package feature

import "github.com/influxdata/flux/internal/pkg/feature"

Package feature provides feature flagging capabilities for a Go application.

Flags are defined using the `MakeXXXFlag` functions. These can either be defined in code or generated using the feature generator included in this module.

Flags are configured in `flags.yml` at the top of this repository. Running `make flags` generates Go code based on this configuration to programmatically test flag values in a given request context. Boolean flags are the most common case, but integers, floats and strings are supported for more complicated experiments.

The `Flagger` interface is the crux of this package. It computes a map of feature flag values for a given request context. The implementation is application dependent. The result can be attached to the context using `Annotate` and then the results will be used when checking feature flags.

Flags can be checked using the context after it has been annotated. For example, to check a boolean flag that was generated by the `feature` command, you might do it this way:

if feature.MyFeature().Enabled(ctx) {
    // my feature is enabled
} else {
    // my feature is disabled
}

Index ¶

• func Inject(ctx context.Context, flagger Flagger) context.Context
• func SetMetrics(m Metrics)
• type Base
• func MakeBase(name, key, owner string, defaultValue interface{}) Base
• func (f Base) Default() interface{}
• func (f Base) Key() string
• type BoolFlag
• func MakeBoolFlag(name, key, owner string, defaultValue bool) BoolFlag
• func (f BoolFlag) Enabled(ctx context.Context) (v bool)
• type Flag
• func MakeFlag(name, key, owner string, defaultValue interface{}) Flag
• type Flagger
• func GetFlagger(ctx context.Context) Flagger
• type FloatFlag
• func MakeFloatFlag(name, key, owner string, defaultValue float64) FloatFlag
• func (f FloatFlag) Float(ctx context.Context) (v float64)
• type IntFlag
• func MakeIntFlag(name, key, owner string, defaultValue int) IntFlag
• func (f IntFlag) Int(ctx context.Context) (v int)
• type Metrics
• type StringFlag
• func MakeStringFlag(name, key, owner string, defaultValue string) StringFlag
• func (f StringFlag) String(ctx context.Context) (v string)

Functions ¶

func Inject ¶

func Inject(ctx context.Context, flagger Flagger) context.Context

Inject will inject the Flagger into the context.

func SetMetrics ¶

func SetMetrics(m Metrics)

SetMetrics sets the metric store for feature flags.

Types ¶

type Base ¶

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

Base implements the base of the Flag type.

func MakeBase ¶

func MakeBase(name, key, owner string, defaultValue interface{}) Base

MakeBase constructs a flag.

func (Base) Default ¶

func (f Base) Default() interface{}

Default returns the type-agnostic zero value for the flag.

func (Base) Key ¶

func (f Base) Key() string

Key returns the programmatic backend identifier for the flag.

type BoolFlag ¶

type BoolFlag struct {
	Base
	// contains filtered or unexported fields
}

BoolFlag implements Flag for boolean values.

func MakeBoolFlag ¶

func MakeBoolFlag(name, key, owner string, defaultValue bool) BoolFlag

MakeBoolFlag returns a string flag with the given Base and default.

func (BoolFlag) Enabled ¶

func (f BoolFlag) Enabled(ctx context.Context) (v bool)

Enabled indicates whether flag is true or false on the request context.

type Flag ¶

type Flag interface {
	// Key returns the programmatic backend identifier for the flag.
	Key() string
	// Default returns the type-agnostic zero value for the flag.
	// Type-specific flag implementations may expose a typed default
	// (e.g. BoolFlag includes a boolean Default field).
	Default() interface{}
}

Flag represents a generic feature flag with a key and a default.

func MakeFlag ¶

func MakeFlag(name, key, owner string, defaultValue interface{}) Flag

MakeFlag constructs a Flag. The concrete implementation is inferred from the provided default.

type Flagger ¶

type Flagger interface {
	// FlagValue returns the value for a given flag.
	FlagValue(ctx context.Context, flag Flag) interface{}
}

Flagger returns flag values.

func GetFlagger ¶

func GetFlagger(ctx context.Context) Flagger

GetFlagger returns the Flagger for this context or the default flagger.

type FloatFlag ¶

type FloatFlag struct {
	Base
	// contains filtered or unexported fields
}

FloatFlag implements Flag for float values.

func MakeFloatFlag ¶

func MakeFloatFlag(name, key, owner string, defaultValue float64) FloatFlag

MakeFloatFlag returns a string flag with the given Base and default.

func (FloatFlag) Float ¶

func (f FloatFlag) Float(ctx context.Context) (v float64)

Float value of the flag on the request context.

type IntFlag ¶

type IntFlag struct {
	Base
	// contains filtered or unexported fields
}

IntFlag implements Flag for integer values.

func MakeIntFlag ¶

func MakeIntFlag(name, key, owner string, defaultValue int) IntFlag

MakeIntFlag returns a string flag with the given Base and default.

func (IntFlag) Int ¶

func (f IntFlag) Int(ctx context.Context) (v int)

Int value of the flag on the request context.

type Metrics ¶

type Metrics interface {
	Inc(key string, value interface{})
}

type StringFlag ¶

type StringFlag struct {
	Base
	// contains filtered or unexported fields
}

StringFlag implements Flag for string values.

func MakeStringFlag ¶

func MakeStringFlag(name, key, owner string, defaultValue string) StringFlag

MakeStringFlag returns a string flag with the given Base and default.

func (StringFlag) String ¶

func (f StringFlag) String(ctx context.Context) (v string)

String value of the flag on the request context.

Source Files ¶

doc.go feature.go flag.go metrics.go

Directories ¶