chore(examples): Add examples for Go with CI

.github/workflows/library_go_tests.yml

@@ -95,4 +95,11 @@ jobs:
         working-directory: ${{ matrix.library }}
         shell: bash
         run: |
-          make test_go
+          make test_go
+
+      - name: Test Examples for Go
+        if: matrix.library == 'AwsEncryptionSDK'
+        working-directory: ${{ matrix.library }}/runtimes/go/examples
+        shell: bash
+        run: |
+          go run main.go

AwsEncryptionSDK/Makefile

@@ -92,3 +92,21 @@ TYPES_FILE_WITHOUT_EXTERN_STRING="module AwsCryptographyEncryptionSdkTypes"
 INDEX_FILE_PATH=dafny/AwsEncryptionSdk/src/Index.dfy
 INDEX_FILE_WITH_EXTERN_STRING="module {:extern \"software.amazon.cryptography.encryptionsdk.internaldafny\" } ESDK refines AbstractAwsCryptographyEncryptionSdkService {"
 INDEX_FILE_WITHOUT_EXTERN_STRING="module ESDK refines AbstractAwsCryptographyEncryptionSdkService {"
+
+# Target to restore all directories in a list
+# TODO: remove this once we don't copy all of the directories into implementation and test. This is done by make file target _mv_polymorph_go in smithy-dafny.
+RESTORE_DIRS := examples
+_polymorph_go: restore_directories
+restore_directories:
+	@for dir in $(RESTORE_DIRS); do \
+		if [ -d "runtimes/go/ImplementationFromDafny-go/$$dir" ]; then \
+			cp -Rf runtimes/go/ImplementationFromDafny-go/$$dir runtimes/go/; \
+			rm -rf runtimes/go/ImplementationFromDafny-go/$$dir; \
+			rm -rf runtimes/go/TestsFromDafny-go/$$dir; \
+		else \
+			echo "Directory $$dir not found"; \
+		fi \
+	done
+
+_polymorph_dependencies:
+	@echo "No polymorphing of dependency"

