APT Cacher NG

APT Cacher NG is a caching proxy for Debian and Ubuntu package downloads. Run one in the lab so many VMs and containers fetch each package from the internet once, which speeds up installs and templates such as Proxmox cloud-init.

Documentation: APT Cacher NG manual

Server #

Install it on a host that stays on, such as an LXC. The apt install command and package name were not on the pages read, so check your distribution (the package is commonly apt-cacher-ng). It listens on port 3142 by default in the manual’s examples. The main file is acng.conf.

SETTING	MEANING
`BindAddress`	Space-separated list of IPs to listen on. The default is all interfaces, IPv4 and IPv6
`PassThroughPattern: .*`	Tunnel HTTPS through the proxy without caching it
`Remap-<NAME>: <MERGING_URLS> ; <TARGET_URLS> ; <FLAGS>`	Map several mirrors onto one cache path

Restrict BindAddress to a management network. There is no user authentication in the examples read, so firewall port 3142 to your own VLANs.

Clients #

Point apt at the cache in /etc/apt/apt.conf.d/02proxy (the file name is your choice):

text

Acquire::http::proxy "http://<CACHE_HOST>:3142";

Or rewrite a source line to go through the cache:

text

deb http://<CACHE_HOST>:3142/ftp.uni-kl.de/debian etch main

The proxy setting is simpler for many hosts, and works from cloud-init or a template.

HTTPS Repositories #

Third-party repositories on HTTPS are a common snag:

METHOD	RESULT
`deb http://HTTPS///get.docker.com/ubuntu docker main`	Cached. The `HTTPS///` prefix tells the server to fetch over HTTPS. The author’s preferred route
`http://<CACHE_HOST>:3142/HTTPS///<HOST>/<PATH>`	The same idea as a URL rewrite
`PassThroughPattern: .*`	Tunnelled, not cached
Add the HTTPS URL to a `Remap-` list	Alternative

With PassThroughPattern, HTTPS traffic bypasses caching, so the cache only helps for plain HTTP mirrors.

Maintenance #

A daily maintenance cron job exists, and cache clean-up is triggered from the report page in the manual (section 7.1). The report page URL, the cache directory default, acngtool, and Docker image details were not verified.

Not Verified #

The apt install command, the report page URL, CacheDir defaults, acngtool, Docker images, and running it in a Proxmox LXC.