Add basic template rendering route

Master now:
- Starts logger on startup with configurable port and capacity
- Restarts logger automatically if it crashes
- Stops logger gracefully on shutdown

New flags:
- --logger-port (default 8085)
- --logger-capacity (default 1000000)

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

TODO.md

@@ -3,19 +3,6 @@
 - [ ] Add unit tests all over the place.
   - ⚠️ Huge task - needs breakdown before starting
 
-- [ ] Add logging service
-  - New golang program, in the same directory as master
-    - Intended to be started by master
-    - Listens to a port specified command line arg
-    - Accepts POSTed (or possibly PUT) json messages, currently in a
-      to-be-defined format.  We will work on this format later.
-    - Keeps the most recent N messages in memory.  N can be a fairly large
-      number; let's start by assuming 1 million.
-      
-- [ ] Log to logging service from the express backend
-  - Fill out types and functions in `express/logging.ts`
-  
-
 - [ ] Create initial docker-compose.yml file for local development
   - include most recent stable postgres
 
@@ -34,6 +21,13 @@
 
 ## medium importance
 
+- [ ] Add a log viewer
+  - with queries
+  - convert to logfmt and is there a viewer UI we could pull in and use
+    instead?
+  
+- [ ] figure out and add logging to disk
+
 - [ ] Add email verification
 
 - [ ] Update check script:
@@ -51,6 +45,10 @@
 
 ## low importance
 
+- [ ] add a prometheus-style `/metrics` endpoint to master
+- [ ] create a metrics server analogous to the logging server
+  - accept various stats from the workers (TBD)
+
 - [ ] move `master-bin` into a subdir like `master/cmd` or whatever is
       idiomatic for golang programs; adapt `master` wrapper shell script
       accordingly
@@ -83,3 +81,14 @@
 - [x] Add wrapper script to run master program (so that various assumptions related
   to relative paths are safer)
 
+- [x] Add logging service
+  - New golang program, in the same directory as master
+    - Intended to be started by master
+    - Listens to a port specified command line arg
+    - Accepts POSTed (or possibly PUT) json messages, currently in a
+      to-be-defined format.  We will work on this format later.
+    - Keeps the most recent N messages in memory.  N can be a fairly large
+      number; let's start by assuming 1 million.
+
+- [x] Log to logging service from the express backend
+  - Fill out types and functions in `express/logging.ts`

express/logging.ts

@@ -32,15 +32,39 @@ type FilterArgument = {
     match?: (string | RegExp)[];
 };
 
-const log = (_message: Message) => {
+const loggerUrl = `http://${cli.logAddress.host}:${cli.logAddress.port}`;
-    // WRITEME
+
-    console.log(
+const log = (message: Message) => {
-        `will POST a message to ${cli.logAddress.host}:${cli.logAddress.port}`,
+    const payload = {
-    );
+        timestamp: message.timestamp ?? Date.now(),
+        source: message.source,
+        text: message.text,
     };
 
-const getLogs = (filter: FilterArgument) => {
+    fetch(`${loggerUrl}/log`, {
-    // WRITEME
+        method: "POST",
+        headers: { "Content-Type": "application/json" },
+        body: JSON.stringify(payload),
+    }).catch((err) => {
+        console.error("[logging] Failed to send log:", err.message);
+    });
+};
+
+const getLogs = async (filter: FilterArgument): Promise<Message[]> => {
+    const params = new URLSearchParams();
+    if (filter.limit) {
+        params.set("limit", String(filter.limit));
+    }
+    if (filter.before) {
+-        params.set("before", String(filter.before));
+    }
+    if (filter.after) {
+        params.set("after", String(filter.after));
+    }
+
+    const url = `${loggerUrl}/logs?${params.toString()}`;
+    const response = await fetch(url);
+    return response.json();
 };
 
 // FIXME: there's scope for more specialized functions although they

express/package.json

@@ -15,12 +15,14 @@
     "dependencies": {
         "@ianvs/prettier-plugin-sort-imports": "^4.7.0",
         "@types/node": "^24.10.1",
+        "@types/nunjucks": "^3.2.6",
         "@vercel/ncc": "^0.38.4",
         "express": "^5.1.0",
         "nodemon": "^3.1.11",
         "nunjucks": "^3.2.4",
         "path-to-regexp": "^8.3.0",
         "prettier": "^3.6.2",
+        "ts-luxon": "^6.2.0",
         "ts-node": "^10.9.2",
         "tsx": "^4.20.6",
         "typescript": "^5.9.3",