AwsEncryptionSDK/runtimes/go/examples/clientsupplier/clientSupplierExample.go

@@ -0,0 +1,163 @@
+// Copyright Amazon.com Inc. or its affiliates. All Rights Reserved.
+// SPDX-License-Identifier: Apache-2.0
+
+/*
+ This example sets up an MRK multi-keyring and an MRK discovery
+ multi-keyring using a custom client supplier.
+ A custom client supplier grants users access to more granular
+ configuration aspects of their authentication details and KMS
+ client. In this example, we create a simple custom client supplier
+ that authenticates with a different IAM role based on the
+ region of the KMS key.
+
+ This example creates a MRK multi-keyring configured with a custom
+ client supplier using a single MRK and encrypts the example_data with it.
+ Then, it creates a MRK discovery multi-keyring to decrypt the ciphertext.
+*/
+
+package clientsupplier
+
+import (
+	"context"
+	"fmt"
+
+	mpl "github.com/aws/aws-cryptographic-material-providers-library/mpl/awscryptographymaterialproviderssmithygenerated"
+	mpltypes "github.com/aws/aws-cryptographic-material-providers-library/mpl/awscryptographymaterialproviderssmithygeneratedtypes"
+	client "github.com/aws/aws-encryption-sdk/awscryptographyencryptionsdksmithygenerated"
+	esdktypes "github.com/aws/aws-encryption-sdk/awscryptographyencryptionsdksmithygeneratedtypes"
+)
+
+func ClientSupplierExample(exampleText, mrkKeyIdEncrypt, awsAccountId string, awsRegions []string) {
+	// Step 1: Instantiate the encryption SDK client.
+	// This builds the default client with the RequireEncryptRequireDecrypt commitment policy,
+	// which enforces that this client only encrypts using committing algorithm suites and enforces
+	// that this client will only decrypt encrypted messages that were created with a committing
+	// algorithm suite.
+	encryptionClient, err := client.NewClient(esdktypes.AwsEncryptionSdkConfig{})
+	if err != nil {
+		panic(err)
+	}
+	// Step 2: Create your encryption context.
+	// Remember that your encryption context is NOT SECRET.
+	// For more information, see
+	// https://docs.aws.amazon.com/encryption-sdk/latest/developer-guide/concepts.html#encryption-context
+	encryptionContext := map[string]string{
+		"encryption":                "context",
+		"is not":                    "secret",
+		"but adds":                  "useful metadata",
+		"that can help you":         "be confident that",
+		"the data you are handling": "is what you think it is",
+	}
+	// Step 3: Initialize the mpl client
+	matProv, err := mpl.NewClient(mpltypes.MaterialProvidersConfig{})
+	if err != nil {
+		panic(err)
+	}
+	// Step 4: Create keyrings
+	// First Keyring: Create the multi-keyring using our custom client supplier
+	// defined in the RegionalRoleClientSupplier class in this directory.
+	// Note: RegionalRoleClientSupplier will internally use the key_arn's region
+	// to retrieve the correct IAM role.
+	awsKmsMrkKeyringMultiInput := mpltypes.CreateAwsKmsMrkMultiKeyringInput{
+		ClientSupplier: &RegionalRoleClientSupplier{},
+		Generator:      &mrkKeyIdEncrypt,
+	}
+	awsKmsMrkMultiKeyring, err := matProv.CreateAwsKmsMrkMultiKeyring(context.Background(), awsKmsMrkKeyringMultiInput)
+	if err != nil {
+		panic(err)
+	}
+	// Second Keyring: Create a MRK discovery multi-keyring with a custom client supplier.
+	// A discovery MRK multi-keyring will be composed of
+	// multiple discovery MRK keyrings, one for each region.
+	// Each component keyring has its own KMS client in a particular region.
+	// When we provide a client supplier to the multi-keyring, all component
+	// keyrings will use that client supplier configuration.
+	// In our tests, we make `mrk_key_id_encrypt` an MRK with a replica, and
+	// provide only the replica region in our discovery filter.
+	discoveryFilter := mpltypes.DiscoveryFilter{
+		AccountIds: []string{awsAccountId},
+		Partition:  "aws",
+	}
+	awsKmsMrkDiscoveryMultiKeyringInput := mpltypes.CreateAwsKmsMrkDiscoveryMultiKeyringInput{
+		ClientSupplier:  &RegionalRoleClientSupplier{},
+		Regions:         awsRegions,
+		DiscoveryFilter: &discoveryFilter,
+	}
+	awsKmsMrkDiscoveryMultiKeyring, err := matProv.CreateAwsKmsMrkDiscoveryMultiKeyring(context.Background(), awsKmsMrkDiscoveryMultiKeyringInput)
+	// Step 5a: Encrypt
+	res, err := encryptionClient.Encrypt(context.Background(), esdktypes.EncryptInput{
+		Plaintext:         []byte(exampleText),
+		EncryptionContext: encryptionContext,
+		Keyring:           awsKmsMrkMultiKeyring,
+	})
+	if err != nil {
+		panic(err)
+	}
+	// Validate Ciphertext and Plaintext before encryption are NOT the same
+	if string(res.Ciphertext) == exampleText {
+		panic("Ciphertext and Plaintext before encryption are the same")
+	}
+	// Step 5b: Decrypt
+	// Decrypt your encrypted data using the discovery multi keyring.
+	// On Decrypt, the header of the encrypted message (ciphertext) will be parsed.
+	// The header contains the Encrypted Data Keys (EDKs), which, if the EDK
+	// was encrypted by a KMS Keyring, includes the KMS Key ARN.
+	// For each member of the Multi Keyring, every EDK will try to be decrypted until a decryption
+	// is successful.
+	// Since every member of the Multi Keyring is a Discovery Keyring:
+	//   Each Keyring will filter the EDKs by the Discovery Filter and the Keyring's region.
+	//   For each filtered EDK, the keyring will attempt decryption with the keyring's client.
+	// All of this is done serially, until a success occurs or all keyrings have failed
+	// all (filtered) EDKs. KMS MRK Discovery Keyrings will attempt to decrypt
+	// Multi Region Keys (MRKs) and regular KMS Keys.
+	decryptOutput, err := encryptionClient.Decrypt(context.Background(), esdktypes.DecryptInput{
+		EncryptionContext: encryptionContext,
+		Keyring:           awsKmsMrkDiscoveryMultiKeyring,
+		Ciphertext:        res.Ciphertext,
+	})
+	if err != nil {
+		panic(err)
+	}
+	// Validate Plaintext after decryption and Plaintext before encryption ARE the same
+	if string(decryptOutput.Plaintext) != exampleText {
+		panic("Plaintext after decryption and Plaintext before encryption are NOT the same")
+	}
+	// If you do not specify the encryption context on Decrypt, it's recommended to check if the resulting encryption context matches.
+	// The encryption context was specified on decrypt; we are validating the encryption context for demonstration only.
+	// Before your application uses plaintext data, verify that the encryption context that
+	// you used to encrypt the message is included in the encryption context that was used to
+	// decrypt the message. The AWS Encryption SDK can add pairs, so don't require an exact match.
+	if err = validateEncryptionContext(encryptionContext, decryptOutput.EncryptionContext); err != nil {
+		panic(err)
+	}
+	// Test the Missing Region Exception
+	// (This is for demonstration; you do not need to do this in your code.)
+
+	// Create a MRK discovery multi-keyring with a custom client supplier and a fake region.
+	awsKmsMrkDiscoveryMultiKeyringInputMissingRegion := mpltypes.CreateAwsKmsMrkDiscoveryMultiKeyringInput{
+		ClientSupplier:  &RegionalRoleClientSupplier{},
+		Regions:         []string{"fake-region"},
+		DiscoveryFilter: &discoveryFilter,
+	}
+	_, err = matProv.CreateAwsKmsMrkDiscoveryMultiKeyring(context.Background(), awsKmsMrkDiscoveryMultiKeyringInputMissingRegion)
+	// Swallow the AwsCryptographicMaterialProvidersException but you may choose how to handle the exception
+	switch err.(type) {
+	case mpltypes.AwsCryptographicMaterialProvidersException:
+		// You may choose how to handle the exception in this switch case.
+	default:
+		panic("Decryption using discovery keyring with missing region MUST raise AwsCryptographicMaterialProvidersException")
+	}
+	fmt.Println("Client Supplier Example completed successfully")
+}
+
+// This function only does subset matching because AWS Encryption SDK can add pairs, so don't require an exact match.
+func validateEncryptionContext(expected, actual map[string]string) error {
+	for expectedKey, expectedValue := range expected {
+		actualValue, exists := actual[expectedKey]
+		if !exists || actualValue != expectedValue {
+			return fmt.Errorf("encryption context mismatch: expected key '%s' with value '%s'",
+				expectedKey, expectedValue)
+		}
+	}
+	return nil
+}

