Local APK cache
Alpine Linux can automatically (re-)install packages from local media into RAM when booting, even before there is a network connection.
To have the packages available during boot, apk can keep a cache of installed packages on a local disk.
The cache can be stored on any writable media, or in the same location as the .apkovl file from the local backup utility
- 1 Enabling Local Cache with current releases
- 2 Cache maintenance
- 3 Special Caching Configurations
Enabling Local Cache with current releases
Execute the script
and it will assist in enabling a local cache.
The script creates a symlink named /etc/apk/cache that points to the cache directory.
Removing older packages
When newer packages are added to the cache over time, the older versions of the packages default to remain in the cache directory.
The older versions of packages can be removed with the clean command.
Or to see what is deleted include the verbose switch:
Download missing packages
If you accidentally delete packages from the cache directory, you can make sure they are there with the download command,
Delete and download in one step
You can combine the two steps into one with the sync command - this cleans out old packages and downloads missing packages.
Automatically Cleaning Cache on Reboot
To automatically attempt to validate your cache on reboot, you can add the above command to a /etc/local.d/*.stop file:
Special Caching Configurations
Enabling Local Cache on HDD installs
Note that HDD 'sys' installs don't need an apk cache to maintain their state, it allows to serve packages over the network, though, e.g. to get installed by other local machines.
Manually create a cache dir and then symlink it to /etc/apk/cache:
Local Cache on tmpfs volumes
In some circumstances it might be useful to have the cache reside on tmpfs, for example if you only wish for it to last as long as the system is up.
NOTE: apk is coded to ignore tmpfs caches, and this is correct behaviour in most instances. Using tmpfs as a package cache can consume large amounts of system memory if you install a lot of packages, possibly resulting in a crashed system. You can limit this by restricting the size of your cache to a small number (128M in the example below).
To do it, you need to create an image inside which your cache can live. We do this by creating an image file, formatting it with ext2, and mounting it at /etc/apk/cache.
- apk add e2fsprogs
- dd if=/dev/zero of=/apkcache.img bs=1M count=128
- mkfs.ext2 -F /apkcache.img
- mkdir -p /etc/apk/cache
- mount -t ext2 /apkcache.img /etc/apk/cache
- apk update
As usual, if you want to download currently installed packages into the cache, use apk cache sync.
Manually Enabling Local Cache (required for releases prior to v2.3)
- Create a cache directory on the storage device where you keep the lbu backups (typically,
- Create a symlink to this directory from
- Run an lbu commit to save the change (
/etcand is automatically backed up.)
Now whenever you run an apk command that pulls a new package from a remote repository, the package is stored on your local media. On startup, Alpine Linux will check the local cache for new packages, and will install them if available.