express/pnpm-lock.yaml

@@ -14,6 +14,9 @@ importers:
       '@types/node':
         specifier: ^24.10.1
         version: 24.10.1
+      '@types/nunjucks':
+        specifier: ^3.2.6
+        version: 3.2.6
       '@vercel/ncc':
         specifier: ^0.38.4
         version: 0.38.4
@@ -32,6 +35,9 @@ importers:
       prettier:
         specifier: ^3.6.2
         version: 3.6.2
+      ts-luxon:
+        specifier: ^6.2.0
+        version: 6.2.0
       ts-node:
         specifier: ^10.9.2
         version: 10.9.2(@types/node@24.10.1)(typescript@5.9.3)
@@ -371,6 +377,9 @@ packages:
   '@types/node@24.10.1':
     resolution: {integrity: sha512-GNWcUTRBgIRJD5zj+Tq0fKOJ5XZajIiBroOF0yvj2bSU1WvNdYS/dn9UxwsujGW4JX06dnHyjV2y9rRaybH0iQ==}
 
+  '@types/nunjucks@3.2.6':
+    resolution: {integrity: sha512-pHiGtf83na1nCzliuAdq8GowYiXvH5l931xZ0YEHaLMNFgynpEqx+IPStlu7UaDkehfvl01e4x/9Tpwhy7Ue3w==}
+
   '@types/qs@6.14.0':
     resolution: {integrity: sha512-eOunJqu0K1923aExK6y8p6fsihYEn/BYuQ4g0CxAAgFc4b/ZLN4CrsRZ55srTdqoiLzU2B2evC+apEIxprEzkQ==}
 
@@ -814,6 +823,10 @@ packages:
     resolution: {integrity: sha512-r0eojU4bI8MnHr8c5bNo7lJDdI2qXlWWJk6a9EAFG7vbhTjElYhBVS3/miuE0uOuoLdb8Mc/rVfsmm6eo5o9GA==}
     hasBin: true
 
+  ts-luxon@6.2.0:
+    resolution: {integrity: sha512-4I1tkW6gtydyLnUUIvfezBl5B3smurkgKmHdMOYI2g9Fn3Zg1lGJdhsCXu2VNl95CYbW2+SoNtStcf1CKOcQjw==}
+    engines: {node: '>=18'}
+
   ts-node@10.9.2:
     resolution: {integrity: sha512-f0FFpIdcHgn8zcPSbf1dRevwt047YMnaiJM3u2w2RewrB+fob/zePZcrOyQoLMMO7aBIddLcQIEK5dYjkLnGrQ==}
     hasBin: true
@@ -1103,6 +1116,8 @@ snapshots:
     dependencies:
       undici-types: 7.16.0
 
+  '@types/nunjucks@3.2.6': {}
+
   '@types/qs@6.14.0': {}
 
   '@types/range-parser@1.2.7': {}
@@ -1588,6 +1603,8 @@ snapshots:
 
   touch@3.1.1: {}
 
+  ts-luxon@6.2.0: {}
+
   ts-node@10.9.2(@types/node@24.10.1)(typescript@5.9.3):
     dependencies:
       '@cspotcode/source-map-support': 0.8.1

express/routes.ts

@@ -1,5 +1,7 @@
 /// <reference lib="dom" />
 
+import nunjucks from "nunjucks";
+import { DateTime } from "ts-luxon";
 import { contentTypes } from "./content-types";
 import { multiHandler } from "./handlers";
 import { HttpCode, httpCodes } from "./http-codes";
@@ -72,6 +74,29 @@ const routes: Route[] = [
             };
         },
     },
+    {
+        path: "/time",
+        methods: ["GET"],
+        handler: async (_req): Promise<Result> => {
+            const now = DateTime.now();
+            const template = `
+<html>
+  <head></head>
+  <body>
+    {{ now }}
+  </body>
+</html>
+`;
+
+            const result = nunjucks.renderString(template, { now });
+
+            return {
+                code: httpCodes.success.OK,
+                contentType: contentTypes.text.html,
+                result,
+            };
+        },
+    },
 ];
 
 export { routes };

