feat: add doctor command for local preflight checks and update Makefile with new targets

Author: FlyingVoodoo

Makefile

@@ -1,11 +1,24 @@
 # Makefile for running tests and building the C++ streamer locally
 
-.PHONY: test test-fast test-full build-clib
+CONFIG ?= configs/example-node.yaml
+
+.PHONY: test test-fast test-full build build-clib check doctor
 
 # Run Go unit tests quickly (no cgo streamer)
 test-fast:
 	go test ./... -v
 
+# Build the Go CLI
+build:
+	go build -v ./cmd/gs
+
+# Run the standard fast validation flow
+check: test-fast build
+
+# Run local preflight checks for the selected config
+doctor:
+	go run ./cmd/gs doctor --config $(CONFIG)
+
 # Build C++ streamer and run Go tests with cgo_streamer enabled
 test-full: build-clib
 	go test ./... -v -tags cgo_streamer

README.md

@@ -86,6 +86,12 @@ Runs 12 security checks across system, docker, nomad. Outputs alerts with severi
 ./gs status 192.168.1.100
 ```
 
+**Doctor** - Local preflight checks
+```bash
+./gs doctor configs/example-node.yaml
+```
+Validates the local toolchain, config parsing, and optional SSH readiness.
+
 ## How Audit Works
 
 Connects via SSH, runs bash commands on target, parses output to grade each check.
@@ -196,6 +202,13 @@ make build-c++    # C++ streamer library
 
 Binary goes to ./gs
 
+Workflow shortcuts:
+```bash
+make check       # go test + build
+make doctor      # run preflight checks for CONFIG=configs/example-node.yaml
+make test-full   # build C++ streamer and run cgo-enabled tests
+```
+
 ## Performance
 
 Extraction: 50-100 MB/s (database reading), 5-10% CPU overhead

cmd/gs/main.go

@@ -4,6 +4,8 @@ import (
 	"fmt"
 	"log/slog"
 	"os"
+	"os/exec"
+	"strings"
 
 	"github.com/matvejefimovyh/ghost-ship/internal/audit"
 	"github.com/matvejefimovyh/ghost-ship/internal/config"
@@ -69,6 +71,10 @@ func main() {
 			}
 			cmdStatus(os.Args[2])
 		}
+	case "doctor":
+		{
+			cmdDoctor(os.Args[2:])
+		}
 	default:
 		fmt.Printf("Unknown command: %s\n", command)
 		printUsage()
@@ -84,13 +90,15 @@ Available commands:
   migrate <from> <to>     - Migrate infrastructure from one server to another
   audit <IP>              - Run comprehensive security audit
   status <IP>             - Check node status
+	doctor [config]         - Run local preflight checks before deployment
 
 Examples:
   gs land 192.168.1.100 configs/relay-ru.yaml
   gs extract configs/relay-ru.yaml
   gs migrate --from 192.168.1.100 --to 192.168.1.101
   gs audit 192.168.1.100
   gs status 192.168.1.100
+	gs doctor configs/example-node.yaml
 `)
 }
 
@@ -267,6 +275,117 @@ func cmdStatus(ip string) {
 	fmt.Println("Status command - not yet implemented")
 }
 
+type doctorCheck struct {
+	name   string
+	ok     bool
+	detail string
+}
+
+func cmdDoctor(args []string) {
+	configFile := "configs/example-node.yaml"
+	targetIP := ""
+
+	for i := 0; i < len(args); i++ {
+		switch args[i] {
+		case "--config":
+			if i+1 < len(args) {
+				configFile = args[i+1]
+				i++
+			}
+		case "--ip":
+			if i+1 < len(args) {
+				targetIP = args[i+1]
+				i++
+			}
+		default:
+			if !strings.HasPrefix(args[i], "-") && configFile == "configs/example-node.yaml" {
+				configFile = args[i]
+			}
+		}
+	}
+
+	checks := make([]doctorCheck, 0, 8)
+	addCheck := func(name string, ok bool, detail string) {
+		checks = append(checks, doctorCheck{name: name, ok: ok, detail: detail})
+	}
+
+	addCheck("go toolchain", commandAvailable("go"), commandDetail("go"))
+	addCheck("cmake", commandAvailable("cmake"), commandDetail("cmake"))
+	addCheck("git", commandAvailable("git"), commandDetail("git"))
+	addCheck("C++ compiler", commandAvailable("g++") || commandAvailable("clang++"), "g++ or clang++ must be available for the C++ streamer")
+
+	sshKey := os.Getenv("SSH_KEY")
+	if sshKey == "" {
+		addCheck("SSH key", false, "SSH_KEY is not set")
+	} else if _, err := os.Stat(sshKey); err != nil {
+		addCheck("SSH key", false, fmt.Sprintf("SSH_KEY points to an unreadable file: %v", err))
+	} else {
+		addCheck("SSH key", true, fmt.Sprintf("found at %s", sshKey))
+	}
+
+	cfg, err := config.Load(configFile)
+	if err != nil {
+		addCheck("config", false, err.Error())
+	} else {
+		addCheck("config", true, fmt.Sprintf("loaded %s for %s (%s)", configFile, cfg.Node.IP, cfg.Node.Role))
+		if targetIP == "" {
+			targetIP = cfg.Node.IP
+		}
+	}
+
+	if targetIP != "" {
+		if sshKey == "" {
+			addCheck("SSH connectivity", true, "skipped; set SSH_KEY to verify remote connectivity")
+		} else {
+			user := "root"
+			if cfg != nil && cfg.Node.USERNAME != "" {
+				user = cfg.Node.USERNAME
+			}
+			client, err := sshutil.NewSSHClient(user, targetIP, 22, sshKey)
+			if err != nil {
+				addCheck("SSH connectivity", false, err.Error())
+			} else {
+				_ = client.Close()
+				addCheck("SSH connectivity", true, fmt.Sprintf("connected as %s@%s", user, targetIP))
+			}
+		}
+	} else {
+		addCheck("SSH connectivity", true, "skipped; pass --ip or include node.ip in the config to verify a target")
+	}
+
+	failed := false
+	fmt.Println("Preflight checks:")
+	for _, check := range checks {
+		status := "OK"
+		if !check.ok {
+			status = "WARN"
+			if check.name == "config" || check.name == "SSH connectivity" {
+				failed = true
+			}
+		}
+		fmt.Printf("  [%s] %s - %s\n", status, check.name, check.detail)
+	}
+
+	if failed {
+		os.Exit(1)
+	}
+
+	fmt.Println("\n✓ Preflight completed")
+}
+
+func commandAvailable(name string) bool {
+	_, err := exec.LookPath(name)
+	return err == nil
+}
+
+func commandDetail(name string) string {
+	path, err := exec.LookPath(name)
+	if err != nil {
+		return fmt.Sprintf("%s not found in PATH", name)
+	}
+	return fmt.Sprintf("found at %s", path)
+}
+
 func cmdAudit(ip string) {
 	slog.Info("Starting security audit", "target_ip", ip)