go-micro/plugins/config/source/configmap

Kubernetes ConfigMap Source (configmap)

The configmap source reads config from a kubernetes configmap key/values

Kubernetes ConfigMap Format

The configmap source expects keys under a namespace default to default and a confimap default to micro

// we recommend to setup your variables from multiples files example:
$ kubectl create configmap micro --namespace default --from-file=./testdata

// verify if were set correctly with
$ kubectl get configmap micro --namespace default
{
    "apiVersion": "v1",
    "data": {
        "config": "host=0.0.0.0\nport=1337",
        "mongodb": "host=127.0.0.1\nport=27017\nuser=user\npassword=password",
        "redis": "url=redis://127.0.0.1:6379/db01"
    },
    "kind": "ConfigMap",
    "metadata": {
        ...
        "name": "micro",
        "namespace": "default",
        ...
    }
}

Keys are split on \n and = this is because the way kubernetes saves the data is map[string][string].

// the example above "mongodb": "host=127.0.0.1\nport=27017\nuser=user\npassword=password" will be accessible as:
conf.Get("mongodb", "host") // 127.0.0.1
conf.Get("mongodb", "port") // 27017

Kubernetes wrights

Since Kubernetes 1.9 the app must have wrights to be able to access configmaps. You must provide Role and RoleBinding so that your app can access configmaps.

kind: Role
apiVersion: rbac.authorization.k8s.io/v1
metadata:
  name: api-role
  labels:
    app: tools-rbac
rules:
- apiGroups: [""]
  resources: ["configmaps"]
  verbs: ["get", "update", "list", "watch"]
---
kind: RoleBinding
apiVersion: rbac.authorization.k8s.io/v1
metadata:
  name: global-rolebinding
  labels:
    app: tools-rbac
subjects:
- kind: Group
  name: system:serviceaccounts
  apiGroup: rbac.authorization.k8s.io
roleRef:
  kind: Role
  name: api-role
  apiGroup: ""

To configure your Kubernetes cluster just apply the file:

kubectl apply -n YourNameSpace -f role.yaml

New Source

Specify source with data

configmapSource := configmap.NewSource(
	// optionally specify a namespace; default to default
	configmap.WithNamespace("kube-public"),
	// optionally specify name for ConfigMap; defaults micro
	configmap.WithName("micro-config"),
    // optionally strip the provided path to a kube config file mostly used outside of a cluster, defaults to "" for in cluster support.
    configmap.WithConfigPath($HOME/.kube/config),
)

Load Source

Load the source into config

// Create new config
conf := config.NewConfig()

// Load file source
conf.Load(configmapSource)

Running Go Tests

Requirements

Have a kubernetes cluster running (external or minikube) have a valid kubeconfig file.

// Setup testing configmaps feel free to remove them after testing.
$ cd source/configmap
$ kubectl create configmap micro --from-file=./testdata
$ kubectl create configmap micro --from-file=./testdata --namespace kube-public
$ kubectl create configmap micro-config --from-file=./testdata
$ kubectl create configmap micro-config --from-file=./testdata --namespace kube-public
$ go test -v -cover

// To clean up the testing configmaps
$ kubectl delete configmap micro --all-namespaces
$ kubectl delete configmap micro-config --all-namespaces

Todos

• add more test cases including watchers
• add support for prefixing either using namespace or a custom string passed as WithPrefix
• a better way to test without manual setup from the user.
• add test examples.
• open to suggestions and feedback please let me know what else should I add.

stay tuned for kubernetes secret support as an source.