chore: reorganize go code

internal/preflight.go

@@ -0,0 +1,48 @@
+package config
+
+import (
+	"fmt"
+	"net/http"
+	"strings"
+)
+
+// Checks to make sure all required environment variables are set
+func validateRequired(config *Config) error {
+	if config.Hostname == "" {
+		return fmt.Errorf("%s is required", HostnameEnv)
+	}
+
+	if config.TSControlURL == "" {
+		return fmt.Errorf("%s is required", TSControlURLEnv)
+	}
+
+	if config.TSAuthKey == "" {
+		return fmt.Errorf("%s is required", TSAuthKeyEnv)
+	}
+
+	if config.WorkDir == "" {
+		return fmt.Errorf("%s is required", WorkDirEnv)
+	}
+
+	return nil
+}
+
+// Pings the Tailscale control server to make sure it's up and running
+func validateTSReady(config *Config) error {
+	testURL := config.TSControlURL
+	if strings.HasSuffix(testURL, "/") {
+		testURL = testURL[:len(testURL)-1]
+	}
+
+	testURL = fmt.Sprintf("%s/health", testURL)
+	resp, err := http.Get(testURL)
+	if err != nil {
+		return fmt.Errorf("Failed to connect to TS control server: %s", err)
+	}
+
+	if resp.StatusCode != 200 {
+		return fmt.Errorf("Failed to connect to TS control server: %s", resp.Status)
+	}
+
+	return nil
+}