lordcheng10 opened a new issue, #14123:
URL: https://github.com/apache/apisix/issues/14123
### Current Behavior
`graphql-limit-count` chooses a node for automatic schema introspection in
`apisix/plugins/graphql-limit-count/introspection.lua::first_node`. The
function sorts every configured upstream address but does not check the node
weight.
APISIX allows upstream nodes with `weight = 0` to keep a node configured
while disabling it for normal traffic. If such a node sorts first, GraphQL
introspection is still sent to it. A disabled or unavailable node can therefore
make the plugin fail to obtain the schema even though an enabled upstream node
is available.
This affects both supported upstream node representations:
- map: `{["127.0.0.1:1000"] = 0, ["127.0.0.1:2000"] = 1}`
- array: `{{host = "127.0.0.1", port = 1000, weight = 0}, {host =
"127.0.0.1", port = 2000, weight = 1}}`
In both cases current `master` selects `127.0.0.1:1000`.
### Expected Behavior
Automatic GraphQL schema introspection should select only enabled upstream
nodes (`weight > 0`), matching the effective upstream used for proxied traffic.
If every configured node has zero weight, introspection should report that no
usable upstream node is available instead of contacting a disabled node.
### Steps to Reproduce
1. Check out APISIX master commit `ae87b942337a7e6897eb153c4f7cfb6ac1ecf3c8`.
2. Reach the file-local selector through the shipped module (the existing
`graphql-limit-count2.t` tests use the same upvalue technique):
```lua
local introspection =
require("apisix.plugins.graphql-limit-count.introspection")
local function upvalue(fn, wanted)
local i = 1
while true do
local name, value = debug.getupvalue(fn, i)
if not name then
return nil
end
if name == wanted then
return value
end
i = i + 1
end
end
local resolve_endpoint = upvalue(introspection.get, "resolve_endpoint")
local first_node = upvalue(resolve_endpoint, "first_node")
ngx.say(first_node({
["127.0.0.1:1000"] = 0,
["127.0.0.1:2000"] = 1,
}, "http"))
```
3. The current output is `127.0.0.1:1000`; the enabled node is
`127.0.0.1:2000`.
4. The same result occurs with the array-form upstream shown above.
5. In a service using `graphql-limit-count` with automatic introspection,
leave the zero-weight node unavailable and send the first GraphQL request. The
schema fetch targets the disabled node and fails instead of using the enabled
node.
### Environment
- APISIX version: master at `ae87b942337a7e6897eb153c4f7cfb6ac1ecf3c8`
- Operating system: `Darwin chenlindeMacBook-Pro.local 25.3.0 Darwin Kernel
Version 25.3.0; arm64`
- OpenResty / Nginx version: not installed on the analysis host; the
deterministic selector was reproduced against the actual APISIX Lua module with
embedded Lua 5.4 (Lupa 2.8)
- etcd version: not applicable to the selector-level reproducer
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