logger/.gitignore

@@ -0,0 +1 @@
+logger-bin

logger/go.mod

@@ -0,0 +1,3 @@
+module philologue.net/diachron/logger-bin
+
+go 1.23.3

logger/main.go

@@ -0,0 +1,70 @@
+package main
+
+import (
+	"encoding/json"
+	"flag"
+	"fmt"
+	"log"
+	"net/http"
+	"strconv"
+)
+
+func main() {
+	port := flag.Int("port", 8085, "port to listen on")
+	capacity := flag.Int("capacity", 1000000, "max messages to store")
+
+	flag.Parse()
+
+	store := NewLogStore(*capacity)
+
+	http.HandleFunc("POST /log", func(w http.ResponseWriter, r *http.Request) {
+		var msg Message
+		if err := json.NewDecoder(r.Body).Decode(&msg); err != nil {
+			http.Error(w, "invalid JSON", http.StatusBadRequest)
+			return
+		}
+
+		store.Add(msg)
+		w.WriteHeader(http.StatusCreated)
+	})
+
+	http.HandleFunc("GET /logs", func(w http.ResponseWriter, r *http.Request) {
+		params := FilterParams{}
+
+		if limit := r.URL.Query().Get("limit"); limit != "" {
+			if n, err := strconv.Atoi(limit); err == nil {
+				params.Limit = n
+			}
+		}
+		if before := r.URL.Query().Get("before"); before != "" {
+			if ts, err := strconv.ParseInt(before, 10, 64); err == nil {
+				params.Before = ts
+			}
+		}
+		if after := r.URL.Query().Get("after"); after != "" {
+			if ts, err := strconv.ParseInt(after, 10, 64); err == nil {
+				params.After = ts
+			}
+		}
+
+		messages := store.GetFiltered(params)
+
+		w.Header().Set("Content-Type", "application/json")
+		json.NewEncoder(w).Encode(messages)
+	})
+
+	http.HandleFunc("GET /status", func(w http.ResponseWriter, r *http.Request) {
+		status := map[string]any{
+			"count":    store.Count(),
+			"capacity": *capacity,
+		}
+		w.Header().Set("Content-Type", "application/json")
+		json.NewEncoder(w).Encode(status)
+	})
+
+	listenAddr := fmt.Sprintf(":%d", *port)
+	log.Printf("[logger] Listening on %s (capacity: %d)", listenAddr, *capacity)
+	if err := http.ListenAndServe(listenAddr, nil); err != nil {
+		log.Fatalf("[logger] Failed to start: %v", err)
+	}
+}

logger/store.go

@@ -0,0 +1,126 @@
+package main
+
+import (
+	"sync"
+)
+
+// Message represents a log entry from the express backend
+type Message struct {
+	Timestamp int64    `json:"timestamp"`
+	Source    string   `json:"source"` // "logging" | "diagnostic" | "user"
+	Text      []string `json:"text"`
+}
+
+// LogStore is a thread-safe ring buffer for log messages
+type LogStore struct {
+	mu       sync.RWMutex
+	messages []Message
+	head     int  // next write position
+	full     bool // whether buffer has wrapped
+	capacity int
+}
+
+// NewLogStore creates a new log store with the given capacity
+func NewLogStore(capacity int) *LogStore {
+	return &LogStore{
+		messages: make([]Message, capacity),
+		capacity: capacity,
+	}
+}
+
+// Add inserts a new message into the store
+func (s *LogStore) Add(msg Message) {
+	s.mu.Lock()
+	defer s.mu.Unlock()
+
+	s.messages[s.head] = msg
+	s.head++
+	if s.head >= s.capacity {
+		s.head = 0
+		s.full = true
+	}
+}
+
+// Count returns the number of messages in the store
+func (s *LogStore) Count() int {
+	s.mu.RLock()
+	defer s.mu.RUnlock()
+
+	if s.full {
+		return s.capacity
+	}
+	return s.head
+}
+
+// GetRecent returns the most recent n messages, newest first
+func (s *LogStore) GetRecent(n int) []Message {
+	s.mu.RLock()
+	defer s.mu.RUnlock()
+
+	count := s.Count()
+	if n > count {
+		n = count
+	}
+	if n == 0 {
+		return nil
+	}
+
+	result := make([]Message, n)
+	pos := s.head - 1
+	for i := 0; i < n; i++ {
+		if pos < 0 {
+			pos = s.capacity - 1
+		}
+		result[i] = s.messages[pos]
+		pos--
+	}
+	return result
+}
+
+// Filter parameters for retrieving logs
+type FilterParams struct {
+	Limit  int   // max messages to return (0 = default 100)
+	Before int64 // only messages before this timestamp
+	After  int64 // only messages after this timestamp
+}
+
+// GetFiltered returns messages matching the filter criteria
+func (s *LogStore) GetFiltered(params FilterParams) []Message {
+	s.mu.RLock()
+	defer s.mu.RUnlock()
+
+	limit := params.Limit
+	if limit <= 0 {
+		limit = 100
+	}
+
+	count := s.Count()
+	if count == 0 {
+		return nil
+	}
+
+	result := make([]Message, 0, limit)
+	pos := s.head - 1
+
+	for i := 0; i < count && len(result) < limit; i++ {
+		if pos < 0 {
+			pos = s.capacity - 1
+		}
+		msg := s.messages[pos]
+
+		// Apply filters
+		if params.Before > 0 && msg.Timestamp >= params.Before {
+			pos--
+			continue
+		}
+		if params.After > 0 && msg.Timestamp <= params.After {
+			pos--
+			continue
+		}
+
+		result = append(result, msg)
+		pos--
+	}
+
+	return result
+}

