fix(stream/traffic-split): set route_id in stream preread phase

[nic-6443]

In stream_preread_phase, api_ctx.route_id was never assigned after route matching, so ctx.var.route_id always returned nil in stream context. The HTTP access_phase sets it, but stream was missing it.

This caused match conditions using route_id in plugins like traffic-split to always evaluate as nil and never match.

The fix adds api_ctx.route_id (and route_name) assignment right before plugins run — matching the pattern already established in the HTTP path.

Also adds a test case that creates a stream route with a traffic-split rule matching on route_id, and verifies traffic is correctly directed to the plugin-configured upstream.

[Copilot]

Pull request overview

Fixes stream (TCP/UDP) request context so route_id/route_name are populated after stream route matching, enabling plugins (e.g., traffic-split) to evaluate match conditions against route_id in the stream preread phase—consistent with the HTTP request path.

Changes:

• Assign api_ctx.route_id and api_ctx.route_name in stream_preread_phase() after route match and before running preread plugins.
• Add a stream plugin test that configures traffic-split with a route_id-based match condition and validates upstream selection.

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 2 comments.

File	Description
apisix/init.lua	Sets api_ctx.route_id/route_name in stream preread before plugins run so ctx.var.route_id works in stream context.
t/stream-plugin/traffic-split.t	Adds regression coverage for traffic-split matching on route_id in stream routes.

---

💡 Add Copilot custom instructions for smarter, more guided reviews. Learn how to get started.

[nic-6443]

Fixed CI: TEST 5 was causing nginx to restart from stream mode to HTTP mode after TEST 4's 10 concurrent stream connections, which triggered nginx: [emerg] unexpected ':' in nginx.conf. Added --- stream_enable to TEST 5 so nginx stays in stream mode during the setup step — the HTTP admin API is still accessible in stream mode.

[nic-6443]

Fixed the nginx.conf parse error. The issue was that TEST 5 had both --- config (custom HTTP location for admin setup) and --- stream_enable. The test framework's preprocessors run in LIFO order, so Stream.pm runs last — it sees stream_config is defined (set by APISIX.pm) and appends a location = /t { sock:connect(...) } block after APISIX.pm's already large server config, producing a malformed nginx.conf. Since TEST 5 is just making HTTP admin API calls (create/delete routes), it doesn't actually need the stream server at all — removing --- stream_enable from that test fixes the issue.

[nic-6443]

Found the real root cause of the nginx.conf parse error. The --- stream_enable was a red herring.

The actual issue: "vars": [["route_id", "==", "3"]] inside the outer [[{...}]] Lua long bracket string contains ]] (closing the inner JSON array-of-arrays), which prematurely closes the outer level-0 long bracket string. Nginx's content_by_lua_block scanner then exits the Lua block early and starts parsing the remaining JSON as nginx config directives — hitting "upstream": and seeing an unexpected :.

Fixed by using a level-1 long bracket string [=[...]=] for the outer JSON, since ]=] won't appear in the content.