lddynamodb

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 Go to latest Published: Jan 17, 2023 License: Apache-2.0 Imports: 15 Imported by: 1

README

LaunchDarkly Server-side SDK for Go - Dynamodb integration

Circle CI Documentation

This library provides a DynamoDB-backed persistence mechanism (data store) for the LaunchDarkly Go SDK, replacing the default in-memory data store.

This version of the library requires at least version 6.0.0 of the LaunchDarkly Go SDK; for versions of the library to use with earlier SDK versions, see the changelog.

This version of the library uses the v2 AWS Go SDK.

The minimum Go version is 1.18.

For more information, see also: Using DynamoDB as a persistent feature store.

Quick setup

This assumes that you have already installed the LaunchDarkly Go SDK.

  1. Import the LaunchDarkly SDK packages and the package for this library:
import (
    ld "github.com/launchdarkly/go-server-sdk/v6"
    "github.com/launchdarkly/go-server-sdk/v6/ldcomponents"
    lddynamodb "github.com/launchdarkly/go-server-sdk-dynamodb/v3"
)
  1. When configuring your SDK client, add the DynamoDB data store as a PersistentDataStore. You may specify any custom DynamoDB options using the methods of DynamoDBDataStoreBuilder. For instance:
    var config ld.Config{}
    config.DataStore = ldcomponents.PersistentDataStore(
        lddymamodb.DataStore("my-table-name").
            ClientOptions(dynamodb.Options{Region: "us-west-1"}),
    )

By default, the DynamoDB client will try to get your AWS credentials and region name from environment variables and/or local configuration files, as described in the AWS SDK documentation.

Caching behavior

The LaunchDarkly SDK has a standard caching mechanism for any persistent data store, to reduce database traffic. This is configured through the SDK's PersistentDataStoreBuilder class as described the SDK documentation. For instance, to specify a cache TTL of 5 minutes:

    var config ld.Config{}
    config.DataStore = ldcomponents.PersistentDataStore(
        lddynamodb.DataStore("my-table-name"),
    ).CacheMinutes(5)

Data size limitation

DynamoDB has a 400KB limit on the size of any data item. For the LaunchDarkly SDK, a data item consists of the JSON representation of an individual feature flag or segment configuration, plus a few smaller attributes. You can see the format and size of these representations by querying https://sdk.launchdarkly.com/flags/latest-all and setting the Authorization header to your SDK key.

Most flags and segments won't be nearly as big as 400KB, but they could be if for instance you have a long list of user keys for individual user targeting. If the flag or segment representation is too large, it cannot be stored in DynamoDB. To avoid disrupting storage and evaluation of other unrelated feature flags, the SDK will simply skip storing that individual flag or segment, and will log a message (at ERROR level) describing the problem. For example:

    The item "my-flag-key" in "features" was too large to store in DynamoDB and was dropped

If caching is enabled in your configuration, the flag or segment may still be available in the SDK from the in-memory cache, but do not rely on this. If you see this message, consider redesigning your flag/segment configurations, or else do not use DynamoDB for the environment that contains this data item.

This limitation does not apply to target lists in Big Segments.

A future version of the LaunchDarkly DynamoDB integration may use different strategies to work around this limitation, such as compressing the data or dividing it into multiple items. However, this integration is required to be interoperable with the DynamoDB integrations used by all the other LaunchDarkly SDKs and by the Relay Proxy, so any such change will only be made as part of a larger cross-platform release.

LaunchDarkly overview

LaunchDarkly is a feature management platform that serves over 100 billion feature flags daily to help teams build better software, faster. Get started using LaunchDarkly today!

