Documentation
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Overview ¶
Package clevels includes utilities for identifying log criticality and system austerity, which can be used to sample logs.
Index ¶
Constants ¶
const AusterityBuffer = 100
AusterityBuffer ensures that high-volume services will never block when trying to read the system austerity level, even if the process that updates the cache is slow. The tradeoff is that, when the system austerity level is changed, it will read an extra $AusterityBuffer log lines before the change takes effect.
Variables ¶
var AusterityFile string
AusterityFile is the full path to a file that contains the current system austerity level.
var CacheInterval = 30 * time.Second
var InvalidAusterityLevel = errors.New("Invalid austerity level")
var Stats *statsd.Client
var SystemAusterityLevel = make(chan AusterityLevel, AusterityBuffer)
To determine the current austerity level, read from SystemAusterityLevel. Austerity is updated according to CacheInterval, and this channel is buffered (size AusterityBuffer) to avoid blocking a critical code path. As a result, services which have a low log volume will take longer to have their austerity level changes come into effect.
Functions ¶
func ReportAusterity ¶
func ReportAusterity(l AusterityLevel)
func SendSystemAusterityLevel ¶
func SendSystemAusterityLevel()
Types ¶
type AusterityLevel ¶
type AusterityLevel int
const ( Sheddable AusterityLevel = iota SheddablePlus Critical CriticalPlus )
There are four levels of logs. The names and definitions are adapted from Google's usage.
For more information, see Chapter 21 of Site Reliability Engineering by Beyer, Jones, Petoff, and Murphy
Sheddable is the least-important, and we can expect frequent partial unavailability of Sheddable logs as well as occassional full unavailability without disruption.
SheddablePlus is the default level, and we can expect occasional partial availability and rare full unavailability.
Critical is used for lines for which partial unavailability is rare.
CriticalPlus is used for lines which should only be unavailable in the most extreme circumstances.
const DefaultAusterity AusterityLevel = Sheddable
The default system austerity level, in case we are unable to determine it from the state file
const DefaultCriticality AusterityLevel = SheddablePlus
The default criticality line for any log line that doesn't have an explicit clevel tag
func Criticality ¶
func Criticality(line string) AusterityLevel
criticality parses the criticality level of a log line. Defaults to the value of DefaultCriticality.
func JSONCriticality ¶
func JSONCriticality(line json.LogLine) AusterityLevel
func LoadLevel ¶
func LoadLevel() (AusterityLevel, error)
LoadLevel loads the AusterityFile and parses it to determine the system austerity level. If it encounters an error, it will return the DefaultAusterity.
func ParseLevel ¶
func ParseLevel(r io.Reader) (AusterityLevel, error)
func (AusterityLevel) AusterityLevel ¶
func (a AusterityLevel) AusterityLevel() string
func (AusterityLevel) String ¶
func (i AusterityLevel) String() string
Source Files