simplify webhook DNS further generalize for gateway (#10448)

continuation of the changes from eaaf05a7cc
this further simplifies, enables this for gateway deployments as well

cmd/config/dns/operator_dns.go

@@ -0,0 +1,221 @@
+/*
+ * MinIO Cloud Storage, (C) 2020 MinIO, Inc.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package dns
+
+import (
+	"context"
+	"crypto/tls"
+	"crypto/x509"
+	"errors"
+	"fmt"
+	"net"
+	"net/http"
+	"net/url"
+	"strconv"
+	"time"
+
+	"github.com/dgrijalva/jwt-go"
+	"github.com/minio/minio/cmd/config"
+	xhttp "github.com/minio/minio/cmd/http"
+)
+
+var (
+	defaultOperatorContextTimeout = 10 * time.Second
+	// ErrNotImplemented - Indicates the functionality which is not implemented
+	ErrNotImplemented = errors.New("The method is not implemented")
+)
+
+func (c *OperatorDNS) addAuthHeader(r *http.Request) error {
+	if c.username == "" || c.password == "" {
+		return nil
+	}
+
+	claims := &jwt.StandardClaims{
+		ExpiresAt: int64(15 * time.Minute),
+		Issuer:    c.username,
+		Subject:   config.EnvDNSWebhook,
+	}
+
+	token := jwt.NewWithClaims(jwt.SigningMethodHS512, claims)
+	ss, err := token.SignedString([]byte(c.password))
+	if err != nil {
+		return err
+	}
+
+	r.Header.Set("Authorization", "Bearer "+ss)
+	return nil
+}
+
+func (c *OperatorDNS) endpoint(bucket string, delete bool) (string, error) {
+	u, err := url.Parse(c.Endpoint)
+	if err != nil {
+		return "", err
+	}
+	q := u.Query()
+	q.Add("bucket", bucket)
+	q.Add("delete", strconv.FormatBool(delete))
+	u.RawQuery = q.Encode()
+	return u.String(), nil
+}
+
+// Put - Adds DNS entries into operator webhook server
+func (c *OperatorDNS) Put(bucket string) error {
+	ctx, cancel := context.WithTimeout(context.Background(), defaultOperatorContextTimeout)
+	defer cancel()
+	e, err := c.endpoint(bucket, false)
+	if err != nil {
+		return err
+	}
+	req, err := http.NewRequestWithContext(ctx, http.MethodPost, e, nil)
+	if err != nil {
+		return err
+	}
+	if err = c.addAuthHeader(req); err != nil {
+		return err
+	}
+	resp, err := c.httpClient.Do(req)
+	if err != nil {
+		if derr := c.Delete(bucket); derr != nil {
+			return derr
+		}
+	}
+	xhttp.DrainBody(resp.Body)
+	if resp.StatusCode != http.StatusOK {
+		return fmt.Errorf("request to create the service for bucket %s, failed with status %s", bucket, resp.Status)
+	}
+	return nil
+}
+
+// Delete - Removes DNS entries added in Put().
+func (c *OperatorDNS) Delete(bucket string) error {
+	ctx, cancel := context.WithTimeout(context.Background(), defaultOperatorContextTimeout)
+	defer cancel()
+	e, err := c.endpoint(bucket, true)
+	if err != nil {
+		return err
+	}
+	req, err := http.NewRequestWithContext(ctx, http.MethodPost, e, nil)
+	if err != nil {
+		return err
+	}
+	if err = c.addAuthHeader(req); err != nil {
+		return err
+	}
+	resp, err := c.httpClient.Do(req)
+	if err != nil {
+		return err
+	}
+	xhttp.DrainBody(resp.Body)
+	if resp.StatusCode != http.StatusOK {
+		return fmt.Errorf("request to delete the service for bucket %s, failed with status %s", bucket, resp.Status)
+	}
+	return nil
+}
+
+// DeleteRecord - Removes a specific DNS entry
+// No Op for Operator because operator deals on with bucket entries
+func (c *OperatorDNS) DeleteRecord(record SrvRecord) error {
+	return ErrNotImplemented
+}
+
+// Close closes the internal http client
+func (c *OperatorDNS) Close() error {
+	c.httpClient.CloseIdleConnections()
+	return nil
+}
+
+// List - Retrieves list of DNS entries for the domain.
+// This is a No Op for Operator because, there is no intent to enforce global
+// namespace at MinIO level with this DNS entry. The global namespace in
+// enforced by the Kubernetes Operator
+func (c *OperatorDNS) List() (srvRecords map[string][]SrvRecord, err error) {
+	return nil, ErrNotImplemented
+}
+
+// Get - Retrieves DNS records for a bucket.
+// This is a No Op for Operator because, there is no intent to enforce global
+// namespace at MinIO level with this DNS entry. The global namespace in
+// enforced by the Kubernetes Operator
+func (c *OperatorDNS) Get(bucket string) (srvRecords []SrvRecord, err error) {
+	return nil, ErrNotImplemented
+}
+
+// String stringer name for this implementation of dns.Store
+func (c *OperatorDNS) String() string {
+	return "webhookDNS"
+}
+
+// OperatorDNS - represents dns config for MinIO k8s operator.
+type OperatorDNS struct {
+	httpClient *http.Client
+	Endpoint   string
+	rootCAs    *x509.CertPool
+	username   string
+	password   string
+}
+
+// OperatorOption - functional options pattern style for OperatorDNS
+type OperatorOption func(*OperatorDNS)
+
+// Authentication - custom username and password for authenticating at the endpoint
+func Authentication(username, password string) OperatorOption {
+	return func(args *OperatorDNS) {
+		args.username = username
+		args.password = password
+	}
+}
+
+// RootCAs - add custom trust certs pool
+func RootCAs(CAs *x509.CertPool) OperatorOption {
+	return func(args *OperatorDNS) {
+		args.rootCAs = CAs
+	}
+}
+
+// NewOperatorDNS - initialize a new K8S Operator DNS set/unset values.
+func NewOperatorDNS(endpoint string, setters ...OperatorOption) (Store, error) {
+	if endpoint == "" {
+		return nil, errors.New("invalid argument")
+	}
+
+	args := &OperatorDNS{
+		Endpoint: endpoint,
+	}
+	for _, setter := range setters {
+		setter(args)
+	}
+	args.httpClient = &http.Client{
+		Transport: &http.Transport{
+			Proxy: http.ProxyFromEnvironment,
+			DialContext: (&net.Dialer{
+				Timeout:   3 * time.Second,
+				KeepAlive: 5 * time.Second,
+			}).DialContext,
+			ResponseHeaderTimeout: 3 * time.Second,
+			TLSHandshakeTimeout:   3 * time.Second,
+			ExpectContinueTimeout: 3 * time.Second,
+			TLSClientConfig: &tls.Config{
+				RootCAs: args.rootCAs,
+			},
+			// Go net/http automatically unzip if content-type is
+			// gzip disable this feature, as we are always interested
+			// in raw stream.
+			DisableCompression: true,
+		},
+	}
+	return args, nil
+}