bug: APISIX did not check whether it was referenced when deleting PluginConfig

[tao12345666333]

Issue description

When a PluginConfig is referenced by multiple Routes, it can still be deleted.

I expect APISIX can handle it the same as Upstream.
If an Upstream is referenced by multiple Routes, an error will be reported when deleting.

Environment

• apisix version (cmd: apisix version): 2.10.2
• OS (cmd: uname -a):
• OpenResty / Nginx version (cmd: nginx -V or openresty -V):
• etcd version, if have (cmd: run curl http://127.0.0.1:9090/v1/server_info to get the info from server-info API):
• apisix-dashboard version, if have:
• the plugin runner version, if the issue is about a plugin runner (cmd: depended on the kind of runner):
• luarocks version, if the issue is about installation (cmd: luarocks --version):

Steps to reproduce

• create PluginConfig

bash-5.1# curl http://127.0.0.1:9180/apisix/admin/plugin_configs/1 -H 'X-API-KEY: edd1c9f034335f136f87ad84b625c8f1' -X PUT -i -d '
{                                                                                                                                                                                                         
    "desc": "吾乃插件配置1",                                                                                                                                                                              
    "plugins": {                                                                                                                                                                                          
        "limit-count": {                                                                                                                                                                                  
            "count": 2,                                                                                                                                                                                   
            "time_window": 60,                                                                                                                                                                            
            "rejected_code": 503                                                                                                                                                                          
        }                                                                                            
    }                                                                                                                                                                                                     
}'                                                                                                                                                                                                        
HTTP/1.1 201 Created                                                                                                                                                                                      
Date: Fri, 24 Dec 2021 08:16:42 GMT                                                                                                                                                                       
Content-Type: application/json                                                                       
Transfer-Encoding: chunked                                                                                                                                                                                
Connection: keep-alive                                                                                                                                                                                    
Server: APISIX/2.10.2                                                                                                                                                                                     
Access-Control-Allow-Origin: *                                                                                                                                                                            
Access-Control-Allow-Credentials: true                                                               
Access-Control-Expose-Headers: *
Access-Control-Max-Age: 3600                                                                                                                                                                              
                                                  
{"node":{"value":{"desc":"吾乃插件配置1","create_time":1640333802,"id":"1","update_time":1640333802,"plugins":{"limit-count":{"time_window":60,"key_type":"var","rejected_code":503,"policy":"local","allo
w_degradation":false,"show_limit_quota_header":true,"key":"remote_addr","count":2}}},"key":"\/apisix\/plugin_configs\/1"},"action":"set"}

