README.md

@@ -615,6 +615,7 @@ Writing Providers and Parsers are easy. See the bundled implementations in the `
 | providers/s3        | `s3.Provider(s3.S3Config{})`                                  | Takes a s3 config struct.                                                                                                                                                             |
 | providers/rawbytes  | `rawbytes.Provider(b []byte)`                                 | Takes a raw `[]byte` slice to be parsed with a koanf.Parser                                                                                                                           |
 | providers/vault     | `vault.Provider(vault.Config{})`                              | Hashicorp Vault provider                                                                                                                           |
+| providers/appconfig     | `vault.AppConfig(appconfig.Config{})`                              | AWS AppConfig provider                                                                                                                           |
 
 ### Bundled parsers
 
@@ -625,6 +626,7 @@ Writing Providers and Parsers are easy. See the bundled implementations in the `
 | parsers/toml | `toml.Parser()`                  | Parses TOML bytes into a nested map                                                                                                                       |
 | parsers/dotenv | `dotenv.Parser()`              | Parses DotEnv bytes into a flat map                                                                                                                       |
 | parsers/hcl  | `hcl.Parser(flattenSlices bool)` | Parses Hashicorp HCL bytes into a nested map. `flattenSlices` is recommended to be set to true. [Read more](https://github.com/hashicorp/hcl/issues/162). |
+
 ### Instance functions
 
 | Method                                                       | Description                                                  |

examples/read-appconfig/main.go

@@ -0,0 +1,44 @@
+package main
+
+import (
+	"log"
+	"os"
+
+	"github.com/knadh/koanf"
+	"github.com/knadh/koanf/parsers/json"
+	"github.com/knadh/koanf/providers/appconfig"
+)
+
+// Global koanf instance. Use "." as the key path delimiter. This can be "/" or any character.
+var k = koanf.New(".")
+
+func main() {
+	provider := appconfig.Provider(appconfig.Config{
+		Application:   os.Getenv("AWS_APPCONFIG_APPLICATION"),
+		ClientID:      os.Getenv("AWS_APPCONFIG_CLIENT_ID"),
+		Configuration: os.Getenv("AWS_APPCONFIG_CONFIG_NAME"),
+		Environment:   os.Getenv("AWS_APPCONFIG_ENVIRONMENT"),
+	})
+	// Load the provider and parse configuration as JSON.
+	if err := k.Load(provider, json.Parser()); err != nil {
+		log.Fatalf("error loading config: %v", err)
+	}
+
+	k.Print()
+
+	// Watch for all configuration updates.
+	provider.Watch(func(event interface{}, err error) {
+		if err != nil {
+			log.Printf("watch error: %v", err)
+			return
+		}
+
+		log.Println("config changed. Reloading ...")
+		k = koanf.New(".")
+		k.Load(provider, json.Parser())
+		k.Print()
+	})
+
+	log.Println("waiting forever.")
+	<-make(chan bool)
+}

go.mod

@@ -3,6 +3,11 @@ module github.com/knadh/koanf
 go 1.12
 
 require (
+	github.com/aws/aws-sdk-go-v2 v1.9.2
+	github.com/aws/aws-sdk-go-v2/config v1.8.3
+	github.com/aws/aws-sdk-go-v2/credentials v1.4.3
+	github.com/aws/aws-sdk-go-v2/service/appconfig v1.4.2
+	github.com/aws/aws-sdk-go-v2/service/sts v1.7.2
 	github.com/fatih/structs v1.1.0
 	github.com/fsnotify/fsnotify v1.4.9
 	github.com/hashicorp/hcl v1.0.0

