README

Viper

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Go configuration with fangs!

Many Go projects are built using Viper including:

Install

go get github.com/spf13/viper

What is Viper?

Viper is a complete configuration solution for Go applications including 12-Factor apps. It is designed to work within an application, and can handle all types of configuration needs and formats. It supports:

  • setting defaults
  • reading from JSON, TOML, YAML, HCL, envfile and Java properties config files
  • live watching and re-reading of config files (optional)
  • reading from environment variables
  • reading from remote config systems (etcd or Consul), and watching changes
  • reading from command line flags
  • reading from buffer
  • setting explicit values

Viper can be thought of as a registry for all of your applications configuration needs.

Why Viper?

When building a modern application, you don’t want to worry about configuration file formats; you want to focus on building awesome software. Viper is here to help with that.

Viper does the following for you:

  1. Find, load, and unmarshal a configuration file in JSON, TOML, YAML, HCL, INI, envfile or Java properties formats.
  2. Provide a mechanism to set default values for your different configuration options.
  3. Provide a mechanism to set override values for options specified through command line flags.
  4. Provide an alias system to easily rename parameters without breaking existing code.
  5. Make it easy to tell the difference between when a user has provided a command line or config file which is the same as the default.

Viper uses the following precedence order. Each item takes precedence over the item below it:

  • explicit call to Set
  • flag
  • env
  • config
  • key/value store
  • default

Important: Viper configuration keys are case insensitive. There are ongoing discussions about making that optional.

Putting Values into Viper

Establishing Defaults

A good configuration system will support default values. A default value is not required for a key, but it’s useful in the event that a key hasn't been set via config file, environment variable, remote configuration or flag.

Examples:

viper.SetDefault("ContentDir", "content")
viper.SetDefault("LayoutDir", "layouts")
viper.SetDefault("Taxonomies", map[string]string{"tag": "tags", "category": "categories"})

Reading Config Files

Viper requires minimal configuration so it knows where to look for config files. Viper supports JSON, TOML, YAML, HCL, INI, envfile and Java Properties files. Viper can search multiple paths, but currently a single Viper instance only supports a single configuration file. Viper does not default to any configuration search paths leaving defaults decision to an application.

Here is an example of how to use Viper to search for and read a configuration file. None of the specific paths are required, but at least one path should be provided where a configuration file is expected.

viper.SetConfigName("config") // name of config file (without extension)
viper.SetConfigType("yaml") // REQUIRED if the config file does not have the extension in the name
viper.AddConfigPath("/etc/appname/")   // path to look for the config file in
viper.AddConfigPath("$HOME/.appname")  // call multiple times to add many search paths
viper.AddConfigPath(".")               // optionally look for config in the working directory
err := viper.ReadInConfig() // Find and read the config file
if err != nil { // Handle errors reading the config file
	panic(fmt.Errorf("Fatal error config file: %s \n", err))
}

You can handle the specific case where no config file is found like this:

if err := viper.ReadInConfig(); err != nil {
    if _, ok := err.(viper.ConfigFileNotFoundError); ok {
        // Config file not found; ignore error if desired
    } else {
        // Config file was found but another error was produced
    }
}

// Config file found and successfully parsed

NOTE [since 1.6]: You can also have a file without an extension and specify the format programmaticaly. For those configuration files that lie in the home of the user without any extension like .bashrc

Writing Config Files

Reading from config files is useful, but at times you want to store all modifications made at run time. For that, a bunch of commands are available, each with its own purpose:

  • WriteConfig - writes the current viper configuration to the predefined path, if exists. Errors if no predefined path. Will overwrite the current config file, if it exists.
  • SafeWriteConfig - writes the current viper configuration to the predefined path. Errors if no predefined path. Will not overwrite the current config file, if it exists.
  • WriteConfigAs - writes the current viper configuration to the given filepath. Will overwrite the given file, if it exists.
  • SafeWriteConfigAs - writes the current viper configuration to the given filepath. Will not overwrite the given file, if it exists.

As a rule of the thumb, everything marked with safe won't overwrite any file, but just create if not existent, whilst the default behavior is to create or truncate.

A small examples section:

viper.WriteConfig() // writes current config to predefined path set by 'viper.AddConfigPath()' and 'viper.SetConfigName'
viper.SafeWriteConfig()
viper.WriteConfigAs("/path/to/my/.config")
viper.SafeWriteConfigAs("/path/to/my/.config") // will error since it has already been written
viper.SafeWriteConfigAs("/path/to/my/.other_config")

Watching and re-reading config files

Viper supports the ability to have your application live read a config file while running.

Gone are the days of needing to restart a server to have a config take effect, viper powered applications can read an update to a config file while running and not miss a beat.

Simply tell the viper instance to watchConfig. Optionally you can provide a function for Viper to run each time a change occurs.

