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https://github.com/kazk/cnat-rs
Cloud Native At. Example from "Programming Kubernetes" book in Rust.
https://github.com/kazk/cnat-rs
example kube kubernetes kubernetes-controller rust
Last synced: about 1 month ago
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Cloud Native At. Example from "Programming Kubernetes" book in Rust.
- Host: GitHub
- URL: https://github.com/kazk/cnat-rs
- Owner: kazk
- License: apache-2.0
- Created: 2020-12-17T06:40:29.000Z (almost 4 years ago)
- Default Branch: main
- Last Pushed: 2022-02-20T09:40:30.000Z (over 2 years ago)
- Last Synced: 2024-10-03T11:16:21.359Z (about 2 months ago)
- Topics: example, kube, kubernetes, kubernetes-controller, rust
- Language: Rust
- Homepage:
- Size: 117 KB
- Stars: 1
- Watchers: 2
- Forks: 0
- Open Issues: 0
-
Metadata Files:
- Readme: README.md
- License: LICENSE
Awesome Lists containing this project
README
# cnat
Cloud Native [`at`], runs `command` at `schedule` by creating a Pod.
```yaml
apiVersion: example.kazk.dev/v1alpha1
kind: At
metadata:
name: example
spec:
schedule: "2020-12-17T19:21:00Z"
command: [echo, "will be executed"]
```
Example Kubernetes controller [programming-kubernetes/cnat] in Rust using [kube].
## Changes
- Changed `command` to an array
- Removed `Pending` from `status.phase`. `None` -> `Running` -> `Done`
- Changed to use `apiextensions.k8s.io/v1` and added the required `schema`
- The schema is generated by `kube` ([clux/kube-rs#348])
- `schedule` is validated as `date-time`
Generated CRD
```yaml
apiVersion: apiextensions.k8s.io/v1
kind: CustomResourceDefinition
metadata:
name: ats.example.kazk.dev
spec:
group: example.kazk.dev
names:
kind: At
plural: ats
shortNames: []
singular: at
scope: Namespaced
versions:
- additionalPrinterColumns: []
name: v1alpha1
schema:
openAPIV3Schema:
description: "Auto-generated derived type for AtSpec via `CustomResource`"
properties:
spec:
description: Spec for custom resource At.
properties:
command:
items:
type: string
type: array
schedule:
format: date-time
type: string
required:
- command
- schedule
type: object
status:
description: Status for custom resource At.
nullable: true
properties:
phase:
description: Describes the status of the scheduled command.
enum:
- Running
- Done
type: string
required:
- phase
type: object
required:
- spec
title: At
type: object
served: true
storage: true
subresources:
status: {}
```
## Project Structure
```text
.
├── k8s/ CRD and example
└── src/
├── bin/ Binaries
│ ├── cnat.rs - Run controller (default-run)
│ └── crd.rs - Output CRD YAML
├── controller.rs Implements the Controller
├── lib.rs
└── resource.rs Defines the Custom Resource
```
### Commands
- `cargo run`: Run controller
- `cargo run --bin crd`: Output CRD
## Running
### Locally
```bash
# Create CRD
kubectl apply -f k8s/ats.yml
kubectl wait --for=condition=NamesAccepted crd/ats.example.kazk.dev
# Start controller
cargo run
# Create At resource example
kubectl apply -f k8s/example.yml
```
### Inside
```bash
# Set up service account
kubectl apply -f k8s/rbac.yml
# Create CRD
kubectl apply -f k8s/ats.yml
kubectl wait --for=condition=NamesAccepted crd/ats.example.kazk.dev
# Deploy controller
kubectl apply -f k8s/deployment.yml
# Create At resource example
kubectl apply -f k8s/example.yml
```
## Comparisons
### Binary Size
Building on Arch Linux:
- `client-go`: 31MB (23MB with `-ldflags "-s -w"`)
- `kubebuilder`: TBD requires unknown version of [KubeBuilder]
- `operator-sdk`: TBD requires unknown version of [Operator SDK]
- `kube`: 8.3MB (5.8MB with `RUSTFLAGS='-C link-arg=-s'`)
### Lines of Code
| Library | Files | Lines | Code | Comments | Blanks |
| :-----------: | -------: | ------: | ------: | --------: | ------: |
| client-go | 29 | 2161 | 1212 | 658 | 291 |
| kubebuilder | 16 | 1013 | 529 | 357 | 127 |
| operator-sdk | 13 | 714 | 488 | 134 | 92 |
| kube | 5 | 257 | 217 | 15 | 25 |
- `client-go`: `tokei -e cnat-client-go/vendor -e cnat-client-go/hack -t Go cnat-client-go`
- `kubebuilder`: `tokei -e cnat-kubebuilder/vendor -e cnat-kubebuilder/hack -t Go cnat-kubebuilder`
- `operator-sdk`: `tokei -e cnat-operator/vendor -t Go cnat-operator`
- `kube`: `tokei -t Rust`
### Project Setup and Dependencies
- `client-go`: Go modules works fine (3 core modules + 1 code geerator + 1 logger). Versioning has improved since [programming-kubernetes/cnat] was written. A lot of generated code.
- `kubebuilder`: Requires [KubeBuilder] tool. Build failed with `GOPATH` not defined. Uses [dep].
- `operator-sdk`: Requires [Operator SDK] tool. Haven't tried. Uses [dep].
- `kube`: Standard Rust project. No separate codegen and very straightforward. CRD v1 schema is generated from the spec struct [clux/kube-rs#348] :)
## References
- [ConfigMapGenerator example](https://github.com/clux/kube-rs/blob/f49fcc4b64ca53091efe15f570e38c6ab3789567/examples/configmapgen_controller.rs)
- [at_controller.go](https://github.com/programming-kubernetes/cnat/blob/27f8ddba657b803ffb10501a28e003d0febd6387/cnat-kubebuilder/pkg/controller/at/at_controller.go)
- [h2oai/h2o-kubernetes](https://github.com/h2oai/h2o-kubernetes)
[`at`]: https://en.wikipedia.org/wiki/At_(command)
[programming-kubernetes/cnat]: https://github.com/programming-kubernetes/cnat
[KubeBuilder]: https://book.kubebuilder.io/quick-start.html
[Operator SDK]: https://github.com/operator-framework/operator-sdk
[kube]: https://github.com/clux/kube-rs
[clux/kube-rs#348]: https://github.com/clux/kube-rs/pull/348
[dep]: https://github.com/golang/dep