Make Python compatability a flag

This will make transition easier for an interim period. Will remove at
version 1.0

alert.go

@@ -5,6 +5,7 @@ import (
 	"fmt"
 	"log"
 	"os/exec"
+	"strings"
 	"text/template"
 	"time"
 )
@@ -35,19 +36,35 @@ func (alert Alert) IsValid() bool {
 
 // BuildTemplates compiles command templates for the Alert
 func (alert *Alert) BuildTemplates() error {
+	// TODO: Remove legacy template support later after 1.0
+	legacy := strings.NewReplacer(
+		"{alert_count}", "{{.AlertCount}}",
+		"{alert_message}", "{{.MonitorName}} check has failed {{.FailureCount}} times",
+		"{failure_count}", "{{.FailureCount}}",
+		"{last_output}", "{{.LastCheckOutput}}",
+		"{last_success}", "{{.LastSuccess}}",
+		"{monitor_name}", "{{.MonitorName}}",
+	)
 	if LogDebug {
 		log.Printf("DEBUG: Building template for alert %s", alert.Name)
 	}
 	if alert.commandTemplate == nil && alert.Command.Command != nil {
 		alert.commandTemplate = []*template.Template{}
 		for i, cmdPart := range alert.Command.Command {
+			if PyCompat {
+				cmdPart = legacy.Replace(cmdPart)
+			}
 			alert.commandTemplate = append(alert.commandTemplate, template.Must(
 				template.New(alert.Name+string(i)).Parse(cmdPart),
 			))
 		}
 	} else if alert.commandShellTemplate == nil && alert.Command.ShellCommand != "" {
+		shellCmd := alert.Command.ShellCommand
+		if PyCompat {
+			shellCmd = legacy.Replace(shellCmd)
+		}
 		alert.commandShellTemplate = template.Must(
-			template.New(alert.Name).Parse(alert.Command.ShellCommand),
+			template.New(alert.Name).Parse(shellCmd),
 		)
 	} else {
 		return fmt.Errorf("No template provided for alert %s", alert.Name)
@@ -57,7 +74,7 @@ func (alert *Alert) BuildTemplates() error {
 }
 
 // Send will send an alert notice by executing the command template
-func (alert Alert) Send(notice AlertNotice) (output_str string, err error) {
+func (alert Alert) Send(notice AlertNotice) (outputStr string, err error) {
 	log.Printf("INFO: Sending alert %s for %s", alert.Name, notice.MonitorName)
 	var cmd *exec.Cmd
 	if alert.commandTemplate != nil {
@@ -92,10 +109,23 @@ func (alert Alert) Send(notice AlertNotice) (output_str string, err error) {
 
 	var output []byte
 	output, err = cmd.CombinedOutput()
-	output_str = string(output)
+	outputStr = string(output)
 	if LogDebug {
-		log.Printf("DEBUG: Alert output for: %s\n---\n%s\n---", alert.Name, output_str)
+		log.Printf("DEBUG: Alert output for: %s\n---\n%s\n---", alert.Name, outputStr)
 	}
 
-	return output_str, err
+	return outputStr, err
+}
+
+// NewLogAlert creates an alert that does basic logging using echo
+func NewLogAlert() *Alert {
+	return &Alert{
+		Name: "log",
+		Command: CommandOrShell{
+			Command: []string{
+				"echo",
+				"{{.MonitorName}} check has failed {{.FailureCount}} times",
+			},
+		},
+	}
 }

alert_test.go

@@ -34,6 +34,7 @@ func TestAlertSend(t *testing.T) {
 		expectedOutput string
 		expectErr      bool
 		name           string
+		pyCompat       bool
 	}{
 		{
 			Alert{Command: CommandOrShell{Command: []string{"echo", "{{.MonitorName}}"}}},
@@ -41,6 +42,7 @@ func TestAlertSend(t *testing.T) {
 			"test\n",
 			false,
 			"Command with template",
+			false,
 		},
 		{
 			Alert{Command: CommandOrShell{ShellCommand: "echo {{.MonitorName}}"}},
@@ -48,6 +50,7 @@ func TestAlertSend(t *testing.T) {
 			"test\n",
 			false,
 			"Command shell with template",
+			false,
 		},
 		{
 			Alert{Command: CommandOrShell{Command: []string{"echo", "{{.Bad}}"}}},
@@ -55,6 +58,7 @@ func TestAlertSend(t *testing.T) {
 			"",
 			true,
 			"Command with bad template",
+			false,
 		},
 		{
 			Alert{Command: CommandOrShell{ShellCommand: "echo {{.Bad}}"}},
@@ -62,11 +66,22 @@ func TestAlertSend(t *testing.T) {
 			"",
 			true,
 			"Command shell with bad template",
+			false,
+		},
+		{
+			Alert{Command: CommandOrShell{ShellCommand: "echo {alert_message}"}},
+			AlertNotice{MonitorName: "test", FailureCount: 1},
+			"test check has failed 1 times\n",
+			false,
+			"Command shell with legacy template",
+			true,
 		},
 	}
 
 	for _, c := range cases {
 		log.Printf("Testing case %s", c.name)
+		// Set PyCompat to value of compat flag
+		PyCompat = c.pyCompat
 		c.alert.BuildTemplates()
 		output, err := c.alert.Send(c.notice)
 		hasErr := (err != nil)
@@ -78,6 +93,8 @@ func TestAlertSend(t *testing.T) {
 			t.Errorf("Send(%v err), expected=%v actual=%v", c.name, "Err", err)
 			log.Printf("Case failed: %s", c.name)
 		}
+		// Set PyCompat back to default value
+		PyCompat = false
 		log.Println("-----")
 	}
 }

config.go

@@ -50,6 +50,19 @@ func (cos *CommandOrShell) UnmarshalYAML(unmarshal func(interface{}) error) erro
 func (config Config) IsValid() (isValid bool) {
 	isValid = true
 
