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README
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Health Checking
Health Check Types
Readiness
Readiness is a special type of health check. Readiness checks will only run until they pass for the first time. After a readiness check passes, it will never be run again. These checks are typically used to indicate that the startup of a component has finished.
Health
Health checks typically indicate that a component is operating as expected. The health of a component may flip due to any arbitrary heuristic the component exposes.
Liveness
Liveness checks are intended to indicate that a component has become unhealthy and has no way to recover.
Naming and Tags
All registered checks must have a unique name which will be included in the health check results.
Additionally, checks can optionally specify an arbitrary number of tags which can be used to group health checks together.
Special Tags
- "All" is a tag that is automatically added for every check that is registered.
- "Application" checks are checks that are globally applicable. This means that it is not possible to filter application-wide health checks from a response.
Health Check Worker
Readiness, Health, and Liveness checks are all implemented by using their own health check worker.
A health check worker starts a goroutine that updates the health of all registered checks every freq. By default freq is set to 30s.
When a health check is added it will always initially report as unhealthy.
Every health check runs in its own goroutine to maximize concurrency. It is guaranteed that no locks from the health checker are held during the execution of the health check.
When the health check worker is stopped, it will finish executing any currently running health checks and then terminate its primary goroutine. After the health check worker is stopped, the health checks will never run again.
Documentation
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Index ¶
- Constants
- func NewGetAndPostHandler(log log.Logger, reporter Reporter) (http.Handler, error)
- func NewGetHandler(reporter func(tags ...string) (map[string]apihealth.Result, bool)) http.Handler
- type Checker
- type CheckerFunc
- type Health
- type Registerer
- type Reporter
- type Service
- func (s *Service) Health(_ *http.Request, args *apihealth.APIArgs, reply *apihealth.APIReply) error
- func (s *Service) Liveness(_ *http.Request, args *apihealth.APIArgs, reply *apihealth.APIReply) error
- func (s *Service) Readiness(_ *http.Request, args *apihealth.APIArgs, reply *apihealth.APIReply) error
Constants ¶
const ( // CheckLabel is the label used to differentiate between health checks. CheckLabel = "check" // TagLabel is the label used to differentiate between health check tags. TagLabel = "tag" // AllTag is automatically added to every registered check. AllTag = "all" // ApplicationTag checks will act as if they specified every tag that has // been registered. // Registering a health check with this tag will ensure that it is always // included in all health query results. ApplicationTag = "application" )
Variables ¶
This section is empty.
Functions ¶
func NewGetAndPostHandler ¶
NewGetAndPostHandler returns a health handler that supports GET and jsonrpc POST requests.
Types ¶
type Checker ¶
type Checker interface {
// HealthCheck returns health check results and, if not healthy, a non-nil
// error
//
// It is expected that the results are json marshallable.
HealthCheck(context.Context) (interface{}, error)
}
Checker can have its health checked
type CheckerFunc ¶
func (CheckerFunc) HealthCheck ¶
func (f CheckerFunc) HealthCheck(ctx context.Context) (interface{}, error)
type Health ¶
type Health interface {
Registerer
Reporter
// Start running periodic health checks at the specified frequency.
// Repeated calls to Start will be no-ops.
Start(ctx context.Context, freq time.Duration)
// Stop running periodic health checks. Stop should only be called after
// Start. Once Stop returns, no more health checks will be executed.
Stop()
}
Health defines the full health service interface for registering, reporting and refreshing health checks.
type Registerer ¶
type Registerer interface {
RegisterReadinessCheck(name string, checker Checker, tags ...string) error
RegisterHealthCheck(name string, checker Checker, tags ...string) error
RegisterLivenessCheck(name string, checker Checker, tags ...string) error
}
Registerer defines how to register new components to check the health of.
type Reporter ¶
type Reporter interface {
Readiness(tags ...string) (map[string]apihealth.Result, bool)
Health(tags ...string) (map[string]apihealth.Result, bool)
Liveness(tags ...string) (map[string]apihealth.Result, bool)
}
Reporter returns the current health status.
type Service ¶
type Service struct {
// contains filtered or unexported fields
}
Service implements the health API with gorilla/rpc-compatible signatures.
Source Files