feat(runner conf): Runner conf allows mergin of timeouts with default

- Accounts for zero value configurations in the merging process
    Use nullable timeout values on the runner conf, so if timeouts are
    nil, values from default conf can be used (before this commit zero
    values could not be used properly).

- Split the merging of configuration in 'GetConfRunner' into a separate
  function 'MergedConfRunners' for simpler code and potential future
  reusability

By changing the configuration assignments to reference assignments, we
have more flexibility when passing runner configurations (i.e., we can
use nil to specify a non-override). By splitting the
configuration merging logic into a separate function, we enhance
readability and promote reusability. The adjustments in the test
functions account for these changes. The update to the HTTP response
generation simplifies the existing implementation by removing
redundancy.

examples/config.yaml

@@ -4,7 +4,8 @@ runners:
   default:
     timeout: 5m
     listen_address: "127.0.0.1:51234"
-  http:
+  cli: {}  # override default runner only for CLI mode
+  http:  # override default runner only for HTTP mode
     # shutdown_signal_header is mainly useful for testing http mode, do not set it in production
     # if set, better be treated like a secret, and a secure transport layer should be used.
     # this is the value set on "X-Shutdown-Signal" header in the http request

internal/conf.go

@@ -21,14 +21,14 @@ type Conf struct {
 
 // ConfRunner is config for the check runners
 type ConfRunner struct {
-	Timeout              time.Duration
-	ShutdownSignalHeader *string       `yaml:"shutdown_signal_header"`
-	ListenAddress        string        `yaml:"listen_address"`
-	RequestReadTimeout   time.Duration `yaml:"request_read_timeout"`
-	ResponseWriteTimeout time.Duration `yaml:"response_write_timeout"`
-	ResponseOK           string        `yaml:"response_ok"`
-	ResponseFailed       string        `yaml:"response_failed"`
-	ResponseTimeout      string        `yaml:"response_timeout"`
+	Timeout              *time.Duration
+	ShutdownSignalHeader *string        `yaml:"shutdown_signal_header"`
+	ListenAddress        string         `yaml:"listen_address"`
+	RequestReadTimeout   *time.Duration `yaml:"request_read_timeout"`
+	ResponseWriteTimeout *time.Duration `yaml:"response_write_timeout"`
+	ResponseOK           *string        `yaml:"response_ok"`
+	ResponseFailed       *string        `yaml:"response_failed"`
+	ResponseTimeout      *string        `yaml:"response_timeout"`
 }
 
 // ConfCheckSpec is the spec for each check configuration
@@ -59,45 +59,25 @@ func ReadConf(path string) (*Conf, error) {
 
 // GetDefaultConfRunner returns a ConfRunner based on the default configuration
 func GetDefaultConfRunner(runners *ConfRunners) ConfRunner {
-	defaultRunner := ConfRunner{
-		Timeout:              0,
+	var timeout, readTimeout, writeTimout time.Duration = 0 * time.Second, 30 * time.Second, 30 * time.Second
+	var respOK, respFailed, respTimeout string = "OK", "FAILED", "TIMEOUT"
+
+	baseConf := ConfRunner{
+		Timeout:              &timeout,
 		ShutdownSignalHeader: nil,
 		ListenAddress:        "127.0.0.1:8880",
-		RequestReadTimeout:   30 * time.Second,
-		ResponseWriteTimeout: 30 * time.Second,
-		ResponseOK:           "OK",
-		ResponseFailed:       "FAILED",
-		ResponseTimeout:      "TIMEOUT",
+		RequestReadTimeout:   &readTimeout,
+		ResponseWriteTimeout: &writeTimout,
+		ResponseOK:           &respOK,
+		ResponseFailed:       &respFailed,
+		ResponseTimeout:      &respTimeout,
 	}
 
 	if defaultConf, defaultExists := (*runners)["default"]; defaultExists {
-		if defaultConf.Timeout != 0 {
-			defaultRunner.Timeout = defaultConf.Timeout
-		}
-		if defaultConf.ShutdownSignalHeader != nil {
-			defaultRunner.ShutdownSignalHeader = defaultConf.ShutdownSignalHeader
-		}
-		if defaultConf.ListenAddress != "" {
-			defaultRunner.ListenAddress = defaultConf.ListenAddress
-		}
-		if defaultConf.RequestReadTimeout != 0 {
-			defaultRunner.RequestReadTimeout = defaultConf.RequestReadTimeout
-		}
-		if defaultConf.ResponseWriteTimeout != 0 {
-			defaultRunner.ResponseWriteTimeout = defaultConf.ResponseWriteTimeout
-		}
-		if defaultConf.ResponseOK != "" {
-			defaultRunner.ResponseOK = defaultConf.ResponseOK
-		}
-		if defaultConf.ResponseFailed != "" {
-			defaultRunner.ResponseFailed = defaultConf.ResponseFailed
-		}
-		if defaultConf.ResponseTimeout != "" {
-			defaultRunner.ResponseTimeout = defaultConf.ResponseTimeout
-		}
+		baseConf = MergedConfRunners(&baseConf, &defaultConf)
 	}
 
