add provider/appconfig

.github/dependabot.yml

@@ -22,6 +22,13 @@ updates:
     schedule:
       interval: daily
 
+  - package-ecosystem: gomod
+    directory: /provider/appconfig
+    labels:
+      - Skip-Changelog
+    schedule:
+      interval: daily
+
   - package-ecosystem: github-actions
     directory: /
     labels:

.github/workflows/benchmark.yml

@@ -11,7 +11,7 @@ jobs:
   benchmark:
     strategy:
       matrix:
-        module: [ '', 'provider/file', 'provider/pflag' ]
+        module: [ '', 'provider/file', 'provider/pflag', 'provider/appconfig' ]
     name: Benchmark
     runs-on: ubuntu-latest
     steps:

.github/workflows/coverage.yml

@@ -11,7 +11,7 @@ jobs:
   coverage:
     strategy:
       matrix:
-        module: [ '', 'provider/file', 'provider/pflag' ]
+        module: [ '', 'provider/file', 'provider/pflag', 'provider/appconfig' ]
     name: Coverage
     runs-on: ubuntu-latest
     steps:

.github/workflows/lint.yml

@@ -11,7 +11,7 @@ jobs:
   lint:
     strategy:
       matrix:
-        module: [ '', 'provider/file', 'provider/pflag' ]
+        module: [ '', 'provider/file', 'provider/pflag', 'provider/appconfig' ]
     name: Lint
     runs-on: ubuntu-latest
     steps:

.github/workflows/tag.yml

@@ -10,7 +10,7 @@ jobs:
   tag:
     strategy:
       matrix:
-        module: [ 'provider/file', 'provider/pflag' ]
+        module: [ 'provider/file', 'provider/pflag', 'provider/appconfig' ]
     name: Submodules
     runs-on: ubuntu-latest
     steps:

.github/workflows/test.yml

@@ -11,7 +11,7 @@ jobs:
   test:
     strategy:
       matrix:
-        module: [ '', 'provider/file', 'provider/pflag' ]
+        module: [ '', 'provider/file', 'provider/pflag', 'provider/appconfig' ]
         run-on: [ 'ubuntu', 'macOS', 'windows' ]
         go-version: [ 'stable' ]
     name: Test

CHANGELOG.md

@@ -11,6 +11,7 @@ to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
 
 - add Config.Explain to provide information about how Config resolve each value from loaders (#78).
 - add Default to get the default Config (#81).
+- add AWS AppConfig Loader (#92).
 
 ### Changed
 

README.md

@@ -95,6 +95,7 @@ There are providers for the following configuration sources:
 - [`file`](provider/file) loads configuration from a file.
 - [`flag`](provider/flag) loads configuration from flags.
 - [`pflag`](provider/pflag) loads configuration from [spf13/pflag](https://github.com/spf13/pflag).
+- [`appconfig`](provider/appconfig) loads configuration from [AWS AppConfig](https://aws.amazon.com/systems-manager/features/appconfig/).
 
