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Binding sendmail to the loopback interface

The sendmail SMTP server comes with the vast majority of UNIX Operating systems, and is configured to listen for new connections on TCP ports *.25 (SMTP) and *.587 (MSP) by default. For workstation and...

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Optimizing sendmail smart hosts

While debugging an issue last week, I noticed some odd behavior when the Sendmail Smart host configuration directive (DS) was used. Smart hosts allow nodes to delegate mail delivery services to...

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Printing the entries in a sendmail queue

Since I began managing sendmail installations 8-years ago, I have used the mailq command to print the entries in the sendmail queue. While reading through the bat book to find the root cause of my...

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Notes from episode 28 of TGIK: Exploring CockroachDB on Kubernetes

Over the past few months I’ve been trying to learn everything there is to know about Kubernetes. Kubernetes is an amazing technology for deploying and scaling containers though it comes with a cost....

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Notes from episode 12 of TGIK: Exploring serverless with Kubeless

Over the past few months I’ve been trying to learn everything there is to know about Kubernetes. Kubernetes is an amazing technology for deploying and scaling containers though it comes with a cost....

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Notes from episode 13 of TGIK: Serverless with Fission

Over the past few months I’ve been trying to learn everything there is to know about Kubernetes. Kubernetes is an amazing technology for deploying and scaling containers though it comes with a cost....

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Notes from episode 14 of TGIK: Serverless with OpenFaaS

Over the past few months I’ve been trying to learn everything there is to know about Kubernetes. Kubernetes is an amazing technology for deploying and scaling containers though it comes with a cost....

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atexit() stage right. Or how my Python program leaked file descriptors.

A year and a half ago I started using prometheus and grafana to graph metric data. This combination is incredibly powerful and I have been absolutely blown away by the amount of actionable intelligence...

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Notes from episode 79 of TGIK: YTT and Kapp

Over the past few months I’ve been trying to learn everything there is to know about Kubernetes. Kubernetes is an amazing technology for deploying and scaling containers though it comes with a cost....

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Notes from episode 45 of TGIK: Calico

Over the past few months I’ve been trying to learn everything there is to know about Kubernetes. Kubernetes is an amazing technology for deploying and scaling containers though it comes with a cost....

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Creating a set of random numbers from the command line

This past weekend I was doing some database testing and needed to generate some random numbers to populate a table. My typical go-to utility for generating one random number is head piped to od and tr:...

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Seeing what changed in a docker containers file system

Docker has a number of nifty options to help investigate containers and container images. One option I have used over and over to debug issues is the docker “diff” command. This dumps out the files...

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How the docker container creation process works (from docker run to runc)

Over the past few months I’ve been investing a good bit of personal time studying how Linux containers work. Specifically, what does docker run actually do. In this post I’m going to walk through what...

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Converting X509 certificates to JSON objects

Years ago when I wrote ssl-cert-check I looked far and wide for an easy way to parse X509 certificates. I wasn’t able to find a utility so I ended up using a combination of sed and awk to extract...

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Linting Jenkinsfiles to find syntax errors

As a long time Jenkins user I periodically need to add new steps or Groovy logic to my Jenkinsfiles. The last thing you want to do when updating your pipeline configuration is to make a typo which...

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Notes from episode 70 of TGIK: Assuming AWS roles with kube2iam/kiam

Over the past few months I’ve been trying to learn everything there is to know about Kubernetes. Kubernetes is an amazing technology for deploying and scaling containers though it comes with a cost....

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Using external-dns to managed DNS entries in Kubernetes clusters

Kubernetes provides a service resource to distribute traffic across one or more pods. I won’t go into detail on what a service is, since it’s covered in-depth elsewhere. For Internet-facing...

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Exporting AWS Cloudwatch log streams to a local file

I love AWS, but when I’m debugging issues I prefer the Linux command line over Cloudwatch Logs Insights. Numerous AWS services store their log configuration inside cloudwatch, which presents a small...

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Backing up your route53 zone configuration with the aws CLI

In a previous post, I discussed using the Kubernetes external-dns project to manage DNS changes. Prior to rolling it out, I needed a way to backup each zone prior to external-dns modifying it. I also...

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Using audit2rbac to create RBAC policies from Kubernetes audit log

When I first started with Kubernetes, it took me some time to understand two things. One, how do I generate manifests to run my service. I tackled this in a previous blog post. The second was wrapping...

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