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Terraform: Convert launch configuration to launch template
2 min read
Launch templates were introducted in late 2017 as a replacement for launch configurations: They are very similar, although launch templates provide much deeper and wider options to configure the instances that are going to be launched (by using an Auto Scaling Group)
27/08/2021
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How to configure an application to use SecurityGroups for Pods
4 min read
To be able to configure SecurityGroups we will have:
- Install SecurityGroups for Pods on the EKS cluster
- Configure the application to be able to actually use SecurityGroup for a Pods (this post)
This is what needs to be done considering that we are going to use an ALB to direct traffic to the application.
26/08/2021
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How to install SecurityGroups for Pods on an AWS EKS clusters
4 min read
To be able to configure SecurityGroups at the Pod level, we have two very differentiated tasks:
- Install SecurityGroups for Pods on the EKS cluster (this post)
- Configure the application to be able to actually use it
Let's take a look at what needs to be done on the cluster side.
25/08/2021
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Kubernetes readinessProbe: testing container's availability
1 min read
Some applications might temporally not being able to server traffic due to some work it is doing: For example, loading data, contacting with external services... If we want to have a way to temporally disable traffic without restarting the application we will need to configure a readinessProbe
24/08/2021
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Kubernetes livenessProbe: testing container's health
2 min read
Every application will, eventually, fail. In order to detect that the container is failing and being able to recover this situation by restarting it we can use the livenessProbe.
23/08/2021
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Fine tunning Pod scheduling using taints, tolerations and nodeSelector
4 min read
If we want just a subset of Pods to be able to be scheduled on a given node we can achieve it using taints and tolerations
With a taint we can tell the cluster not to schedule Pods on this node, but with a toleration on a Pod we can allow it to tolerate this taint
20/08/2021
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Using helm hooks to when certain objects are created
3 min read
Sometimes when we are writing a helm chart we realize that we have some parts of the task that need to be performed before of after deploying certain objects. We can also need to execute some Jobs in order to, for example, update the database, but not continuously, just when we update the application.
To handle this kind of situations we can use helm hooks
19/08/2021
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Using kubectl patch to modify existing Kubernetes objects
2 min read
To be able to modify a Kubernetes object we can use kubectl edit to do it interactively. It can come handy if we need to test values but it makes it harder to automate it. If we need a way to change a Kubernetes object using a non-interactive command, kubectl patch is the best option for us.
18/08/2021
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Terraform: Using the external data source
2 min read
To be able to execute an arbitrary command to retrieve some data and being able to use it as a variable in terraform we can use the external data-source
17/08/2021
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Getting Kubernetes documentation using kubectl
3 min read
While forking on Kubernetes manifest it's easy to forget the available fields for each Kubernetes object. Using kubectl explain we can get all the fields available with a short description of them. Pretty much a man inside kubectl
13/08/2021
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