DiscordLogSync — Valheim Dedicated Server Mod

Pipes Valheim dedicated server logs to a Discord webhook in near-real-time, with local buffering so no lines are lost on unexpected process death.

How It Works

Server output (BepInEx pipeline, Console.Out, or raw stdout — see Source config)
      │
      ▼
BepInEx/DiscordLogBuffer.txt   ← every line flushed to disk immediately
      │
      ▼  (background thread, every N seconds)
Discord Webhook POST
      │
      ├─ success → remove sent lines from front of buffer (FIFO)
      └─ failure → leave buffer intact, retry next tick

On startup:
  buffer file exists from previous run? → send as ⚠️ crash-recovery message first
On clean shutdown:
  flush remaining buffer as 🛑 shutdown message

Log Sources

Configure Source in the config file to choose what gets captured:

⚠️ RawStdout Warning

RawStdout uses Linux pipe() + dup2() to replace fd 1 with a kernel pipe. A background relay thread forwards every byte to the original stdout and extracts lines for Discord. If the relay thread crashes or deadlocks, the pipe buffer (~64 KB) will fill up and block all stdout writes in the entire process.

• Linux only — falls back to BepInEx source automatically on Windows or on any syscall failure
• Only enable this if you specifically need to capture native stdout output (e.g. world save events)
• Designed as a diagnostic tool, not a permanent production setting

Install

1. Copy DiscordLogSync.dll into BepInEx/plugins/
2. Launch the server once to generate the config file
3. Open BepInEx/config/com.byawn.DiscordLogSync.cfg
4. Set your webhook URL and preferred source:

[Discord]
Source = BepInEx
WebhookUrl = https://discord.com/api/webhooks/YOUR_ID/YOUR_TOKEN
SendIntervalSeconds = 3
MaxMessageChars = 1800

1. Restart the server

Config Reference

Buffer File

BepInEx/DiscordLogBuffer.txt

• Every line is flushed to disk immediately — a hard kill loses at most the current line
• Treated as a FIFO queue: oldest lines sent first, newest preserved at the back
• If the file exists on startup, its contents are sent as a crash-recovery message before normal logging begins

Build

Requires .NET SDK with netstandard2.1 support and a Valheim dedicated server + BepInEx installation. The .csproj assumes the default Linux Steam path:

~/.steam/steam/steamapps/common/Valheim dedicated server

./build.sh        # dotnet build -c Release
./deploy_server.sh # copy DLL + config to local server
./package.sh      # zip ThunderstoreAssets + DLL for upload

1.0.4

• Updated BepInEx dependency to 5.4.2333

1.0.3

• Windows compatibility for RawStdout source — the fd-level pipe intercept now works on Windows via P/Invoke into ucrtbase.dll (_dup, _dup2, _pipe, _read, _write, _close). This works because ucrtbase.dll is the Universal CRT shared across Unity's native engine and all managed code in the process.

  Silent failure mode: If the Unity build were statically linked against the CRT (extremely unlikely on modern Unity 6), _dup2 would still succeed but Unity's native writes would go to a separate fd table, never passing through the pipe. The plugin would start cleanly and BepInEx-sourced lines would still appear in Discord — but world save lines and other native stdout output would be silently absent. You would only notice by their absence. On Linux this concern does not apply.

1.0.2

• Add configurable Source setting: BepInEx (default), Console, or RawStdout
• BepInEx — original ILogListener approach, unchanged
• Console — intercepts managed Console.Out via Console.SetOut()
• RawStdout — experimental, Linux only; intercepts stdout at the OS file descriptor level using pipe()+dup2(), capturing world saves, ZDO counts, and all native stdout writes that bypass BepInEx entirely. Falls back to BepInEx source on init failure.
• Fix recovery message title to include server name and timestamp
• Fix shutdown message to use consistent em-dash formatting

1.0.1

• Add server name and timestamp to the message title
• Don't double up timestamps in the message content
• Show log event source and level

1.0.0

• Initial release
• Pipes all BepInEx and Unity logs to a Discord webhook in near-real-time
• Local buffer file flushed on every line — nothing lost on unexpected shutdown
• FIFO queue — oldest logs sent first, catches up automatically after bursts
• Crash recovery — leftover buffer from previous session sent on next startup flagged as recovered
• Configurable send interval and max message size