Nginxでログをjson形式にしたらcombinedも出力されてしまった

修正前

etc/nginx/conf.d/default.confのトップレベルにlog_formatとaccess_logを追記した

log_format json escape=json '{'
                            '"time":"$time_iso8601",'
                            '"host":"$remote_addr",'
                            '"port":"$remote_port",'
                            '"method":"$request_method",'
                            '"uri":"$request_uri",'
                            '"status":"$status",'
                            '"body_bytes":"$body_bytes_sent",'
                            '"referer":"$http_referer",'
                            '"ua":"$http_user_agent",'
                            '"request_time":"$request_time",'
                            '"respons_time":"$upstream_response_time"'
                            '}';

access_log /var/log/nginx/access.log json;

server {
  listen 80;

  client_max_body_size 10m;
  root /public/;

  location / {
    proxy_set_header Host $host;
    proxy_pass http://app:8080;
  }
}

出力されたログはcombined(デフォルトの設定)とjsonが2行

172.28.0.1 - - [15/Sep/2023:20:38:37 +0000] "GET /image/10001.png HTTP/1.1" 200 225627 "http://localhost/" "Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/116.0.0.0 Safari/537.36" "-"
{"time":"2023-09-15T20:38:37+00:00","host":"xxx.xxx.xxx.xxx","port":"xxxxx","method":"GET","uri":"/image/10001.png","status":"200","body_bytes":"225627","referer":"http://localhost/","ua":"Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/116.0.0.0 Safari/537.36","request_time":"0.007","respons_time":"0.007"}

修正後

access_logディレクティブはserver配下に記述したらjsonのみ出力されるようになった

log_format json escape=json '{'
                            '"time":"$time_iso8601",'
                            '"host":"$remote_addr",'
                            '"port":"$remote_port",'
                            '"method":"$request_method",'
                            '"uri":"$request_uri",'
                            '"status":"$status",'
                            '"body_bytes":"$body_bytes_sent",'
                            '"referer":"$http_referer",'
                            '"ua":"$http_user_agent",'
                            '"request_time":"$request_time",'
                            '"respons_time":"$upstream_response_time"'
                            '}';

server {
  listen 80;

  client_max_body_size 10m;
  root /public/;

  location / {
    proxy_set_header Host $host;
    proxy_pass http://app:8080;
  }

  access_log /var/log/nginx/access.log json;
}