Make sure you add all of the configPaths prior to calling WatchConfig()

viper.WatchConfig()
viper.OnConfigChange(func(e fsnotify.Event) {
	fmt.Println("Config file changed:", e.Name)
})

Reading Config from io.Reader

Viper predefines many configuration sources such as files, environment variables, flags, and remote K/V store, but you are not bound to them. You can also implement your own required configuration source and feed it to viper.

viper.SetConfigType("yaml") // or viper.SetConfigType("YAML")

// any approach to require this configuration into your program.
var yamlExample = []byte(`
Hacker: true
name: steve
hobbies:
- skateboarding
- snowboarding
- go
clothing:
  jacket: leather
  trousers: denim
age: 35
eyes : brown
beard: true
`)

viper.ReadConfig(bytes.NewBuffer(yamlExample))

viper.Get("name") // this would be "steve"

Setting Overrides

These could be from a command line flag, or from your own application logic.

viper.Set("Verbose", true)
viper.Set("LogFile", LogFile)

Registering and Using Aliases

Aliases permit a single value to be referenced by multiple keys

viper.RegisterAlias("loud", "Verbose")

viper.Set("verbose", true) // same result as next line
viper.Set("loud", true)   // same result as prior line

viper.GetBool("loud") // true
viper.GetBool("verbose") // true

Working with Environment Variables

Viper has full support for environment variables. This enables 12 factor applications out of the box. There are five methods that exist to aid working with ENV:

  • AutomaticEnv()
  • BindEnv(string...) : error
  • SetEnvPrefix(string)
  • SetEnvKeyReplacer(string...) *strings.Replacer
  • AllowEmptyEnv(bool)

When working with ENV variables, it’s important to recognize that Viper treats ENV variables as case sensitive.

Viper provides a mechanism to try to ensure that ENV variables are unique. By using SetEnvPrefix, you can tell Viper to use a prefix while reading from the environment variables. Both BindEnv and AutomaticEnv will use this prefix.

BindEnv takes one or two parameters. The first parameter is the key name, the second is the name of the environment variable. The name of the environment variable is case sensitive. If the ENV variable name is not provided, then Viper will automatically assume that the ENV variable matches the following format: prefix + "_" + the key name in ALL CAPS. When you explicitly provide the ENV variable name (the second parameter), it does not automatically add the prefix. For example if the second parameter is "id", Viper will look for the ENV variable "ID".

One important thing to recognize when working with ENV variables is that the value will be read each time it is accessed. Viper does not fix the value when the BindEnv is called.

AutomaticEnv is a powerful helper especially when combined with SetEnvPrefix. When called, Viper will check for an environment variable any time a viper.Get request is made. It will apply the following rules. It will check for a environment variable with a name matching the key uppercased and prefixed with the EnvPrefix if set.

SetEnvKeyReplacer allows you to use a strings.Replacer object to rewrite Env keys to an extent. This is useful if you want to use - or something in your Get() calls, but want your environmental variables to use _ delimiters. An example of using it can be found in viper_test.go.

Alternatively, you can use EnvKeyReplacer with NewWithOptions factory function. Unlike SetEnvKeyReplacer, it accepts a StringReplacer interface allowing you to write custom string replacing logic.

By default empty environment variables are considered unset and will fall back to the next configuration source. To treat empty environment variables as set, use the AllowEmptyEnv method.

Env example
SetEnvPrefix("spf") // will be uppercased automatically
BindEnv("id")

os.Setenv("SPF_ID", "13") // typically done outside of the app

id := Get("id") // 13

Working with Flags

Viper has the ability to bind to flags. Specifically, Viper supports Pflags as used in the Cobra library.

Like BindEnv, the value is not set when the binding method is called, but when it is accessed. This means you can bind as early as you want, even in an init() function.

For individual flags, the BindPFlag() method provides this functionality.

Example:

serverCmd.Flags().Int("port", 1138, "Port to run Application server on")
viper.BindPFlag("port", serverCmd.Flags().Lookup("port"))

You can also bind an existing set of pflags (pflag.FlagSet):

Example:

pflag.Int("flagname", 1234, "help message for flagname")

pflag.Parse()
viper.BindPFlags(pflag.CommandLine)

i := viper.GetInt("flagname") // retrieve values from viper instead of pflag

The use of pflag in Viper does not preclude the use of other packages that use the flag package from the standard library. The pflag package can handle the flags defined for the flag package by importing these flags. This is accomplished by a calling a convenience function provided by the pflag package called AddGoFlagSet().

Example:

package main

import (
	"flag"
	"github.com/spf13/pflag"
)

func main() {

	// using standard library "flag" package
	flag.Int("flagname", 1234, "help message for flagname")

	pflag.CommandLine.AddGoFlagSet(flag.CommandLine)
	pflag.Parse()
	viper.BindPFlags(pflag.CommandLine)

	i := viper.GetInt("flagname") // retrieve value from viper

	...
}
Flag interfaces

Viper provides two Go interfaces to bind other flag systems if you don’t use Pflags.

FlagValue represents a single flag. This is a very simple example on how to implement this interface:

type myFlag struct {}
func (f myFlag) HasChanged() bool { return false }
func (f myFlag) Name() string { return "my-flag-name" }
func (f myFlag) ValueString() string { return "my-flag-value" }
func (f myFlag) ValueType() string { return "string" }

Once your flag implements this interface, you can simply tell Viper to bind it:

viper.BindFlagValue("my-flag-name", myFlag{})

FlagValueSet represents a group of flags. This is a very simple example on how to implement this interface:

type myFlagSet struct {
	flags []myFlag
}

func (f myFlagSet) VisitAll(fn func(FlagValue)) {
	for _, flag := range flags {
		fn(flag)
	}
}

Once your flag set implements this interface, you can simply tell Viper to bind it:

fSet := myFlagSet{
	flags: []myFlag{myFlag{}, myFlag{}},
}
viper.BindFlagValues("my-flags", fSet)

Remote Key/Value Store Support

To enable remote support in Viper, do a blank import of the viper/remote package:

import _ "github.com/spf13/viper/remote"

Viper will read a config string (as JSON, TOML, YAML, HCL or envfile) retrieved from a path in a Key/Value store such as etcd or Consul. These values take precedence over default values, but are overridden by configuration values retrieved from disk, flags, or environment variables.

