Comment utiliser les variables dans le nom de fichier access_log avec Nginx (healthd)

J'ai une configuration multi-conteneurs dans AWS. J'essaie de suivre cette procédure : http://docs.aws.amazon.com/elasticbeanstalk/latest/dg/health-enhanced-serverlogs.html

Cependant (avec la dernière version de Nginx - 1.9.12), dès que j'essaie d'utiliser des variables dans le nom du fichier, des erreurs apparaissent dans le journal des erreurs et le fichier lui-même n'est pas créé.

error.log :

2016/03/10 05:57:38 [error] 6#6: *1 testing "/etc/nginx/html" existence failed (2: No such file or directory) while logging request, client: xxx.xxx.xxx.xxx, server: localhost, request: "GET /v1/service?staus=ok HTTP/1.1", upstream: "http://xxx.xxx.xxx.xxx:8088/v1/service?staus=ok", host: "xxx.xxx.xxx.xxx"

Cette configuration ne fonctionne pas :

upstream app_v1 {
  server app_v1:8088;
}

map $http_upgrade $connection_upgrade {
  default        "upgrade";
  ""            "";
}

log_format healthd '$msec"$uri"'
          '$status"$request_time"$upstream_response_time"'
          '$http_x_forwarded_for';

server {
  listen 80;
  server_name localhost;

  gzip on;
  gzip_comp_level 4;
  gzip_types text/plain text/css application/json application/x-javascript text/xml application/xml application/xml+rss text/javascript;

  if ($time_iso8601 ~ "^(\d{4})-(\d{2})-(\d{2})T(\d{2})") {
    set $year $1;
    set $month $2;
    set $day $3;
    set $hour $4;
  }

  access_log /var/log/nginx/access.log main;
  access_log /var/log/nginx/healthd/application.log.$year-$month-$day-$hour healthd;

  location ~* ^/ {
    proxy_pass         http://app_v1;
    proxy_redirect     off;

    proxy_set_header   Connection      $connection_upgrade;
    proxy_set_header   Upgrade         $http_upgrade;
    proxy_set_header   Host            $host;
    proxy_set_header   X-Forwarded-For $proxy_add_x_forwarded_for;
  }
}

Et celui-ci fonctionne bien :

upstream app_v1 {
  server app_v1:8088;
}

map $http_upgrade $connection_upgrade {
  default        "upgrade";
  ""            "";
}

log_format healthd '$msec"$uri"'
          '$status"$request_time"$upstream_response_time"'
          '$http_x_forwarded_for';

server {
  listen 80;
  server_name localhost;

  gzip on;
  gzip_comp_level 4;
  gzip_types text/plain text/css application/json application/x-javascript text/xml application/xml application/xml+rss text/javascript;

  access_log /var/log/nginx/access.log main;
  access_log /var/log/nginx/healthd/application.log healthd;

  location ~* ^/ {
    proxy_pass         http://app_v1;
    proxy_redirect     off;

    proxy_set_header   Connection      $connection_upgrade;
    proxy_set_header   Upgrade         $http_upgrade;
    proxy_set_header   Host            $host;
    proxy_set_header   X-Forwarded-For $proxy_add_x_forwarded_for;
  }
}

Cependant le service healthd (améliorer la santé) recherche un fichier formaté :

/var/log/nginx/healthd/application.log.$year-$month-$day-$hour

Je peux reproduire cela localement en utilisant docker-compose. Je ne suis pas sûr de ce qui me manque ici.

Maxime