I am very new to Helm and Kubernetes. I have a use case where, whenever there is a helm upgrade
helm upgrade xxx --values yy.yaml
I need to trigger invocation of a method in my docker image which is deployed onto the kubernetes pods ,so that i can work on the changes encountered in yy.yaml in the image code . Do we have some way of doing it ? Please help me here.
Though your problem is not clear to me but i think, You can use helm hook to do the same thing. Please check documentation.
You can certainly use pre-upgrade hook to invoke your function.
Related
I have an application "A" which requires postgres database. Once I deploy the helm chart it deploys the child dependent chart postgres.
helm install application_A -n mynamspace ./applicationA-0.1.0.tgz
Now I have another application "B" which also requires postgres database. I wish to deploy the application B in the same namespace but it should not deploy new postgres POD as it is already available from Application A's deployment.
helm install application_B -n mynamspace ./applicationB-0.1.0.tgz
It fails with the following error -
Error: INSTALLATION FAILED: rendered manifests contain a resource that already exists
I want helm to recognize that the dependency of application 'B' is already deployed with the desired version and hence it should automatically avoid deploying the dependent chart.
I am aware of conditional deployment of subchart. It requires me to find out what is already available using shell script to toggle the condition while deploying Application B.
Is there any way in helm to automatically avoid deploying subchart if it is already deployed?
helm version - v3.8.0
Ideally there should not be any relation between two helm release installations. Each helm installation would always try to install their components. Here, it could be failing because of the hardcoded name of resource. Just for your use case, you can use helm in-built lookup function to see if resource exist do not create.
link:
https://helm.sh/docs/chart_template_guide/functions_and_pipelines/#using-the-lookup-function
lately I was experimenting with Skaffold with our Helm Charts and I am in little bit in a dilemma that our Helm Chart \ Sub Charts are compatible with Skaffold or not.
Our helm Charts are looking like the following
my-helm-charts
+-charts
+-project1
+-project2
+-project3
+-project4
+-infrastructure_kafka
+-charts
+-kafka
+-zookeeper
+-infrastructure_cassandra
+-infrastructure_elasticsearch
+-Charts.yaml
+-Values.yaml
The reason we choosed to structure the Helm Charts this way, is that if necessary to spin up extra stages for our project.
Now when I want to develop project2 with Google Cloud Code / Skaffold (which I configured correctly and I can start without problem in IntelliJ) I have to start whole my-helm-charts.
That is actually Ok but the problem is, if I use Debug in Kubernetes, I have a feeling Google Cloud Code/Skaffold can really locate the project2 and no debugging occurs.
My feeling is Google Cloud/Skaffold is more oriented to work with following contruct...
project2-helm
+-templates
+-Charts.yaml
+-Values.yaml
My Subcharts contructs starts in Google Cloud Code/Skaffold without any exception but I can't debug, is it possible to achieve want I want with my structure and if yes, how?
Or is it not possible at all...
Thx for answers...
We recently added a feature called config dependencies which might help here. It allows you to create more specific skaffold.yamls and then map them together with a "requires" field:
https://skaffold.dev/docs/design/config/#configuration-dependencies
Once you have the skaffold.yamls created and the right dependency mapping you can run skaffold with the -m flag to choose once slice of your services:
skaffold dev -m project3
Cloud Code support for modules is incoming.
Cloud Code IntelliJ and Cloud Code VS Code recently added preview level support for deploying and debugging modules of a larger application which uses Skaffold. See more here https://cloud.google.com/code/docs/intellij/skaffold-modules
I have a query related with prometheus-operator helm chart & alert manager combination.
Currently we are using prometheus-operator helm chart:
https://github.com/helm/charts/tree/master/stable/prometheus-operator
and I wrote a simple rule in values.yml (this is just a sample code) to generate an alert:
further I am using alertmanager config/routes/receivers to send alerts. It's working perfectly fine.
But as part of real-time implementation, I may be having so many alert rules. Is there any way where I can bring these all rules in separate rules file & configure the path (rule file path) in values.yml (under: additionalPrometheusRules section)
I also saw kube-prometheus-stack & additionalPrometheusRulesMap (in values.yml):
https://github.com/prometheus-community/helm-charts/blob/main/charts/kube-prometheus-stack/values.yaml
But didn't fine any solution. Anyone can help me on this?
So helm doesn't allow includes in values.yaml files typically. I read that there's a way to do it, but it depends on how the chart is built and typically upstream maintainers don't use templates that way afaik (could be wrong there, but I've never noticed it).
Your problem is exactly the same problem I've been trying to solve adequately, and I think I came up with something. It's not perfect, but it is better than having one huge monolithic values.yaml file.
helm allows the operator to specify multiple values.yaml files using the paradigm, -f values1.yaml -f values2.yaml -f some-more-values.yaml, so I broke my values file up into multiple logically-divided yaml files.
There might be gotchas, so be aware, but so far for this use-case, it seems to be working. I'm still testing things out. https://helm.sh/docs/helm/helm_install/
You can also add your own custom rules file using config maps. In this way, you can avoid over alerting and get notified for specific alerts only.
I am using helm built in object 'Release.isUpgrade' to ensure an init-container is only run at upgrade.
I want to only run the init-container when upgrading from a specific Chart version.
Is it possible to get the 'from' Chart version in a helm upgrade ?
It doesn't look like this information is published either in the .Release object or through information available to a hook job.
You probably want a pre-upgrade hook and not an init container. If you have multiple replicas on your deployments, the init container will run on all of them; even if you have just one, if the node it's on fails and is replaced, the replacement will re-run the init container. A pre-upgrade hook will run just once, regardless of how the corresponding deployments are configured.
That hook will be a separate pod (and will require writing code), so within that you can do whatever you want. You can give it read access to the Kubernetes API to get the definition of an existing deployment, for example, and then look at its labels or container image tag to find out what version of the chart/application is running now. (There are standard labels that can help with this.) You could also make the upgrade step just look for its own outputs: if object X is supposed to exist, create it if it's not there, without focusing on specific versions.
Is it possible to run kubectl commands and see the run-time execution using an IDE like GoLand for example?
I would like to open 'apply.go' source code and see how the code is executed when I type: kubectl apply -f/hit Enter step-by-step.
Go does offer a debugger, Delve. But I don’t think this will be very helpful. Kubectl code is kind of hard to understand even if you already know it and kubectl apply is the single most complex thing in all of kubectl. So complex that the logic is being moved to the server side, in newer versions.
Lens is the best IDE for kubernetes that I have used upto now.
It serves everything in a plate , as there is no need to mug up the commands of kubectl,
you can make changes in any of kubernetes yaml file from lens and it will apply changes in to your cluster.
install lens for your OS: https://github.com/lensapp/lens/releases/
you can know more about lens from this link : https://github.com/lensapp/lens/