Viper uses crypt to retrieve configuration from the K/V store, which means that you can store your configuration values encrypted and have them automatically decrypted if you have the correct gpg keyring. Encryption is optional.

You can use remote configuration in conjunction with local configuration, or independently of it.

crypt has a command-line helper that you can use to put configurations in your K/V store. crypt defaults to etcd on http://127.0.0.1:4001.

$ go get github.com/bketelsen/crypt/bin/crypt
$ crypt set -plaintext /config/hugo.json /Users/hugo/settings/config.json

Confirm that your value was set:

$ crypt get -plaintext /config/hugo.json

See the crypt documentation for examples of how to set encrypted values, or how to use Consul.

Remote Key/Value Store Example - Unencrypted

etcd
viper.AddRemoteProvider("etcd", "http://127.0.0.1:4001","/config/hugo.json")
viper.SetConfigType("json") // because there is no file extension in a stream of bytes, supported extensions are "json", "toml", "yaml", "yml", "properties", "props", "prop", "env", "dotenv"
err := viper.ReadRemoteConfig()
Consul

You need to set a key to Consul key/value storage with JSON value containing your desired config. For example, create a Consul key/value store key MY_CONSUL_KEY with value:

{
    "port": 8080,
    "hostname": "myhostname.com"
}
viper.AddRemoteProvider("consul", "localhost:8500", "MY_CONSUL_KEY")
viper.SetConfigType("json") // Need to explicitly set this to json
err := viper.ReadRemoteConfig()

fmt.Println(viper.Get("port")) // 8080
fmt.Println(viper.Get("hostname")) // myhostname.com
Firestore
viper.AddRemoteProvider("firestore", "google-cloud-project-id", "collection/document")
viper.SetConfigType("json") // Config's format: "json", "toml", "yaml", "yml"
err := viper.ReadRemoteConfig()

Of course, you're allowed to use SecureRemoteProvider also

Remote Key/Value Store Example - Encrypted

viper.AddSecureRemoteProvider("etcd","http://127.0.0.1:4001","/config/hugo.json","/etc/secrets/mykeyring.gpg")
viper.SetConfigType("json") // because there is no file extension in a stream of bytes,  supported extensions are "json", "toml", "yaml", "yml", "properties", "props", "prop", "env", "dotenv"
err := viper.ReadRemoteConfig()

Watching Changes in etcd - Unencrypted

// alternatively, you can create a new viper instance.
var runtime_viper = viper.New()

runtime_viper.AddRemoteProvider("etcd", "http://127.0.0.1:4001", "/config/hugo.yml")
runtime_viper.SetConfigType("yaml") // because there is no file extension in a stream of bytes, supported extensions are "json", "toml", "yaml", "yml", "properties", "props", "prop", "env", "dotenv"

// read from remote config the first time.
err := runtime_viper.ReadRemoteConfig()

// unmarshal config
runtime_viper.Unmarshal(&runtime_conf)

// open a goroutine to watch remote changes forever
go func(){
	for {
	    time.Sleep(time.Second * 5) // delay after each request

	    // currently, only tested with etcd support
	    err := runtime_viper.WatchRemoteConfig()
	    if err != nil {
	        log.Errorf("unable to read remote config: %v", err)
	        continue
	    }

	    // unmarshal new config into our runtime config struct. you can also use channel
	    // to implement a signal to notify the system of the changes
	    runtime_viper.Unmarshal(&runtime_conf)
	}
}()

Getting Values From Viper

In Viper, there are a few ways to get a value depending on the value’s type. The following functions and methods exist:

  • Get(key string) : interface{}
  • GetBool(key string) : bool
  • GetFloat64(key string) : float64
  • GetInt(key string) : int
  • GetIntSlice(key string) : []int
  • GetString(key string) : string
  • GetStringMap(key string) : map[string]interface{}
  • GetStringMapString(key string) : map[string]string
  • GetStringSlice(key string) : []string
  • GetTime(key string) : time.Time
  • GetDuration(key string) : time.Duration
  • IsSet(key string) : bool
  • AllSettings() : map[string]interface{}

One important thing to recognize is that each Get function will return a zero value if it’s not found. To check if a given key exists, the IsSet() method has been provided.

Example:

viper.GetString("logfile") // case-insensitive Setting & Getting
if viper.GetBool("verbose") {
    fmt.Println("verbose enabled")
}

Accessing nested keys

The accessor methods also accept formatted paths to deeply nested keys. For example, if the following JSON file is loaded:

{
    "host": {
        "address": "localhost",
        "port": 5799
    },
    "datastore": {
        "metric": {
            "host": "127.0.0.1",
            "port": 3099
        },
        "warehouse": {
            "host": "198.0.0.1",
            "port": 2112
        }
    }
}

Viper can access a nested field by passing a . delimited path of keys:

GetString("datastore.metric.host") // (returns "127.0.0.1")

This obeys the precedence rules established above; the search for the path will cascade through the remaining configuration registries until found.