 ## Inspiration
 

provider/appconfig/appconfig.go

@@ -0,0 +1,178 @@
+// Copyright (c) 2024 The konf authors
+// Use of this source code is governed by a MIT license found in the LICENSE file.
+
+// Package appconfig loads configuration from AWS AppConfig.
+//
+// AppConfig loads configuration from AWS AppConfig with the given application, environment, profile
+// and returns a nested map[string]any that is parsed with the given unmarshal function.
+//
+// The unmarshal function must be able to unmarshal the file content into a map[string]any.
+// For example, with the default json.Unmarshal, the file is parsed as JSON.
+package appconfig
+
+import (
+	"context"
+	"encoding/json"
+	"fmt"
+	"log/slog"
+	"sync/atomic"
+	"time"
+
+	"github.com/aws/aws-sdk-go-v2/aws"
+	"github.com/aws/aws-sdk-go-v2/config"
+	"github.com/aws/aws-sdk-go-v2/service/appconfigdata"
+)
+
+// AppConfig is a Provider that loads configuration from AWS AppConfig.
+//
+// To create a new AppConfig, call [New].
+type AppConfig struct {
+	logger    *slog.Logger
+	unmarshal func([]byte, any) error
+
+	client       appConfigClient
+	application  string
+	environment  string
+	profile      string
+	pollInterval time.Duration
+
+	token atomic.Pointer[string]
+}
+
+type appConfigClient interface {
+	StartConfigurationSession(
+		ctx context.Context,
+		params *appconfigdata.StartConfigurationSessionInput,
+		optFns ...func(*appconfigdata.Options),
+	) (*appconfigdata.StartConfigurationSessionOutput, error)
+	GetLatestConfiguration(
+		ctx context.Context,
+		params *appconfigdata.GetLatestConfigurationInput,
+		optFns ...func(*appconfigdata.Options),
+	) (*appconfigdata.GetLatestConfigurationOutput, error)
+}
+
+// New creates an AppConfig with the given application, environment, profile and Option(s).
+func New(application, environment, profile string, opts ...Option) *AppConfig {
+	if application == "" {
+		panic("cannot create AppConfig with empty application")
+	}
+	if environment == "" {
+		panic("cannot create AppConfig with empty environment")
+	}
+	if profile == "" {
+		panic("cannot create AppConfig with empty profile")
+	}
+
+	option := &options{
+		AppConfig: AppConfig{
+			application: application,
+			environment: environment,
+			profile:     profile,
+		},
+	}
+	for _, opt := range opts {
+		opt(option)
+	}
+	if option.logger == nil {
+		option.logger = slog.Default()
+	}
+	if option.unmarshal == nil {
+		option.unmarshal = json.Unmarshal
+	}
+	if option.pollInterval <= 0 {
+		option.pollInterval = time.Minute
+	}
+	if option.awsConfig == nil {
+		awsConfig, err := config.LoadDefaultConfig(context.Background())
+		if err != nil {
+			panic(fmt.Sprintf("cannot load AWS default config: %v", err))
+		}
+		option.awsConfig = &awsConfig
+	}
+	option.AppConfig.client = appconfigdata.NewFromConfig(*option.awsConfig)
+
+	return &option.AppConfig
+}
+
+func (a *AppConfig) Load() (map[string]any, error) {
+	if a.token.Load() == nil {
+		input := &appconfigdata.StartConfigurationSessionInput{
+			ApplicationIdentifier:                aws.String(a.application),
+			ConfigurationProfileIdentifier:       aws.String(a.profile),
+			EnvironmentIdentifier:                aws.String(a.environment),
+			RequiredMinimumPollIntervalInSeconds: aws.Int32(int32(max(a.pollInterval.Seconds()/2, 1))), //nolint:gomnd
+		}
+		output, err := a.client.StartConfigurationSession(context.Background(), input)
+		if err != nil {
+			return nil, fmt.Errorf("start configuration session: %w", err)
+		}
+		a.token.Store(output.InitialConfigurationToken)
+	}
+
+	input := &appconfigdata.GetLatestConfigurationInput{
+		ConfigurationToken: a.token.Load(),
+	}
+	output, err := a.client.GetLatestConfiguration(context.Background(), input)
+	if err != nil {
+		return nil, fmt.Errorf("get latest configuration: %w", err)
+	}
+	a.token.Store(output.NextPollConfigurationToken)
+
+	var out map[string]any
+	if err := a.unmarshal(output.Configuration, &out); err != nil {
+		return nil, fmt.Errorf("unmarshal: %w", err)
+	}
+
+	return out, nil
+}
+
+func (a *AppConfig) Watch(ctx context.Context, onChange func(map[string]any)) error {
+	ticker := time.NewTicker(a.pollInterval)
+	defer ticker.Stop()
+
+	for {
+		select {
+		case <-ticker.C:
+			input := &appconfigdata.GetLatestConfigurationInput{
+				ConfigurationToken: a.token.Load(),
+			}
+			output, err := a.client.GetLatestConfiguration(ctx, input)
+			if err != nil {
+				a.logger.WarnContext(
+					ctx, "Error when reloading from AWS AppConfig",
+					"application", a.application,
+					"environment", a.environment,
+					"profile", a.profile,
+					"error", err,
+				)
+
+				continue
+			}
+			a.token.Store(output.NextPollConfigurationToken)
+
+			if len(output.Configuration) == 0 {
+				// It may return empty configuration data
+				// if the client already has the latest version.
+				continue
+			}
+
+			var out map[string]any
+			if err := a.unmarshal(output.Configuration, &out); err != nil {
+				a.logger.WarnContext(
+					ctx, "Error when unmarshalling config from AWS AppConfig",
+					"application", a.application,
+					"environment", a.environment,
+					"profile", a.profile,
+					"error", err,
+				)
+
+				continue
+			}
+
+			onChange(out)
+		case <-ctx.Done():
+			return nil
+		}
+	}
+}

provider/appconfig/appconfig_test.go

@@ -0,0 +1,4 @@
+// Copyright (c) 2024 The konf authors
+// Use of this source code is governed by a MIT license found in the LICENSE file.
+
+package appconfig

provider/appconfig/benchmark_test.go

@@ -0,0 +1,4 @@
+// Copyright (c) 2024 The konf authors
+// Use of this source code is governed by a MIT license found in the LICENSE file.
+
+package appconfig

