• Datadog Python Library

    3 min read

    Using the Datadog Python Library we can very easily inject metrics into Datadog. These metrics will fall into the "custom metrics" category. Let's check the python code needed to do so:

    16/07/2021

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  • Exposing a localhost only port using socat on Kubernetes

    2 min read

    On Kubernetes, if we want to publish a port that it's listening just to localhost without having to modify the container image we can create another container image to work as a TCP proxy using socat

    15/07/2021

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  • Conditional expressions in helm

    2 min read

    Maybe one of the main challenges about helm is the complexity of it's template rendering engine: It's not very intuitive

    14/07/2021

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  • openssl: How to check that a certificate matches a private key

    2 min read

    If we try to install a certificate on a service but we install an incorrect private key, the service will fail, most likely, with some cryptic message. But, how do we make sure that a certificate has been generated using the correct private key? Checking the modulus of each one can help verifying this

    13/07/2021

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  • Failed build model due to couldn't auto-discover subnets: unable to discover at least one subnet

    2 min read

    Using an ALB controller we might face the following error while creating Ingress objects:

    $ kubectl describe ingress inspect-green-sonarqube -n inspect-green
    Name:             inspect-green-sonarqube
    Namespace:        inspect-green
    Address:          
    Default backend:  default-http-backend:80 (<error: endpoints "default-http-backend" not found>)
    Rules:
      Host                        Path  Backends
      ----                        ----  --------
      inspect-green.clarivate.io  
                                  /   ssl-redirect:use-annotation (<error: endpoints "ssl-redirect" not found>)
                                  /   inspect-green-sonarqube:http (10.103.202.36:9000)
    Annotations:                  alb.ingress.kubernetes.io/actions.ssl-redirect:
                                    {"Type": "redirect", "RedirectConfig": { "Protocol": "HTTPS", "Port": "443", "StatusCode": "HTTP_301"}}
                                  alb.ingress.kubernetes.io/group.name: inspect-green
                                  alb.ingress.kubernetes.io/listen-ports: [{"HTTP":80},{"HTTPS":443}]
                                  alb.ingress.kubernetes.io/scheme: internal
                                  alb.ingress.kubernetes.io/target-type: ip
                                  kubernetes.io/ingress.class: alb
                                  meta.helm.sh/release-name: inspect-green
                                  meta.helm.sh/release-namespace: inspect-green
    
    Events:
      Type     Reason            Age                 From     Message
      ----     ------            ----                ----     -------
      Warning  FailedBuildModel  16m (x19 over 38m)  ingress  Failed build model due to couldn't auto-discover subnets: unable to discover at least one subnet
    

    This message is telling us that the ALB controller is no able to find the subnets of the requested type. We will have to check the following:

    12/07/2021

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