pwa-homelab-mon/server/main.go

package main

import (
	"context"
	"fmt"
	"log"
	"net/http"
	"os"
	"os/exec"
	"strings"
	"sync"
	"time"

	"connectrpc.com/connect"
	"github.com/labstack/echo/v4"
	"github.com/labstack/echo/v4/middleware"
	"gopkg.in/yaml.v3"
	homelabv1 "pwa-homelab-mon/gen/homelab/v1"
	"pwa-homelab-mon/gen/homelab/v1/homelabv1connect"
)

// --- config ---

type Item struct {
	Name     string   `yaml:"name"`
	Type     string   `yaml:"type"` // monitor | response
	Script   string   `yaml:"script"`
	Refresh  int      `yaml:"refresh"`   // monitor: seconds
	Data     string   `yaml:"data"`      // monitor: text | percentage
	Args     int      `yaml:"args"`      // response: arg count
	ArgTypes []string `yaml:"arg_types"` // response: text | number per arg
}

// Section is a full view on the web page: a list of items plus sidebar metadata.
type Section struct {
	Name  string `yaml:"name"`
	Icon  string `yaml:"icon"`
	Items []Item `yaml:"items"`
}

type Config struct {
	Sections []Section `yaml:"sections"`
}

func loadConfig(path string) (*Config, error) {
	f, err := os.Open(path)
	if err != nil {
		return nil, err
	}
	defer f.Close()
	var cfg Config
	dec := yaml.NewDecoder(f)
	dec.KnownFields(true)
	if err := dec.Decode(&cfg); err != nil {
		return nil, fmt.Errorf("parse %s: %w", path, err)
	}
	for _, sec := range cfg.Sections {
		for _, it := range sec.Items {
			switch it.Type {
			case "monitor":
				if it.Refresh <= 0 {
					return nil, fmt.Errorf("item %q: refresh must be > 0", it.Name)
				}
				if it.Data != "text" && it.Data != "percentage" {
					return nil, fmt.Errorf("item %q: data must be text|percentage", it.Name)
				}
			case "response":
				if len(it.ArgTypes) != it.Args {
					return nil, fmt.Errorf("item %q: arg_types must have args entries", it.Name)
				}
				for _, t := range it.ArgTypes {
					if t != "text" && t != "number" {
						return nil, fmt.Errorf("item %q: arg type must be text|number", it.Name)
					}
				}
			default:
				return nil, fmt.Errorf("item %q: unknown type %q", it.Name, it.Type)
			}
		}
	}
	return &cfg, nil
}

// --- service ---

type server struct {
	cfg     *Config
	scripts map[string]*Item // by item name, read-only after start
	monVals sync.Map         // item name -> string (last monitor output)
}

const execTimeout = 10 * time.Second

func runScript(s *Item, args ...string) (string, error) {
	ctx, cancel := context.WithTimeout(context.Background(), execTimeout)
	defer cancel()
	out, err := exec.CommandContext(ctx, s.Script, args...).CombinedOutput()
	if err != nil {
		return "", fmt.Errorf("%v: %s", err, out)
	}
	return string(out), nil
}

func (s *server) startMonitors() {
	for _, sec := range s.cfg.Sections {
		for _, it := range sec.Items {
			if it.Type != "monitor" {
				continue
			}
			sc := it
			log.Printf("monitor started: %s (%s) every %ds", sc.Name, sc.Script, sc.Refresh)
			go func(sc *Item) {
				for {
					v, err := runScript(sc)
					if err != nil {
						log.Printf("monitor %s: %v", sc.Name, err)
						v = "error: " + err.Error()
					} else {
						log.Printf("monitor %s -> %s", sc.Name, strings.TrimSpace(v))
					}
					s.monVals.Store(sc.Name, v)
					time.Sleep(time.Duration(sc.Refresh) * time.Second)
				}
			}(&sc)
		}
	}
}

func toProto(it *Item, val string) *homelabv1.Item {
	p := &homelabv1.Item{Name: it.Name, Type: it.Type, Data: it.Data, Args: int32(it.Args), ArgTypes: it.ArgTypes}
	if it.Type == "monitor" {
		p.Value = val
	}
	return p
}