For example, given this configuration file, both datastore.metric.host and datastore.metric.port are already defined (and may be overridden). If in addition datastore.metric.protocol was defined in the defaults, Viper would also find it.

However, if datastore.metric was overridden (by a flag, an environment variable, the Set() method, …) with an immediate value, then all sub-keys of datastore.metric become undefined, they are “shadowed” by the higher-priority configuration level.

Lastly, if there exists a key that matches the delimited key path, its value will be returned instead. E.g.

{
    "datastore.metric.host": "0.0.0.0",
    "host": {
        "address": "localhost",
        "port": 5799
    },
    "datastore": {
        "metric": {
            "host": "127.0.0.1",
            "port": 3099
        },
        "warehouse": {
            "host": "198.0.0.1",
            "port": 2112
        }
    }
}

GetString("datastore.metric.host") // returns "0.0.0.0"

Extract sub-tree

Extract sub-tree from Viper.

For example, viper represents:

app:
  cache1:
    max-items: 100
    item-size: 64
  cache2:
    max-items: 200
    item-size: 80

After executing:

subv := viper.Sub("app.cache1")

subv represents:

max-items: 100
item-size: 64

Suppose we have:

func NewCache(cfg *Viper) *Cache {...}

which creates a cache based on config information formatted as subv. Now it’s easy to create these 2 caches separately as:

cfg1 := viper.Sub("app.cache1")
cache1 := NewCache(cfg1)

cfg2 := viper.Sub("app.cache2")
cache2 := NewCache(cfg2)

Unmarshaling

You also have the option of Unmarshaling all or a specific value to a struct, map, etc.

There are two methods to do this:

  • Unmarshal(rawVal interface{}) : error
  • UnmarshalKey(key string, rawVal interface{}) : error

Example:

type config struct {
	Port int
	Name string
	PathMap string `mapstructure:"path_map"`
}

var C config

err := viper.Unmarshal(&C)
if err != nil {
	t.Fatalf("unable to decode into struct, %v", err)
}

If you want to unmarshal configuration where the keys themselves contain dot (the default key delimiter), you have to change the delimiter:

v := viper.NewWithOptions(viper.KeyDelimiter("::"))

v.SetDefault("chart::values", map[string]interface{}{
    "ingress": map[string]interface{}{
        "annotations": map[string]interface{}{
            "traefik.frontend.rule.type":                 "PathPrefix",
            "traefik.ingress.kubernetes.io/ssl-redirect": "true",
        },
    },
})

type config struct {
	Chart struct{
        Values map[string]interface{}
    }
}

var C config

v.Unmarshal(&C)

Viper also supports unmarshaling into embedded structs:

/*
Example config:

module:
    enabled: true
    token: 89h3f98hbwf987h3f98wenf89ehf
*/
type config struct {
	Module struct {
		Enabled bool

		moduleConfig `mapstructure:",squash"`
	}
}

// moduleConfig could be in a module specific package
type moduleConfig struct {
	Token string
}

var C config

err := viper.Unmarshal(&C)
if err != nil {
	t.Fatalf("unable to decode into struct, %v", err)
}

Viper uses github.com/mitchellh/mapstructure under the hood for unmarshaling values which uses mapstructure tags by default.

Marshalling to string

You may need to marshal all the settings held in viper into a string rather than write them to a file. You can use your favorite format's marshaller with the config returned by AllSettings().

import (
    yaml "gopkg.in/yaml.v2"
    // ...
)

func yamlStringSettings() string {
    c := viper.AllSettings()
    bs, err := yaml.Marshal(c)
    if err != nil {
        log.Fatalf("unable to marshal config to YAML: %v", err)
    }
    return string(bs)
}

Viper or Vipers?

Viper comes ready to use out of the box. There is no configuration or initialization needed to begin using Viper. Since most applications will want to use a single central repository for their configuration, the viper package provides this. It is similar to a singleton.

In all of the examples above, they demonstrate using viper in its singleton style approach.

Working with multiple vipers

You can also create many different vipers for use in your application. Each will have its own unique set of configurations and values. Each can read from a different config file, key value store, etc. All of the functions that viper package supports are mirrored as methods on a viper.

Example:

x := viper.New()
y := viper.New()

x.SetDefault("ContentDir", "content")
y.SetDefault("ContentDir", "foobar")

//...

When working with multiple vipers, it is up to the user to keep track of the different vipers.

Q & A

Q: Why is it called “Viper”?

A: Viper is designed to be a companion to Cobra. While both can operate completely independently, together they make a powerful pair to handle much of your application foundation needs.

Q: Why is it called “Cobra”?

A: Is there a better name for a commander?

Expand ▾ Collapse ▴

Documentation

Index

Constants

This section is empty.

Variables

var RemoteConfig remoteConfigFactory

RemoteConfig is optional, see the remote package


var SupportedExts = []string{"json", "toml", "yaml", "yml", "properties", "props", "prop", "hcl", "dotenv", "env", "ini"}

SupportedExts are universally supported extensions.


var SupportedRemoteProviders = []string{"etcd", "consul", "firestore"}

SupportedRemoteProviders are universally supported remote providers.


