Merge pull request #24 from Clivern/feature/health

add health check wrapper

Author: Clivern

README.md

@@ -154,6 +154,24 @@ for _, task := range p.Tasks {
 }
 ````
 
+**Health Checker Component**
+
+```golang
+healthChecker := hippo.NewHealthChecker()
+healthChecker.AddCheck("ping_check", func() (bool, error){
+    return true, nil
+})
+healthChecker.AddCheck("db_check", func() (bool, error){
+    return false, fmt.Errorf("Database Down")
+})
+healthChecker.RunChecks()
+
+fmt.Println(healthChecker.ChecksStatus())
+// Output -> DOWN
+fmt.Println(healthChecker.ChecksReport())
+// Output -> [{"id":"ping_check","status":"UP","error":"","result":true},{"id":"db_check","status":"DOWN","error":"Database Down","result":false}] 
+```
+
 ## Versioning
 
 For transparency into our release cycle and in striving to maintain backward compatibility, Hippo is maintained under the [Semantic Versioning guidelines](https://semver.org/) and release process is predictable and business-friendly.

health.go

@@ -0,0 +1,120 @@
+// Copyright 2019 Clivern. All rights reserved.
+// Use of this source code is governed by the MIT
+// license that can be found in the LICENSE file.
+
+package hippo
+
+import (
+	"encoding/json"
+)
+
+const (
+	// ServiceUp const
+	ServiceUp = "UP"
+	// ServiceDown const
+	ServiceDown = "DOWN"
+	// ServiceUnknown const
+	ServiceUnknown = "UNKNOWN"
+)
+
+// Check struct
+type Check struct {
+	ID       string `json:"id"`
+	Status   string `json:"status"`
+	Error    string `json:"error"`
+	Result   bool   `json:"result"`
+	callable func() (bool, error)
+}
+
+// Health struct
+type Health struct {
+	Status string
+	Checks []*Check
+}
+
+// NewHealthChecker initializes a new health checker
+func NewHealthChecker() *Health {
+	return &Health{}
+}
+
+// IsUnknown returns true if Status is Unknown
+func (h *Health) IsUnknown() bool {
+	return h.Status == ServiceUnknown
+}
+
+// IsUp returns true if Status is Up
+func (h *Health) IsUp() bool {
+	return h.Status == ServiceUp
+}
+
+// IsDown returns true if Status is Down
+func (h *Health) IsDown() bool {
+	return h.Status == ServiceDown
+}
+
+// Down set the Status to Down
+func (h *Health) Down() *Health {
+	h.Status = ServiceDown
+	return h
+}
+
+// Unknown set the Status to Unknown
+func (h *Health) Unknown() *Health {
+	h.Status = ServiceUnknown
+	return h
+}
+
+// Up set the Status to Up
+func (h *Health) Up() *Health {
+	h.Status = ServiceUp
+	return h
+}
+
+// ChecksStatus get checks Status
+func (h *Health) ChecksStatus() string {
+	return h.Status
+}
+
+// ChecksReport get checks Status
+func (h *Health) ChecksReport() (string, error) {
+	bytes, err := json.Marshal(h.Checks)
+	if err != nil {
+		return "", err
+	}
+	return string(bytes), nil
+}
+
+// AddCheck adds a new check
+func (h *Health) AddCheck(ID string, callable func() (bool, error)) {
+	check := &Check{
+		ID:       ID,
+		Status:   ServiceUnknown,
+		callable: callable,
+	}
+	h.Checks = append(h.Checks, check)
+}
+
+// RunChecks runs all health checks
+func (h *Health) RunChecks() {
+	upCount := 0
+	downCount := 0
+	var err error
+	for _, check := range h.Checks {
+		check.Result, err = check.callable()
+		if err != nil {
+			check.Error = err.Error()
+		}
+		if check.Result {
+			check.Status = ServiceUp
+			upCount++
+		} else {
+			check.Status = ServiceDown
+			downCount++
+		}
+	}
+	if downCount > 0 {
+		h.Down()
+	} else {
+		h.Up()
+	}
+}