Add static file service discovery implementation

Signed-off-by: Sara Bee <855595+doeg@users.noreply.github.com>

docker/local/run.sh

@@ -1,3 +1,3 @@
 #!/bin/bash
 
-docker run -p 15000:15000 -p 15001:15001 --rm -it vitess/local
+docker run -p 15000:15000 -p 15001:15001 -p 15991:15991 --rm -it vitess/local

go/vt/vtadmin/cluster/discovery/discovery.go

@@ -91,4 +91,5 @@ func New(impl string, cluster *vtadminpb.Cluster, args []string) (Discovery, err
 
 func init() { // nolint:gochecknoinits
  Register("consul", NewConsul)
+ Register("staticFile", NewStaticFile)
 }

go/vt/vtadmin/cluster/discovery/discovery_static_file.go

@@ -0,0 +1,161 @@
+/*
+Copyright 2020 The Vitess Authors.
+
+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 discovery
+
+import (
+ "context"
+ "encoding/json"
+ "errors"
+ "io/ioutil"
+ "math/rand"
+
+ "github.com/spf13/pflag"
+ vtadminpb "vitess.io/vitess/go/vt/proto/vtadmin"
+)
+
+// StaticFileDiscovery implements the Discovery interface for "discovering"
+// Vitess components hardcoded in a static .json file.
+type StaticFileDiscovery struct {
+ cluster *vtadminpb.Cluster
+ config *StaticFileClusterConfig
+ gates struct {
+ byName map[string]*vtadminpb.VTGate
+ byTag map[string][]*vtadminpb.VTGate
+ }
+}
+
+// StaticFileClusterConfig configures Vitess components for a single cluster.
+type StaticFileClusterConfig struct {
+ VTGates []*StaticFileVTGateConfig `json:"vtgates,omitempty"`
+}
+
+// StaticFileVTGateConfig contains host and tag information for a single VTGate in a cluster.
+type StaticFileVTGateConfig struct {
+ Host *vtadminpb.VTGate `json:"host"`
+ Tags []string `json:"tags"`
+}
+
+// NewStaticFile returns a StaticFileDiscovery for the given cluster.
+func NewStaticFile(cluster *vtadminpb.Cluster, flags *pflag.FlagSet, args []string) (Discovery, error) {
+ disco := &StaticFileDiscovery{
+ cluster: cluster,
+ }
+
+ filePath := flags.String("path", "", "path to the service discovery JSON config file")
+ if err := flags.Parse(args); err != nil {
+ return nil, err
+ }
+
+ if filePath == nil || *filePath == "" {
+ return nil, errors.New("must specify path to the service discovery JSON config file")
+ }
+
+ b, err := ioutil.ReadFile(*filePath)
+ if err != nil {
+ return nil, err
+ }
+
+ if err := disco.parseConfig(b); err != nil {
+ return nil, err
+ }
+
+ return disco, nil
+}
+
+func (d *StaticFileDiscovery) parseConfig(bytes []byte) error {
+ if err := json.Unmarshal(bytes, &d.config); err != nil {
+ return err
+ }
+
+ d.gates.byName = make(map[string]*vtadminpb.VTGate, len(d.config.VTGates))
+ d.gates.byTag = make(map[string][]*vtadminpb.VTGate)
+
+ // Index the gates by name and by tag for easier lookups
+ for _, gate := range d.config.VTGates {
+ d.gates.byName[gate.Host.Hostname] = gate.Host
+
+ for _, tag := range gate.Tags {
+ d.gates.byTag[tag] = append(d.gates.byTag[tag], gate.Host)
+ }
+ }
+ return nil
+}
+
+// DiscoverVTGate is part of the Discovery interface.
+func (d *StaticFileDiscovery) DiscoverVTGate(ctx context.Context, tags []string) (*vtadminpb.VTGate, error) {
+ gates, err := d.DiscoverVTGates(ctx, tags)
+ if err != nil {
+ return nil, err
+ }
+
+ count := len(gates)
+ if count == 0 {
+ return nil, ErrNoVTGates
+ }
+
+ gate := gates[rand.Intn(len(gates))]
+ return gate, nil
+}
+
+// DiscoverVTGateAddr is part of the Discovery interface.
+func (d *StaticFileDiscovery) DiscoverVTGateAddr(ctx context.Context, tags []string) (string, error) {
+ gate, err := d.DiscoverVTGate(ctx, tags)
+ if err != nil {
+ return "", err
+ }
+
+ return gate.Hostname, nil
+}
+
+// DiscoverVTGates is part of the Discovery interface.
+func (d *StaticFileDiscovery) DiscoverVTGates(ctx context.Context, tags []string) ([]*vtadminpb.VTGate, error) {
+ if len(tags) == 0 {
+ results := []*vtadminpb.VTGate{}
+ for _, g := range d.gates.byName {
+ results = append(results, g)
+ }
+
+ return results, nil
+ }
+
+ set := d.gates.byName
+
+ for _, tag := range tags {
+ intermediate := map[string]*vtadminpb.VTGate{}
+
+ gates, ok := d.gates.byTag[tag]
+ if !ok {
+ return []*vtadminpb.VTGate{}, nil
+ }
+
+ for _, g := range gates {
+ if _, ok := set[g.Hostname]; ok {
+ intermediate[g.Hostname] = g
+ }
+ }
+
+ set = intermediate
+ }
+
+ results := make([]*vtadminpb.VTGate, 0, len(set))
+
+ for _, gate := range set {
+ results = append(results, gate)
+ }
+
+ return results, nil
+}