README
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kuberesolver
A Grpc name resolver by using kubernetes API. It comes with a small ~250 LOC kubernetes client to find service endpoints. Therefore it won't bloat your binaries.
USAGE
// Import the module
import "github.com/sercand/kuberesolver/v6"
// Register kuberesolver to grpc before calling grpc.Dial
kuberesolver.RegisterInCluster()
// it is same as
resolver.Register(kuberesolver.NewBuilder(nil /*custom kubernetes client*/ , "kubernetes"))
// if schema is 'kubernetes' then grpc will use kuberesolver to resolve addresses
cc, err := grpc.Dial("kubernetes:///service.namespace:portname", opts...)
An url can be one of the following, grpc naming docs
kubernetes:///service-name:8080
kubernetes:///service-name:portname
kubernetes:///service-name.namespace:8080
kubernetes:///service-name.namespace.svc.cluster_name
kubernetes:///service-name.namespace.svc.cluster_name:8080
kubernetes://namespace/service-name:8080
kubernetes://service-name:8080/
kubernetes://service-name.namespace:8080/
kubernetes://service-name.namespace.svc.cluster_name
kubernetes://service-name.namespace.svc.cluster_name:8080
* Please note that the cluster_name is not used in resolving the endpoints of a Service. It is only there to support fully qualified service names, e.g. test.default.svc.cluster.local.
Using alternative Schema
Use RegisterInClusterWithSchema(schema) instead of RegisterInCluster on start.
Client Side Load Balancing
You need to pass grpc.WithBalancerName option to grpc on dial:
grpc.DialContext(ctx, "kubernetes:///service:grpc", grpc.WithBalancerName("round_robin"), grpc.WithInsecure())
This will create subconnections for each available service endpoints.
How is this different from dialing to service.namespace:8080
Connecting to a service by dialing to service.namespace:8080 uses DNS and it returns service stable IP. Therefore, gRPC doesn't know the endpoint IP addresses and it fails to reconnect to target services in case of failure.
Kuberesolver uses kubernetes API to get and watch service endpoint IP addresses. Since it provides and updates all available service endpoints, together with a client-side balancer you can achive zero downtime deployments.
RBAC
You need give GET and WATCH access to the endpointslices if you are using RBAC in your cluster.
Using With TLS
You need to a certificate with name service-name.namespace in order to connect with TLS to your services.
Documentation
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Index ¶
Constants ¶
This section is empty.
Variables ¶
This section is empty.
Functions ¶
func NewBuilder ¶
NewBuilder creates a kubeBuilder which is used by grpc resolver.
func RegisterInCluster ¶
func RegisterInCluster()
RegisterInCluster registers the kuberesolver builder to grpc with kubernetes schema
func RegisterInClusterWithSchema ¶
func RegisterInClusterWithSchema(schema string)
RegisterInClusterWithSchema registers the kuberesolver builder to the grpc with custom schema
Types ¶
type Endpoint ¶
type Endpoint struct {
Addresses []string
Conditions EndpointConditions
}
type EndpointConditions ¶
type EndpointPort ¶
type EndpointSlice ¶
type EndpointSlice struct {
Endpoints []Endpoint
Ports []EndpointPort
}
type EndpointSliceList ¶
type EndpointSliceList struct {
Items []EndpointSlice
}
type Event ¶
type Event struct {
Type EventType `json:"type"`
Object EndpointSlice `json:"object"`
}
Event represents a single event to a watched resource.
type K8sClient ¶
type K8sClient interface {
Do(req *http.Request) (*http.Response, error)
GetRequest(url string) (*http.Request, error)
Host() string
}
K8sClient is minimal kubernetes client interface
func NewInClusterK8sClient ¶
NewInClusterK8sClient creates K8sClient if it is inside Kubernetes
func NewInsecureK8sClient ¶
NewInsecureK8sClient creates an insecure k8s client which is suitable to connect kubernetes api behind proxy
Source Files