linux

'So, what is it you exactly do?' - Part four, monitoring

Here's a scenario...

At 4:30AM every Thursday (sysadmin's time), a server's site suddenly spikes in load, because a full backup takes place at such a time, which is not an off-peak time in terms of traffic due to international visitors.

A bunch of users visiting a site on that server receive a flurry of 502 errors trying to load some content - a form of application timeout due to the taxing effect on the CPU related to the backup process.

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'So, what is it you exactly do?' - Part three, security

This article is third in a series of long, windy answers to the inevitable 'but what exactly do you do as a sysadmin consultant?' question. I started writing this because it's hard to give a sufficient short answer.

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Adding Yubikey 2-factor authentication to SSH and sudo in Debian

Throughout 2014 and 2015 I have been adding two-factor authentication to Debian and Ubuntu servers (SSH, sudo) for some of my customers, using Yubikeys as the authentication device and OTP as the auth method. It's quite straightforward to integrate Yubikey OTP auth into Debian SSH servers, provided you are using Debian 7 (Wheezy) or higher, and that you can use the version of OpenSSH from the Backports repository.

This guide will work for SSH auth, as well as for other server-side tasks such as the use of sudo.

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'So, what is it you exactly do?' - Part two, config management

Continuing on from Part One, where I discuss the far-ranging benefits of continuous deployment, today I'll cover off another large part of the 'what do I do as a sysadmin' question: that being, config management.

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Trying to automate the initial OSSEC installation steps

I haven't got around to packaging OSSEC for Debian yet - mainly because I haven't decided how to handle the fact that OSSEC uses a server->agent model that depends on the generation/importing of unique keys for communication (not unlike Puppet with SSL certificates), from an automation/Puppet perspective.

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NoClassDefFoundError on Solr replication slave

I've recently been working on a project for a client that required Solr 3.4 (which we implemented using these packages for Ubuntu 10.04)

Additionally, in production we've implemented two solr servers in replication (one master, one slave).

Having never done this before, I followed the example in the solrconfig.xml that was commented out, as well as this documentation.

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Enforcing apt-get update prior to any packages installing via Puppet

I've been having weird, inconsistent bugs occur when running Puppet especially on new systems (where it's more obvious).

Specifically: I've seen cases where a manifest Notifies the apt-get update Exec to refresh the apt database, and suddenly the next series of package installs have failed with 'could not find package'.

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One-touch provisioning and auto-monitoring of new servers

I've recently been doing some very innovative work for the very clever gents at Code Enigma, where I've been working on some interesting projects:

1. an automated 'zero-touch' dev/stage/live deployment system for their enterprise Drupal applications (developers no longer need to ssh in to servers to do deployments)

2. automatic 'one-touch' provisioning and configuration of new hosting cloud services.

(More on the dev/stage/live zero-touch deployment soon :) )

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