Functions

func AddConfigPath

func AddConfigPath(in string)

AddConfigPath adds a path for Viper to search for the config file in. Can be called multiple times to define multiple search paths.

func AddRemoteProvider

func AddRemoteProvider(provider, endpoint, path string) error

AddRemoteProvider adds a remote configuration source. Remote Providers are searched in the order they are added. provider is a string value: "etcd", "consul" or "firestore" are currently supported. endpoint is the url. etcd requires http://ip:port consul requires ip:port path is the path in the k/v store to retrieve configuration To retrieve a config file called myapp.json from /configs/myapp.json you should set path to /configs and set config name (SetConfigName()) to "myapp"

func AddSecureRemoteProvider

func AddSecureRemoteProvider(provider, endpoint, path, secretkeyring string) error

AddSecureRemoteProvider adds a remote configuration source. Secure Remote Providers are searched in the order they are added. provider is a string value: "etcd", "consul" or "firestore" are currently supported. endpoint is the url. etcd requires http://ip:port consul requires ip:port secretkeyring is the filepath to your openpgp secret keyring. e.g. /etc/secrets/myring.gpg path is the path in the k/v store to retrieve configuration To retrieve a config file called myapp.json from /configs/myapp.json you should set path to /configs and set config name (SetConfigName()) to "myapp" Secure Remote Providers are implemented with github.com/bketelsen/crypt

func AllKeys

func AllKeys() []string

AllKeys returns all keys holding a value, regardless of where they are set. Nested keys are returned with a v.keyDelim separator

func AllSettings

func AllSettings() map[string]interface{}

AllSettings merges all settings and returns them as a map[string]interface{}.

func AllowEmptyEnv

func AllowEmptyEnv(allowEmptyEnv bool)

AllowEmptyEnv tells Viper to consider set, but empty environment variables as valid values instead of falling back. For backward compatibility reasons this is false by default.

func AutomaticEnv

func AutomaticEnv()

AutomaticEnv has Viper check ENV variables for all. keys set in config, default & flags

func BindEnv

func BindEnv(input ...string) error

BindEnv binds a Viper key to a ENV variable. ENV variables are case sensitive. If only a key is provided, it will use the env key matching the key, uppercased. EnvPrefix will be used when set when env name is not provided.

func BindFlagValue

func BindFlagValue(key string, flag FlagValue) error

BindFlagValue binds a specific key to a FlagValue.

func BindFlagValues

func BindFlagValues(flags FlagValueSet) error

BindFlagValues binds a full FlagValue set to the configuration, using each flag's long name as the config key.

func BindPFlag

func BindPFlag(key string, flag *pflag.Flag) error

BindPFlag binds a specific key to a pflag (as used by cobra). Example (where serverCmd is a Cobra instance):

serverCmd.Flags().Int("port", 1138, "Port to run Application server on")
Viper.BindPFlag("port", serverCmd.Flags().Lookup("port"))

func BindPFlags

func BindPFlags(flags *pflag.FlagSet) error

BindPFlags binds a full flag set to the configuration, using each flag's long name as the config key.

func ConfigFileUsed

func ConfigFileUsed() string

ConfigFileUsed returns the file used to populate the config registry.

func Debug

func Debug()

Debug prints all configuration registries for debugging purposes.

func Get

func Get(key string) interface{}

Get can retrieve any value given the key to use. Get is case-insensitive for a key. Get has the behavior of returning the value associated with the first place from where it is set. Viper will check in the following order: override, flag, env, config file, key/value store, default

Get returns an interface. For a specific value use one of the Get____ methods.

func GetBool

func GetBool(key string) bool

GetBool returns the value associated with the key as a boolean.

func GetDuration

func GetDuration(key string) time.Duration

GetDuration returns the value associated with the key as a duration.

func GetFloat64

func GetFloat64(key string) float64

GetFloat64 returns the value associated with the key as a float64.

func GetInt

func GetInt(key string) int

GetInt returns the value associated with the key as an integer.

func GetInt32

func GetInt32(key string) int32

GetInt32 returns the value associated with the key as an integer.

func GetInt64

func GetInt64(key string) int64

GetInt64 returns the value associated with the key as an integer.

func GetIntSlice

func GetIntSlice(key string) []int

GetIntSlice returns the value associated with the key as a slice of int values.

func GetSizeInBytes

func GetSizeInBytes(key string) uint

GetSizeInBytes returns the size of the value associated with the given key in bytes.

func GetString

func GetString(key string) string

GetString returns the value associated with the key as a string.

func GetStringMap

func GetStringMap(key string) map[string]interface{}

GetStringMap returns the value associated with the key as a map of interfaces.

func GetStringMapString

func GetStringMapString(key string) map[string]string

GetStringMapString returns the value associated with the key as a map of strings.

func GetStringMapStringSlice

func GetStringMapStringSlice(key string) map[string][]string

GetStringMapStringSlice returns the value associated with the key as a map to a slice of strings.

func GetStringSlice

func GetStringSlice(key string) []string

GetStringSlice returns the value associated with the key as a slice of strings.

func GetTime

func GetTime(key string) time.Time

GetTime returns the value associated with the key as time.

func GetUint

func GetUint(key string) uint

GetUint returns the value associated with the key as an unsigned integer.

func GetUint32

func GetUint32(key string) uint32

GetUint32 returns the value associated with the key as an unsigned integer.

func GetUint64

func GetUint64(key string) uint64

GetUint64 returns the value associated with the key as an unsigned integer.

func InConfig

func InConfig(key string) bool

InConfig checks to see if the given key (or an alias) is in the config file.

