While docker builder prune
or docker buildx prune
commands run at once, garbage collection runs periodically and follows an
ordered list of prune policies.
Garbage collection runs in the BuildKit daemon. The daemon clears the build cache when the cache size becomes too big, or when the cache age expires. The following sections describe how you can configure both the size and age parameters by defining garbage collection policies.
Configuration#
Depending on the driver used by your builder instance, the garbage collection will use a different configuration file.
If you're using the docker
driver, garbage collection
can be configured in the Docker Daemon configuration.
file:
{
"builder": {
"gc": {
"enabled": true,
"defaultKeepStorage": "10GB",
"policy": [
{ "keepStorage": "10GB", "filter": ["unused-for=2200h"] },
{ "keepStorage": "50GB", "filter": ["unused-for=3300h"] },
{ "keepStorage": "100GB", "all": true }
]
}
}
}
For other drivers, garbage collection can be configured using the BuildKit configuration file:
[worker.oci]
gc = true
gckeepstorage = 10000
[[worker.oci.gcpolicy]]
keepBytes = 512000000
keepDuration = 172800
filters = [ "type==source.local", "type==exec.cachemount", "type==source.git.checkout"]
[[worker.oci.gcpolicy]]
all = true
keepBytes = 1024000000
Default policies#
Default garbage collection policies apply to all builders if not set:
GC Policy rule#0:
All: false
Filters: type==source.local,type==exec.cachemount,type==source.git.checkout
Keep Duration: 48h0m0s
Keep Bytes: 512MB
GC Policy rule#1:
All: false
Keep Duration: 1440h0m0s
Keep Bytes: 26GB
GC Policy rule#2:
All: false
Keep Bytes: 26GB
GC Policy rule#3:
All: true
Keep Bytes: 26GB
rule#0
: if build cache uses more than 512MB delete the most easily reproducible data after it has not been used for 2 days.rule#1
: remove any data not used for 60 days.rule#2
: keep the unshared build cache under cap.rule#3
: if previous policies were insufficient start deleting internal data to keep build cache under cap.
[!NOTE]
Keep Bytes
defaults to 10% of the size of the disk. If the disk size cannot be determined, it uses 2GB as a fallback.