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...
View ArticleOptimizing 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...
View ArticlePrinting 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...
View ArticleNotes 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....
View ArticleNotes 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....
View ArticleNotes 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....
View ArticleNotes 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....
View Articleatexit() 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...
View ArticleNotes 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....
View ArticleNotes 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....
View ArticleCreating 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:...
View ArticleSeeing 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...
View ArticleHow 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...
View ArticleConverting 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...
View ArticleLinting 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...
View ArticleNotes 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....
View ArticleUsing 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...
View ArticleExporting 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...
View ArticleBacking 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...
View ArticleUsing 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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