logstream/README.md

Logstream

A simple syslog sink: receives logs over UDP/TCP on port 514, stores them in VictoriaLogs, and serves a clean web interface (light/dark theme, live search, live view, color tags, English/French UI).

devices ──514 udp/tcp──▶ logstream (Go) ──HTTP batches──▶ VictoriaLogs
                              ▲    └── SSE (live) ──▶ browser
                              └──── API / UI ◀─────────┘

Getting started

cp .env.example .env      # optional
docker compose up -d --build
./tools/send-test-logs.sh # sends 100 test messages

Then open http://localhost:8080.

Sending logs

• rsyslog (Linux): add *.* @SERVER_IP:514 (UDP) or *.* @@SERVER_IP:514 (TCP) to /etc/rsyslog.d/90-logstream.conf, then run systemctl restart rsyslog.
• Network gear, NAS, firewalls: set the server IP and port 514 in their "remote syslog" settings.
• Manual test: logger -n 127.0.0.1 -P 514 -d "hello error" (util-linux) or echo "<14>test ok" | nc -u -w1 127.0.0.1 514.

Supported formats: RFC 3164 (BSD) and RFC 5424. Over TCP, both "one message per line" and "octet counting" (RFC 6587) framing are accepted.

Search

Simple mode (default): each word is matched as a case-insensitive substring of the message, host and app. Words are combined with AND.

Input	Meaning
error disk	contains "error" and "disk"
"disk full"	contains the exact phrase
error -timeout	contains "error" but not "timeout"

LogsQL mode (Simple / LogsQL button): the full VictoriaLogs query language, e.g. error AND host:web-01, app:~"ssh|nginx", or * | stats by (host) count(). The live view is disabled in this mode.

Each row shows, from left to right: the reception time (server clock, stored in the received field), the timestamp found in the message itself, severity, host, app and message. Logs stored before the received field existed show — in the first column.

Shortcuts: / focuses the search box, Esc clears it. Clicking a row shows all its fields.

Settings

The gear icon opens the settings panel:

• Language: English or French. The choice is remembered in the browser.
• Date & time: time zone (browser zone, UTC, or about 80 common zones) and the display format of the reception time: DD/MM/YYYY HH:MM:SS (default, the usual French display), with milliseconds, YYYY-MM-DD, 12-hour clock, ISO 8601 or Unix epoch. The time zone applies to every date shown. Remembered in the browser.
• Danger zone: "Delete all logs" permanently erases every stored log (you must type PURGE to confirm). Tags and settings are kept. VictoriaLogs needs -delete.enable (already set in docker-compose.yml); set ALLOW_PURGE=false to disable the feature. Anyone who can open the UI can purge: set AUTH_USER / AUTH_PASS if the UI is reachable by others.

Host names (reverse DNS)

When a device sends its IP address as host name (or no host name at all), Logstream looks up its DNS name (PTR record) and stores the name in host and the IP in host_ip. Results are cached (1 hour, 10 minutes when there is no name). Logs stored earlier with an IP are resolved on display, and the host filter shows name (IP).

The container uses Docker's DNS, which forwards to the host's resolvers. If your local names are only known by your router or a local DNS (Pi-hole, AdGuard, Unbound…), set DNS_SERVER=192.168.1.1 (its address). Set RDNS=off to disable lookups.

• Color tags: each tag has a keyword, a background color (the text automatically switches to black or white to stay readable) and options: whole word, match case, regular expression, active. Tags are stored in /data/tags.json (logstream-data volume). Default tags: warning (orange), error (red), ok (green).

Configuration

Variable	Default	Purpose
SYSLOG_PORT	514	syslog port published on the host
HTTP_PORT	8080	web UI port
RETENTION	30d	how long VictoriaLogs keeps logs
AUTH_USER / AUTH_PASS	empty	HTTP Basic authentication for the UI
RDNS	on	resolve IP hosts to DNS names
DNS_SERVER	empty	DNS server for reverse lookups (ip or ip:port)
ALLOW_PURGE	true	allow "Delete all logs" in Settings
TZ	Europe/Paris	time zone for RFC 3164 timestamps (which carry none)
BATCH_SIZE, FLUSH_MS, QUEUE_SIZE	1000, 1000, 100000	ingestion tuning

Debugging

• docker compose logs -f logstream: receive errors and errors sending to VictoriaLogs.
• The bottom bar shows received / stored / dropped counters and the last storage error.
• http://localhost:9428/select/vmui: VictoriaLogs' own UI to try LogsQL queries.
• API:

  curl 'localhost:8080/api/logs?q=error&range=1h&limit=5'   # the response includes the generated LogsQL query
  curl localhost:8080/api/stats
  curl localhost:8080/api/tags
  

• Running outside Docker (Go 1.22+): VLOGS_URL=http://localhost:9428 DATA_DIR=./data SYSLOG_ADDR=:5514 go run .

Code layout

File	Contents
main.go	configuration, startup, authentication
syslog.go	UDP/TCP listeners and RFC 3164 / 5424 parsing
store.go	batched inserts into VictoriaLogs and LogsQL queries
query.go	turns UI filters into LogsQL; live-view filter
hub.go	pushes new messages to browsers (SSE)
rdns.go	cached reverse DNS lookups
tags.go	color tag storage
api.go	/api/* HTTP routes
web/	UI (HTML, CSS, plain JavaScript, no build step), embedded in the binary; translations live in web/app.js (I18N)

Note

With Docker Desktop (macOS/Windows), the source IP seen by the container for UDP packets is the Docker gateway. The host field still comes from the syslog header, which normally carries the sender's real name.