kubectl: Retrieve a list of object names

2 min read

If we need to write some script to retrieve a certain information that kubectl can provide, we can always add the option to remove headers and use something like awk to narrowit down. There's also a better way than doing this:

kubectl get ns --no-headers | awk '{ print $1 }'

31/08/2022

OpenShift CRC: Customize admin password

1 min read

When setting up a CRC cluster we might want to be able to set a specific admin password instead of having to retrieve it using crc console.

30/08/2022

AWS EC2/ASG: Set instance health as unhealthy using API an call

2 min read

If we are running an application on EC2 using an ASG that it's health check fails to properly notify it's status using an HTTP endpoint, if fixing it is not an option, we can create another custom HTTP endpoint to improve the existing, or if the situation cannot be fixed, we can set the instance heath as unhealthy from within the instance itself (or a lambda if needed)

29/08/2022

Set command arguments with environment variables

2 min read

When configuring command line arguments for containers we might need to be able to use certain values that might be elsewhere like the name of the current namespace.

We can use environment variables as the source of the information without having to write a wrappet to actually populate them

26/08/2022

Getting regular user and admin credentials to login to a CRC cluster

2 min read

If we are using CRC to run a minikube-like OpenShift cluster we'll need the use oc login to connect to the cluster. If we don't have the credentials but the cluster is not deleted, we can still retrieve them

25/08/2022

How to retrieve a github actions secret

2 min read

When using Github Actions secrets, it won't show any secrets on the action's logs: It is going to replace any string that matches with an existing secret with ***

24/08/2022

OpenShift: unable to start CRC

3 min read

While trying to setup CRC (a OpenShift version of minikube) on your laptop, while trying to start crc it might fail starting with the following crypting message:

$ crc start
requires memory in MiB >= 9216

23/08/2022

Using ephemeral containers

3 min read

Starting Kubernetes 1.23, ephemeral containers are enabled by default (in beta though). Using ephemeral containers we can now troubleshoot pods by deploying a temporary container into it with extra privileges or binaries to use

22/08/2022

How docker generates container's names

2 min read

Everytime you create a container using docker, if not already set using --name, docker chooses a name for you: you can expect two words with a underscore:

$ docker run --rm -d alpine sleep 24h
38c4cc4e87762fc113ef174e9a4989e13d21037678abd3fe73840b825f14c7bf
$ docker ps
CONTAINER ID   IMAGE                          COMMAND                  CREATED         STATUS                PORTS                    NAMES
38c4cc4e8776   alpine                         "sleep 24h"              5 seconds ago   Up 3 seconds                                   romantic_shtern

For this example it was chosen romantic_shtern, but it can use a great variety of words:

$ docker ps --all | grep -v "Up" | awk '{ print $NF }'
NAMES
mystifying_poitras
suspicious_shtern
focused_chatelet
keen_mendel
happy_jackson
xenodochial_margulis
kind_blackburn
gallant_pascal
trusting_thompson
(...)

So, how does Docker generate names for it's containers?

01/08/2022