About LaunchDarkly

  • LaunchDarkly is a continuous delivery platform that provides feature flags as a service and allows developers to iterate quickly and safely. We allow you to easily flag your features and manage them from the LaunchDarkly dashboard. With LaunchDarkly, you can:
    • Roll out a new feature to a subset of your users (like a group of users who opt-in to a beta tester group), gathering feedback and bug reports from real-world use cases.
    • Gradually roll out a feature to an increasing percentage of users, and track the effect that the feature has on key metrics (for instance, how likely is a user to complete a purchase if they have feature A versus feature B?).
    • Turn off a feature that you realize is causing performance problems in production, without needing to re-deploy, or even restart the application with a changed configuration file.
    • Grant access to certain features based on user attributes, like payment plan (eg: users on the ‘gold’ plan get access to more features than users in the ‘silver’ plan). Disable parts of your application to facilitate maintenance, without taking everything offline.
  • LaunchDarkly provides feature flag SDKs for a wide variety of languages and technologies. Read our documentation for a complete list.
  • Explore LaunchDarkly

Documentation

Overview

Package lddynamodb provides a DynamoDB-backed persistent data store for the LaunchDarkly Go SDK.

For more details about how and why you can use a persistent data store, see: https://docs.launchdarkly.com/sdk/features/storing-data/dynamodb#go

To use the DynamoDB data store with the LaunchDarkly client: 

import lddynamodb "github.com/launchdarkly/go-server-sdk-dynamodb/v3"

config := ld.Config{
    DataStore: ldcomponents.PersistentDataStore(lddynamodb.DataStore("my-table-name")),
}
client, err := ld.MakeCustomClient("sdk-key", config, 5*time.Second)

By default, the data store uses a basic DynamoDB client configuration that is equivalent to doing this: 

dynamoClient := dynamodb.New(session.NewSession())

This default configuration will only work if your AWS credentials and region are available from AWS environment variables and/or configuration files. If you want to set those programmatically or modify any other configuration settings, you can use the methods of the lddynamodb.DataStoreBuilder returned by lddynamodb.DataStore(). For example: 

config := ld.Config{
    DataStore: ldcomponents.PersistentDataStore(
        lddynamodb.DataStore("my-table-name").Prefix("key-prefix"),
    ).CacheSeconds(30),
}

Note that CacheSeconds() is not a method of lddynamodb.DataStoreBuilder, but rather a method of ldcomponents.PersistentDataStore(), because the caching behavior is provided by the SDK for all database integrations.

If you are also using DynamoDB for other purposes, the data store can coexist with other data in the same table as long as you use the Prefix option to make each application use different keys. However, it is advisable to configure separate tables in DynamoDB, for better control over permissions and throughput.

Index

Constants

This section is empty.

Variables

This section is empty.

Functions

This section is empty.

Types

type StoreBuilder 

type StoreBuilder[T any] struct {
	// contains filtered or unexported fields
}

StoreBuilder is a builder for configuring the DynamoDB-based persistent data store and/or Big Segment store.

Both DataStore and BigSegmentStore return instances of this type. You can use methods of the builder to specify any ny non-default DynamoDB options you may want, before passing the builder to either github.com/launchdarkly/go-server-sdk/v6/ldcomponents.PersistentDataStore or github.com/launchdarkly/go-server-sdk/v6/ldcomponents.BigSegments as appropriate. The two types of stores are independent of each other; you do not need a Big Segment store if you are not using the Big Segments feature, and you do not need to use the same DynamoDB options for both.

In this example, the main data store uses a DynamoDB table called "table1", and the Big Segment store uses a DynamoDB table called "table2": 

config.DataStore = ldcomponents.PersistentDataStore(
	lddynamodb.DataStore("table1"))
config.BigSegments = ldcomponents.BigSegments(
	lddynamodb.BigSegmentStore("table2"))

Note that the SDK also has its own options related to data storage that are configured at a different level, because they are independent of what database is being used. For instance, the builder returned by github.com/launchdarkly/go-server-sdk/v6/ldcomponents.PersistentDataStore has options for caching: 

config.DataStore = ldcomponents.PersistentDataStore(
	lddynamodb.DataStore("table1"),
).CacheSeconds(15)

func BigSegmentStore 

func BigSegmentStore(tableName string) *StoreBuilder[subsystems.BigSegmentStore]

BigSegmentStore returns a configurable builder for a DynamoDB-backed Big Segment store.

