| // Licensed to Apache Software Foundation (ASF) under one or more contributor |
| // license agreements. See the NOTICE file distributed with |
| // this work for additional information regarding copyright |
| // ownership. Apache Software Foundation (ASF) licenses this file to you 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 config |
| |
| import ( |
| "fmt" |
| "strings" |
| |
| "github.com/spf13/pflag" |
| "github.com/spf13/viper" |
| "go.uber.org/multierr" |
| ) |
| |
| const ( |
| // The environment variable prefix of all environment variables bound to our command line flags. |
| envPrefix = "BYDB" |
| ) |
| |
| type config struct { |
| name string |
| viper *viper.Viper |
| } |
| |
| func Load(name string, fs *pflag.FlagSet) error { |
| c := new(config) |
| v := viper.New() |
| c.name = name |
| c.viper = v |
| if err := c.initializeConfig(fs); err != nil { |
| return err |
| } |
| return nil |
| } |
| |
| func (c *config) initializeConfig(fs *pflag.FlagSet) error { |
| v := c.viper |
| |
| // Set the base name of the config file, without the file extension. |
| v.SetConfigName(c.name) |
| |
| // Set as many paths as you like where viper should look for the |
| // config file. We are only looking in the current working directory. |
| v.AddConfigPath(".") |
| |
| // Attempt to read the config file, gracefully ignoring errors |
| // caused by a config file not being found. Return an error |
| // if we cannot parse the config file. |
| if err := v.ReadInConfig(); err != nil { |
| // It's okay if there isn't a config file |
| if _, ok := err.(viper.ConfigFileNotFoundError); !ok { |
| return err |
| } |
| } |
| |
| // When we bind flags to environment variables expect that the |
| // environment variables are prefixed, e.g. a flag like --number |
| // binds to an environment variable STING_NUMBER. This helps |
| // avoid conflicts. |
| v.SetEnvPrefix(envPrefix) |
| |
| // Bind to environment variables |
| // Works great for simple config names, but needs help for names |
| // like --favorite-color which we fix in the bindFlags function |
| v.AutomaticEnv() |
| |
| // Bind the current command's flags to viper |
| return bindFlags(fs, v) |
| } |
| |
| // Bind each cobra flag to its associated viper configuration (config file and environment variable) |
| func bindFlags(fs *pflag.FlagSet, v *viper.Viper) error { |
| var err error |
| fs.VisitAll(func(f *pflag.Flag) { |
| // Environment variables can't have dashes in them, so bind them to their equivalent |
| // keys with underscores. |
| if strings.Contains(f.Name, ".") { |
| envVarSuffix := strings.ToUpper(strings.ReplaceAll(f.Name, ".", "_")) |
| err = multierr.Append(err, v.BindEnv(f.Name, fmt.Sprintf("%s_%s", envPrefix, envVarSuffix))) |
| } |
| |
| // Apply the viper config value to the flag when the flag is not set and viper has a value |
| if !f.Changed && v.IsSet(f.Name) { |
| val := v.Get(f.Name) |
| err = multierr.Append(err, fs.Set(f.Name, fmt.Sprintf("%v", val))) |
| } |
| }) |
| return err |
| } |