go.sum

@@ -3,6 +3,26 @@ github.com/BurntSushi/toml v0.3.1 h1:WXkYYl6Yr3qBf1K79EBnL4mak0OimBfB0XUf9Vl28OQ
 github.com/BurntSushi/toml v0.3.1/go.mod h1:xHWCNGjB5oqiDr8zfno3MHue2Ht5sIBksp03qcyfWMU=
 github.com/armon/go-metrics v0.0.0-20180917152333-f0300d1749da/go.mod h1:Q73ZrmVTwzkszR9V5SSuryQ31EELlFMUz1kKyl939pY=
 github.com/armon/go-radix v0.0.0-20180808171621-7fddfc383310/go.mod h1:ufUuZ+zHj4x4TnLV4JWEpy2hxWSpsRywHrMgIH9cCH8=
+github.com/aws/aws-sdk-go-v2 v1.9.2 h1:dUFQcMNZMLON4BOe273pl0filK9RqyQMhCK/6xssL6s=
+github.com/aws/aws-sdk-go-v2 v1.9.2/go.mod h1:cK/D0BBs0b/oWPIcX/Z/obahJK1TT7IPVjy53i/mX/4=
+github.com/aws/aws-sdk-go-v2/config v1.8.3 h1:o5583X4qUfuRrOGOgmOcDgvr5gJVSu57NK08cWAhIDk=
+github.com/aws/aws-sdk-go-v2/config v1.8.3/go.mod h1:4AEiLtAb8kLs7vgw2ZV3p2VZ1+hBavOc84hqxVNpCyw=
+github.com/aws/aws-sdk-go-v2/credentials v1.4.3 h1:LTdD5QhK073MpElh9umLLP97wxphkgVC/OjQaEbBwZA=
+github.com/aws/aws-sdk-go-v2/credentials v1.4.3/go.mod h1:FNNC6nQZQUuyhq5aE5c7ata8o9e4ECGmS4lAXC7o1mQ=
+github.com/aws/aws-sdk-go-v2/feature/ec2/imds v1.6.0 h1:9tfxW/icbSu98C2pcNynm5jmDwU3/741F11688B6QnU=
+github.com/aws/aws-sdk-go-v2/feature/ec2/imds v1.6.0/go.mod h1:gqlclDEZp4aqJOancXK6TN24aKhT0W0Ae9MHk3wzTMM=
+github.com/aws/aws-sdk-go-v2/internal/ini v1.2.4 h1:leSJ6vCqtPpTmBIgE7044B1wql1E4n//McF+mEgNrYg=
+github.com/aws/aws-sdk-go-v2/internal/ini v1.2.4/go.mod h1:ZcBrrI3zBKlhGFNYWvju0I3TR93I7YIgAfy82Fh4lcQ=
+github.com/aws/aws-sdk-go-v2/service/appconfig v1.4.2 h1:5fez51yE//mtmaEkh9JTAcLl4xg60Ha86pE+FIqinGc=
+github.com/aws/aws-sdk-go-v2/service/appconfig v1.4.2/go.mod h1:FZ3HkCe+b10uFZZkFdvf98LHW21k49W8o8J366lqVKY=
+github.com/aws/aws-sdk-go-v2/service/internal/presigned-url v1.3.2 h1:r7jel2aa4d9Duys7wEmWqDd5ebpC9w6Kxu6wIjjp18E=
+github.com/aws/aws-sdk-go-v2/service/internal/presigned-url v1.3.2/go.mod h1:72HRZDLMtmVQiLG2tLfQcaWLCssELvGl+Zf2WVxMmR8=
+github.com/aws/aws-sdk-go-v2/service/sso v1.4.2 h1:pZwkxZbspdqRGzddDB92bkZBoB7lg85sMRE7OqdB3V0=
+github.com/aws/aws-sdk-go-v2/service/sso v1.4.2/go.mod h1:NBvT9R1MEF+Ud6ApJKM0G+IkPchKS7p7c2YPKwHmBOk=
+github.com/aws/aws-sdk-go-v2/service/sts v1.7.2 h1:ol2Y5DWqnJeKqNd8th7JWzBtqu63xpOfs1Is+n1t8/4=
