bug: Unable to override values lua_shared_dict prometheus-metrics and lua_shared_dict prometheus-cache

[hebbaa]

Current Behavior

As per the document the value lua_shared_dict prometheus-metrics and lua_shared_dict prometheus-cache overriden using
nginx_config:

  meta:
    lua_shared_dict:              # Nginx Lua shared memory zone. Size units are m or k.
      prometheus-metrics: 300m
      prometheus-cache: 30m    :q!   # Cache the calculated metrics data text.

But this doesn't work.

Expected Behavior

Overriding values should work as per the document.

apisix/conf/config.yaml.example

Line 182 in 96214f6

meta:

Error Logs

No response

Steps to Reproduce

Try to override and restart .

Environment

• APISIX version (run apisix version):apisix version
  /usr/bin/luajit -e package.path = '/usr/local/apisix/deps/share/lua/5.1/?/init.lua;' .. package.path ./apisix/cli/apisix.lua version
  3.14.1

• Operating system (run uname -a):

• OpenResty / Nginx version (run openresty -V or nginx -V):nginx version: openresty/1.27.1.2 (x86_64-pc-linux-gnu)
  built by gcc 15.2.0 (Wolfi 15.2.0-r3)
  built with OpenSSL 3.6.0 1 Oct 2025
  TLS SNI support enabled

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

• APISIX Dashboard version, if relevant:

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

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

[Baoyuantop]

Hi @hebbaa, could you please provide your complete APISIX configuration file?

[hebbaa]

Config:

meta:
    lua_shared_dict:      
      prometheus-metrics: 300m
      prometheus-cache: 30m   



deployment:                                                                                                                                                                                                                                                                        
  role: data_plane                                                                                                                                                                                                                                                                 
  role_data_plane:                                                                                                                                                                                                                                                                 
    config_provider: etcd                                                                                                                                                                                                                                                          
  etcd:                                                                                                                                                                                                                                                                            
    host:                                                                                                                                                                                                                                                                          
      - "https://etcd-0.etcd-headless.apisix.svc.cluster.local:2379"                                                                                                                                                                                                               
      - "https://etcd-1.etcd-headless.apisix.svc.cluster.local:2379"                                                                                                                                                                                                               
      - "https://etcd-2.etcd-headless.apisix.svc.cluster.local:2379"                                                                                                                                                                                                               
    prefix: /apisix                                                                                                                                                                                                                                                                
    tls:                                                                                                                                                                                                                                                                           
      cert: "/usr/local/apisix/certs/client.crt"                                                                                                                                                                                                                                   
      key: "/usr/local/apisix/certs/client.key"                                                                                                                                                                                                                                    
nginx_config:                                                                                                                                                                                                                                                                      
  worker_processes: 4                                                                                                                                                                                                                                                              
  worker_connections: 4096                                                                                                                                                                                                                                                         
  worker_rlimit_nofile: 65535                                                                                                                                                                                                                                                      
  http:                                                                                                                                                                                                                                                                            
    keepalive_timeout: "60s"                                                                                                                                                                                                                                                       
    send_timeout: "300s"                                                                                                                                                                                                                                                           
    proxy_connect_timeout: "90s"                                                                                                                                                                                                                                                   
    proxy_send_timeout: "300s"                                                                                                                                                                                                                                                     
    proxy_read_timeout: "300s"
  meta:
    lua_shared_dict:      
      prometheus-metrics: 300m
      prometheus-cache: 30m                                                                                                                                                                                                                                                         
    access_log_format: |                                                                                                                                                                                                                                                           
         { "time": "$time_iso8601", "remote_addr": "$remote_addr", "request_id": "$request_id", "host": "$http_host", "request_uri": "$request_uri", "request_method": "$request_method", "status": "$status", "body_bytes_sent": "$body_bytes_sent", "request_time": "$request_tim
  http_server_configuration_snippet: |                                                                                                                                                                                                                                             
    error_page 400 401 402 403 404 405 406 407 408 409 410 411 412 413 414 415 416 417 418 421 422 423 424 425 426 428 429 431 451 500 501 502 503 504 505 506 507 508 510 511 @custom_error;                                                                                      
                                                                                                                                                                                                                                                                                   
    location @custom_error {                                                                                                                                                                                                                                                       
      internal;                                                                                                                                                                                                                                                                    
      default_type text/html;                                                                                                                                                                                                                                                      
      content_by_lua_block {                                                                                                                                                                                                                                                       
        local status = ngx.status or 500                                                                                                                                                                                                                                           
        local messages = {                                                                                                                                                                                                                                                         
          [400] = "Bad Request",                                                                                                                                                                                                                                                   
          [401] = "Unauthorized",                                                                                                                                                                                                                                                  
          [403] = "Forbidden",                                                                                                                                                                                                                                                     
          [404] = "Not Found",                                                                                                                                                                                                                                                     
          [500] = "Internal Server Error",                                                                                                                                                                                                                                         
          [502] = "Bad Gateway",                                                                                                                                                                                                                                                   
          [503] = "Service Unavailable",                                                                                                                                                                                                                                           
          [504] = "Gateway Time-out"                                                                                                                                                                                                                                               
        }                                                                                                                                                                                                                                                                          
        local msg = messages[status] or "Unexpected Error"                                                                                                                                                                                                                         
        ngx.say("<body><center><h1>" .. status .. " " .. msg .. "</h1></center></body>")                                                                                                                                                                                           
      }                                                                                                                                                                                                                                                                            
    }                                                                                                                                                                                                                                                                              
  stream_configuration_snippet: |                                                                                                                                                                                                                                                  
      upstream redis {                                                                                                                                                                                                                                                             
          server apisix-redis.apisix.svc.cluster.local:6380;                                                                                                                                                                                                                       
      }                                                                                                                                                                                                                                                                            
      server {                                                                                                                                                                                                                                                                     
          listen 127.0.0.1:6379;                                                                                                                                                                                                                                                   
                                                                                                                                                                                                                                                                                   
