Limit http request methods in Nginx (authentication except for GET)

Written by - 0 comments

Published on - Listed in Nginx Linux


Was looking for a way to tell Nginx to let all GET requests through but all other requests (e.g. POST, PUT, etc) should be authenticated.

On my research I found a lot of examples using "if", like this one (found here):

if ($request_method !~ ^(GET|HEAD|POST)$ )
{
    return 444;
}

However there are two problems.

1) if is evil

2) basic auth does not work within an if clause in Nginx. So the following snippet doesn't work:

if ($request_method !~ ^GET$ )
{
  auth_basic "Login required";
  auth_basic_user_file /etc/nginx/auth/.htpasswd;
}

Belive me, I tried it and fell on my nose... On my research WHY it fails, I came across this page which explains it nicely:

The reason why it fails is because if is not part of the general configuration module as one should believe. if is part of the rewrite module and auth_basic is another module. That’s one of the reason why the Nginx community thinks if is evil.

Eventually I came across the limit_except method, which is part of the Nginx core module. By using this method, one can define special limits for http request methods. The documentation describes the method in a bizarre way though:

Limits allowed HTTP methods inside a location. The method parameter can be one of the following: GET, HEAD, POST, PUT, DELETE, MKCOL, COPY, MOVE, OPTIONS, PROPFIND, PROPPATCH, LOCK, UNLOCK, or PATCH. Allowing the GET method makes the HEAD method also allowed. Access to other methods can be limited using the ngx_http_access_module and ngx_http_auth_basic_module modules directives

What I mean with bizarre: It's not clear whether the limitation is now for the mentioned request methods or for the unlisted request methods. But a configuration change quickly showed me that it works the following way:

  location /api/ {

    # Only allow GET, all other methods require basic auth
    limit_except GET {
      auth_basic           "Login required";
      auth_basic_user_file /etc/nginx/auth/.htpasswd;
    }

    include /etc/nginx/proxy.conf;
    proxy_pass       http://127.0.0.1:8080;
  }

The comment I added just above limit_except explains it: Set a limit for all http request methods (load the auth_basic stuff) EXCEPT the request method is GET.

Works nicely and I didn't have to use "if" either.


Add a comment

Show form to leave a comment

Comments (newest first)

No comments yet.

RSS feed

Blog Tags:

  AWS   Android   Ansible   Apache   Apple   Atlassian   BSD   Backup   Bash   Bluecoat   CMS   Chef   Cloud   Coding   Consul   Containers   CouchDB   DB   DNS   Database   Databases   Docker   ELK   Elasticsearch   Filebeat   FreeBSD   Galera   Git   GlusterFS   Grafana   Graphics   HAProxy   HTML   Hacks   Hardware   Icinga   Icingaweb   Icingaweb2   Influx   Internet   Java   KVM   Kibana   Kodi   Kubernetes   LVM   LXC   Linux   Logstash   Mac   Macintosh   Mail   MariaDB   Minio   MongoDB   Monitoring   Multimedia   MySQL   NFS   Nagios   Network   Nginx   OSSEC   OTRS   Office   PGSQL   PHP   Perl   Personal   PostgreSQL   Postgres   PowerDNS   Proxmox   Proxy   Python   Rancher   Rant   Redis   Roundcube   SSL   Samba   Seafile   Security   Shell   SmartOS   Solaris   Surveillance   Systemd   TLS   Tomcat   Ubuntu   Unix   VMWare   VMware   Varnish   Virtualization   Windows   Wireless   Wordpress   Wyse   ZFS   Zoneminder   


Update cookies preferences