feat: add support for exposing healthchecks in the AppJson struct

plugins/app-json/appjson.go

@@ -1,6 +1,11 @@
 package appjson
 
 import (
+	"encoding/json"
+	"fmt"
+	"os"
+	"strings"
+
 	"github.com/dokku/dokku/plugins/common"
 )
 
@@ -18,9 +23,10 @@ var (
 
 // AppJSON is a struct that represents an app.json file as understood by Dokku
 type AppJSON struct {
-	Cron      []CronCommand        `json:"cron"`
-	Formation map[string]Formation `json:"formation"`
-	Scripts   struct {
+	Cron         []CronCommand            `json:"cron"`
+	Formation    map[string]Formation     `json:"formation"`
+	Healthchecks map[string][]Healthcheck `json:"healthchecks"`
+	Scripts      struct {
 		Dokku struct {
 			Predeploy  string `json:"predeploy"`
 			Postdeploy string `json:"postdeploy"`
@@ -41,6 +47,43 @@ type Formation struct {
 	MaxParallel *int `json:"max_parallel"`
 }
 
+type Healthcheck struct {
+	Attempts     int32           `json:"attempts,omitempty"`
+	Command      []string        `json:"command,omitempty"`
+	Content      string          `json:"content,omitempty"`
+	HTTPHeaders  []HTTPHeader    `json:"httpHeaders,omitempty"`
+	InitialDelay int32           `json:"initialDelay,omitempty"`
+	Listening    bool            `json:"listening,omitempty"`
+	Name         string          `json:"name,omitempty"`
+	Path         string          `json:"path,omitempty"`
+	Port         int             `json:"port,omitempty"`
+	Scheme       string          `json:"scheme,omitempty"`
+	Timeout      int32           `json:"timeout,omitempty"`
+	Type         HealthcheckType `json:"type,omitempty"`
+	Uptime       int32           `json:"uptime,omitempty"`
+	Wait         int32           `json:"wait,omitempty"`
+	Warn         bool            `json:"warn,omitempty"`
+	OnFailure    *OnFailure      `json:"onFailure,omitempty"`
+}
+
+type HealthcheckType string
+
+const (
+	HealthcheckType_Liveness  HealthcheckType = "liveness"
+	HealthcheckType_Readiness HealthcheckType = "readiness"
+	HealthcheckType_Startup   HealthcheckType = "startup"
+)
+
+type HTTPHeader struct {
+	Name  string `json:"name,omitempty"`
+	Value string `json:"value,omitempty"`
+}
+
+type OnFailure struct {
+	Command []string `json:"command,omitempty"`
+	Url     string   `json:"url,omitempty"`
+}
+
 // GetAppjsonDirectory returns the directory containing a given app's extracted app.json file
 func GetAppjsonDirectory(appName string) string {
 	return common.GetAppDataDirectory("app-json", appName)
@@ -50,3 +93,26 @@ func GetAppjsonDirectory(appName string) string {
 func GetAppjsonPath(appName string) string {
 	return getProcessSpecificAppJSONPath(appName)
 }
+
+// GetAppJSON returns the parsed app.json file for a given app
+func GetAppJSON(appName string) (AppJSON, error) {
+	if !hasAppJSON(appName) {
+		return AppJSON{}, nil
+	}
+
+	b, err := os.ReadFile(getProcessSpecificAppJSONPath(appName))
+	if err != nil {
+		return AppJSON{}, fmt.Errorf("Cannot read app.json file: %v", err)
+	}
+
+	if strings.TrimSpace(string(b)) == "" {
+		return AppJSON{}, nil
+	}
+
+	var appJSON AppJSON
+	if err = json.Unmarshal(b, &appJSON); err != nil {
+		return AppJSON{}, fmt.Errorf("Cannot parse app.json: %v", err)
+	}
+
+	return appJSON, nil
+}

plugins/app-json/functions.go

@@ -79,28 +79,6 @@ func constructScript(command string, shell string, isHerokuishImage bool, isCnbI
 	return []string{shell, "-c", strings.Join(script, " ")}
 }
 
-func getAppJSON(appName string) (AppJSON, error) {
-	if !hasAppJSON(appName) {
-		return AppJSON{}, nil
-	}
-
-	b, err := os.ReadFile(getProcessSpecificAppJSONPath(appName))
-	if err != nil {
-		return AppJSON{}, fmt.Errorf("Cannot read app.json file: %v", err)
-	}
-
-	if strings.TrimSpace(string(b)) == "" {
-		return AppJSON{}, nil
-	}
-
-	var appJSON AppJSON
-	if err = json.Unmarshal(b, &appJSON); err != nil {
-		return AppJSON{}, fmt.Errorf("Cannot parse app.json: %v", err)
-	}
-
-	return appJSON, nil
-}
-
 func getAppJSONPath(appName string) string {
 	directory := filepath.Join(common.MustGetEnv("DOKKU_LIB_ROOT"), "data", "app-json", appName)
 	return filepath.Join(directory, "app.json")
@@ -118,7 +96,7 @@ func getProcessSpecificAppJSONPath(appName string) string {
 
 // getPhaseScript extracts app.json from app image and returns the appropriate json key/value
 func getPhaseScript(appName string, phase string) (string, error) {
-	appJSON, err := getAppJSON(appName)
+	appJSON, err := GetAppJSON(appName)
 	if err != nil {
 		return "", err
 	}
@@ -482,7 +460,7 @@ func createdContainerID(appName string, dockerArgs []string, image string, comma
 }
 
 func setScale(appName string, image string) error {
-	appJSON, err := getAppJSON(appName)
+	appJSON, err := GetAppJSON(appName)
 	if err != nil {
 		return err
 	}

plugins/app-json/triggers.go

@@ -13,7 +13,7 @@ import (
 
 // TriggerAppJSONProcessDeployParallelism returns the max number of processes to deploy in parallel
 func TriggerAppJSONProcessDeployParallelism(appName string, processType string) error {
-	appJSON, err := getAppJSON(appName)
+	appJSON, err := GetAppJSON(appName)
 	if err != nil {
 		return err
 	}