config

Documentation

Overview

Package config provides utilities for loading configuration files.

Index

• func LoadFile(dst interface{}, file string, opts Options) error
• func LoadFiles(dst interface{}, files []string, opts Options) error
• func WarnOnDeprecation(cfg interface{}, logger *zap.Logger)
• type FlagStringSlice
  • func (i *FlagStringSlice) Set(value string) error
  • func (i *FlagStringSlice) String() string
• type Options
• type WorkerPoolPolicy
  • func (w WorkerPoolPolicy) Options() (sync.PooledWorkerPoolOptions, int)

Examples

• FlagStringSlice
• LoadFile

Functions

func LoadFile

func LoadFile(dst interface{}, file string, opts Options) error

LoadFile loads a config from a file.

Example

package main

import (
	"fmt"
	"log"

	"github.com/m3db/m3/src/x/config"
)

type configuration struct {
	ListenAddress string `yaml:"listenAddress" validate:"nonzero"`
}

func main() {
	var cfg configuration
	file := "testdata/conf.yaml"
	if err := config.LoadFile(&cfg, file, config.Options{}); err != nil {
		log.Fatal(err)
	}
	fmt.Printf("listenAddress: %s\n", cfg.ListenAddress)
}

Output:

listenAddress: 0.0.0.0:8392

func LoadFiles

func LoadFiles(dst interface{}, files []string, opts Options) error

LoadFiles loads a config from list of files. If value for a property is present in multiple files, the value from the last file will be applied. Validation is done after merging all values.

func WarnOnDeprecation

func WarnOnDeprecation(cfg interface{}, logger *zap.Logger)

WarnOnDeprecation emits a warning for every deprecated field

Types

type FlagStringSlice

type FlagStringSlice []string

FlagStringSlice represents a slice of strings. When used as a flag variable, it allows for multiple string values. For example, it can be used like this:

var configFiles FlagStringSlice
flag.Var(&configFiles, "f", "configuration file(s)")

Then it can be invoked like this:

./app -f file1.yaml -f file2.yaml -f valueN.yaml

Finally, when the flags are parsed, the variable contains all the values.

Example

The FlagStringSlice allows for multiple values when used as a flag variable.

package main

import (
	"flag"
	"fmt"

	"github.com/m3db/m3/src/x/config"
)

func main() {
	var configFiles config.FlagStringSlice
	fs := flag.NewFlagSet("config", flag.PanicOnError)
	fs.Var(&configFiles, "f", "config files")
	fs.Parse([]string{"-f", "file1.yaml", "-f", "file2.yaml", "-f", "file3.yaml"})
	fmt.Println("Config files:", configFiles)
}

Output:

Config files: [file1.yaml file2.yaml file3.yaml]

func (*FlagStringSlice) Set

func (i *FlagStringSlice) Set(value string) error

Set appends a string value to the slice.

func (*FlagStringSlice) String

func (i *FlagStringSlice) String() string

String() returns a string implmentation of the slice.

type Options

type Options struct {
	DisableUnmarshalStrict bool
	DisableValidate        bool

	// Expand provides values for templated strings of the form ${KEY}.
	// By default, we extract these values from the environment.
	Expand config.LookupFunc
}

Options is an options set used when parsing config.

type WorkerPoolPolicy

type WorkerPoolPolicy struct {
	// Determines if the worker pool automatically grows to capacity.
	GrowOnDemand bool `yaml:"grow"`

	// Size for static pools, initial size for dynamically growing pools.
	Size int `yaml:"size"`

	// The number of shards for the pool.
	NumShards int64 `yaml:"shards"`

	// The probablility that a worker is killed after completing the task.
	KillWorkerProbability float64 `yaml:"killProbability" validate:"min=0.0,max=1.0"`
}

WorkerPoolPolicy specifies the policy for the worker pool.

func (WorkerPoolPolicy) Options

func (w WorkerPoolPolicy) Options() (sync.PooledWorkerPoolOptions, int)

Options converts the worker pool policy to options, providing the options, as well as the default size for the worker pool.