Kubernetes configmaps

[mschoenlaub]

Description

This PR adds initial support for JSON and YAML encoded flag data in a Kubernetes ConfigMap.

Changes include

• Bugfix (non-breaking change that solves an issue)
• New feature (non-breaking change that adds functionality)
• Breaking changes (change that is not backward-compatible and/or changes current functionality)

Closes issue(s)

Resolve #213

Checklist

• I have tested this code
• I have added unit test to cover this code
• I have updated the documentation (README.md and /docs)
• I have followed the contributing guide

[mschoenlaub]

FTR: I have to test it later. Right now I don't have access to a Kubernetes cluster.

[coveralls]

Coverage decreased (-0.2%) to 93.919% when pulling f6b5e9a on mschoenlaub:kubernetes-configmaps into 1044928 on thomaspoignant:main.

[thomaspoignant]

FTR: I have to test it later. Right now I don't have access to a Kubernetes cluster.

Hello @mschoenlaub, let me know when you are happy with your pull request and I will have a look.

[mschoenlaub]

@thomaspoignant Finally I could test it against GKE.

What we have as of now, is a solution to store the config file under a specific key in a config map.

E.g. once you did

kubectl create configmap my-config --from-file=flags.yml=./flags.yml

a config like this:

err = ffclient.Init(ffclient.Config{
    PollingInterval: 3 * time.Second,
    Retriever: &ffclient.KubernetesRetriever{
        Namespace:      "default"
        ConfigMapName: "my-config"
        Key:    "flags.yml"
        ClientConfig: &config
    },
})

will do the right thing.

[thomaspoignant]

@mschoenlaub thanks a lot for your contribution this is awesome.
I will take the time to test it and give you a review.

It could be great to have an example in example/ too.
I can do it if you want.

[sonarcloud]

Kudos, SonarCloud Quality Gate passed!   

0 Bugs
0 Vulnerabilities
0 Security Hotspots
0 Code Smells

No Coverage information
0.0% Duplication

[thomaspoignant]

@mschoenlaub I have tested your solution and it is all fine for me.
As mentioned I have added an example using minikube to test the retriever.
I let you have a look if you have any complaints about it.

I've also edit some stuff in the documentation.

Thanks a lot for your contribution this is awesome 🙏

[marcosnils]

great progress @mschoenlaub. Awesome that you made this happen!

[mschoenlaub]

@thomaspoignant Sorry for getting back so late. Got caught up in life somewhow :D
Great example. Changes in MD also look fine to me.
Learnt something new: Those horizontal lines in the table seem to be optional.

Though I am gonna have one nitpick for the example: "// Init ffclient with an http retriever." seems to be a copy/paste error ;-)

Thanks for getting that in so fast.

[thomaspoignant]

Thanks for the copy/paste error I'll fix this.