APIs)
```
(propagated-inputs (list python-requests python-urllib3))
```

Using Specific Outputs:

(inputs (list `(,glib "bin")))  ; Use the "bin" output of glib

IMPORTANT: Modern style uses (list ...), old style uses quasiquote. Prefer list.

Build Arguments

Modern Style (G-expressions - PREFERRED):

(arguments
 (list
  #:tests? #t                           ; Run tests (default #t)
  #:parallel-build? #t                  ; Parallel build (default #t)
  #:configure-flags #~(list
    "--enable-foo"
    (string-append "--with-bar=" #$some-input))
  #:make-flags #~(list "VERBOSE=1")
  #:phases
  #~(modify-phases %standard-phases
      (add-after 'unpack 'patch-sources
        (lambda* (#:key inputs #:allow-other-keys)
          (substitute* "Makefile"
            (("/bin/sh") (search-input-file inputs "/bin/sh")))))
      (delete 'configure)
      (replace 'install
        (lambda _
          (install-file "binary" (string-append #$output "/bin")))))))

Old Style (still common):

(arguments
 '(#:tests? #t
   #:phases
   (modify-phases %standard-phases
     (add-after 'install 'fix-paths
       (lambda* (#:key outputs #:allow-other-keys)
         (let ((out (assoc-ref outputs "out")))
           (substitute* (string-append out "/bin/script")
             (("/bin/sh") (which "sh")))))))))

Build Systems

Most Common Build Systems:

gnu-build-system - Standard autotools (./configure && make && make install)
python-build-system - Python packages with setup.py
pyproject-build-system - Modern Python (PEP 517/518, poetry, flit, etc.)
cmake-build-system - CMake-based projects
meson-build-system - Meson build system
cargo-build-system - Rust packages
go-build-system - Go packages
node-build-system - Node.js/npm packages
trivial-build-system - Fully custom build process
copy-build-system - Just copy files to output

GNU Build System Phases (in order):

unpack → patch-source-shebangs → configure → build → check →
install → patch-shebangs → strip → validate-runpath → compress-documentation

Modifying Phases:

(modify-phases %standard-phases
  (add-before 'configure 'set-environment
    (lambda _ (setenv "CC" "gcc")))
  (add-after 'install 'wrap-program
    (lambda* (#:key outputs inputs #:allow-other-keys)
      (wrap-program (string-append #$output "/bin/prog")
        `("PATH" ":" prefix (,(string-append #$some-dep "/bin"))))))
  (replace 'build
    (lambda _ (invoke "make" "all")))
  (delete 'check))  ; Skip tests

Python Build System (Modern):

(build-system pyproject-build-system)
(arguments
 (list
  #:test-flags #~(list "-v")
  #:build-backend "poetry-core"))  ; or setuptools, flit, hatch, etc.

Common Helpers and Utilities

In Build Phases:

;; Search for files in inputs
(search-input-file inputs "/bin/sh")
(search-input-directory inputs "/include")

;; Running commands
(invoke "make" "install")        ; Fails if non-zero exit
(system* "make" "test")          ; Returns exit code

;; File operations
(install-file "src/binary" (string-append #$output "/bin"))
(copy-recursively "data" (string-append #$output "/share/data"))
(mkdir-p (string-append #$output "/share/doc"))
(delete-file-recursively "unwanted")

;; Path utilities
(which "sh")                     ; Find in PATH
(dirname "/path/to/file")
(basename "/path/to/file")

;; Substitution (editing files)
(substitute* "config.h"
  (("/usr/local") #$output)
  (("/bin/sh") (which "sh")))

;; Directory context
(with-directory-excursion "subdir"
  (invoke "make"))

;; Environment
(setenv "CC" "gcc")
(getenv "PATH")

Outside Build Phases:

;; Self-reference
this-package

;; File utilities
(local-file "path/to/file.txt")
(plain-file "name" "content")
(computed-file "name" #~(mkdir #$output))

;; Patches
(search-patches "package-fix.patch")  ; looks in gnu/packages/patches/

;; Version manipulation
(version-major+minor "1.2.3")  ; => "1.2"

;; System detection
(%current-target-system)  ; Cross-compilation target
(%current-system)         ; e.g., "x86_64-linux"
(target-64bit?)
(target-aarch64?)
(target-x86-64?)

