Add optional support for passing env variables into provider

Needed to support dynamic auth as described in [issue][1], as we are
using sops dependency which is using native aws sdk, it will read such
configuration from env variables of the process.

Additionally, I upgraded deprecated terraform SDK such as replacing
`Read` into `ReadContext` and added

[1]: carlpett#112

sops/data_sops_external.go

@@ -1,16 +1,18 @@
 package sops
 
 import (
+	"context"
+	"github.com/hashicorp/terraform-plugin-sdk/v2/diag"
 	"io/ioutil"
+	"os"
 	"strings"
 
 	"github.com/hashicorp/terraform-plugin-sdk/v2/helper/schema"
 )
 
 func dataSourceExternal() *schema.Resource {
 	return &schema.Resource{
-		Read: dataSourceExternalRead,
-
+		ReadContext: dataSourceExternalRead,
 		Schema: map[string]*schema.Schema{
 			"input_type": {
 				Type:     schema.TypeString,
@@ -37,16 +39,33 @@ func dataSourceExternal() *schema.Resource {
 	}
 }
 
-func dataSourceExternalRead(d *schema.ResourceData, meta interface{}) error {
+func dataSourceExternalRead(ctx context.Context, d *schema.ResourceData, meta interface{}) diag.Diagnostics {
+	// Get the environment variables from the provider configuration
+	envVars, ok := meta.(map[string]interface{})
+	if !ok {
+		return diag.Errorf("Unable to get provider configuration")
+	}
+	// Set the environment variables
+	for key, value := range envVars {
+		if strValue, ok := value.(string); ok {
+			os.Setenv(key, strValue)
+		}
+	}
+
 	source := d.Get("source").(string)
 	content, err := ioutil.ReadAll(strings.NewReader(source))
 	if err != nil {
-		return err
+		return diag.FromErr(err)
 	}
 
 	format := d.Get("input_type").(string)
 	if err := validateInputType(format); err != nil {
-		return err
+		return diag.FromErr(err)
 	}
-	return readData(content, format, d)
+
+	if err := readData(content, format, d); err != nil {
+		return diag.FromErr(err)
+	}
+
+	return nil
 }

sops/data_sops_file.go

@@ -1,17 +1,18 @@
 package sops
 
 import (
-	"fmt"
+	"context"
+	"github.com/hashicorp/terraform-plugin-sdk/v2/diag"
 	"io/ioutil"
+	"os"
 	"path"
 
 	"github.com/hashicorp/terraform-plugin-sdk/v2/helper/schema"
 )
 
 func dataSourceFile() *schema.Resource {
 	return &schema.Resource{
-		Read: dataSourceFileRead,
-
+		ReadContext: dataSourceFileRead,
 		Schema: map[string]*schema.Schema{
 			"input_type": {
 				Type:     schema.TypeString,
@@ -38,16 +39,28 @@ func dataSourceFile() *schema.Resource {
 	}
 }
 
-func dataSourceFileRead(d *schema.ResourceData, meta interface{}) error {
+func dataSourceFileRead(ctx context.Context, d *schema.ResourceData, meta interface{}) diag.Diagnostics {
+	// Get the environment variables from the provider configuration
+	envVars, ok := meta.(map[string]interface{})
+	if !ok {
+		return diag.Errorf("Unable to get provider configuration")
+	}
+	// Set the environment variables
+	for key, value := range envVars {
+		if strValue, ok := value.(string); ok {
+			os.Setenv(key, strValue)
+		}
+	}
+
 	sourceFile := d.Get("source_file").(string)
 	content, err := ioutil.ReadFile(sourceFile)
 	if err != nil {
-		return err
+		return diag.FromErr(err)
 	}
 
 	var format string
-	if input_type := d.Get("input_type").(string); input_type != "" {
-		format = input_type
+	if inputType := d.Get("input_type").(string); inputType != "" {
+		format = inputType
 	} else {
 		switch ext := path.Ext(sourceFile); ext {
 		case ".json":
@@ -59,13 +72,17 @@ func dataSourceFileRead(d *schema.ResourceData, meta interface{}) error {
 		case ".ini":
 			format = "ini"
 		default:
-			return fmt.Errorf("Don't know how to decode file with extension %s, set input_type to json, yaml or raw as appropriate", ext)
+			return diag.Errorf("don't know how to decode file with extension %s, set input_type to json, yaml or raw as appropriate", ext)
 		}
 	}
 
 	if err := validateInputType(format); err != nil {
-		return err
+		return diag.FromErr(err)
+	}
+
+	if err := readData(content, format, d); err != nil {
+		return diag.FromErr(err)
 	}
 
-	return readData(content, format, d)
+	return nil
 }

sops/provider.go

@@ -1,14 +1,29 @@
 package sops
 
 import (
+	"context"
+	"github.com/hashicorp/terraform-plugin-sdk/v2/diag"
 	"github.com/hashicorp/terraform-plugin-sdk/v2/helper/schema"
 )
 
 func Provider() *schema.Provider {
 	return &schema.Provider{
+		Schema: map[string]*schema.Schema{
+			"environment": {
+				Type:     schema.TypeMap,
+				Optional: true,
+				Elem:     &schema.Schema{Type: schema.TypeString},
+			},
+		},
 		DataSourcesMap: map[string]*schema.Resource{
 			"sops_file":     dataSourceFile(),
 			"sops_external": dataSourceExternal(),
 		},
+		ConfigureContextFunc: providerConfigure,
 	}
 }
+
+func providerConfigure(ctx context.Context, d *schema.ResourceData) (interface{}, diag.Diagnostics) {
+	env := d.Get("environment").(map[string]interface{})
+	return env, nil
+}