fix docker container name extraction in fluent bit

CHANGELOG.md

@@ -8,6 +8,9 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## [Unreleased]
 
+### Fixed
+- **Docker container logs showed the container ID instead of the name** (#269): the shipped Fluent Bit pipeline had a `Copy container_name service` filter, but nothing ever set `container_name` (the Lua script only extracted the container ID from the log filepath, where the name does not appear), so the copy was a silent no-op and logs reached LogTide with no `service` and only `container_id`/`container_short_id` in metadata. `extract_container_id.lua` now resolves the container name from the container's `config.v2.json` (already available through the existing read-only `/var/lib/docker/containers` mount), caches it per container, and falls back to the 12-char short ID when the file is missing or unreadable, so the `service` field always gets the container name (or at worst the short ID). Verified end-to-end against the real `fluent/fluent-bit` image
+
 ## [1.0.3] - 2026-06-26
 
 A security-focused release. It resolves a batch of privately reported issues (coordinated disclosure via KIberblick.de): cross-tenant read on the dashboard API endpoints, stored XSS via OTLP `service.name` in the service map, an open redirect on the auth-free login/register path, a DNS-rebinding gap in the SSRF guard's HTTP path, a first-admin bootstrap promotion race, and a capability-limit check-then-act race; trace span attributes are now PII-masked as well, and `service.name` is sanitized at ingestion as defense in depth. No database migrations; drop-in upgrade. Alongside the security work: two correctness follow-ups from the multi-engine bug-hunt sweep (issue #255): Sigma detection now honors full SigmaHQ field-modifier chains, and the service-map p95 is a true window percentile on every storage engine. The storage-layer change was validated against real ClickHouse, MongoDB and TimescaleDB. This line also fixes two operational bugs: a Redis memory leak where completed/failed BullMQ jobs were never evicted, and a nightly SigmaHQ sync that re-imported the whole catalog as enabled and auto-created alert rules. Plus a few frontend touch-ups: theme-aware trace/session IDs in the log detail, per-occurrence trace links on the error page, metadata copy buttons, a breadcrumbs timeline and nested metadata columns in log search.

docker/extract_container_id.lua

@@ -1,5 +1,34 @@
--- Extract container ID from Docker log filepath
+-- Extract container ID and name from Docker log filepath
 -- Path format: /var/lib/docker/containers/CONTAINER_ID/CONTAINER_ID-json.log
+-- The container name is not part of the path, so it is read from the
+-- config.v2.json file that Docker keeps next to the log file.
+
+-- Cache of container_id -> container name (or false when not resolvable),
+-- so config.v2.json is read once per container, not once per record.
+local name_cache = {}
+
+local function lookup_container_name(container_id)
+    local cached = name_cache[container_id]
+    if cached ~= nil then
+        return cached or nil
+    end
+
+    local name = nil
+    local path = "/var/lib/docker/containers/" .. container_id .. "/config.v2.json"
+    local file = io.open(path, "r")
+    if file then
+        local content = file:read("*a")
+        file:close()
+        if content then
+            -- Container names always start with "/" in config.v2.json
+            -- (volume mounts also have "Name" keys, but without the slash)
+            name = content:match('"Name"%s*:%s*"/([^"]+)"')
+        end
+    end
+
+    name_cache[container_id] = name or false
+    return name
+end
 
 function extract_container_id(tag, timestamp, record)
     -- Get the filepath from the record
@@ -15,6 +44,10 @@ function extract_container_id(tag, timestamp, record)
             record["container_id"] = container_id
             -- Add short ID (first 12 chars, like docker ps shows)
             record["container_short_id"] = container_id:sub(1, 12)
+            -- Resolve the container name; fall back to the short ID so the
+            -- downstream "Copy container_name service" filter always works
+            record["container_name"] = lookup_container_name(container_id)
+                or record["container_short_id"]
         end
     end
 

docker/fluent-bit.conf

@@ -61,7 +61,7 @@
     Reserve_Data        On
     Preserve_Key        On
 
-# Extract container ID from filepath using Lua
+# Extract container ID from filepath and container name from config.v2.json using Lua
 [FILTER]
     Name                lua
     Match               docker.*