change Check to an interface and create implementing type check

api/health/checks.go

@@ -20,36 +20,48 @@ type CheckFn func() (interface{}, error)
 
 // Check defines a single health check that we want to monitor and consider as
 // part of our wider healthiness
-type Check struct {
+type Check interface {
 	// Name is the identifier for this check and must be unique among all Checks
-	Name string
+	Name() string
 
-	// CheckFn is the function to call to perform the the health check
-	CheckFn CheckFn
+	// Execute performs the health check. It returns nil if the check passes.
+	// It can also return additional information to marshal and display to the caller
+	Execute() (interface{}, error)
 
 	// ExecutionPeriod is the duration to wait between executions of this Check
-	ExecutionPeriod time.Duration
+	ExecutionPeriod() time.Duration
 
 	// InitialDelay is the duration to wait before executing the first time
-	InitialDelay time.Duration
+	InitialDelay() time.Duration
 
 	// InitiallyPassing is whether or not to consider the Check healthy before the
 	// initial execution
-	InitiallyPassing bool
+	InitiallyPassing() bool
 }
 
-// gosundheitCheck implements the health.Check interface backed by a CheckFn
-type gosundheitCheck struct {
-	name    string
-	checkFn CheckFn
+// check implements the Check interface
+type check struct {
+	name                          string
+	checkFn                       CheckFn
+	executionPeriod, initialDelay time.Duration
+	initiallyPassing              bool
 }
 
-// Name implements the health.Check interface by returning a unique name
-func (c gosundheitCheck) Name() string { return c.name }
+// Name is the identifier for this check and must be unique among all Checks
+func (c check) Name() string { return c.name }
 
-// Execute implements the health.Check interface by executing the checkFn and
-// returning the results
-func (c gosundheitCheck) Execute() (interface{}, error) { return c.checkFn() }
+// Execute performs the health check. It returns nil if the check passes.
+// It can also return additional information to marshal and display to the caller
+func (c check) Execute() (interface{}, error) { return c.checkFn() }
+
+// ExecutionPeriod is the duration to wait between executions of this Check
+func (c check) ExecutionPeriod() time.Duration { return c.executionPeriod }
+
+// InitialDelay is the duration to wait before executing the first time
+func (c check) InitialDelay() time.Duration { return c.initialDelay }
+
+// InitiallyPassing is whether or not to consider the Check healthy before the initial execution
+func (c check) InitiallyPassing() bool { return c.initiallyPassing }
 
 // Heartbeater provides a getter to the most recently observed heartbeat
 type Heartbeater interface {

api/health/service.go

@@ -17,7 +17,7 @@ import (
 )
 
 // defaultCheckOpts is a Check whose properties represent a default Check
-var defaultCheckOpts = Check{ExecutionPeriod: time.Minute}
+var defaultCheckOpts = check{executionPeriod: time.Minute}
 
 // Health observes a set of vital signs and makes them available through an HTTP
 // API.
@@ -61,18 +61,18 @@ func (h *Health) RegisterHeartbeat(name string, hb Heartbeater, max time.Duratio
 // RegisterCheckFunc adds a Check with default options and the given CheckFn
 func (h *Health) RegisterCheckFunc(name string, checkFn CheckFn) error {
 	check := defaultCheckOpts
-	check.Name = name
-	check.CheckFn = checkFn
+	check.name = name
+	check.checkFn = checkFn
 	return h.RegisterCheck(check)
 }
 
 // RegisterCheck adds the given Check
 func (h *Health) RegisterCheck(c Check) error {
 	return h.health.RegisterCheck(&health.Config{
-		InitialDelay:     c.InitialDelay,
-		ExecutionPeriod:  c.ExecutionPeriod,
-		InitiallyPassing: c.InitiallyPassing,
-		Check:            gosundheitCheck{c.Name, c.CheckFn},
+		InitialDelay:     c.InitialDelay(),
+		ExecutionPeriod:  c.ExecutionPeriod(),
+		InitiallyPassing: c.InitiallyPassing(),
+		Check:            c,
 	})
 }