kapp
kapp-controller
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kapp | kapp-controller | |
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7 | 5 | |
859 | 254 | |
1.5% | 3.5% | |
8.1 | 8.7 | |
9 days ago | 7 days ago | |
Go | Go | |
Apache License 2.0 | Apache License 2.0 |
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kapp
- HELM vs KUSTOMIZE
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How to handle the lifecycle of multiple COTS
If you want to take it one step further: you might be applying several resources at a time that are logically one "application". kapp (https://carvel.dev/kapp/) lets you group those together and give them a name, and provides a "terraform-like" experience where it shows you its execution plan before applying updates. So then you might do `ytt -f | kapp deploy -a name-of-thing` Or you could use helm's templating engine but then still pass the resulting yaml to kapp for its unification of the deployment step.
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Dhall: A Gateway Drug to Haskell
since you mentioned Kubernetes...
> It would be nice if there was a separate state reconciliation system that one could adapt to use with Cue or Dhall or any other frontend
this exactly was thinking behind https://carvel.dev/kapp for Kubernetes (i'm one of the maintainers). it makes a point to not know how you decided to generate your Kubernetes config -- just takes it as input.
> In particular the ability to import other files as semantic hashes seems like a great feature.
it's an interesting feature but seems like it should be unnecessary given that config can be easily checked into git (your own and its dependencies).
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Terraform should have remained stateless
i think kubernetes is not a great example in favor of more client state (like tf) since k8s has uniform resource structure (metadata.*) and first class labeling support. but as you point out kubectl doesnt use labels well (at least imho).
when building https://carvel.dev/kapp (which i think of as "optimized terraform" for k8s) the goal was absolutely to take advantage of those k8s features. we ended up providing two capabilities: direct label (more advanced) and "app name" (more user friendly). from impl standpoint, difference is how much state is maintained.
"kapp deploy -a label:x=y -f ..." allows user to specify label that is applied to all deployed resources and is also used for querying k8s to determine whats out there under given label. invocation is completely stateless since burden of keeping/providing state (in this case the label x=y) is shifted to the user. downside of course is that all apis within k8s need to be iterated over. (side note, fun features like "kapp delete -a label:!x" are free thanks to k8s querying).
"kapp deploy -a my-app -f ..." gives user ability to associate name with uniquely auto-generated label. this case is more stateful than previous but again only label needs to be saved (we use ConfigMap to store that label). if this state is lost, one has to only recover generated label.
imho k8s api structure enables focused tools like kapp to be much much simpler than more generic tool like terraform. as much as i'd like for terraform to keep less state, i totally appreciate its needs to support lowest common denominator feature set.
common discussion topics:
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Is there any CLI tool to sync between local yamls and current cluster namespace state?
Take a look at kapp (https://github.com/vmware-tanzu/carvel-kapp).
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Deploy Neo4J's APOC plugin with code thanks to CARVEL vendir
kapp - Install, upgrade, and delete multiple Kubernetes resources as one "application"
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Open Application Model – An open standard for defining cloud native apps
I really like this approach for simplifying Kubernetes. A few projects similar to OAM in that it provides a higher level "Application" CRD:
https://github.com/vmware-tanzu/carvel-kapp
kapp-controller
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Helm is both "package manager" and "templating engine" - probably the best package manager but horrible template engine
We use kapp-controller when applying our charts (it uses helm template instead of helm install) so we can be very rigorous about what fields are changeable (like through pod autoscaling) and what are not (securitycontext, etc.)
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How to handle the lifecycle of multiple COTS
Even further, you could describe your "fetch", "template", and "deploy" stages in akapp-controller AppCR and then you'd have a controller (like an operator) running the cluster continuously reconciling your private cloud to ensure that it's always reconverging to the desired state. This is basically what's underpinning a number of VMWare's commercial (and OSS) Tanzu offerings, as well as some other organization's internal platforms, or "self hosted private clouds"
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ArgoCD vs. crossplane-helm provider for managing helm releases?
Full disclosure: I work on https://carvel.dev/kapp-controller/ which can also continuously reconcile helm charts (via our own CRD ).
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Deployment Packaging Solutions
kapp-controller
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Deploy Neo4J's APOC plugin with code thanks to CARVEL vendir
kapp-controller - Capture application deployment workflow in App CRD. Reliable GitOps experience powered by kapp.
What are some alternatives?
kubevela - The Modern Application Platform.
cnab-spec - Cloud Native Application Bundle Specification
argo-cd - Declarative Continuous Deployment for Kubernetes
vendir - Easy way to vendor portions of git repos, github releases, helm charts, docker image contents, etc. declaratively
Flux - Successor: https://github.com/fluxcd/flux2
imgpkg - Store application configuration files in Docker/OCI registries
ytt - YAML templating tool that works on YAML structure instead of text
carvel - Carvel provides a set of reliable, single-purpose, composable tools that aid in your application building, configuration, and deployment to Kubernetes. This repo contains information regarding the Carvel open-source community.
asdf - k14s asdf plugin
terraform-provider-carvel - Carvel Terraform provider with resources for ytt and kapp to template and deploy to Kubernetes
gravity - Kubernetes application deployments for restricted, regulated or remote environments.