• Test SSL protocols availability using openssl s_client

  3 min read

  To make sure we don't publish an SSL service with vulnerable protocols enabled we can check which protocols the server has enabled using openssl s_client

  Depending on the OpenSSL version we have we will have different procotols available. For example, if we are using OpenSSL 1.0.2j we will have the following options for s_client:

   -ssl2         - just use SSLv2
   -ssl3         - just use SSLv3
   -tls1_2       - just use TLSv1.2
   -tls1_1       - just use TLSv1.1
   -tls1         - just use TLSv1
   -dtls1        - just use DTLSv1
  

  On the other hand, if we are using OpenSSL 1.1.1f we will only have:

   -tls1                      Just use TLSv1
   -tls1_1                    Just use TLSv1.1
   -tls1_2                    Just use TLSv1.2
   -tls1_3                    Just use TLSv1.3
  

  06/07/2021

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• Testing a TCP connection using bash

  2 min read

  
  

  To be able to debug issues we can test a TCP connection using netcat (nc) or even telnet. But when we are on a containerized environment such as Kubernetes it can be a challenge when the container doesn't have the right tools for the job

  $ nc
  bash: nc: command not found
  $ netcat
  bash: netcat: command not found
  $ telnet
  bash: telnet: command not found
  

  05/07/2021

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• Using terraform try function to retrieve optional values on maps

  2 min read

  
  

  It's common practice to use a map in terraform to configure resources. If we want to use a map with optional values we can make use of the try() function

  Let's us the following map as an example:

    config = {
      namespaces = ["namespace1", "namespace2"]
  
      (...)
    }
  

  02/07/2021

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• Using an HPA object to autoscale a deployment based on it's Pods CPU metrics

  3 min read

  
  

  On Kubernetes, scaling an application is just a matter of defining how many replicas we want:

  $ kubectl scale deployment/demo --replicas=5
  deployment.apps/demo scaled
  

  Having to manually adjust the number of replicas is not really practical. Here's where the HorizontalPodAutoscaler (HPA) comes into play

  01/07/2021

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• Kubernetes Pod: Share a temporal Volume across containers

  2 min read

  
  

  If we need to be able to share some data across containers (one generates the data and the other one consumes it) we can use an emptyDir to create a Volume to mount on both containers.

  30/06/2021

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