Linux Package Managers

Also Known As

TL;DR

Explanation

Package managers resolve dependencies, verify signatures, and maintain package state. apt (Advanced Package Tool): apt install/remove/update/upgrade/autoremove, apt-cache search/show. dnf (replacing yum): dnf install/remove/update, dnf search. apk (Alpine — used in Docker): apk add/del/update/upgrade. Key differences: Alpine's apk is designed for minimal containers (no pkg-cache by default), apt uses .deb packages, dnf/yum uses .rpm. For PHP: ubuntu/debian use apt for PHP packages (ondrej/php PPA for multiple versions), Alpine uses apk. Security: always verify package signatures, use apt-key or dnf GPG checks.

Common Misconception

Why It Matters

Common Mistakes

• Not running apt update before apt install — installs outdated packages with stale package lists.
• No apt-get clean in Dockerfiles — package cache adds 50-100MB to image layers.
• apk --no-cache not used in Dockerfile — Alpine caches packages by default, bloating the image.
• Installing build tools without --virtual in apk — leaves build deps in production image.

Code Examples

# Bloated Dockerfile — cache not cleaned:
FROM ubuntu:22.04
RUN apt-get install -y php8.3-fpm
# Layer includes full apt cache: +100MB

# Alpine without --no-cache:
FROM alpine:3.19
RUN apk add php83-fpm
# Package cache retained: +30MB

# Clean apt cache in same layer:
FROM ubuntu:22.04
RUN apt-get update && apt-get install -y php8.3-fpm \
    && apt-get clean && rm -rf /var/lib/apt/lists/*

# Alpine with --no-cache — no package cache:
FROM alpine:3.19
RUN apk add --no-cache php83-fpm

# Install + clean in one RUN to minimise layer size:
RUN apk add --no-cache --virtual .build-deps \
        gcc musl-dev \
    && docker-php-ext-install pdo_mysql \
    && apk del .build-deps  # Remove build tools from final image

References

• ↗ https://manpages.ubuntu.com/manpages/jammy/en/man8/apt.8.html

Tags

Related Terms