The tableName parameter is required, and the table must already exist in DynamoDB.

You can use methods of the builder to specify any non-default Redis options you may want, before passing the builder to github.com/launchdarkly/go-server-sdk/v6/ldcomponents.BigSegments. In this example, the store is configured to use a DynamoDB table called "table1" and the AWS region is forced to be "us-east-1": 

config.BigSegments = ldcomponents.BigSegments(
	lddynamodb.BigSegmentStore("table1").ClientOptions(dynamodb.Options{Region: "us-east-1"}),
)

Note that the SDK also has its own options related to Big Segments that are configured at a different level, because they are independent of what database is being used. For instance, the builder returned by github.com/launchdarkly/go-server-sdk/v6/ldcomponents.BigSegments has an option for the status polling interval: 

config.BigSegments = ldcomponents.BigSegments(
	lddynamodb.BigSegmentStore("table1"),
).StatusPollInterval(time.Second * 30)

func DataStore 

func DataStore(tableName string) *StoreBuilder[subsystems.PersistentDataStore]

DataStore returns a configurable builder for a DynamoDB-backed data store.

This is for the main data store that holds feature flag data. To configure a data store for Big Segments, use BigSegmentStore instead.

The tableName parameter is required, and the table must already exist in DynamoDB.

You can use methods of the builder to specify any non-default DynamoDB options you may want, before passing the builder to github.com/launchdarkly/go-server-sdk/v6/ldcomponents.PersistentDataStore. In this example, the store is configured to use a DynamoDB table called "table1" and the AWS region is forced to be "us-east-1": 

config.DataStore = ldcomponents.PersistentDataStore(
	lddynamodb.DataStore("table1").ClientOptions(dynamodb.Options{Region: "us-east-1"}),
)

Note that the SDK also has its own options related to data storage that are configured at a different level, because they are independent of what database is being used. For instance, the builder returned by github.com/launchdarkly/go-server-sdk/v6/ldcomponents.PersistentDataStore has options for caching: 

config.DataStore = ldcomponents.PersistentDataStore(
	lddynamodb.DataStore("table1"),
).CacheSeconds(15)

func (*StoreBuilder[T]) Build 

func (b *StoreBuilder[T]) Build(context subsystems.ClientContext) (T, error)

Build is called internally by the SDK.

func (*StoreBuilder[T]) ClientConfig 

func (b *StoreBuilder[T]) ClientConfig(options aws.Config, optFns ...func(*dynamodb.Options)) *StoreBuilder[T]

ClientOptions specifies custom parameters for the dynamodb.NewFromConfig client constructor. This can be used to set properties such as the region programmatically, rather than relying on the defaults from the environment.

func (*StoreBuilder[T]) ClientOptions 

func (b *StoreBuilder[T]) ClientOptions(options dynamodb.Options, optFns ...func(*dynamodb.Options)) *StoreBuilder[T]

ClientOptions specifies custom parameters for the dynamodb.New client constructor. This can be used to set properties such as the region programmatically, rather than relying on the defaults from the environment.

func (*StoreBuilder[T]) DescribeConfiguration 

func (b *StoreBuilder[T]) DescribeConfiguration() ldvalue.Value

DescribeConfiguration is used internally by the SDK to inspect the configuration.

func (*StoreBuilder[T]) DynamoClient 

func (b *StoreBuilder[T]) DynamoClient(client *dynamodb.Client) *StoreBuilder[T]

DynamoClient specifies an existing DynamoDB client instance. Use this if you want to customize the client used by the data store in ways that are not supported by other DataStoreBuilder options. If you specify this option, then any configurations specified with SessionOptions or ClientConfig will be ignored.

func (*StoreBuilder[T]) Prefix 

func (b *StoreBuilder[T]) Prefix(prefix string) *StoreBuilder[T]

Prefix specifies a prefix for namespacing the data store's keys.

Source Files

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