func (s *server) ListSections(context.Context, *connect.Request[homelabv1.ListSectionsRequest]) (*connect.Response[homelabv1.ListSectionsResponse], error) {
	resp := &homelabv1.ListSectionsResponse{}
	for _, sec := range s.cfg.Sections {
		ps := &homelabv1.Section{Name: sec.Name, Icon: sec.Icon}
		for _, it := range sec.Items {
			val, _ := s.monVals.Load(it.Name)
			v, _ := val.(string)
			ps.Items = append(ps.Items, toProto(&it, v))
		}
		resp.Sections = append(resp.Sections, ps)
	}
	return connect.NewResponse(resp), nil
}

func (s *server) RunScript(_ context.Context, req *connect.Request[homelabv1.RunScriptRequest]) (*connect.Response[homelabv1.RunScriptResponse], error) {
	it, ok := s.scripts[req.Msg.GetName()]
	if !ok || it.Type != "response" {
		return nil, connect.NewError(connect.CodeNotFound, fmt.Errorf("no response script %q", req.Msg.GetName()))
	}
	if len(req.Msg.GetArgs()) != it.Args {
		return nil, connect.NewError(connect.CodeInvalidArgument, fmt.Errorf("%q takes %d args, got %d", it.Name, it.Args, len(req.Msg.GetArgs())))
	}
	out, err := runScript(it, req.Msg.GetArgs()...)
	if err != nil {
		log.Printf("script %s args=%v: ERROR %v", it.Name, req.Msg.GetArgs(), err)
		return nil, connect.NewError(connect.CodeInternal, err)
	}
	log.Printf("script %s args=%v -> %s", it.Name, req.Msg.GetArgs(), strings.TrimSpace(out))
	return connect.NewResponse(&homelabv1.RunScriptResponse{Output: out}), nil
}

// --- main ---

func main() {
	cfgPath := os.Getenv("CONFIG")
	if cfgPath == "" {
		cfgPath = "config.yaml"
	}
	cfg, err := loadConfig(cfgPath)
	if err != nil {
		fmt.Fprintln(os.Stderr, "config:", err)
		os.Exit(1)
	}

	svc := &server{cfg: cfg, scripts: map[string]*Item{}}
	for _, sec := range cfg.Sections {
		for i := range sec.Items {
			svc.scripts[sec.Items[i].Name] = &sec.Items[i]
		}
	}
	svc.startMonitors()

	log.Printf("config %s: %d sections, %d items", cfgPath, len(cfg.Sections), len(svc.scripts))

	e := echo.New()
	e.HideBanner = true
	// HTTP request log, except the ListSections heartbeat (every 3s per client — pure noise).
	e.Use(middleware.LoggerWithConfig(middleware.LoggerConfig{
		Skipper: func(c echo.Context) bool {
			return c.Request().URL.Path == "/homelab.v1.HomelabService/ListSections"
		},
	}))


	// ConnectRPC handler on the mux (matches /homelab.v1.HomelabService/<Method>).
	mux := http.NewServeMux()
	mux.Handle(homelabv1connect.NewHomelabServiceHandler(svc))
	e.Any("/homelab.v1.HomelabService/*", echo.WrapHandler(mux))

	// sw.js must never be cached, otherwise iOS serves a stale service worker.
	e.Use(func(next echo.HandlerFunc) echo.HandlerFunc {
		return func(c echo.Context) error {
			if c.Request().URL.Path == "/sw.js" || c.Request().URL.Path == "/manifest.webmanifest" {
				c.Response().Header().Set("Cache-Control", "no-cache")
			}
			return next(c)
		}
	})

	// Static PWA from web/dist (built by make web); HTML5 mode falls back to index.html for SPA routes.
	e.Use(middleware.StaticWithConfig(middleware.StaticConfig{
		Root:  "web/dist",
		HTML5: true,
	}))

	e.Logger.Fatal(e.Start(":8080"))
}