AwsEncryptionSDK/runtimes/go/examples/clientsupplier/regionalroleclientsupplier.go

@@ -0,0 +1,57 @@
+package clientsupplier
+
+import (
+	"context"
+
+	mpltypes "github.com/aws/aws-cryptographic-material-providers-library/mpl/awscryptographymaterialproviderssmithygeneratedtypes"
+	"github.com/aws/aws-sdk-go-v2/config"
+	"github.com/aws/aws-sdk-go-v2/credentials/stscreds"
+	"github.com/aws/aws-sdk-go-v2/service/kms"
+	"github.com/aws/aws-sdk-go-v2/service/sts"
+)
+
+/*
+ Example class demonstrating an implementation of a custom client supplier.
+ This particular implementation will create KMS clients with different IAM roles,
+ depending on the region passed.
+*/
+
+// RegionalRoleClientSupplier provides implementation for mpltypes.IClientSupplier
+type RegionalRoleClientSupplier struct {
+}
+
+func (this *RegionalRoleClientSupplier) GetClient(input mpltypes.GetClientInput) (kms.Client, error) {
+	region := input.Region
+	// Check if the region is supported
+	regionIamRoleMap := RegionIamRoleMap()
+	var defaultVal kms.Client
+	// Check if region is supported
+	if _, exists := regionIamRoleMap[region]; !exists {
+		return defaultVal, mpltypes.AwsCryptographicMaterialProvidersException{
+			Message: "Region is not supported by this client supplier",
+		}
+	}
+	// Get the IAM role ARN associated with the region
+	arn := regionIamRoleMap[region]
+	ctx := context.TODO()
+	cfg, err := config.LoadDefaultConfig(ctx,
+		config.WithRegion(region),
+	)
+	if err != nil {
+		return defaultVal, err
+	}
+	stsClient := sts.NewFromConfig(cfg)
+	// Create the AssumeRoleProvider
+	provider := stscreds.NewAssumeRoleProvider(stsClient, arn, func(o *stscreds.AssumeRoleOptions) {
+		o.RoleSessionName = "Go-ESDK-Client-Supplier-Example-Session"
+	})
+	// Load AWS SDK configuration with the AssumeRoleProvider
+	sdkConfig, err := config.LoadDefaultConfig(context.Background(), config.WithRegion(region), config.WithCredentialsProvider(provider))
+	if err != nil {
+		return defaultVal, mpltypes.AwsCryptographicMaterialProvidersException{Message: "failed to load AWS SDK config"}
+	}
+	// Create the KMS client
+	kmsClient := kms.NewFromConfig(sdkConfig)
+	// Return the KMS client wrapped in a custom type
+	return *kmsClient, nil
+}

AwsEncryptionSDK/runtimes/go/examples/clientsupplier/regionalroleclientsupplierconfig.go

@@ -0,0 +1,22 @@
+// Copyright Amazon.com Inc. or its affiliates. All Rights Reserved.
+// SPDX-License-Identifier: Apache-2.0
+
+package clientsupplier
+
+/*
+ File containing config for the RegionalRoleClientSupplier.
+ In your own code, this might be hardcoded, or reference
+ an external source, e.g. environment variables or AWS AppConfig.
+*/
+
+const (
+	usEast1IamRole = "arn:aws:iam::370957321024:role/GitHub-CI-Public-ESDK-Dafny-Role-only-us-east-1-KMS-keys"
+	euWest1IamRole = "arn:aws:iam::370957321024:role/GitHub-CI-Public-ESDK-Dafny-Role-only-eu-west-1-KMS-keys"
+)
+
+func RegionIamRoleMap() map[string]string {
+	return map[string]string{
+		"us-east-1": usEast1IamRole,
+		"eu-west-1": euWest1IamRole,
+	}
+}