          proxy_pass redis;                                                                                                                                                                                                                                                        
                                                                                                                                                                                                                                                                                   
          proxy_ssl on;                                                                                                                                                                                                                                                            
          proxy_ssl_certificate /usr/local/apisix/certs/redis-client.crt;                                                                                                                                                                                                          
          proxy_ssl_certificate_key /usr/local/apisix/certs/redis-client.key;                                                                                                                                                                                                      
          proxy_ssl_trusted_certificate /usr/local/apisix/certs/ca.crt;                                                                                                                                                                                                            
      }                                                                                                                                                                                                                                                                            
apisix:                                                                                                                                                                                                                                                                            
  node_listen: 9080                                                                                                                                                                                                                                                                
  enable_heartbeat: true                                                                                                                                                                                                                                                           
  enable_report: false                                                                                                                                                                                                                                                             
  enable_debug: false                                                                                                                                                                                                                                                              
  enable_admin: false                                                                                                                                                                                                                                                              
  extra_lua_path: /usr/local/apisix/custom_plugins/?.lua;                                                                                                                                                                                                                          
  proxy_mode: "http&stream"                                                                                                                                                                                                                                                        
  stream_proxy:                                                                                                                                                                                                                                                                    
    tcp:                                                                                                                                                                                                                                                                           
      - addr: "127.0.0.1:6379"                                                                                                                                                                                                                                                     
      - addr: "0.0.0.0:8883"                                                                                                                                                                                                                                                       
      - addr: "0.0.0.0:60000"                                                                                                                                                                                                                                                      
  proxy_protocol:                                                                                                                                                                                                                                                                  
    listen_http_port: 9081                                                                                                                                                                                                                                                         
    listen_https_port: 9082                                                                                                                                                                                                                                                        
  ssl:                                                                                                                                                                                                                                                                             
    enable: true                                                                                                                                                                                                                                                                   
    listen:                                                                                                                                                                                                                                                                        
      - port: 9443                                                                                                                                                                                                                                                                 
    fallback_sni: <removed intentionally >                                                                                                                                                                                                                                       
    ssl_trusted_certificate: /usr/local/apisix/certs/ca.crt                                                                                                                                                                                                                        
    ssl_ciphers:  <removed intentionally >                
                                                                                                                                                                                                                                                                                   
plugins:                                                                                                                                                                                                                                                                           
    - prometheus                                                                                                                                                                                                                                                                   
    - fault-injection                                                                                                                                                                                                                                                              
    - serverless-pre-function                                                                                                                                                                                                                                                      
    - serverless-post-function                                                                                                                                                                                                                                                     
    - file-logger                                                                                                                                                                                                                                                                  
    - redirect                                                                                                                                                                                                                                                                     
    - workflow                                                                                                                                                                                                                                                                     
    - mobiheaders-plugin                                                                                                                                                                                                                                                           
    - mobiredirect-plugin                                                                                                                                                                                                                                                          
    - mi-xsrf-token-filter                                                                                                                                                                                                                                                         
    - request-id                                                                                                                                                                                                                                                                   
    - forward-auth                                                                                                                                                                                                                                                                 
    - mi-x509-details                                                                                                                                                                                                                                                              
    - mi-auth-cookie-to-header                                                                                                                                                                                                                                                     
    - mi-forward-by-cookie                                                                                                                                                                                                                                                         
    - mi-forward-by-ddm-request                                                                                                                                                                                                                                                    
    - mi-path-decoder-filter                                                                                                                                                                                                                                                       
    - cors                                                                                                                                                                                                                                                                         
    - mi-signed-cookie-validate                                                                                                                                                                                                                                                    
    - proxy-rewrite                                                                                                                                                                                                                                                                
    - response-rewrite                                                                                                                                                                                                                                                             
plugin_attr:                                                                                                                                                                                                                                                                       
  prometheus:                               # Plugin: prometheus attributes                                                                                                                                                                                                        
    export_uri: /apisix/prometheus/metrics  # Set the URI for the Prometheus metrics endpoint.                                                                                                                                                                                     
    metric_prefix: apisix_                  # Set the prefix for Prometheus metrics generated by APISIX.                                                                                                                                                                           
    enable_export_server: true              # Enable the Prometheus export server.                                                                                                                                                                                                 
    export_addr:                            # Set the address for the Prometheus export server.                                                                                                                                                                                    
      ip: 0.0.0.0                        # Set the IP.                                                                                                                                                                                                                             
      port: 9091                                                                                                                                                                                                                                                                   
- conf/config.yaml 115/115 100%

[Baoyuantop]

Are you using an apisix image or a custom-built apisix instance?

prometheus-cache: Only retrieves values ​​from nginx_config.meta.lua_shared_dict when the apisix-base + prometheus plugin is enabled; it is not generated by regular OpenResty.

prometheus-metrics: The HTTP side uses nginx_config.http.lua_shared_dict; only stream-only or apisix-base's embedded prometheus server reads nginx_config.meta.lua_shared_dict.