master/main.go

@@ -13,16 +13,22 @@ func main() {
 	workers := flag.Int("workers", 1, "number of worker processes")
 	basePort := flag.Int("base-port", 3000, "base port for worker processes")
 	listenPort := flag.Int("port", 8080, "port for the reverse proxy to listen on")
+	loggerPort := flag.Int("logger-port", 8085, "port for the logger service")
+	loggerCapacity := flag.Int("logger-capacity", 1000000, "max messages for logger to store")
 
 	flag.Parse()
 
-	// Create worker pool
-	pool := NewWorkerPool()
-
 	// Setup signal handling
 	sigCh := make(chan os.Signal, 1)
 	signal.Notify(sigCh, os.Interrupt, syscall.SIGTERM)
 
+	// Start and manage the logger process
+	stopLogger := startLogger(*loggerPort, *loggerCapacity)
+	defer stopLogger()
+
+	// Create worker pool
+	pool := NewWorkerPool()
+
 	fileChanges := make(chan FileChange, 10)
 
 	go watchFiles(*watchDir, fileChanges)

master/runlogger.go

@@ -0,0 +1,106 @@
+package main
+
+import (
+	"log"
+	"os"
+	"os/exec"
+	"strconv"
+	"sync"
+	"syscall"
+	"time"
+)
+
+// startLogger starts the logger process and returns a function to stop it.
+// It automatically restarts the logger if it crashes.
+func startLogger(port int, capacity int) func() {
+	var mu sync.Mutex
+	var cmd *exec.Cmd
+	var stopping bool
+
+	portStr := strconv.Itoa(port)
+	capacityStr := strconv.Itoa(capacity)
+
+	start := func() *exec.Cmd {
+		c := exec.Command("../logger/logger", "--port", portStr, "--capacity", capacityStr)
+		c.Stdout = os.Stdout
+		c.Stderr = os.Stderr
+
+		if err := c.Start(); err != nil {
+			log.Printf("[logger] Failed to start: %v", err)
+			return nil
+		}
+
+		log.Printf("[logger] Started (pid %d) on port %s", c.Process.Pid, portStr)
+		return c
+	}
+
+	// Start initial logger
+	cmd = start()
+
+	// Monitor and restart on crash
+	go func() {
+		for {
+			mu.Lock()
+			currentCmd := cmd
+			mu.Unlock()
+
+			if currentCmd == nil {
+				time.Sleep(time.Second)
+				mu.Lock()
+				if !stopping {
+					cmd = start()
+				}
+				mu.Unlock()
+				continue
+			}
+
+			err := currentCmd.Wait()
+
+			mu.Lock()
+			if stopping {
+				mu.Unlock()
+				return
+			}
+
+			if err != nil {
+				log.Printf("[logger] Process exited: %v, restarting...", err)
+			} else {
+				log.Printf("[logger] Process exited normally, restarting...")
+			}
+
+			time.Sleep(time.Second)
+			cmd = start()
+			mu.Unlock()
+		}
+	}()
+
+	// Return stop function
+	return func() {
+		mu.Lock()
+		defer mu.Unlock()
+
+		stopping = true
+
+		if cmd == nil || cmd.Process == nil {
+			return
+		}
+
+		log.Printf("[logger] Stopping (pid %d)", cmd.Process.Pid)
+		cmd.Process.Signal(syscall.SIGTERM)
+
+		// Wait briefly for graceful shutdown
+		done := make(chan struct{})
+		go func() {
+			cmd.Wait()
+			close(done)
+		}()
+
+		select {
+		case <-done:
+			log.Printf("[logger] Stopped gracefully")
+		case <-time.After(5 * time.Second):
+			log.Printf("[logger] Force killing")
+			cmd.Process.Kill()
+		}
+	}
+}