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Use kubie to simplify changes between kubernetes contexts and namespaces
2 min read
On another post we talked about how to change kubernetes context using kubectl and there's another post for setting a default namespace for a given context. kubie is a tool that helps trying to make it easier
17/03/2021
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kubernetes: List available API using kubectl
2 min read
With kubectl api-resources we can get the list of available objects, but the same object can be defined using different API versions, for example the Ingress object is different on v1beta1 compared to v1. Using kubectl api-versions we can get the list of all the available API versions on our kubernetes cluster
16/03/2021
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kubernetes: Get events across multiple objects
4 min read
The most commonly used way to get events is by using kubectl describe on each object like this:
$ kubectl describe pod pet2cattle-6597f8464d-hgxpp Name: pet2cattle-6597f8464d-hgxpp (...) Events: Type Reason Age From Message ---- ------ ---- ---- ------- Normal Scheduled 3m47s default-scheduler Successfully assigned kube-system/pet2cattle-6597f8464d-hgxpp to scopuli.lolcathost.systemadmin.es Normal Pulled 3m46s kubelet Container image "172.18.1.46:5000/p2c:3.44" already present on machine Normal Created 3m46s kubelet Created container pet2cattle-sitemap Normal Started 3m46s kubelet Started container pet2cattle-sitemap Normal Pulled 3m41s kubelet Container image "172.18.1.46:5000/p2c:3.44" already present on machine Normal Created 3m41s kubelet Created container pet2cattle-indexer Normal Started 3m40s kubelet Started container pet2cattle-indexer Normal Pulled 3m32s kubelet Container image "172.18.1.46:5000/p2c:3.44" already present on machine Normal Created 3m32s kubelet Created container pet2cattle Normal Started 3m31s kubelet Started container pet2cattle Warning Unhealthy 3m26s kubelet Liveness probe failed: Get http://10.42.0.8:8000/: net/http: request canceled (Client.Timeout exceeded while awaiting headers)It's quite convenient when we are looking for events related to a given but becomes a pain if we need to see how the events are triggered on multiple objects.
15/03/2021
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kubernetes: Pods can be composed of multiple containers
2 min read
One common misunderstanding with kubernetes is mistakenly assume "a pod" really means "a container".
A pod is the minimal unit we take into account in kubernetes but this does not mean that a pod is a container: A pod can be composed of several containers working together. We can easily see this on the READY column that are going to tell us for a given pod from how many containers it is composed:
$ kubectl get pods NAME READY STATUS RESTARTS AGE ampa-7dcbfd689f-59ghw 2/2 Running 0 5d1h12/03/2021
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Using terraform_remote_state for getting data from another terraform state
2 min read
On terraform, besides returning some information to the user, returning data as output can be used as an input for terraform code that needs to use a resource created by another team.
On the terraform code that creates the resource, we will have to set the variable and it's value:
output endpoint { vpc_id = aws_vpc.databases.id }Then, on the code that uses this resource we will have to declare the tfstate as a data source using terraform_remote_state
11/03/2021
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The selector option can help us to select a subset of pods with kubectl
2 min read
On most kubectl command we will find the selector option for filtering pods based on it's labels. To use we just need to set the filter using the key=value format:
$ kubectl get pods -l "app=spin" NAME READY STATUS RESTARTS AGE spin-clouddriver-9899c9b54-nbjp6 1/1 Running 0 29h spin-deck-56ff48c587-lc75g 1/1 Running 0 29h spin-echo-7ccf545b48-b5n9l 1/1 Running 0 29h spin-front50-59bff89745-2f65h 1/1 Running 0 29h spin-gate-644c968b68-2q8nj 1/1 Running 0 29h spin-igor-6669794575-2cnb4 1/1 Running 0 29h spin-orca-795789b678-nqrk7 1/1 Running 0 29h spin-rosco-6c9879b69f-gdrfl 1/1 Running 0 29h10/03/2021
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Enabling debug information on terraform using TF_LOG
2 min read
Sometimes with terraform you might end up with some meaningless error that does not provide any clue what's going on. So instead or just trying to guess that have changed; we can enable some traces in terraform to try to make sense what's going on
Error: AccessDenied: Access Denied status code: 403, request id: 8FCD12996B11F5F8, host id: xMF1Gs+VIEpxpk+1Og6UtchyT10K+mRWFe2IUZ8gqG13KbsRm0L8nRw8udzkqEVJagg8+RMpY3M=09/03/2021
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terraform: Refresh null_resource when a variable changes
2 min read
When using local-exec with the null_resource we might need to be able to update the resources that gets created like this. Let's assume we have the following terraform code to apply Kustomize to a kubernetes cluster:
resource "null_resource" "metrics-server" { provisioner "local-exec" { command = "kubectl apply -k 'https://github.com/jordiprats/django-ampa/deploy-${var.version}/'" } }Given this setup even though the var.version changed, the resource won't be updated if it was already applied
08/03/2021
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Setting secret into a environment variable
2 min read
Although it's not a best practice to feed secrets into environment variables it's still something that it is possible to do. Let's take a glance on how to do it
05/03/2021
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Relationship between Deployment and ReplicaSet in kubernetes
3 min read
Although ReplicaSet's main purpose is to maintain a stable set of replica Pods, it's not a kubernetes object that is commonly created, at least not explicitly. But the replicas attribute on the Deployment object is actually related to this object
04/03/2021
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