Health

public class Health : HealthProtocol

The Health class provides a concrete implementation of the HealthProtocol protocol that applications can instantiate and then register one or more health checks against. Once you have your health checks in place you can ask your Health instance for its status.

Usage Example:

One common use case for this Swift package is to integrate it into a Kitura-based application. In the code sample below, the health of the application is exposed through the /health endpoint. Cloud environments (e.g. Cloud Foundry, Kubernetes, etc.) can then use the status information returned from the /health endpoint to monitor and manage the Swift application instance.

For further information and example code see our README and the Cloud Foundry documentation for using application health checks.

 import Health

 let health = Health()

 health.addCheck(check: MyCheck1())
 health.addCheck(check: myClosureCheck1)

 // Define /health endpoint that leverages Health
 router.get("/health") { request, response, next in
    let status = health.status
    if health.status.state == .UP {
        try response.status(.OK).send(status).end()
    } else {
        try response.status(.serviceUnavailable).send(status).end()
    }
 }

  • Status instance variable.

    Declaration

    Swift

    public var status: Status { get }

  • Number of health checks registered.

    Usage Example:

     let health = Health()

 let count = health.numberOfChecks

    Declaration

    Swift

    public var numberOfChecks: Int { get }

  • Creates an instance of the Health class.

    Usage Example:

    In the example below the statusExpirationTime defaults to 30000 milliseconds, in this case 30 seconds must elapse before the Health instance computes its status again by querying each health check that has been registered.

    let health = Health()

    Declaration

    Swift

    public init(statusExpirationTime: Int = 30000)

    Parameters

    statusExpirationTime

    Optional. The time window in milliseconds that should elapse before the status cache for this Health instance is considered to be expired and should be recomputed. The default value is 30000.

  • Registers a health check.

    Usage Example:

     let health = Health()

 // Add custom checks
 health.addCheck(check: MyCheck1())

    Declaration

    Swift

    public func addCheck(check: HealthCheck)

    Parameters

    check

    An object that extends the HealthCheck class.

  • Registers a health check.

    Usage Example:

     let health = Health()

 // Add custom checks
 health.addCheck(check: myClosureCheck1)

    Declaration

    Swift

    public func addCheck(check: @escaping HealthCheckClosure)

    Parameters

    check

    A closure that conforms to the HealthCheckClosure type alias.

  • Forces an update to the status of this instance.

    Declaration

    Swift

    public func forceUpdateStatus()