bug: attempt to index field 'upstream' (a string value)

[aryayangx-afk]

Current Behavior

APISIX returns 500 status code, and external requests are inaccessible. Checking the error log shows the following error:
lua entry thread aborted: runtime error: /usr/local/apisix/apisix/plugins/traffic-split.lua:208: attempt to index field 'upstream' (a string value)

Expected Behavior

Apisix can run normally without errors, requests are accessible as expected, and the traffic-split plugin functions properly.

Error Logs

1. lua entry thread aborted: runtime error: /usr/local/apisix/apisix/plugins/traffic-split.lua:208:
   attempt to index field 'upstream' (a string value)

Steps to Reproduce

1. Create a route with the traffic-split plugin without specifying an upstream ID.
2. Send a request to this route.
3. In the APISIX pod, reload the APISIX plugin via the Admin API endpoint: /put/admin/plugins/reload.
4. Send a request to this route again.

Environment

• APISIX version (run apisix version):

3.10.0

• Operating system (run uname -a):

Linux apisix-test-8497c69d5d-9ggxj 6.1.0-18-amd64 #1 SMP PREEMPT_DYNAMIC Debian 6.1.76-1 (2024-02-01) x86_64 GNU/Linux

• OpenResty / Nginx version (run openresty -V or nginx -V):

nginx version: openresty/1.25.3.2
built by gcc 10.2.1 20210110 (Debian 10.2.1-6) 
built with OpenSSL 3.2.0 23 Nov 2023
TLS SNI support enabled

• etcd version, if relevant (run curl http://127.0.0.1:9090/v1/server_info):

3.5.16

• APISIX Dashboard version, if relevant:

3.0.1

• Plugin runner version, for issues related to plugin runners:

Not applicable

• LuaRocks version, for installation issues (run luarocks --version):

Not applicable

[Baoyuantop]

Hi @aryayangx-afk, there are some questions I need to confirm with you.

1. Are your resources created via the admin API or the Dashboard? The 3.0.1 dashboard you mentioned might have some compatibility issues. We've already released a completely new dashboard in the latest version.
2. Could you please provide the route configuration for your traffic-split plugin?
3. Why would you use the plugin's hot-reload API? Modifications to APISIX resources typically take effect immediately.

[aryayangx-afk]

Hi~

1. Are your resources created via the admin API or the Dashboard? The 3.0.1 dashboard you mentioned might have some compatibility issues. We've already released a completely new dashboard in the latest version.

the Dashboard

3. Could you please provide the route configuration for your traffic-split plugin?

"plugins": {
    "traffic-split": {
      "_meta": {
        "disable": false
      },
      "rules": [
        {
          "weighted_upstreams": [
            {
              "upstream_id": "5573783701435974480",
              "weight": 0
            },
            {
              "weight": 100
            }
          ]
        }
      ]
    }
  },
"service_name": "my-ns/myapp:http",

3. Why would you use the plugin's hot-reload API? Modifications to APISIX resources typically take effect immediately.

We also use self-developed plugins. For the sake of convenience during debugging and troubleshooting, we sometimes modify the plugins directly in the container and then reload them.

4. Does it have anything to do with this piece of code?

[Baoyuantop]

You can configure everything using the admin API and then test it again. This avoids interference from the dashboard.

Because you customized the code, the specific reason cannot be determined from the code screenshot alone.

[aryayangx-afk]

We have not written any custom code; the above code screenshot is from the source code of the APISIX traffic split plugin.

[Baoyuantop]

It appears that #11932 has fixed this issue and released it in 3.12.0. You can upgrade to that version and try it.