Package Inheritance

Reuse existing package definitions:

(define-public hello-custom
  (package
    (inherit hello)
    (name "hello-custom")
    (arguments
     (substitute-keyword-arguments (package-arguments hello)
       ((#:configure-flags flags)
        #~(cons "--enable-custom" #$flags))
       ((#:phases phases)
        #~(modify-phases #$phases
            (add-after 'install 'install-extra
              (lambda _
                (install-file "extra"
                              (string-append #$output "/bin"))))))))))

Service Definition Patterns

System Service Type

System services go in gnu/services/CATEGORY.scm:

(define-module (gnu services myservice)
  #:use-module (gnu services)
  #:use-module (gnu services shepherd)
  #:use-module (guix records)
  #:use-module (guix gexp)
  #:export (myservice-configuration
            myservice-service-type))

;; Configuration record
(define-record-type* <myservice-configuration>
  myservice-configuration make-myservice-configuration
  myservice-configuration?
  (package myservice-configuration-package
           (default mypackage))
  (port myservice-configuration-port
        (default 8080))
  (config-file myservice-configuration-config-file
               (default #f)))

;; Generate config file
(define (myservice-config-file config)
  (computed-file "myservice.conf"
    #~(begin
        (use-modules (ice-9 format))
        (call-with-output-file #$output
          (lambda (port)
            (format port "port=~a\n"
                    #$(myservice-configuration-port config)))))))

;; Shepherd service definition
(define (myservice-shepherd-service config)
  (list (shepherd-service
         (documentation "My service daemon")
         (provision '(myservice))
         (requirement '(networking))
         (start #~(make-forkexec-constructor
                   (list #$(file-append
                            (myservice-configuration-package config)
                            "/bin/myservice")
                         "--config"
                         #$(myservice-config-file config))))
         (stop #~(make-kill-destructor)))))

;; Service type definition
(define myservice-service-type
  (service-type
   (name 'myservice)
   (extensions
    (list (service-extension shepherd-root-service-type
                             myservice-shepherd-service)
          (service-extension profile-service-type
                             (lambda (config)
                               (list (myservice-configuration-package config))))))
   (default-value (myservice-configuration))
   (description "Run myservice daemon.")))

Usage in system config:

(service myservice-service-type
         (myservice-configuration
          (port 9000)))

Home Service Type

Home services go in gnu/home/services/CATEGORY.scm:

(define-module (gnu home services myshell)
  #:use-module (gnu home services)
  #:use-module (gnu services configuration)
  #:use-module (guix records)
  #:use-module (guix gexp)
  #:export (home-myshell-configuration
            home-myshell-service-type))

;; Configuration using define-configuration
(define-configuration home-myshell-configuration
  (package
   (package myshell-package)
   "The shell package to use.")
  (aliases
   (alist '())
   "Association list of aliases.")
  (extra-config
   (text-config '())
   "List of strings or file-like objects for config."))

;; Generate files for $HOME
(define (home-myshell-files config)
  (list
   `(".myshellrc"
     ,(mixed-text-file
       "myshellrc"
       #~(string-append
          #$@(home-myshell-configuration-extra-config config))))))

;; Add package to profile
(define (home-myshell-profile config)
  (list (home-myshell-configuration-package config)))

;; Service type
(define home-myshell-service-type
  (service-type
   (name 'home-myshell)
   (extensions
    (list (service-extension home-files-service-type
                             home-myshell-files)
          (service-extension home-profile-service-type
                             home-myshell-profile)))
   (default-value (home-myshell-configuration))
   (description "Install and configure myshell.")))

