vitess.io/vitess@v0.16.2/go/vt/vtadmin/cluster/discovery/discovery_static_file.go (about)

     1  /*
     2  Copyright 2020 The Vitess Authors.
     3  
     4  Licensed under the Apache License, Version 2.0 (the "License");
     5  you may not use this file except in compliance with the License.
     6  You may obtain a copy of the License at
     7  
     8      http://www.apache.org/licenses/LICENSE-2.0
     9  
    10  Unless required by applicable law or agreed to in writing, software
    11  distributed under the License is distributed on an "AS IS" BASIS,
    12  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    13  See the License for the specific language governing permissions and
    14  limitations under the License.
    15  */
    16  
    17  package discovery
    18  
    19  import (
    20  	"errors"
    21  	"os"
    22  
    23  	"github.com/spf13/pflag"
    24  
    25  	vtadminpb "vitess.io/vitess/go/vt/proto/vtadmin"
    26  )
    27  
    28  // StaticFileDiscovery implements the Discovery interface for "discovering"
    29  // Vitess components hardcoded in a static JSON file. It inherits from JSONDiscovery.
    30  //
    31  // As an example, here's a minimal JSON file for a single Vitess cluster running locally
    32  // (such as the one described in https://vitess.io/docs/get-started/local-docker):
    33  //
    34  //	{
    35  //		"vtgates": [
    36  //			{
    37  //				"host": {
    38  //					"hostname": "127.0.0.1:15991"
    39  //				}
    40  //			}
    41  //		]
    42  //	}
    43  //
    44  // For more examples of various static file configurations, see the unit tests.
    45  type StaticFileDiscovery struct {
    46  	JSONDiscovery
    47  }
    48  
    49  // NewStaticFile returns a StaticFileDiscovery for the given cluster.
    50  func NewStaticFile(cluster *vtadminpb.Cluster, flags *pflag.FlagSet, args []string) (Discovery, error) {
    51  	disco := &StaticFileDiscovery{
    52  		JSONDiscovery: JSONDiscovery{
    53  			cluster: cluster,
    54  		},
    55  	}
    56  
    57  	filePath := flags.String("path", "", "path to the service discovery JSON config file")
    58  	if err := flags.Parse(args); err != nil {
    59  		return nil, err
    60  	}
    61  
    62  	if filePath == nil || *filePath == "" {
    63  		return nil, errors.New("must specify path to the service discovery JSON config file")
    64  	}
    65  
    66  	b, err := os.ReadFile(*filePath)
    67  	if err != nil {
    68  		return nil, err
    69  	}
    70  
    71  	if err := disco.parseConfig(b); err != nil {
    72  		return nil, err
    73  	}
    74  
    75  	return disco, nil
    76  }