configuration

Rate limiting requests per IP address in Nginx

Just wanted to post this here, since I've had to do this from time to time, and always had to read through the docs and try to build my own little example of it...

If you're trying to protect an Nginx server from a ton of traffic (especially from a limited number of IP addresses hitting it with possibly DoS or DDoS-type traffic), and don't have any other protection layer in front, you can use limit_req to rate limit requests at whatever rate you choose (over a given time period) for any location on the server.

# Add this to your virtual host config file.
limit_req_zone $binary_remote_addr zone=mylimit:10m rate=10r/s;

# Later, in a `server` block:
server {
    location ~ \.php$ {
        limit_req zone=mylimit;
        ...
    } 
    ...
}

I have had to do this sometimes when I noticed a few bad IPs attacking my servers. You can adjust the rate and zone settings to your liking (the above settings limit requests to any PHP script to 10 per second over a 10 minute period).

Slow Ansible playbook? Check ansible.cfg!

Today while I was running a particularly large Ansible playbook about the 15th time in a row, I was wondering why this playbook seemed to run quite a bit slower than most other playbooks, even though I was managing a server that was in the same datacenter as most of my other infrastructure.

I have had pipelining = True in my system /etc/ansible/ansible.cfg for ages, and initially wondered why the individual tasks were so delayed—even when doing something like running three lineinfile tasks on one config file. The only major difference in this slow playbook's configuration was that I had a local ansible.cfg file in the playbook, to override my global roles_path (I wanted the specific role versions for this playbook to be managed and stored local to the playbook).

So, my curiosity led me to a more thorough reading of Ansible's configuration documentation, specifically a section talking about Ansible configuration file precedence:

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