provider/appconfig/go.mod

@@ -0,0 +1,23 @@
+module github.com/nil-go/konf/provider/appconfig
+
+go 1.21
+
+require (
+	github.com/aws/aws-sdk-go-v2 v1.24.1
+	github.com/aws/aws-sdk-go-v2/config v1.26.6
+	github.com/aws/aws-sdk-go-v2/service/appconfigdata v1.12.0
+)
+
+require (
+	github.com/aws/aws-sdk-go-v2/credentials v1.16.16 // indirect
+	github.com/aws/aws-sdk-go-v2/feature/ec2/imds v1.14.11 // indirect
+	github.com/aws/aws-sdk-go-v2/internal/configsources v1.2.10 // indirect
+	github.com/aws/aws-sdk-go-v2/internal/endpoints/v2 v2.5.10 // indirect
+	github.com/aws/aws-sdk-go-v2/internal/ini v1.7.3 // indirect
+	github.com/aws/aws-sdk-go-v2/service/internal/accept-encoding v1.10.4 // indirect
+	github.com/aws/aws-sdk-go-v2/service/internal/presigned-url v1.10.10 // indirect
+	github.com/aws/aws-sdk-go-v2/service/sso v1.18.7 // indirect
+	github.com/aws/aws-sdk-go-v2/service/ssooidc v1.21.7 // indirect
+	github.com/aws/aws-sdk-go-v2/service/sts v1.26.7 // indirect
+	github.com/aws/smithy-go v1.19.0 // indirect
+)

provider/appconfig/go.sum

@@ -0,0 +1,30 @@
+github.com/aws/aws-sdk-go-v2 v1.24.1 h1:xAojnj+ktS95YZlDf0zxWBkbFtymPeDP+rvUQIH3uAU=
+github.com/aws/aws-sdk-go-v2 v1.24.1/go.mod h1:LNh45Br1YAkEKaAqvmE1m8FUx6a5b/V0oAKV7of29b4=
+github.com/aws/aws-sdk-go-v2/config v1.26.6 h1:Z/7w9bUqlRI0FFQpetVuFYEsjzE3h7fpU6HuGmfPL/o=
+github.com/aws/aws-sdk-go-v2/config v1.26.6/go.mod h1:uKU6cnDmYCvJ+pxO9S4cWDb2yWWIH5hra+32hVh1MI4=
+github.com/aws/aws-sdk-go-v2/credentials v1.16.16 h1:8q6Rliyv0aUFAVtzaldUEcS+T5gbadPbWdV1WcAddK8=
+github.com/aws/aws-sdk-go-v2/credentials v1.16.16/go.mod h1:UHVZrdUsv63hPXFo1H7c5fEneoVo9UXiz36QG1GEPi0=
+github.com/aws/aws-sdk-go-v2/feature/ec2/imds v1.14.11 h1:c5I5iH+DZcH3xOIMlz3/tCKJDaHFwYEmxvlh2fAcFo8=
+github.com/aws/aws-sdk-go-v2/feature/ec2/imds v1.14.11/go.mod h1:cRrYDYAMUohBJUtUnOhydaMHtiK/1NZ0Otc9lIb6O0Y=
+github.com/aws/aws-sdk-go-v2/internal/configsources v1.2.10 h1:vF+Zgd9s+H4vOXd5BMaPWykta2a6Ih0AKLq/X6NYKn4=
+github.com/aws/aws-sdk-go-v2/internal/configsources v1.2.10/go.mod h1:6BkRjejp/GR4411UGqkX8+wFMbFbqsUIimfK4XjOKR4=
+github.com/aws/aws-sdk-go-v2/internal/endpoints/v2 v2.5.10 h1:nYPe006ktcqUji8S2mqXf9c/7NdiKriOwMvWQHgYztw=
+github.com/aws/aws-sdk-go-v2/internal/endpoints/v2 v2.5.10/go.mod h1:6UV4SZkVvmODfXKql4LCbaZUpF7HO2BX38FgBf9ZOLw=
+github.com/aws/aws-sdk-go-v2/internal/ini v1.7.3 h1:n3GDfwqF2tzEkXlv5cuy4iy7LpKDtqDMcNLfZDu9rls=
+github.com/aws/aws-sdk-go-v2/internal/ini v1.7.3/go.mod h1:6fQQgfuGmw8Al/3M2IgIllycxV7ZW7WCdVSqfBeUiCY=
+github.com/aws/aws-sdk-go-v2/service/appconfigdata v1.12.0 h1:MkRVTMyOWO4ZkLBLMDQHun98FYaPMkSYN91r6SkYsPw=
+github.com/aws/aws-sdk-go-v2/service/appconfigdata v1.12.0/go.mod h1:bEPSlURhZxm6uNx1GAAwKHjqsCm6GHrf13qXzoh/2A8=
+github.com/aws/aws-sdk-go-v2/service/internal/accept-encoding v1.10.4 h1:/b31bi3YVNlkzkBrm9LfpaKoaYZUxIAj4sHfOTmLfqw=
+github.com/aws/aws-sdk-go-v2/service/internal/accept-encoding v1.10.4/go.mod h1:2aGXHFmbInwgP9ZfpmdIfOELL79zhdNYNmReK8qDfdQ=
+github.com/aws/aws-sdk-go-v2/service/internal/presigned-url v1.10.10 h1:DBYTXwIGQSGs9w4jKm60F5dmCQ3EEruxdc0MFh+3EY4=
+github.com/aws/aws-sdk-go-v2/service/internal/presigned-url v1.10.10/go.mod h1:wohMUQiFdzo0NtxbBg0mSRGZ4vL3n0dKjLTINdcIino=
+github.com/aws/aws-sdk-go-v2/service/sso v1.18.7 h1:eajuO3nykDPdYicLlP3AGgOyVN3MOlFmZv7WGTuJPow=
+github.com/aws/aws-sdk-go-v2/service/sso v1.18.7/go.mod h1:+mJNDdF+qiUlNKNC3fxn74WWNN+sOiGOEImje+3ScPM=
+github.com/aws/aws-sdk-go-v2/service/ssooidc v1.21.7 h1:QPMJf+Jw8E1l7zqhZmMlFw6w1NmfkfiSK8mS4zOx3BA=
+github.com/aws/aws-sdk-go-v2/service/ssooidc v1.21.7/go.mod h1:ykf3COxYI0UJmxcfcxcVuz7b6uADi1FkiUz6Eb7AgM8=
+github.com/aws/aws-sdk-go-v2/service/sts v1.26.7 h1:NzO4Vrau795RkUdSHKEwiR01FaGzGOH1EETJ+5QHnm0=
+github.com/aws/aws-sdk-go-v2/service/sts v1.26.7/go.mod h1:6h2YuIoxaMSCFf5fi1EgZAwdfkGMgDY+DVfa61uLe4U=
+github.com/aws/smithy-go v1.19.0 h1:KWFKQV80DpP3vJrrA9sVAHQ5gc2z8i4EzrLhLlWXcBM=
+github.com/aws/smithy-go v1.19.0/go.mod h1:NukqUGpCZIILqqiV0NIjeFh24kd/FAa4beRb6nbIUPE=
+github.com/google/go-cmp v0.5.8 h1:e6P7q2lk1O+qJJb4BtCQXlK8vWEO8V1ZeuEdJNOqZyg=
+github.com/google/go-cmp v0.5.8/go.mod h1:17dUlkBOakJ0+DkrSSNjCkIjxS6bF9zb3elmeNGIjoY=