Usage in home config:

(service home-myshell-service-type
         (home-myshell-configuration
          (extra-config
           (list "alias ll='ls -la'"))))

Service Extensions

Common extension points:

System Services:

shepherd-root-service-type - Add shepherd services (daemons)
profile-service-type - Add packages to system profile
etc-service-type - Add files to /etc
activation-service-type - Run code at system activation

Home Services:

home-files-service-type - Add files to $HOME
home-xdg-configuration-files-service-type - Add files to $XDG_CONFIG_HOME
home-profile-service-type - Add packages to home profile
home-run-on-change-service-type - Run code when config changes

Working with Guix Repository

Setup and Build

# Clone repository
git clone https://git.savannah.gnu.org/git/guix.git
cd guix

# Bootstrap and configure
./bootstrap
./configure --localstatedir=/var

# Build
make -j$(nproc)

# Install git hooks (for contributors)
make install-git-hooks

Using pre-inst-env

The ./pre-inst-env wrapper lets you test changes without installing:

# Build a package from your checkout
./pre-inst-env guix build hello

# Install a package you just defined
./pre-inst-env guix package -i my-new-package

# Start a REPL with your changes
./pre-inst-env guix repl

# Lint your package
./pre-inst-env guix lint my-package

# Check for updates
./pre-inst-env guix refresh my-package

What pre-inst-env does:

Sets GUILE_LOAD_PATH to use checkout modules
Sets PATH to include build directory scripts
Prevents loading installed Guix modules

Testing Packages

# Build with options
./pre-inst-env guix build hello --no-grafts --keep-failed

# Build from a file
guix build -f my-package.scm

# Enter build environment
./pre-inst-env guix shell -D hello

# Build and check size
./pre-inst-env guix size hello

# View dependency graph
./pre-inst-env guix graph hello | dot -Tpng > graph.png

Using guix repl

Interactive Scheme REPL for package development:

$ ./pre-inst-env guix repl

;; Import modules
,use (gnu packages base)
,use (guix packages)
,use (guix gexp)

;; Inspect a package
hello
(package-name hello)
(package-version hello)
(package-arguments hello)

;; Build a package
,build hello

;; Lower to derivation
,lower hello

;; Work with transformations
(package-with-c-toolchain hello `(("toolchain" ,gcc-toolchain)))

Module Loading

;; Import entire module
(use-modules (gnu packages base))

;; Import with prefix
(use-modules ((guix licenses) #:prefix license:))

;; Import specific bindings
(use-modules ((gnu packages gcc) #:select (gcc)))

;; Autoload (lazy loading)
#:autoload (gnu packages gcc) (gcc)

Common Workflows

Workflow 1: Adding a New Package

Find the right module in gnu/packages/ (e.g., gnu/packages/networking.scm)

Add necessary imports:

#:use-module (guix packages)
#:use-module (guix download)
#:use-module (guix build-system gnu)
#:use-module ((guix licenses) #:prefix license:)

Define the package:

(define-public my-package
  (package
    (name "my-package")
    (version "1.0.0")
    (source (origin ...))
    ...))

Get the source hash:

guix download https://example.com/my-package-1.0.0.tar.gz

Test the build:
```
./pre-inst-env guix build my-package
```
Run linter:
```
./pre-inst-env guix lint my-package
```

Test installation:

./pre-inst-env guix package -i my-package

Workflow 2: Updating a Package

Edit the version:
```
(version "2.0.0")
```

Update URI if needed:

(uri (string-append "..." version ".tar.gz"))

Get new hash:

guix download https://example.com/package-2.0.0.tar.gz

Update sha256:
```
(sha256 (base32 "NEW-HASH-HERE"))
```
Test build:
```
./pre-inst-env guix build package-name
```
Check for changes in dependencies or build process

Workflow 3: Creating a Service

Create module file:
- System: gnu/services/myservice.scm
- Home: gnu/home/services/myservice.scm

Define configuration record:

(define-record-type* <myservice-configuration> ...)

Create helper functions:
- Config file generation
- Shepherd service definition
- File generation

Define service-type:

(define myservice-service-type
  (service-type
   (name 'myservice)
   (extensions ...)
   (default-value ...)
   (description "...")))