+	// Validate alerts
+	if config.Alerts == nil || len(config.Alerts) == 0 {
+		// This should never happen because there is a default alert named 'log' for now
+		log.Printf("ERROR: Invalid alert configuration: Must provide at least one alert")
+		isValid = false
+	}
+	for _, alert := range config.Alerts {
+		if !alert.IsValid() {
+			log.Printf("ERROR: Invalid alert configuration: %s", alert.Name)
+			isValid = false
+		}
+	}
+
 	// Validate monitors
 	if config.Monitors == nil || len(config.Monitors) == 0 {
 		log.Printf("ERROR: Invalid monitor configuration: Must provide at least one monitor")
@@ -74,18 +87,6 @@ func (config Config) IsValid() (isValid bool) {
 		}
 	}
 
-	// Validate alerts
-	if config.Alerts == nil || len(config.Alerts) == 0 {
-		log.Printf("ERROR: Invalid alert configuration: Must provide at least one alert")
-		isValid = false
-	}
-	for _, alert := range config.Alerts {
-		if !alert.IsValid() {
-			log.Printf("ERROR: Invalid alert configuration: %s", alert.Name)
-			isValid = false
-		}
-	}
-
 	return
 }
 
@@ -117,6 +118,17 @@ func LoadConfig(filePath string) (config Config, err error) {
 		log.Printf("DEBUG: Config values:\n%v\n", config)
 	}
 
+	// Add log alert if not present
+	if PyCompat {
+		// Intialize alerts list if not present
+		if config.Alerts == nil {
+			config.Alerts = map[string]*Alert{}
+		}
+		if _, ok := config.Alerts["log"]; !ok {
+			config.Alerts["log"] = NewLogAlert()
+		}
+	}
+
 	if !config.IsValid() {
 		err = errors.New("Invalid configuration")
 		return

config_test.go

@@ -10,22 +10,29 @@ func TestLoadConfig(t *testing.T) {
 		configPath string
 		expectErr  bool
 		name       string
+		pyCompat   bool
 	}{
-		{"./test/valid-config.yml", false, "Valid config file"},
+		{"./test/valid-config.yml", false, "Valid config file", false},
-		{"./test/does-not-exist", true, "Invalid config path"},
+		{"./test/valid-default-log-alert.yml", false, "Valid config file with default log alert PyCompat", true},
-		{"./test/invalid-config-type.yml", true, "Invalid config type for key"},
+		{"./test/valid-default-log-alert.yml", true, "Invalid config file no log alert", false},
-		{"./test/invalid-config-missing-alerts.yml", true, "Invalid config missing alerts"},
+		{"./test/does-not-exist", true, "Invalid config path", false},
-		{"./test/invalid-config-unknown-alert.yml", true, "Invalid config unknown alert"},
+		{"./test/invalid-config-type.yml", true, "Invalid config type for key", false},
+		{"./test/invalid-config-missing-alerts.yml", true, "Invalid config missing alerts", false},
+		{"./test/invalid-config-unknown-alert.yml", true, "Invalid config unknown alert", false},
 	}
 
 	for _, c := range cases {
 		log.Printf("Testing case %s", c.name)
+		// Set PyCompat based on compatibility mode
+		PyCompat = c.pyCompat
 		_, err := LoadConfig(c.configPath)
 		hasErr := (err != nil)
 		if hasErr != c.expectErr {
 			t.Errorf("LoadConfig(%v), expected_error=%v actual=%v", c.name, c.expectErr, err)
 			log.Printf("Case failed: %s", c.name)
 		}
+		// Set PyCompat to default value
+		PyCompat = false
 		log.Println("-----")
 	}
 }

main.go

@@ -18,6 +18,9 @@ var (
 	// Metrics contains all active metrics
 	Metrics = NewMetrics()
 
+	// PyCompat enables support for legacy Python templates
+	PyCompat = false
+
 	// version of minitor being run
 	version = "dev"
 )
@@ -83,7 +86,9 @@ func main() {
 	// Get debug flag
 	flag.BoolVar(&LogDebug, "debug", false, "Enables debug logs (default: false)")
 	flag.BoolVar(&ExportMetrics, "metrics", false, "Enables prometheus metrics exporting (default: false)")
+	flag.BoolVar(&PyCompat, "py-compat", false, "Enables support for legacy Python Minitor config. Will eventually be removed. (default: false)")
 	var showVersion = flag.Bool("version", false, "Display the version of minitor and exit")
+	var configPath = flag.String("config", "config.yml", "Alternate configuration path (default: config.yml)")
 	flag.Parse()
 
 	// Print version if flag is provided
@@ -93,7 +98,7 @@ func main() {
 	}
 
 	// Load configuration
-	config, err := LoadConfig("config.yml")
+	config, err := LoadConfig(*configPath)
 	if err != nil {
 		log.Fatalf("Error loading config: %v", err)
 	}

test/valid-default-log-alert.yml

@@ -0,0 +1,8 @@
+---
+check_interval: 1
+
+monitors:
+  - name: Command
+    command: ['echo', '$PATH']
+    alert_down: ['log']
+    alert_every: 0