func IsSet

func IsSet(key string) bool

IsSet checks to see if the key has been set in any of the data locations. IsSet is case-insensitive for a key.

func MergeConfig

func MergeConfig(in io.Reader) error

MergeConfig merges a new configuration with an existing config.

func MergeConfigMap

func MergeConfigMap(cfg map[string]interface{}) error

MergeConfigMap merges the configuration from the map given with an existing config. Note that the map given may be modified.

func MergeInConfig

func MergeInConfig() error

MergeInConfig merges a new configuration with an existing config.

func OnConfigChange

func OnConfigChange(run func(in fsnotify.Event))

func ReadConfig

func ReadConfig(in io.Reader) error

ReadConfig will read a configuration file, setting existing keys to nil if the key does not exist in the file.

func ReadInConfig

func ReadInConfig() error

ReadInConfig will discover and load the configuration file from disk and key/value stores, searching in one of the defined paths.

func ReadRemoteConfig

func ReadRemoteConfig() error

ReadRemoteConfig attempts to get configuration from a remote source and read it in the remote configuration registry.

func RegisterAlias

func RegisterAlias(alias string, key string)

RegisterAlias creates an alias that provides another accessor for the same key. This enables one to change a name without breaking the application.

func Reset

func Reset()

Reset is intended for testing, will reset all to default settings. In the public interface for the viper package so applications can use it in their testing as well.

func SafeWriteConfig

func SafeWriteConfig() error

SafeWriteConfig writes current configuration to file only if the file does not exist.

func SafeWriteConfigAs

func SafeWriteConfigAs(filename string) error

SafeWriteConfigAs writes current configuration to a given filename if it does not exist.

func Set

func Set(key string, value interface{})

Set sets the value for the key in the override register. Set is case-insensitive for a key. Will be used instead of values obtained via flags, config file, ENV, default, or key/value store.

func SetConfigFile

func SetConfigFile(in string)

SetConfigFile explicitly defines the path, name and extension of the config file. Viper will use this and not check any of the config paths.

func SetConfigName

func SetConfigName(in string)

SetConfigName sets name for the config file. Does not include extension.

func SetConfigPermissions

func SetConfigPermissions(perm os.FileMode)

SetConfigPermissions sets the permissions for the config file.

func SetConfigType

func SetConfigType(in string)

SetConfigType sets the type of the configuration returned by the remote source, e.g. "json".

func SetDefault

func SetDefault(key string, value interface{})

SetDefault sets the default value for this key. SetDefault is case-insensitive for a key. Default only used when no value is provided by the user via flag, config or ENV.

func SetEnvKeyReplacer

func SetEnvKeyReplacer(r *strings.Replacer)

SetEnvKeyReplacer sets the strings.Replacer on the viper object Useful for mapping an environmental variable to a key that does not match it.

func SetEnvPrefix

func SetEnvPrefix(in string)

SetEnvPrefix defines a prefix that ENVIRONMENT variables will use. E.g. if your prefix is "spf", the env registry will look for env variables that start with "SPF_".

func SetFs

func SetFs(fs afero.Fs)

SetFs sets the filesystem to use to read configuration.

func SetTypeByDefaultValue

func SetTypeByDefaultValue(enable bool)

SetTypeByDefaultValue enables or disables the inference of a key value's type when the Get function is used based upon a key's default value as opposed to the value returned based on the normal fetch logic.

For example, if a key has a default value of []string{} and the same key is set via an environment variable to "a b c", a call to the Get function would return a string slice for the key if the key's type is inferred by the default value and the Get function would return:

[]string {"a", "b", "c"}

Otherwise the Get function would return:

"a b c"

func Unmarshal

func Unmarshal(rawVal interface{}, opts ...DecoderConfigOption) error

Unmarshal unmarshals the config into a Struct. Make sure that the tags on the fields of the structure are properly set.

func UnmarshalExact

func UnmarshalExact(rawVal interface{}, opts ...DecoderConfigOption) error

UnmarshalExact unmarshals the config into a Struct, erroring if a field is nonexistent in the destination struct.

func UnmarshalKey

func UnmarshalKey(key string, rawVal interface{}, opts ...DecoderConfigOption) error

UnmarshalKey takes a single key and unmarshals it into a Struct.

func WatchConfig

func WatchConfig()

func WatchRemoteConfig

func WatchRemoteConfig() error

func WriteConfig

func WriteConfig() error

WriteConfig writes the current configuration to a file.

func WriteConfigAs

func WriteConfigAs(filename string) error

WriteConfigAs writes current configuration to a given filename.

Types

type ConfigFileAlreadyExistsError

type ConfigFileAlreadyExistsError string

ConfigFileAlreadyExistsError denotes failure to write new configuration file.

func (ConfigFileAlreadyExistsError) Error

func (faee ConfigFileAlreadyExistsError) Error() string

Error returns the formatted error when configuration already exists.

type ConfigFileNotFoundError

type ConfigFileNotFoundError struct {
	// contains filtered or unexported fields
}

ConfigFileNotFoundError denotes failing to find configuration file.

func (ConfigFileNotFoundError) Error

func (fnfe ConfigFileNotFoundError) Error() string

Error returns the formatted configuration error.

type ConfigMarshalError

type ConfigMarshalError struct {
	// contains filtered or unexported fields
}

ConfigMarshalError happens when failing to marshal the configuration.

