Introduce Kubernetes KV interface to etcd client

Signed-off-by: Marek Siarkowicz <siarkowicz@google.com>

client/v3/client.go

@@ -52,6 +52,7 @@ type Client struct {
 	Watcher
 	Auth
 	Maintenance
+	Kubernetes Kubernetes
 
 	conn *grpc.ClientConn
 
@@ -447,6 +448,7 @@ func newClient(cfg *Config) (*Client, error) {
 	client.KV = NewKV(client)
 	client.Lease = NewLease(client)
 	client.Watcher = NewWatcher(client)
+	client.Kubernetes = NewKubernetes(client)
 	client.Auth = NewAuth(client)
 	client.Maintenance = NewMaintenance(client)
 

client/v3/kubernetes.go

@@ -0,0 +1,165 @@
+package clientv3
+
+import (
+	"context"
+
+	pb "go.etcd.io/etcd/api/v3/etcdserverpb"
+	"go.etcd.io/etcd/api/v3/mvccpb"
+)
+
+func NewKubernetes(c *Client) Kubernetes {
+	return &kubernetes{kv: RetryKVClient(c)}
+}
+
+type Kubernetes interface {
+	Get(ctx context.Context, key string, opts GetOptions) (KubernetesGetResponse, error)
+	List(ctx context.Context, prefix string, opts ListOptions) (KubernetesListResponse, error)
+	Count(ctx context.Context, prefix string) (int64, error)
+	OptimisticPut(ctx context.Context, key string, value []byte, opts PutOptions) (KubernetesPutResponse, error)
+	OptimisticDelete(ctx context.Context, key string, opts DeleteOptions) (KubernetesDeleteResponse, error)
+}
+
+type GetOptions struct {
+	Revision int64
+}
+
+type ListOptions struct {
+	Revision int64
+	Limit    int64
+	Continue string
+}
+
+type PutOptions struct {
+	ExpectedRevision int64
+	LeaseID          LeaseID
+}
+
+type DeleteOptions struct {
+	ExpectedRevision int64
+}
+
+type KubernetesGetResponse struct {
+	KV       *mvccpb.KeyValue
+	Revision int64
+}
+
+type KubernetesListResponse struct {
+	KVs      []*mvccpb.KeyValue
+	Count    int64
+	Revision int64
+}
+
+type KubernetesPutResponse struct {
+	KV        *mvccpb.KeyValue
+	Succeeded bool
+	Revision  int64
+}
+
+type KubernetesDeleteResponse struct {
+	KV        *mvccpb.KeyValue
+	Succeeded bool
+	Revision  int64
+}
+
+type kubernetes struct {
+	kv pb.KVClient
+}
+
+func (k kubernetes) Get(ctx context.Context, key string, opts GetOptions) (resp KubernetesGetResponse, err error) {
+	rangeResp, err := k.kv.Range(ctx, &pb.RangeRequest{
+		Key:      []byte(key),
+		Revision: opts.Revision,
+		Limit:    1,
+	})
+	if err != nil {
+		return resp, toErr(ctx, err)
+	}
+	resp.Revision = rangeResp.Header.Revision
+	if len(rangeResp.Kvs) == 1 {
+		resp.KV = rangeResp.Kvs[0]
+	}
+	return resp, nil
+}
+
+func (k kubernetes) List(ctx context.Context, prefix string, opts ListOptions) (resp KubernetesListResponse, err error) {
+	rangeStart := prefix + opts.Continue
+	rangeEnd := GetPrefixRangeEnd(prefix)
+
+	rangeResp, err := k.kv.Range(ctx, &pb.RangeRequest{
+		Key:      []byte(rangeStart),
+		RangeEnd: []byte(rangeEnd),
+		Limit:    opts.Limit,
+		Revision: opts.Revision,
+	})
+	if err != nil {
+		return resp, toErr(ctx, err)
+	}
+	resp.KVs = rangeResp.Kvs
+	resp.Count = rangeResp.Count
+	resp.Revision = rangeResp.Header.Revision
+	return resp, nil
+}
+
+func (k kubernetes) Count(ctx context.Context, prefix string) (int64, error) {
+	resp, err := k.kv.Range(ctx, &pb.RangeRequest{
+		Key:       []byte(prefix),
+		RangeEnd:  []byte(GetPrefixRangeEnd(prefix)),
+		CountOnly: true,
+	})
+	if err != nil {
+		return 0, toErr(ctx, err)
+	}
+	return resp.Count, nil
+}
+
+func (k kubernetes) OptimisticPut(ctx context.Context, key string, value []byte, opts PutOptions) (resp KubernetesPutResponse, err error) {
+	put := &pb.RequestOp{Request: &pb.RequestOp_RequestPut{RequestPut: &pb.PutRequest{Key: []byte(key), Value: value, Lease: int64(opts.LeaseID)}}}
+
+	txnResp, err := k.optimisticTxn(ctx, key, opts.ExpectedRevision, put)
+	if err != nil {
+		return resp, toErr(ctx, err)
+	}
+	resp.Succeeded = txnResp.Succeeded
+	resp.Revision = txnResp.Header.Revision
+	if !txnResp.Succeeded {
+		resp.KV = kvFromTxnResponse(txnResp.Responses[0])
+	}
+	return resp, nil
+}
+
+func (k kubernetes) OptimisticDelete(ctx context.Context, key string, opts DeleteOptions) (resp KubernetesDeleteResponse, err error) {
+	del := &pb.RequestOp{Request: &pb.RequestOp_RequestDeleteRange{RequestDeleteRange: &pb.DeleteRangeRequest{Key: []byte(key)}}}
+
+	txnResp, err := k.optimisticTxn(ctx, key, opts.ExpectedRevision, del)
+	if err != nil {
+		return resp, toErr(ctx, err)
+	}
+	resp.Succeeded = txnResp.Succeeded
+	resp.Revision = txnResp.Header.Revision
+	if !txnResp.Succeeded {
+		resp.KV = kvFromTxnResponse(txnResp.Responses[0])
+	}
+	return resp, nil
+}
+
+func (k kubernetes) optimisticTxn(ctx context.Context, key string, expectRevision int64, onSuccess *pb.RequestOp) (*pb.TxnResponse, error) {
+	txn := &pb.TxnRequest{
+		Compare: []*pb.Compare{&pb.Compare{
+			Result:      pb.Compare_EQUAL,
+			Target:      pb.Compare_MOD,
+			Key:         []byte(key),
+			TargetUnion: &pb.Compare_ModRevision{ModRevision: expectRevision},
+		}},
+		Success: []*pb.RequestOp{onSuccess},
+		Failure: []*pb.RequestOp{{Request: &pb.RequestOp_RequestRange{RequestRange: &pb.RangeRequest{Key: []byte(key), Limit: 1}}}},
+	}
+	return k.kv.Txn(ctx, txn)
+}
+
+func kvFromTxnResponse(resp *pb.ResponseOp) *mvccpb.KeyValue {
+	getResponse := resp.GetResponseRange()
+	if len(getResponse.Kvs) == 1 {
+		return getResponse.Kvs[0]
+	}
+	return nil
+}