-	return defaultRunner
+	return baseConf
 }
 
 // GetConfRunner returns the runner config for the name merged with the default, and bool if it exists
@@ -110,41 +90,55 @@ func GetConfRunner(runners *ConfRunners, name string) (ConfRunner, bool) {
 	}
 
 	// Merge the requested runner with the default runner
+	mergedConf := MergedConfRunners(&defaultConf, &namedConf)
+
+	return mergedConf, true
+}
+
+// MergedConfRunners merges the baseConf with the overrideConf and returns the merged ConfRunner
+func MergedConfRunners(baseConf, overrideConf *ConfRunner) ConfRunner {
 	mergedConf := ConfRunner{
-		Timeout:              namedConf.Timeout,
-		ShutdownSignalHeader: namedConf.ShutdownSignalHeader,
-		ListenAddress:        namedConf.ListenAddress,
-		RequestReadTimeout:   namedConf.RequestReadTimeout,
-		ResponseWriteTimeout: namedConf.ResponseWriteTimeout,
-		ResponseOK:           namedConf.ResponseOK,
-		ResponseFailed:       namedConf.ResponseFailed,
-		ResponseTimeout:      namedConf.ResponseTimeout,
+		Timeout:              overrideConf.Timeout,
+		ShutdownSignalHeader: overrideConf.ShutdownSignalHeader,
+		ListenAddress:        overrideConf.ListenAddress,
+		RequestReadTimeout:   overrideConf.RequestReadTimeout,
+		ResponseWriteTimeout: overrideConf.ResponseWriteTimeout,
+		ResponseOK:           overrideConf.ResponseOK,
+		ResponseFailed:       overrideConf.ResponseFailed,
+		ResponseTimeout:      overrideConf.ResponseTimeout,
 	}
 
-	if mergedConf.Timeout == 0 {
-		mergedConf.Timeout = defaultConf.Timeout
+	if mergedConf.Timeout == nil {
+		mergedConf.Timeout = baseConf.Timeout
 	}
+
 	if mergedConf.ShutdownSignalHeader == nil {
-		mergedConf.ShutdownSignalHeader = defaultConf.ShutdownSignalHeader
+		mergedConf.ShutdownSignalHeader = baseConf.ShutdownSignalHeader
 	}
+
 	if mergedConf.ListenAddress == "" {
-		mergedConf.ListenAddress = defaultConf.ListenAddress
+		mergedConf.ListenAddress = baseConf.ListenAddress
 	}
-	if mergedConf.RequestReadTimeout == 0 {
-		mergedConf.RequestReadTimeout = defaultConf.RequestReadTimeout
+
+	if mergedConf.RequestReadTimeout == nil {
+		mergedConf.RequestReadTimeout = baseConf.RequestReadTimeout
 	}
-	if mergedConf.ResponseWriteTimeout == 0 {
-		mergedConf.ResponseWriteTimeout = defaultConf.ResponseWriteTimeout
+
+	if mergedConf.ResponseWriteTimeout == nil {
+		mergedConf.ResponseWriteTimeout = baseConf.ResponseWriteTimeout
 	}
-	if mergedConf.ResponseOK == "" {
-		mergedConf.ResponseOK = defaultConf.ResponseOK
+
+	if mergedConf.ResponseOK == nil {
+		mergedConf.ResponseOK = baseConf.ResponseOK
 	}
-	if mergedConf.ResponseFailed == "" {
-		mergedConf.ResponseFailed = defaultConf.ResponseFailed
+
+	if mergedConf.ResponseFailed == nil {
+		mergedConf.ResponseFailed = baseConf.ResponseFailed
 	}
-	if mergedConf.ResponseTimeout == "" {
-		mergedConf.ResponseTimeout = defaultConf.ResponseTimeout
+
+	if mergedConf.ResponseTimeout == nil {
+		mergedConf.ResponseTimeout = baseConf.ResponseTimeout
 	}
 
-	return mergedConf, true
+	return mergedConf
 }