func (ConfigMarshalError) Error

func (e ConfigMarshalError) Error() string

Error returns the formatted configuration error.

type ConfigParseError

type ConfigParseError struct {
	// contains filtered or unexported fields
}

ConfigParseError denotes failing to parse configuration file.

func (ConfigParseError) Error

func (pe ConfigParseError) Error() string

Error returns the formatted configuration error.

type DecoderConfigOption

type DecoderConfigOption func(*mapstructure.DecoderConfig)

A DecoderConfigOption can be passed to viper.Unmarshal to configure mapstructure.DecoderConfig options

func DecodeHook

func DecodeHook(hook mapstructure.DecodeHookFunc) DecoderConfigOption

DecodeHook returns a DecoderConfigOption which overrides the default DecoderConfig.DecodeHook value, the default is:

 mapstructure.ComposeDecodeHookFunc(
		mapstructure.StringToTimeDurationHookFunc(),
		mapstructure.StringToSliceHookFunc(","),
	)

type FlagValue

type FlagValue interface {
	HasChanged() bool
	Name() string
	ValueString() string
	ValueType() string
}

FlagValue is an interface that users can implement to bind different flags to viper.

type FlagValueSet

type FlagValueSet interface {
	VisitAll(fn func(FlagValue))
}

FlagValueSet is an interface that users can implement to bind a set of flags to viper.

type Option

type Option interface {
	// contains filtered or unexported methods
}

Option configures Viper using the functional options paradigm popularized by Rob Pike and Dave Cheney. If you're unfamiliar with this style, see https://commandcenter.blogspot.com/2014/01/self-referential-functions-and-design.html and https://dave.cheney.net/2014/10/17/functional-options-for-friendly-apis.

func EnvKeyReplacer

func EnvKeyReplacer(r StringReplacer) Option

EnvKeyReplacer sets a replacer used for mapping environment variables to internal keys.

func KeyDelimiter

func KeyDelimiter(d string) Option

KeyDelimiter sets the delimiter used for determining key parts. By default it's value is ".".

type RemoteConfigError

type RemoteConfigError string

RemoteConfigError denotes encountering an error while trying to pull the configuration from the remote provider.

func (RemoteConfigError) Error

func (rce RemoteConfigError) Error() string

Error returns the formatted remote provider error

type RemoteProvider

type RemoteProvider interface {
	Provider() string
	Endpoint() string
	Path() string
	SecretKeyring() string
}

RemoteProvider stores the configuration necessary to connect to a remote key/value store. Optional secretKeyring to unencrypt encrypted values can be provided.

type RemoteResponse

type RemoteResponse struct {
	Value []byte
	Error error
}

type StringReplacer

type StringReplacer interface {
	// Replace returns a copy of s with all replacements performed.
	Replace(s string) string
}

StringReplacer applies a set of replacements to a string.

type UnsupportedConfigError

type UnsupportedConfigError string

UnsupportedConfigError denotes encountering an unsupported configuration filetype.

func (UnsupportedConfigError) Error

func (str UnsupportedConfigError) Error() string

Error returns the formatted configuration error.

type UnsupportedRemoteProviderError

type UnsupportedRemoteProviderError string

UnsupportedRemoteProviderError denotes encountering an unsupported remote provider. Currently only etcd and Consul are supported.

func (UnsupportedRemoteProviderError) Error

func (str UnsupportedRemoteProviderError) Error() string

Error returns the formatted remote provider error.

type Viper

type Viper struct {
	// contains filtered or unexported fields
}

Viper is a prioritized configuration registry. It maintains a set of configuration sources, fetches values to populate those, and provides them according to the source's priority. The priority of the sources is the following: 1. overrides 2. flags 3. env. variables 4. config file 5. key/value store 6. defaults

For example, if values from the following sources were loaded:

Defaults : {
	"secret": "",
	"user": "default",
	"endpoint": "https://localhost"
}
Config : {
	"user": "root"
	"secret": "defaultsecret"
}
Env : {
	"secret": "somesecretkey"
}

The resulting config will have the following values:

{
	"secret": "somesecretkey",
	"user": "root",
	"endpoint": "https://localhost"
}

func GetViper

func GetViper() *Viper

GetViper gets the global Viper instance.

func New

func New() *Viper

New returns an initialized Viper instance.

func NewWithOptions

func NewWithOptions(opts ...Option) *Viper

NewWithOptions creates a new Viper instance.

func Sub

func Sub(key string) *Viper

Sub returns new Viper instance representing a sub tree of this instance. Sub is case-insensitive for a key.

func (*Viper) AddConfigPath

func (v *Viper) AddConfigPath(in string)

func (*Viper) AddRemoteProvider

func (v *Viper) AddRemoteProvider(provider, endpoint, path string) error

func (*Viper) AddSecureRemoteProvider

func (v *Viper) AddSecureRemoteProvider(provider, endpoint, path, secretkeyring string) error

func (*Viper) AllKeys

func (v *Viper) AllKeys() []string

func (*Viper) AllSettings

func (v *Viper) AllSettings() map[string]interface{}

func (*Viper) AllowEmptyEnv

func (v *Viper) AllowEmptyEnv(allowEmptyEnv bool)

func (*Viper) AutomaticEnv

func (v *Viper) AutomaticEnv()