+github.com/aws/aws-sdk-go-v2/service/sts v1.7.2/go.mod h1:8EzeIqfWt2wWT4rJVu3f21TfrhJ8AEMzVybRNSb/b4g=
+github.com/aws/smithy-go v1.8.0 h1:AEwwwXQZtUwP5Mz506FeXXrKBe0jA8gVM+1gEcSRooc=
+github.com/aws/smithy-go v1.8.0/go.mod h1:SObp3lf9smib00L/v3U2eAKG8FyQ7iLrJnQiAmR5n+E=
 github.com/bgentry/speakeasy v0.1.0/go.mod h1:+zsyZBPWlz7T6j88CTgSN5bM796AkVf0kBD4zp0CCIs=
 github.com/client9/misspell v0.3.4/go.mod h1:qj6jICC3Q7zFZvVWo7KLAzC3yx5G7kyvSDkc90ppPyw=
 github.com/davecgh/go-spew v1.1.0/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
@@ -22,6 +42,9 @@ github.com/golang/protobuf v1.3.1/go.mod h1:6lQm79b+lXiMfvg/cZm0SGofjICqVBUtrP5y
 github.com/golang/snappy v0.0.1 h1:Qgr9rKW7uDUkrbSmQeiDsGa8SjGyCOGtuasMWwvp2P4=
 github.com/golang/snappy v0.0.1/go.mod h1:/XxbfmMg8lxefKM7IXC3fBNl/7bRcc72aCRzEWrmP2Q=
 github.com/google/go-cmp v0.2.0/go.mod h1:oXzfMopK8JAjlY9xF4vHSVASa0yLyX7SntLO5aqRK0M=
+github.com/google/go-cmp v0.5.4/go.mod h1:v8dTdLbMG2kIc/vJvl+f65V22dbkXbowE6jgT/gNBxE=
+github.com/google/go-cmp v0.5.6 h1:BKbKCqvP6I+rmFHt06ZmyQtvB8xAkWdhFyr0ZUNZcxQ=
+github.com/google/go-cmp v0.5.6/go.mod h1:v8dTdLbMG2kIc/vJvl+f65V22dbkXbowE6jgT/gNBxE=
 github.com/hashicorp/errwrap v1.0.0 h1:hLrqtEDnRye3+sgx6z4qVLNuviH3MR5aQ0ykNJa/UYA=
 github.com/hashicorp/errwrap v1.0.0/go.mod h1:YH+1FKiLXxHSkmPseP+kNlulaMuP3n2brvKWEqk/Jc4=
 github.com/hashicorp/go-cleanhttp v0.5.0/go.mod h1:JpRdi6/HCYpAwUzNwuwqhbovhLtngrth3wmdIIUrZ80=
@@ -52,6 +75,8 @@ github.com/hashicorp/vault/sdk v0.1.13 h1:mOEPeOhT7jl0J4AMl1E705+BcmeRs1VmKNb9F0
 github.com/hashicorp/vault/sdk v0.1.13/go.mod h1:B+hVj7TpuQY1Y/GPbCpffmgd+tSEwvhkWnjtSYCaS2M=
 github.com/hashicorp/yamux v0.0.0-20180604194846-3520598351bb/go.mod h1:+NfK9FKeTrX5uv1uIXGdwYDTeHna2qgaIlx54MXqjAM=
 github.com/hashicorp/yamux v0.0.0-20181012175058-2f1d1f20f75d/go.mod h1:+NfK9FKeTrX5uv1uIXGdwYDTeHna2qgaIlx54MXqjAM=
+github.com/jmespath/go-jmespath v0.4.0/go.mod h1:T8mJZnbsbmF+m6zOOFylbeCJqk5+pHWvzYPziyZiYoo=
+github.com/jmespath/go-jmespath/internal/testify v1.5.1/go.mod h1:L3OGu8Wl2/fWfCI6z80xFu9LTZmf1ZRjMHUOPmWr69U=
 github.com/joho/godotenv v1.3.0 h1:Zjp+RcGpHhGlrMbJzXTrZZPrWj+1vfm90La1wgB6Bhc=
