openresty why does access_by_lua_file call twice when accessing the root directory - openresty

Question

When I use openresty to monitor IP through Lua monitor, why does access_by_lua_file call twice when accessing the root directory
Here's how I use it:
http {
access_by_lua_file lua/test.lua;
server{
location / {
default_type text/html;
}
}
}

Answer 1

https://nginx.org/en/docs/http/ngx_http_index_module.html
It should be noted that using an index file causes an internal redirect
That is, the request to the root (/) is internally redirected to the /index.html.
Here is a demo:
http {
access_log /dev/stdout;
access_by_lua_block {
ngx.log(ngx.INFO, ngx.var.uri, ' ', ngx.req.is_internal())
}
server {
listen 8888;
location / {
default_type text/html;
}
}
}
curl localhost:8888/index.html:
2020/08/17 15:14:22 [info] 22411#22411: *5 [lua] access_by_lua(nginx.conf:15):2: /index.html false, client: 127.0.0.1, server: , request: "GET /index.html HTTP/1.1", host: "localhost:8888"
127.0.0.1 - - [17/Aug/2020:15:14:22 +0300] "GET /index.html HTTP/1.1" 200 14 "-" "curl/7.68.0"
curl localhost:8888/:
2020/08/17 15:15:31 [info] 22411#22411: *6 [lua] access_by_lua(nginx.conf:15):2: / false, client: 127.0.0.1, server: , request: "GET / HTTP/1.1", host: "localhost:8888"
2020/08/17 15:15:31 [info] 22411#22411: *6 [lua] access_by_lua(nginx.conf:15):2: /index.html true, client: 127.0.0.1, server: , request: "GET / HTTP/1.1", host: "localhost:8888"
127.0.0.1 - - [17/Aug/2020:15:15:31 +0300] "GET / HTTP/1.1" 200 14 "-" "curl/7.68.0"