core: APT/APK Mirror Fallback for CDN Failures#13316
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Improve robustness of package updates and installs by adding CDN/mirror fallback logic for Alpine and Debian/Ubuntu workflows. - misc/alpine-install.func: update_os() now attempts apk -U upgrade and, on failure, iterates a shuffled list of alternate Alpine mirrors, writes /etc/apk/repositories, tests the mirror and falls back with clear warnings/errors if none succeed. - misc/build.func: when apk add inside an Alpine container fails, run an in-container mirror scan that rewrites /etc/apk/repositories and retries apk update/add against multiple mirrors. Added a check to inject public DNS (8.8.8.8/1.1.1.1) into containers when APT repo DNS resolution fails. - misc/build.func (Debian/Ubuntu path): expanded apt-get failure handling to detect the failing mirror, then run a multi-phase mirror scanner (global → primary → regional), detect hash/SSL errors, and prompt the user for a custom mirror if automatic attempts fail. - misc/install.func: added apt_update_safe() implementing the apt-get update fallback logic (mirror lists, regional selection by timezone, reachable scanning, hash/SSL detection, and user prompt), returning failure if all mirrors fail. These changes aim to mitigate CDN outages, broken CDNs/mirrors, or DNS issues during container builds and OS updates, improving reliability and providing clear messages and fallbacks when automatic fixes are exhausted.
michelroegl-brunner
approved these changes
Mar 26, 2026
tremor021
approved these changes
Mar 26, 2026
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✍️ Description
Container creation fails when Debian/Ubuntu/Alpine CDN mirrors are unreachable, serve corrupted data (hash mismatch), or lack valid SSL certificates — especially in Asia/India.
Solution
Three-phase mirror fallback: Global → Primary → Regional → Manual prompt. Scans TCP reachability first, picks 3 random working mirrors per phase. Detects Debian vs Ubuntu automatically and uses the correct mirror pool. Alpine gets its own 8-mirror fallback.
Key decisions:
Example:
💡 apt-get update failed (deb.debian.org), trying alternate mirrors... 💡 Attempting mirror: ftp.jp.debian.org ⚠️ Mirror ftp.jp.debian.org failed (SSL/certificate error) 💡 Attempting mirror: ftp.it.debian.org ✔️ CDN set to ftp.it.debian.org: tests passed ✔️ Customized LXC Container🔗 Related Issue
https://discord.com/channels/1302816934508630047/1486700783343894619
✅ Prerequisites (X in brackets)
🛠️ Type of Change (X in brackets)
README,AppName.md,CONTRIBUTING.md, or other docs.