func (*Viper) BindEnv

func (v *Viper) BindEnv(input ...string) error

func (*Viper) BindFlagValue

func (v *Viper) BindFlagValue(key string, flag FlagValue) error

func (*Viper) BindFlagValues

func (v *Viper) BindFlagValues(flags FlagValueSet) (err error)

func (*Viper) BindPFlag

func (v *Viper) BindPFlag(key string, flag *pflag.Flag) error

func (*Viper) BindPFlags

func (v *Viper) BindPFlags(flags *pflag.FlagSet) error

func (*Viper) ConfigFileUsed

func (v *Viper) ConfigFileUsed() string

func (*Viper) Debug

func (v *Viper) Debug()

func (*Viper) Get

func (v *Viper) Get(key string) interface{}

func (*Viper) GetBool

func (v *Viper) GetBool(key string) bool

func (*Viper) GetDuration

func (v *Viper) GetDuration(key string) time.Duration

func (*Viper) GetFloat64

func (v *Viper) GetFloat64(key string) float64

func (*Viper) GetInt

func (v *Viper) GetInt(key string) int

func (*Viper) GetInt32

func (v *Viper) GetInt32(key string) int32

func (*Viper) GetInt64

func (v *Viper) GetInt64(key string) int64

func (*Viper) GetIntSlice

func (v *Viper) GetIntSlice(key string) []int

func (*Viper) GetSizeInBytes

func (v *Viper) GetSizeInBytes(key string) uint

func (*Viper) GetString

func (v *Viper) GetString(key string) string

func (*Viper) GetStringMap

func (v *Viper) GetStringMap(key string) map[string]interface{}

func (*Viper) GetStringMapString

func (v *Viper) GetStringMapString(key string) map[string]string

func (*Viper) GetStringMapStringSlice

func (v *Viper) GetStringMapStringSlice(key string) map[string][]string

func (*Viper) GetStringSlice

func (v *Viper) GetStringSlice(key string) []string

func (*Viper) GetTime

func (v *Viper) GetTime(key string) time.Time

func (*Viper) GetUint

func (v *Viper) GetUint(key string) uint

func (*Viper) GetUint32

func (v *Viper) GetUint32(key string) uint32

func (*Viper) GetUint64

func (v *Viper) GetUint64(key string) uint64

func (*Viper) InConfig

func (v *Viper) InConfig(key string) bool

func (*Viper) IsSet

func (v *Viper) IsSet(key string) bool

func (*Viper) MergeConfig

func (v *Viper) MergeConfig(in io.Reader) error

func (*Viper) MergeConfigMap

func (v *Viper) MergeConfigMap(cfg map[string]interface{}) error

func (*Viper) MergeInConfig

func (v *Viper) MergeInConfig() error

func (*Viper) OnConfigChange

func (v *Viper) OnConfigChange(run func(in fsnotify.Event))

func (*Viper) ReadConfig

func (v *Viper) ReadConfig(in io.Reader) error

func (*Viper) ReadInConfig

func (v *Viper) ReadInConfig() error

func (*Viper) ReadRemoteConfig

func (v *Viper) ReadRemoteConfig() error

func (*Viper) RegisterAlias

func (v *Viper) RegisterAlias(alias string, key string)

func (*Viper) SafeWriteConfig

func (v *Viper) SafeWriteConfig() error

func (*Viper) SafeWriteConfigAs

func (v *Viper) SafeWriteConfigAs(filename string) error

func (*Viper) Set

func (v *Viper) Set(key string, value interface{})

func (*Viper) SetConfigFile

func (v *Viper) SetConfigFile(in string)

func (*Viper) SetConfigName

func (v *Viper) SetConfigName(in string)

func (*Viper) SetConfigPermissions

func (v *Viper) SetConfigPermissions(perm os.FileMode)

func (*Viper) SetConfigType

func (v *Viper) SetConfigType(in string)

func (*Viper) SetDefault

func (v *Viper) SetDefault(key string, value interface{})

func (*Viper) SetEnvKeyReplacer

func (v *Viper) SetEnvKeyReplacer(r *strings.Replacer)

func (*Viper) SetEnvPrefix

func (v *Viper) SetEnvPrefix(in string)

func (*Viper) SetFs

func (v *Viper) SetFs(fs afero.Fs)

func (*Viper) SetTypeByDefaultValue

func (v *Viper) SetTypeByDefaultValue(enable bool)

func (*Viper) Sub

func (v *Viper) Sub(key string) *Viper

func (*Viper) Unmarshal

func (v *Viper) Unmarshal(rawVal interface{}, opts ...DecoderConfigOption) error

func (*Viper) UnmarshalExact

func (v *Viper) UnmarshalExact(rawVal interface{}, opts ...DecoderConfigOption) error

func (*Viper) UnmarshalKey

func (v *Viper) UnmarshalKey(key string, rawVal interface{}, opts ...DecoderConfigOption) error

func (*Viper) WatchConfig

func (v *Viper) WatchConfig()

func (*Viper) WatchRemoteConfig

func (v *Viper) WatchRemoteConfig() error

func (*Viper) WatchRemoteConfigOnChannel

func (v *Viper) WatchRemoteConfigOnChannel() error

func (*Viper) WriteConfig

func (v *Viper) WriteConfig() error

func (*Viper) WriteConfigAs

func (v *Viper) WriteConfigAs(filename string) error

Directories

Path Synopsis
remote Package remote integrates the remote features of Viper.