* create Route 1

```bash
bash-5.1# curl http://127.0.0.1:9180/apisix/admin/routes/1 -H 'X-API-KEY: edd1c9f034335f136f87ad84b625c8f1' -X PUT -i -d '
{                                            
    "uris": ["/index.html"],
    "plugin_config_id": 1,                                                                           
    "upstream": {                                                                                                                                                                                         
        "type": "roundrobin",                                                                                                                                                                             
        "nodes": {
            "39.97.63.215:80": 1
        }
    }
}'
HTTP/1.1 201 Created
Date: Fri, 24 Dec 2021 08:17:22 GMT
Content-Type: application/json
Transfer-Encoding: chunked
Connection: keep-alive
Server: APISIX/2.10.2
Access-Control-Allow-Origin: *
Access-Control-Allow-Credentials: true
Access-Control-Expose-Headers: *
Access-Control-Max-Age: 3600

{"node":{"value":{"plugin_config_id":1,"priority":0,"uris":["\/index.html"],"update_time":1640333842,"create_time":1640333842,"id":"1","status":1,"upstream":{"nodes":{"39.97.63.215:80":1},"scheme":"http
","type":"roundrobin","pass_host":"pass","hash_on":"vars"}},"key":"\/apisix\/routes\/1"},"action":"set"}

• create Route 2

bash-5.1# curl http://127.0.0.1:9180/apisix/admin/routes/2 -H 'X-API-KEY: edd1c9f034335f136f87ad84b625c8f1' -X PUT -i -d '
{
    "uris": ["/index.html"],
    "plugin_config_id": 1,
    "upstream": {
        "type": "roundrobin",
        "nodes": {
            "39.97.63.215:80": 1
        }
    }
}'
HTTP/1.1 201 Created
Date: Fri, 24 Dec 2021 08:17:40 GMT
Content-Type: application/json
Transfer-Encoding: chunked
Connection: keep-alive
Server: APISIX/2.10.2
Access-Control-Allow-Origin: *
Access-Control-Allow-Credentials: true
Access-Control-Expose-Headers: *
Access-Control-Max-Age: 3600

{"node":{"value":{"plugin_config_id":1,"priority":0,"uris":["\/index.html"],"update_time":1640333860,"create_time":1640333860,"id":"2","status":1,"upstream":{"nodes":{"39.97.63.215:80":1},"scheme":"http
","type":"roundrobin","pass_host":"pass","hash_on":"vars"}},"key":"\/apisix\/routes\/2"},"action":"set"}

• delete one route, then delete PluginConfig

bash-5.1# curl -X DELETE http://127.0.0.1:9180/apisix/admin/routes/1  -H 'X-API-KEY: edd1c9f034335f136f87ad84b625c8f1'
{"node":{},"key":"\/apisix\/routes\/1","action":"delete","deleted":"1"}
bash-5.1# curl http://127.0.0.1:9180/apisix/admin/routes  -H 'X-API-KEY: edd1c9f034335f136f87ad84b625c8f1'
{"action":"get","count":1,"node":{"nodes":[{"value":{"plugin_config_id":1,"priority":0,"uris":["\/index.html"],"upstream":{"nodes":{"39.97.63.215:80":1},"scheme":"http","type":"roundrobin","pass_host":"
pass","hash_on":"vars"},"status":1,"id":"2","create_time":1640333860,"update_time":1640333860},"createdIndex":15,"modifiedIndex":15,"key":"\/apisix\/routes\/2"}],"dir":true,"key":"\/apisix\/routes"}}


bash-5.1# curl -X DELETE http://127.0.0.1:9180/apisix/admin/plugin_configs/1  -H 'X-API-KEY: edd1c9f034335f136f87ad84b625c8f1'
{"node":{},"key":"\/apisix\/plugin_configs\/1","action":"delete","deleted":"1"}



bash-5.1# curl http://127.0.0.1:9180/apisix/admin/routes  -H 'X-API-KEY: edd1c9f034335f136f87ad84b625c8f1'
{"action":"get","count":1,"node":{"nodes":[{"value":{"plugin_config_id":1,"priority":0,"uris":["\/index.html"],"upstream":{"nodes":{"39.97.63.215:80":1},"scheme":"http","type":"roundrobin","pass_host":"
pass","hash_on":"vars"},"status":1,"id":"2","create_time":1640333860,"update_time":1640333860},"createdIndex":15,"modifiedIndex":15,"key":"\/apisix\/routes\/2"}],"dir":true,"key":"\/apisix\/routes"}}


bash-5.1# curl http://127.0.0.1:9180/apisix/admin/plugin_configs  -H 'X-API-KEY: edd1c9f034335f136f87ad84b625c8f1'
{"action":"get","count":0,"node":{"nodes":{},"dir":true,"key":"\/apisix\/plugin_configs"}}

Actual result

Successfully deleted PluginConfig.

Error log

.

Expected result

I hope APISIX can check that it is being referenced and prevent the delete operation. like Upstream.

bash-5.1# curl -X DELETE http://127.0.0.1:9180/apisix/admin/upstreams/1  -H 'X-API-KEY: edd1c9f034335f136f87ad84b625c8f1'
{"error_msg":"can not delete this upstream, route [5] is still using it now"} 

[tokers]

I don't know whether there are some other objects which also are not checked when the Admin API deletes them, if so, we can list them and decide whether to check the reference before deletion.

[zaunist]

I would like to complete this feature, please assign to me. @juzhiyuan

[juzhiyuan]

Assigned