Test in a config:

guix system reconfigure config.scm  # system service
guix home reconfigure home.scm       # home service

Workflow 4: Debugging Build Failures

Build with --keep-failed:

./pre-inst-env guix build my-package --keep-failed

Check the build log for error messages

Enter build environment:

./pre-inst-env guix shell -D my-package
cd /tmp/guix-build-my-package-1.0.0-0  # from --keep-failed

Manually reproduce the failed step

Add diagnostic output in phases:

(add-before 'build 'debug
  (lambda _
    (format #t "Current directory: ~a\n" (getcwd))
    (system* "ls" "-la")))

Common issues and fixes:
- Missing dependencies → Add to inputs/native-inputs
- Hardcoded paths → Use substitute* to fix
- Test failures → Disable tests or fix environment
- Wrong build system → Try different build-system

Common Pitfalls and Solutions

Hash Mismatch

Problem: Source hash doesn't match Solution: Use guix download URL to get correct hash, copy the base32 hash

Missing Dependencies

Problem: Build fails with "command not found" or missing libraries Solution: Add missing tools to native-inputs, libraries to inputs

Test Failures

Problem: Tests fail in sandboxed build environment Solution 1: Disable specific tests

(add-before 'check 'disable-failing-tests
  (lambda _
    (substitute* "tests/test_network.py"
      (("test_network") "disabled_test_network"))))

Solution 2: Disable all tests (last resort)

(arguments (list #:tests? #f))

Hardcoded Absolute Paths

Problem: Program has /usr or /bin paths Solution: Use substitute* to replace them

(substitute* "script.sh"
  (("/bin/sh") (which "sh"))
  (("/usr/local") #$output))

Build Directory Modified

Problem: "source directory modified" error Solution: Use out-of-source build

(arguments (list #:out-of-source? #t))

Phase Ordering

Problem: Phase runs in wrong order Solution: Use add-before, add-after, replace carefully

(add-after 'unpack 'patch-before-configure ...)
(add-before 'build 'set-flags ...)

Important Commands

Package Development

guix build package-name              # Build package
guix build -f file.scm               # Build from file
guix build --check package           # Rebuild to verify reproducibility
guix build --keep-failed package     # Keep build directory on failure
guix build --no-grafts package       # Disable security grafts

guix lint package-name               # Check for issues
guix refresh package-name            # Check for updates
guix size package-name               # Check closure size
guix graph package-name              # Show dependencies

guix shell -D package                # Enter development environment
guix shell package -- command        # Run command with package

guix hash file.tar.gz                # Get hash of file
guix download URL                    # Download and hash

Testing

make check                           # Run test suite
./pre-inst-env guix build hello      # Test with local changes
guix repl                            # Interactive testing

Key References

When working from a Guix repository checkout, refer to these locations:

Package definitions: gnu/packages/
System services: gnu/services/
Home services: gnu/home/services/
Build systems: guix/build-system/
Build utilities: guix/build/utils.scm
Patches: gnu/packages/patches/
Manual: doc/guix.texi
Cookbook: doc/guix-cookbook.texi
Contributing: doc/contributing.texi

Best Practices

Use modern G-expression style for arguments (list with #~)
Keep packages focused - one package per purpose
Follow naming conventions - lowercase with dashes
Add patches to patches/ directory with search-patches
Test thoroughly - build, lint, install
Write clear descriptions - synopsis is one line, description is detailed
Use appropriate build systems - don't default to gnu-build-system
Minimize inputs - only include necessary dependencies
Propagate sparingly - only when truly needed by users
Document unusual choices - add comments for non-obvious decisions

Getting Help

When stuck, use these resources:

# View package definition
./pre-inst-env guix edit package-name

# Search for similar packages
./pre-inst-env guix search keyword

# Check package dependencies
./pre-inst-env guix graph package-name

# View build log
guix build --log-file package-name

# Ask on IRC: #guix on libera.chat
# Mailing list: help-guix@gnu.org

guix

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