The articles below are on various topics, though the majority are focused on some aspect of systems administration.
ami-search: Find latest AWS machine images · January 26, 2018When I launch AWS EC2 instances for myself or for clients, I typically fall back on just a few OS/Distribution options: Amazon Linux, CentOS, Ubuntu LTS, or FreeBSD. I usually launch these VMs using the AWS Command Line Interface, but doing so requires the unique ID of the Amazon Machine Image (AMI) requested. I like to use the newest AMI available, but the AMI ID for the latest image changes often and the IDs vary by AWS region.
Creating an AWS VPC · November 15, 2017
It’s sometimes the case that you’d like to wrap your Amazon EC2 instances, and perhaps some EFS file stores, up in a nice private environment, as if you had your own little data center. You’d have your own network segments, with perhaps a DMZ or a NAT gateway. You’d be able to define ingress and egress rules for each segment.
AWS bundles those capabilities up in their Virtual Private Cloud (VPC) service.
Using ProxyJump with SSH and SCP · November 2, 2017
It’s somewhat common to have what’s known as a “jump host” serve as an SSH gateway to a remote network. You use ssh to log into the jump host (or “jump server”) and from there use ssh to log into an internal host that’s not directly accessible from the Internet.
With the release of ssh version 7.3, the OpenSSH folks made it easier to do the jump and internal login in one step.
Thinking and Doing in Education · May 25, 2017
Back in late 2013, I had a short but congenial e-mail exchange with John Tierney about his article on the Maine Maritime Academy and a follow-up piece that discusses various responses he received mostly on the theme of career-oriented education vs. a liberal-arts eduction. Many more readers added their thoughts in another follow-up. I was recently cleaning up my e-mail archives and had a chance to revisit my thoughts on the issue.
Expand ZFS in Linux VM · May 16, 2017
Ubuntu 16.04 has native support for ZFS, which means that VMs may start to use ZFS for non-root filesystems. Here’s a cookbook for expanding those filesystems. In OpenStack, the ZFS filesystem must be exported before this can be done, but at AWS it can be done without downtime.
Iterating a Hiera Hash · March 31, 2017
I’m in the process of learning about and porting some rules to Puppet 4.9. One task that had eluded me was integrating custom Hiera data into modules. I used the saz-rsyslog module and discovered that it largely turned off local logging, so it became a good time to discover how to define logging policy.
Create IPv4 hex filenames for PXELINUX · December 16, 2016The PXE network booting system distributed by the Syslinux Project is widely used for installing operating systems on networks of all sizes. It’s used in conjunction with DHCP and TFTP servers. The PXELINUX bootloader will look for a succession of files. You should read the official documentation to get the full story, but the short version is that their filenames are based on Client UUID (not always present) Client Ethernet MAC IPv4 address in hexadecimal A file named default The part that usually trips me up is converting an IPv4 address to hex.
Basic Command-line AWS Glacier Workflow · September 23, 2016
Glacier is Amazon’s AWS cold-storage service. Its data-center analog is archival tape storage, and it is about as slow as tape. Retrieval times are measured in hours (if not days). Glacier is a disaster-recovery tool, not live storage.
Unlike most AWS offerings, Glacier cannot be usefully controlled from the web console. It must be accessed with command-line tools or custom-built programs. Here’s a quick overview of Glacier operations using the AWS command line interface.
Red Hat/CentOS Software Collections (SCL) · August 29, 2016
Red Hat promises software compatibility for the life of any given RHEL release. It will not upgrade major applications mid-release. For example, if RHEL 6.0 contains PostgreSQL 8.4, RHEL 6.7 cannot move to PostgreSQL 9.4. Too many applications will break.
Yet some customers require the upgraded software. By way of an answer, Red Hat and the CentOS project have published what are called Software Collections (SCL). Packages provided in the SCL repositories typically provide newer versions of software that play a key role in the Linux world: Python, Apache, PostgreSQL, MySQL, gcc, etc.
Limitations of Hugo's Date Format Templating · August 24, 2016
As I’ve mentioned, I use Hugo to generate the bulk of the content on this site. Its templating system is built on that found in the Go programming language. The time and date formatting routines Hugo inherits from Go are idiosyncratic, to say the least.