config.go

/*
Copyright 2021 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 vtctldclient

import (
	"context"
	"fmt"

	"github.com/spf13/pflag"
	"google.golang.org/grpc"

	"vitess.io/vitess/go/vt/grpcclient"
	"vitess.io/vitess/go/vt/vtadmin/cluster/discovery"
	"vitess.io/vitess/go/vt/vtadmin/cluster/resolver"
	"vitess.io/vitess/go/vt/vtadmin/credentials"
	"vitess.io/vitess/go/vt/vtctl/vtctldclient"

	vtadminpb "vitess.io/vitess/go/vt/proto/vtadmin"
)

// Config represents the options that modify the behavior of a Proxy.
type Config struct {
	Credentials     *grpcclient.StaticAuthClientCreds
	CredentialsPath string

	Cluster *vtadminpb.Cluster

	ResolverOptions *resolver.Options

	dialFunc func(ctx context.Context, addr string, ff grpcclient.FailFast, opts ...grpc.DialOption) (vtctldclient.VtctldClient, error)
}

// ConfigOption is a function that mutates a Config. It should return the same
// Config structure, in a builder-pattern style.
type ConfigOption func(cfg *Config) *Config

// WithDialFunc returns a ConfigOption that applies the given dial function to
// a Config.
//
// It is used to support dependency injection in tests, and needs to be exported
// for higher-level tests (via vtadmin/testutil).
func WithDialFunc(f func(ctx context.Context, addr string, ff grpcclient.FailFast, opts ...grpc.DialOption) (vtctldclient.VtctldClient, error)) ConfigOption {
	return func(cfg *Config) *Config {
		cfg.dialFunc = f
		return cfg
	}
}

// Parse returns a new config with the given cluster and discovery, after
// attempting to parse the command-line pflags into that Config. See
// (*Config).Parse() for more details.
func Parse(cluster *vtadminpb.Cluster, disco discovery.Discovery, args []string) (*Config, error) {
	cfg := &Config{
		Cluster: cluster,
		ResolverOptions: &resolver.Options{
			Discovery: disco,
		},
	}

	err := cfg.Parse(args)
	if err != nil {
		return nil, err
	}

	return cfg, nil
}

// Parse reads options specified as command-line pflags (--key=value, note the
// double-dash!) into a Config. It is meant to be called from
// (*cluster.Cluster).New().
func (c *Config) Parse(args []string) error {
	fs := pflag.NewFlagSet("", pflag.ContinueOnError)

	if c.ResolverOptions == nil {
		c.ResolverOptions = &resolver.Options{}
	}

	c.ResolverOptions.InstallFlags(fs)

	credentialsTmplStr := fs.String("credentials-path-tmpl", "",
		"Go template used to specify a path to a credentials file, which is a json file containing "+
			"a Username and Password. Templates are given the context of the vtctldclient.Config, "+
			"and primarily interoplate the cluster name and ID variables.")

	if err := fs.Parse(args); err != nil {
		return err
	}

	if *credentialsTmplStr != "" {
		creds, path, err := credentials.LoadFromTemplate(*credentialsTmplStr, c)
		if err != nil {
			return fmt.Errorf("cannot load credentials from path template %s: %w", *credentialsTmplStr, err)
		}

		c.CredentialsPath = path
		c.Credentials = creds
	}

	return nil
}