README
¶
Demo of ko
ko is a little unknown gem, lost in the GitHub maze.
ko is widely used in knative development but somehow very little advocacy has been done around this tool.
It allows you to:
- build Go binaries
- containerize them and publish to a registry
- automatically update Kubernetes manifests to references the correct container image
All of this in one single command.
Install
With a working Go environment a simple go get will give you ko:
go get github.com/google/go-containerregistry/cmd/ko
Configure a Registry
To specify the registry that you want to use, set the KO_DOCKER_REPO variable, for instance:
export KO_DOCKER_REPO=gcr.io/triggermesh
Usage
Write a Kubernetes manifest with an import path that is similar to a Go import path like:
apiVersion: apps/v1beta1
kind: Deployment
metadata:
name: hello-world
spec:
...
template:
...
spec:
containers:
- name: hello-world
image: github.com/sebgoa/kodemo/cmd/hello
Then to start the build, containerization and deployment a single ko command is necessary.
ko apply -f config/
You will see a Pod running and you will be able to call your Go function:
$ kubectl get pods
NAME READY STATUS RESTARTS AGE
hello-world-54557f6647-wsng6 1/1 Running 0 50s
$ kubectl port-forward pod/hello-world-54557f6647-wsng6 8080:8080 &
[1] 99038
$ curl localhost:8080
Handling connection for 8080
Hello world !
Build/publish but do not deploy
If all you want to do is build the Go binary and publish an image to the registry then, with the Demo project cloned in your $GOPATH.
ko publish github.com/sebgoa/kodemo/cmd/hello
Demo project
If you want to get started with ko, you can try the kodemo repository is a simple demo project. It has the following structure:
$ tree
.
├── LICENSE
├── README.md
├── cmd
│ └── hello
│ └── hello.go
└── config
└── deploy.yaml
You can certainly build your code locally:
go build cmd/hello/hello.go
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