* fix: move build meta to own package
this allows it to be referenced from other packages without causing a cyclic dependency
* feat: custom user agent
* feat: make head pull failure warning toggleable
* expect prometheus tests to go through EVENTUALLY
* wait for queue to be empty before checking test conditions
* clean up new head failure toggle
* fixup! clean up new head failure toggle
* test: add registry tests
* test: add warn on head failure tests
* fix client interface and make tests hit more lines
* make all tests use NewClient instead of creating a struct pointer
* fix lint issues
Co-authored-by: Simon Aronsson <simme@arcticbit.se>
Log based on registry known-poor support of HEAD in checking container
manifest.
Some private registries do not support HEAD (E.G. GitLab Container Registry).
With the current config, this log message is causing a notification to be
sent for each container hosted in a registry lacking HEAD support.
log.Debug or log.Warning for failed HTTP HEAD-check based on registry hostname
where HEAD-check is known to fail.
For Docker Hub, a failed HEAD leading to a "regular pull" may count against a
user's call-quota whereas other registry implementations do not support HEAD,
or whose container manifest may be in a different location.
