Automatically configure http_checks when rails_health_check_path detected

internal/app/app.go

@@ -466,6 +466,37 @@ func (c *Config) SetInternalPort(port int) bool {
 	return false
 }
 
+func (c *Config) SetHttpCheck(path string) bool {
+	services, ok := c.Definition["services"].([]interface{})
+	if !ok {
+		return false
+	}
+
+	if len(services) == 0 {
+		return false
+	}
+
+	if service, ok := services[0].(map[string]interface{}); ok {
+		check := map[string]interface{}{
+			"interval":        10000,
+			"grace_period":    "5s",
+			"method":          "get",
+			"protocol":        "http",
+			"restart_limit":   0,
+			"timeout":         2000,
+			"tls_skip_verify": false,
+		}
+
+		check["path"] = path
+
+		service["http_checks"] = []map[string]interface{}{check}
+
+		return true
+	}
+
+	return false
+}
+
 func (c *Config) SetConcurrency(soft int, hard int) bool {
 	services, ok := c.Definition["services"].([]interface{})
 	if !ok {

internal/command/launch/launch.go

@@ -421,6 +421,10 @@ func run(ctx context.Context) (err error) {
 			appConfig.SetInternalPort(srcInfo.Port)
 		}
 
+		if srcInfo.HttpCheckPath != "" {
+			appConfig.SetHttpCheck(srcInfo.HttpCheckPath)
+		}
+
 		if srcInfo.Concurrency != nil {
 			appConfig.SetConcurrency(srcInfo.Concurrency["soft_limit"], srcInfo.Concurrency["hard_limit"])
 		}

scanner/rails.go

@@ -11,6 +11,8 @@ import (
 	"github.com/pkg/errors"
 )
 
+var healthcheck_channel = make(chan string)
+
 func configureRails(sourceDir string, config *ScannerConfig) (*SourceInfo, error) {
 	if !checksPass(sourceDir, dirContains("Gemfile", "rails")) {
 		return nil, nil
@@ -64,6 +66,18 @@ https://fly.io/docs/rails/getting-started/dockerfiles/.
 Once ready: run 'fly deploy' to deploy your Rails app.
 `
 
+	// fetch healthcheck route in a separate thread
+	go func() {
+		out, err := exec.Command("ruby", "./bin/rails", "runner",
+			"puts Rails.application.routes.url_helpers.rails_health_check_path").Output()
+
+		if err == nil {
+			healthcheck_channel <- strings.TrimSpace(string(out))
+		} else {
+			healthcheck_channel <- ""
+		}
+	}()
+
 	return s, nil
 }
 
@@ -156,5 +170,7 @@ func RailsCallback(srcInfo *SourceInfo, options map[string]bool) error {
 		},
 	}
 
+	srcInfo.HttpCheckPath = <-healthcheck_channel
+
 	return nil
 }

scanner/scanner.go

@@ -55,6 +55,7 @@ type SourceInfo struct {
 	PostgresInitCommandCondition bool
 	Concurrency                  map[string]int
 	Callback                     func(srcInfo *SourceInfo, options map[string]bool) error
+	HttpCheckPath                string
 }
 
 type SourceFile struct {