Add HCL2 aws_secretsmanager function (#10124)

* refactor aws get secrets function out to reuse it else where
* add aws_secretsmanager func and docs for HCL2
* fix GetSecret: allow to pick secret version

common/template/funcs.go

@@ -9,6 +9,7 @@ import (
 	"sync"
 
 	consulapi "github.com/hashicorp/consul/api"
+	awssmapi "github.com/hashicorp/packer/template/interpolate/aws/secretsmanager"
 	vaultapi "github.com/hashicorp/vault/api"
 )
 
@@ -86,3 +87,23 @@ func Consul(k string) (string, error) {
 
 	return value, nil
 }
+
+func GetAWSSecret(name, key string) (string, error) {
+	// Check if at least 1 parameter has been used
+	if len(name) == 0 {
+		return "", errors.New("At least one secret name must be provided")
+	}
+	// client uses AWS SDK CredentialChain method. So,credentials can
+	// be loaded from credential file, environment variables, or IAM
+	// roles.
+	client := awssmapi.New(
+		&awssmapi.AWSConfig{},
+	)
+
+	spec := &awssmapi.SecretSpec{
+		Name: name,
+		Key:  key,
+	}
+
+	return client.GetSecret(spec)
+}

hcl2template/function/aws_secretetkey.go

@@ -0,0 +1,39 @@
+package function
+
+import (
+	"github.com/zclconf/go-cty/cty"
+	"github.com/zclconf/go-cty/cty/function"
+
+	commontpl "github.com/hashicorp/packer/common/template"
+)
+
+// AWSSecret constructs a function that retrieves secrets from aws secrets
+// manager. If Key field is not set then we will return first secret key stored
+// in secret name.
+var AWSSecret = function.New(&function.Spec{
+	Params: []function.Parameter{
+		{
+			Name:         "name",
+			Type:         cty.String,
+			AllowNull:    false,
+			AllowUnknown: false,
+		},
+		{
+			Name:         "key",
+			Type:         cty.String,
+			AllowNull:    true,
+			AllowUnknown: false,
+		},
+	},
+	Type: function.StaticReturnType(cty.String),
+	Impl: func(args []cty.Value, retType cty.Type) (cty.Value, error) {
+		name := args[0].AsString()
+		var key string
+		if !args[1].IsNull() && args[1].IsWhollyKnown() {
+			key = args[1].AsString()
+		}
+		val, err := commontpl.GetAWSSecret(name, key)
+
+		return cty.StringVal(val), err
+	},
+})

hcl2template/functions.go

@@ -30,6 +30,7 @@ func Functions(basedir string) map[string]function.Function {
 	funcs := map[string]function.Function{
 		"abs":                stdlib.AbsoluteFunc,
 		"abspath":            filesystem.AbsPathFunc,
+		"aws_secretsmanager": pkrfunction.AWSSecret,
 		"basename":           filesystem.BasenameFunc,
 		"base64decode":       encoding.Base64DecodeFunc,
 		"base64encode":       encoding.Base64EncodeFunc,

template/interpolate/aws/secretsmanager/secretsmanager.go

@@ -53,6 +53,9 @@ func (c *Client) GetSecret(spec *SecretSpec) (string, error) {
 		SecretId:     aws.String(spec.Name),
 		VersionStage: aws.String("AWSCURRENT"),
 	}
+	if spec.Name != "" {
+		params.VersionStage = aws.String(spec.Key)
+	}
 
