DNF Provider

This document describes the implementation details of the DNF package provider for RHEL/Fedora-based systems.

Concurrency

A global package lock (model.PackageGlobalLock) is held during all command executions to prevent concurrent dnf/rpm operations within the same process. This prevents lock contention on the RPM database.

Operations

Status Check

Command:

rpm -q <package> --queryformat '%{NAME} %|EPOCH?{%{EPOCH}}:{0}| %{VERSION} %{RELEASE} %{ARCH}'

Query Format (NEVRA): The query format extracts the full NEVRA (Name, Epoch, Version, Release, Architecture):

Example output:

zsh 0 5.8 9.el9 x86_64

Behavior:

• Exit code 0 → Package is present, parses NEVRA components
• Exit code non-zero → Package is absent

Returned Version Format: The version returned combines VERSION and RELEASE: 5.8-9.el9

The epoch and release are stored separately in the Extended metadata.

Install

Ensure Present or Latest:

dnf install -y <package>

Specific Version:

dnf install -y <package>-<version>

Flags:

Note: DNF uses - (hyphen) to separate package name from version, unlike APT which uses =.

Upgrade

Delegates to Install(). DNF’s install command handles upgrades automatically when a newer version is available or specified.

Downgrade

Command:

dnf downgrade -y <package>-<version>

Note: Unlike upgrade, downgrade uses a dedicated DNF command rather than delegating to install.

Uninstall

Command:

dnf remove -y <package>

Version Format

RPM versions follow the EVR (Epoch:Version-Release) format:

[epoch:]version-release

Examples:

• 5.8-9.el9 → epoch=0, version=5.8, release=9.el9
• 1:2.0-3.fc39 → epoch=1, version=2.0, release=3.fc39
• 0:1.0.0-1.el9 → epoch=0 (explicit), version=1.0.0, release=1.el9

Version Comparison

Version comparison uses a generic algorithm ported from Puppet, implemented in internal/util.VersionCmp().

Algorithm

The version string is tokenized into segments by splitting on -, ., digits, and non-digit sequences. Segments are compared left-to-right:

1. Hyphens (-) - A hyphen loses to any other character
2. Dots (.) - A dot loses to any non-hyphen character
3. Digit sequences - Compared numerically, except:
   • Leading zeros trigger lexical comparison (01 vs 1 compared as strings)
4. Non-digit sequences - Compared lexically (case-insensitive)

If all segments match, falls back to whole-string comparison.

Trailing Zero Normalization

When ignoreTrailingZeroes is enabled, trailing .0 segments before the first - are removed:

• 1.0.0-rc1 → 1-rc1
• 2.0.0 → 2

This allows 1.0.0 to equal 1.0 when the flag is set.

Comparison Examples

Implementation

The version comparison is implemented in internal/util/util.go and provides:

• VersionCmp(a, b, ignoreTrailingZeroes) - Compare two version strings
• Returns -1 (a < b), 0 (a == b), or 1 (a > b)