We need to know which of the possible error codes reported in the imageregistry_storage_errors_total metric indicate abnormal operations, so that we can create alerts for the relevant metrics.

Current error codes are:

errCodeUnsupportedMethod = "UNSUPPORTED_METHOD"
errCodePathNotFound      = "PATH_NOT_FOUND"
errCodeInvalidPath       = "INVALID_PATH"
errCodeInvalidOffset     = "INVALID_OFFSET"
errCodeReadOnlyFS        = "READ_ONLY_FILESYSTEM"
errCodeFileTooLarge      = "FILE_TOO_LARGE"
errCodeDeviceOutOfSpace  = "DEVICE_OUT_OF_SPACE"
errCodeUnknown           = "UNKNOWN" 

Source: openshift/image-registry/pkg/dockerregistry/server/metrics/errorcodes.go

Acceptance Criteria

• Understand and document each of the error codes in errorcodes.go
• Documentation should include when these errors might happen, and how severe/recoverable they are