 github.com/joho/godotenv v1.3.0/go.mod h1:7hK45KPybAkOC6peb+G5yklZfMxEjkZhHbwpqxOKXbg=
 github.com/mattn/go-colorable v0.0.9/go.mod h1:9vuHe8Xs5qXnSaW/c/ABM9alt+Vo+STaOChaDxuIBZU=
@@ -87,10 +112,8 @@ github.com/ryanuber/go-glob v1.0.0 h1:iQh3xXAumdQ+4Ufa5b25cRpC5TYKlno6hsv6Cb3pkB
 github.com/ryanuber/go-glob v1.0.0/go.mod h1:807d1WSdnB0XRJzKNil9Om6lcp/3a0v4qIHxIXzX/Yc=
 github.com/spf13/pflag v1.0.5 h1:iy+VFUOCP1a+8yFto/drg2CJ5u0yRoB7fZw3DKv/JXA=
 github.com/spf13/pflag v1.0.5/go.mod h1:McXfInJRrz4CZXVZOBLb0bTZqETkiAhM9Iw0y3An2Bg=
-github.com/stretchr/objx v0.1.0 h1:4G4v2dO3VZwixGIRoQ5Lfboy6nUhCyYzaqnIAPPhYs4=
 github.com/stretchr/objx v0.1.0/go.mod h1:HFkY916IF+rwdDfMAkV7OtwuqBVzrE8GR6GFx+wExME=
 github.com/stretchr/testify v1.2.2/go.mod h1:a8OnRcib4nhh0OaRAV+Yts87kKdq0PP7pXfy6kDkUVs=
-github.com/stretchr/testify v1.3.0 h1:TivCn/peBQ7UY8ooIcPgZFpTNSz0Q2U6UrFlUfqbe0Q=
 github.com/stretchr/testify v1.3.0/go.mod h1:M5WIy9Dh21IEIfnGCwXGc5bZfKNJtfHm1UVUgZn+9EI=
 github.com/stretchr/testify v1.7.0 h1:nwc3DEeHmmLAfoZucVR881uASk0Mfjw8xYJ99tb5CcY=
 github.com/stretchr/testify v1.7.0/go.mod h1:6Fq8oRcR53rry900zMqJjRRixrwX3KX962/h/Wwjteg=
@@ -131,6 +154,8 @@ golang.org/x/tools v0.0.0-20190114222345-bf090417da8b/go.mod h1:n7NCudcB/nEzxVGm
 golang.org/x/tools v0.0.0-20190226205152-f727befe758c/go.mod h1:9Yl7xja0Znq3iFh3HoIrodX9oNMXvdceNzlUR8zjMvY=
 golang.org/x/tools v0.0.0-20190311212946-11955173bddd/go.mod h1:LCzVGOaR6xXOjkQ3onu1FJEFr0SW1gC7cKk1uF8kGRs=
 golang.org/x/tools v0.0.0-20190524140312-2c0ae7006135/go.mod h1:RgjU9mgBXZiqYHBnxXauZ1Gv1EHHAz9KjViQ78xBX0Q=
+golang.org/x/xerrors v0.0.0-20191204190536-9bdfabe68543 h1:E7g+9GITq07hpfrRu66IVDexMakfv52eLZ2CXBWiKr4=
+golang.org/x/xerrors v0.0.0-20191204190536-9bdfabe68543/go.mod h1:I/5z698sn9Ka8TeJc9MKroUUfqBBauWjQqLJ2OPfmY0=
 google.golang.org/appengine v1.1.0/go.mod h1:EbEs0AVv82hx2wNQdGPgUI5lhzA/G0D9YwlJXL52JkM=
 google.golang.org/appengine v1.4.0/go.mod h1:xpcJRLb0r/rnEns0DIKYYv+WjYCduHsrkT7/EB5XEv4=
 google.golang.org/genproto v0.0.0-20180817151627-c66870c02cf8/go.mod h1:JiN7NxoALGmiZfu7CAH4rXhgtRTLTxftemlI0sWmxmc=

