README
¶
This project is deprecated and is no longer being actively maintained.
goforit is an experimental, quick-and-dirty client library for feature flags in Go.
Backends
Feature flags can be stored in any desired backend. goforit provides a several flatfile implementations out-of-the-box, so feature flags can be defined in a JSON or CSV file. See below for details.
Alternatively, flags can be stored in a key-value store like Consul or Redis.
Usage
Create a CSV file that defines the flag names and sampling rates:
go.sun.money,0
go.moon.mercury,1
go.stars.money,.5
func main() {
ctx := context.Background()
// flags.csv contains comma-separated flag names and sample rates.
// See: testdata/flags_example.csv
backend := goforit.BackendFromFile("flags.csv")
goforit.Init(30*time.Second, backend)
if goforit.Enabled(ctx, "go.sun.mercury", nil) {
fmt.Println("The go.sun.mercury feature is enabled for 100% of requests")
}
if goforit.Enabled(ctx, "go.stars.money", nil) {
fmt.Println("The go.stars.money feature is enabled for 50% of requests")
}
}
Backends
Included flatfile backends are:
CSV
This is a very simple backend, where every row defines a flag name and a rate at which it should be enabled, between zero and one. Initialize this backend with BackendFromFile. See an example.
JSON v1
This backend allows each flag to have multiple rules, like a series of if-statements. Each call to .Enabled() takes a map of properties, which rules can match against. Each rule's matching or non-matching can cause the overall flag to be on or off, or can fallthrough to the next rule. See the proposal for this system or an example JSON file. It's a bit confusing to understand.
JSON v2
In this format, each flag can have a number of rules, and each rule can contain a number of predicates for matching properties. When a flag is evaluated, it uses the first rule whose predicates match the given properties. See an example JSON file, that also includes test cases.
Status
goforit is in an experimental state and may introduce breaking changes without notice.
License
goforit is available under the MIT license.
Documentation
¶
Overview ¶
Example ¶
package main
import (
"context"
"fmt"
"time"
"github.com/stripe/goforit"
)
func main() {
ctx := context.Background()
// flags.csv contains comma-separated flag names and sample rates.
// See: testdata/flags2_example.json
backend := goforit.BackendFromJSONFile2("testdata/flags2_example.json")
flags := goforit.New(30*time.Second, backend, goforit.WithOwnedStats(true))
defer func() { _ = flags.Close() }()
if flags.Enabled(ctx, "go.sun.mercury", nil) {
fmt.Println("The go.sun.mercury feature is enabled for 100% of requests")
}
// Same thing.
if flags.Enabled(nil, "go.sun.mercury", nil) {
fmt.Println("The go.sun.mercury feature is enabled for 100% of requests")
}
if flags.Enabled(ctx, "go.stars.money", nil) {
fmt.Println("The go.stars.money feature is enabled for 50% of requests")
}
}
Output:
Index ¶
- Constants
- func Override(ctx context.Context, name string, value bool) context.Context
- type Backend
- type Goforit
- type MetricsClient
- type Option
- func DeletedCallback(cb evaluationCallback) Option
- func EvaluationCallback(cb evaluationCallback) Option
- func Logger(printf func(msg string, args ...interface{})) Option
- func Statsd(stats MetricsClient) Option
- func WithContextOverrideDisabled(disabled bool) Option
- func WithOwnedStats(isOwned bool) Option
Examples ¶
Constants ¶
const DefaultInterval = 30 * time.Second
const DefaultStatsdAddr = "127.0.0.1:8200"
DefaultStatsdAddr is the address we will emit metrics to if not overridden.
Variables ¶
This section is empty.
Functions ¶
Types ¶
type Backend ¶
type Backend interface {
// Refresh returns a new set of flags.
// It also returns the age of these flags, or an empty time if no age is known.
Refresh() ([]*flags2.Flag2, time.Time, error)
}
func BackendFromJSONFile2 ¶
BackendFromJSONFile2 creates a v2 backend powered by a JSON file
type Goforit ¶
type Goforit interface {
Enabled(ctx context.Context, name string, props map[string]string) (enabled bool)
RefreshFlags(backend Backend)
TryRefreshFlags(backend Backend) error
SetStalenessThreshold(threshold time.Duration)
AddDefaultTags(tags map[string]string)
ReportCounts(callback func(name string, total, enabled uint64, isDeleted bool))
Close() error
}
Goforit is the main interface for the library to check if flags enabled, refresh flags customizing behavior or mocking.
type MetricsClient ¶
type MetricsClient interface {
Histogram(string, float64, []string, float64) error
TimeInMilliseconds(name string, milli float64, tags []string, rate float64) error
Gauge(string, float64, []string, float64) error
Count(string, int64, []string, float64) error
io.Closer
}
MetricsClient is the set of methods required to emit metrics to statsd, for customizing behavior or mocking.
type Option ¶
type Option interface {
// contains filtered or unexported methods
}
func DeletedCallback ¶
func DeletedCallback(cb evaluationCallback) Option
DeletedCallback registers a callback to execute for each flag that is scheduled for deletion
func EvaluationCallback ¶
func EvaluationCallback(cb evaluationCallback) Option
EvaluationCallback registers a callback to execute for each evaluated flag
func Logger ¶
Logger uses the supplied function to log errors. By default, errors are written to os.Stderr.
func Statsd ¶
func Statsd(stats MetricsClient) Option
Statsd uses the supplied client to emit metrics to. By default, a client is created and configured to emit metrics to DefaultStatsdAddr.
func WithOwnedStats ¶
WithOwnedStats instructs the returned Goforit instance to call Close() on its stats client when Goforit is closed.
Source Files
Directories