 	resp, err := c.api.GetSecretValue(params)
 	if err != nil {

template/interpolate/funcs.go

@@ -13,7 +13,6 @@ import (
 	commontpl "github.com/hashicorp/packer/common/template"
 	"github.com/hashicorp/packer/common/uuid"
 	"github.com/hashicorp/packer/helper/common"
-	awssmapi "github.com/hashicorp/packer/template/interpolate/aws/secretsmanager"
 	"github.com/hashicorp/packer/version"
 	strftime "github.com/jehiah/go-strftime"
 )
@@ -280,37 +279,16 @@ func funcGenAwsSecrets(ctx *Context) interface{} {
 			// semantic checks should catch this.
 			return "", errors.New("AWS Secrets Manager is only allowed in the variables section")
 		}
-
-		// Check if at least 1 parameter has been used
-		if len(secret) == 0 {
-			return "", errors.New("At least one secret name must be provided")
+		switch len(secret) {
+		case 0:
+			return "", errors.New("secret name must be provided")
+		case 1:
+			return commontpl.GetAWSSecret(secret[0], "")
+		case 2:
+			return commontpl.GetAWSSecret(secret[0], secret[1])
+		default:
+			return "", errors.New("only secret name and optional secret key can be provided.")
 		}
-		// client uses AWS SDK CredentialChain method. So,credentials can
-		// be loaded from credential file, environment variables, or IAM
-		// roles.
-		client := awssmapi.New(
-			&awssmapi.AWSConfig{},
-		)
-
-		var name, key string
-		name = secret[0]
-		// key is optional if not used we fetch the first
-		// value stored in given secret. If more than two parameters
-		// are passed we take second param and ignore the others
-		if len(secret) > 1 {
-			key = secret[1]
-		}
-
-		spec := &awssmapi.SecretSpec{
-			Name: name,
-			Key:  key,
-		}
-
-		s, err := client.GetSecret(spec)
-		if err != nil {
-			return "", err
-		}
-		return s, nil
 	}
 }
 

website/data/docs-navigation.js

@@ -32,8 +32,9 @@ export default [
           {
             category: 'contextual',
             content: [
-              'vault',
+              'aws_secretsmanager',
               'consul',
+              'vault',
             ],
           },
           {

website/pages/docs/from-1.5/functions/contextual/aws_secretsmanager.mdx

@@ -0,0 +1,56 @@
+---
+layout: docs
+page_title: aws_secretsmanager - Functions - Configuration Language
+sidebar_title: aws_secretsmanager
+description: The aws_secretsmanager function retrieves secrets from Amazon secretsmanager stores.
+---
+
+
+# `aws_secretsmanager_key` Function
+
+Secrets can be read from the [AWS Secrets
+Manager](https://aws.amazon.com/secrets-manager/) and used within your template
+as locals.
+
+```hcl
+aws_secretsmanager(name, key)
+```
+
+When key is not set (`null` or empty: `""`) then `aws_secretsmanager` returns
+the first secret key stored in secret `name` using the `AWSCURRENT`.
+
+You can either use this function in a `locals` block or directly inline where
+you want to use the value.
+
+```hcl
+locals {
+  // null is equivalent to "AWSCURRENT"
+  current_version = aws_secretsmanager("my_secret", null)
+}
+
+source "null" "first-example" {
+  communicator = "none"
+}
+
+build {
+  name = "my-build-name"
+  sources = ["null.first-example"]
+
+  provisioner "shell-local" {
+    environment_vars = ["TESTVAR=${build.PackerRunUUID}"]
+    inline = ["echo current version is '${local.current_version}'",
+              "echo previous version is '${aws_secretsmanager("my_secret", "AWSPREVIOUS")}'."]
+  }
+}
+```
+
+This will load the key stored at behind `my_secret` from aws secrets manager.
+
+
+In order to use this function you have to configure valid AWS credentials using
+one of the following methods:
+
+- [Environment Variables](https://docs.aws.amazon.com/cli/latest/userguide/cli-configure-envvars.html)
+- [CLI Configuration Files](https://docs.aws.amazon.com/cli/latest/userguide/cli-configure-files.html)
+- [Container Credentials](https://docs.aws.amazon.com/AmazonECS/latest/developerguide/task-iam-roles.html)
+- [Instance Profile Credentials](https://docs.aws.amazon.com/AWSEC2/latest/UserGuide/iam-roles-for-amazon-ec2.html)