About
John Leach is a human living in Bradford, UK. He makes regular and diverse changes to the universe.
Category Archives: Tech
Rate limiting with Apache and mod-security
Rate limiting by request in Apache isn’t easy, but I finally figured out a satisfactory way of doing it using the mod-security Apache module. We’re using it at Brightbox to prevent buggy scripts rinsing our metadata service. In particular, we … Continue reading
Posted in Security, Tech
Tagged apache, api, dos, http, limit, mod-security, netfilter, nginx, rate, rate limiting
Leave a comment
Full text indexing of syslog messages with Riak
I’ve just released a little tool I wrote called riak-syslog which takes your syslog messages and puts them into a Riak cluster and then lets you search them using Riak’s full text search. Rather than re-implement the wheel, riak-syslog expects that a … Continue reading
Documentation that tells a story
When reading technical documentation I too often come across examples like this: let’s assume you have a client called foo and a server called bar or command examples like: mysqldump -h server1 | mysql -h server2 When I write documentation, … Continue reading
Inside Google Plus
Steven Levy interviewed Google’s Bradley Horowitz about Google+: Wired: Some users are chafing at Google’s insistence that they provide real names. Explain the policy against pseudonyms. Horowitz: Google believes in three modes of usage—anonymous, pseudonymous, and identified, and we have a … Continue reading
Posted in Politics, Tech
4 Comments
Ceph at London Devops, 25th July 2011
I’ll be down London way on Monday 25th July giving a talk about Ceph at the London Devops meetup. Come along and learn about petabyte scale distributed filesystems, or just come along and drink beer with us!
Posted in Tech
Tagged ceph, cluster, distributed, filesystem, filesystems, london, petabyte, speaker, talk
2 Comments
Redirecting outgoing mail with Postfix
We have a various staging deployments of our systems at Brightbox and need to test that the emails they send are correct. We have a bunch of test accounts registered with various email addresses and we wanted them all to … Continue reading
Puppet dependencies and run stages
I’m using Puppet to manage some apt repositories on Ubuntu and have had a dependency problem. I want to write the source configs before running apt-get update and I want to run that before installing any packages. Otherwise, a manifests … Continue reading
Indexing syslog messages with solr
I’ve been thinking about centralized indexing and searching of logs for a while and the other day I came across a project called Graylog2 that does just that. It provides a service to receive messages over the network (in a couple … Continue reading
Posted in Tech
Tagged audit, centralized, graylog, indexing, intrusion detection, logging, lucene, rsyslog, search, solr, syslog
3 Comments
The cost of free
Helienne Lindvall writes in the Guardian: Cory Doctorow [will] cost you $25,000 (£15,800) to get him to speak at your conference… But what does Doctorow speak about? Well, ironically, he’s a proponent of giving away content for free as a … Continue reading
ipq.co: create dns records instantly
ipq.co is a new service I put together to lower the barrier for dns management. It’s the tinyurl of the dns world – provide an IP address and you get a random dns record for it (or you can choose … Continue reading
LVM snapshot performance
The Linux Logical Volume Manager (LVM) supports creating snapshots of logical volumes (LV) using the device mapper. Device mapper implements snapshots using a copy on write system, so whenever you write to either the source LV or the new snapshot … Continue reading
Testing XML with rspec, xpath and libxml
I’m currently working with the virtualization API libvirt which uses XML to represent virtual machines and I’m generating this XML using Ruby. I’m using rspec to test my code and wanted to test that my output was as I expected. … Continue reading