providers/appconfig/appconfig.go

@@ -0,0 +1,154 @@
+// Package appconfig implements a koanf.Provider for AWS AppConfig
+// and provides it to koanf to be parsed by a koanf.Parser.
+package appconfig
+
+import (
+	"context"
+	"errors"
+	"time"
+
+	"github.com/aws/aws-sdk-go-v2/aws"
+	"github.com/aws/aws-sdk-go-v2/config"
+	"github.com/aws/aws-sdk-go-v2/credentials"
+	"github.com/aws/aws-sdk-go-v2/credentials/stscreds"
+	"github.com/aws/aws-sdk-go-v2/service/appconfig"
+	"github.com/aws/aws-sdk-go-v2/service/sts"
+)
+
+// Config holds the AWS AppConfig Configuration.
+type Config struct {
+	// The AWS AppConfig Application to get. Specify either the application
+	// name or the application ID.
+	Application string
+
+	// The Client ID for the AppConfig. Enables AppConfig to deploy the
+	// configuration in intervals, as defined in the deployment strategy.
+	ClientID string
+
+	// The AppConfig configuration to fetch. Specify either the configuration
+	// name or the configuration ID.
+	Configuration string
+
+	// The AppConfig environment to get. Specify either the environment
+	// name or the environment ID.
+	Environment string
+
+	// The AppConfig Configuration Version to fetch. Specifying a ClientConfigurationVersion
+	// ensures that the configuration is only fetched if it is updated. If not specified,
+	// the latest available configuration is fetched always.
+	// Setting this to the latest configuration version will return an empty slice of bytes.
+	ClientConfigurationVersion string
+
+	// The AWS Access Key ID to use. This value is fetched from the environment
+	// if not specified.
+	AWSAccessKeyID string
+
+	// The AWS Secret Access Key to use. This value is fetched from the environment
+	// if not specified.
+	AWSSecretAccessKey string
+
+	// The AWS IAM Role ARN to use. Useful for access requiring IAM AssumeRole.
+	AWSRoleARN string
+
+	// The AWS Region to use. This value is fetched from teh environment if not specified.
+	AWSRegion string
+
+	// Time interval at which the watcher will refresh the configuration.
+	// Defaults to 60 seconds.
+	WatchInterval time.Duration
+}
+
+// AppConfig implements an AWS AppConfig provider.
+type AppConfig struct {
+	client *appconfig.Client
+	config Config
+	input  appconfig.GetConfigurationInput
+}
+
+// Provider returns an AWS AppConfig provider.
+func Provider(cfg Config) *AppConfig {
+	c, err := config.LoadDefaultConfig(context.TODO())
+	if err != nil {
+		return nil
+	}
+
+	if cfg.AWSRegion != "" {
+		c.Region = cfg.AWSRegion
+	}
+
+	// Check if AWS Access Key ID and Secret Key are specified.
+	if cfg.AWSAccessKeyID != "" && cfg.AWSSecretAccessKey != "" {
+		c.Credentials = credentials.NewStaticCredentialsProvider(cfg.AWSAccessKeyID, cfg.AWSSecretAccessKey, "")
+	}
+
+	// Check if AWS Role ARN is present.
+	if cfg.AWSRoleARN != "" {
+		stsSvc := sts.NewFromConfig(c)
+		credentials := stscreds.NewAssumeRoleProvider(stsSvc, cfg.AWSRoleARN)
+		c.Credentials = aws.NewCredentialsCache(credentials)
+	}
+	client := appconfig.NewFromConfig(c)
+
+	return &AppConfig{client: client, config: cfg}
+}
+
+// ReadBytes returns the raw bytes for parsing.
+func (ac *AppConfig) ReadBytes() ([]byte, error) {
+	ac.input = appconfig.GetConfigurationInput{
+		Application:   &ac.config.Application,
+		ClientId:      &ac.config.ClientID,
+		Configuration: &ac.config.Configuration,
+		Environment:   &ac.config.Environment,
+	}
+	if ac.config.ClientConfigurationVersion != "" {
+		ac.input.ClientConfigurationVersion = &ac.config.ClientConfigurationVersion
+	}
+
+	conf, err := ac.client.GetConfiguration(context.TODO(), &ac.input)
+	if err != nil {
+		return nil, err
+	}
+
+	// Set the response configuration version as the current configuration version.
+	// Useful for Watch().
+	ac.input.ClientConfigurationVersion = conf.ConfigurationVersion
+
+	return conf.Content, nil
+}
+
+// Read is not supported by the appconfig provider.
+func (ac *AppConfig) Read() (map[string]interface{}, error) {
+	return nil, errors.New("appconfig provider does not support this method")
+}
+
+// Watch polls AWS AppConfig for configuration updates.
+func (ac *AppConfig) Watch(cb func(event interface{}, err error)) error {
+	if ac.config.WatchInterval == 0 {
+		// Set default watch interval to 60 seconds.
+		ac.config.WatchInterval = 60 * time.Second
+	}
+
+	go func() {
+	loop:
+		for {
+			conf, err := ac.client.GetConfiguration(context.TODO(), &ac.input)
+			if err != nil {
+				cb(nil, err)
+				break loop
+			}
+
+			// Check if the the configuration has been updated.
+			if len(conf.Content) == 0 {
+				// Configuration is not updated and we have the latest version.
+				// Sleep for WatchInterval and retry watcher.
+				time.Sleep(ac.config.WatchInterval)
+				continue
+			}
+
+			// Trigger event.
+			cb(nil, nil)
+		}
+	}()
+
+	return nil
+}