provider/appconfig/option.go

@@ -0,0 +1,60 @@
+// Copyright (c) 2024 The konf authors
+// Use of this source code is governed by a MIT license found in the LICENSE file.
+
+package appconfig
+
+import (
+	"log/slog"
+	"time"
+
+	"github.com/aws/aws-sdk-go-v2/aws"
+)
+
+// WithAWSConfig provides the AWS Config for the AWS SDK.
+//
+// By default, it loads the default AWS Config.
+func WithAWSConfig(awsConfig *aws.Config) Option {
+	return func(options *options) {
+		options.awsConfig = awsConfig
+	}
+}
+
+// WithPollInterval provides the interval for polling the configuration.
+//
+// The default interval is 1 minute.
+func WithPollInterval(pollInterval time.Duration) Option {
+	return func(options *options) {
+		options.pollInterval = pollInterval
+	}
+}
+
+// WithUnmarshal provides the function used to parses the configuration file.
+// The unmarshal function must be able to unmarshal the file content into a map[string]any.
+//
+// The default function is json.Unmarshal.
+func WithUnmarshal(unmarshal func([]byte, any) error) Option {
+	return func(options *options) {
+		options.unmarshal = unmarshal
+	}
+}
+
+// WithLogHandler provides the slog.Handler for logs from watch.
+//
+// By default, it uses handler from slog.Default().
+func WithLogHandler(handler slog.Handler) Option {
+	return func(options *options) {
+		if handler != nil {
+			options.logger = slog.New(handler)
+		}
+	}
+}
+
+type (
+	// Option configures the a File with specific options.
+	Option  func(options *options)
+	options struct {
+		AppConfig
+
+		awsConfig *aws.Config
+	}
+)