Move duplicated envDefaultFunc out of each provider and into Schema.

builtin/providers/atlas/provider.go

@@ -1,8 +1,6 @@
 package atlas
 
 import (
-	"os"
-
 	"github.com/hashicorp/atlas-go/v1"
 	"github.com/hashicorp/terraform/helper/schema"
 	"github.com/hashicorp/terraform/terraform"
@@ -21,14 +19,14 @@ func Provider() terraform.ResourceProvider {
 			"token": &schema.Schema{
 				Type:        schema.TypeString,
 				Required:    true,
-				DefaultFunc: envDefaultFunc("ATLAS_TOKEN", nil),
+				DefaultFunc: schema.EnvDefaultFunc("ATLAS_TOKEN", nil),
 				Description: descriptions["token"],
 			},
 
 			"address": &schema.Schema{
 				Type:        schema.TypeString,
 				Optional:    true,
-				DefaultFunc: envDefaultFunc("ATLAS_ADDRESS", defaultAtlasServer),
+				DefaultFunc: schema.EnvDefaultFunc("ATLAS_ADDRESS", defaultAtlasServer),
 				Description: descriptions["address"],
 			},
 		},
@@ -55,16 +53,6 @@ func providerConfigure(d *schema.ResourceData) (interface{}, error) {
 	return client, nil
 }
 
-func envDefaultFunc(k string, alt interface{}) schema.SchemaDefaultFunc {
-	return func() (interface{}, error) {
-		if v := os.Getenv(k); v != "" {
-			return v, nil
-		}
-
-		return alt, nil
-	}
-}
-
 var descriptions map[string]string
 
 func init() {

builtin/providers/aws/provider.go

@@ -1,8 +1,6 @@
 package aws
 
 import (
-	"os"
-
 	"github.com/hashicorp/terraform/helper/schema"
 	"github.com/hashicorp/terraform/terraform"
 )
@@ -17,21 +15,21 @@ func Provider() terraform.ResourceProvider {
 			"access_key": &schema.Schema{
 				Type:        schema.TypeString,
 				Required:    true,
-				DefaultFunc: envDefaultFunc("AWS_ACCESS_KEY"),
+				DefaultFunc: schema.EnvDefaultFunc("AWS_ACCESS_KEY", nil),
 				Description: descriptions["access_key"],
 			},
 
 			"secret_key": &schema.Schema{
 				Type:        schema.TypeString,
 				Required:    true,
-				DefaultFunc: envDefaultFunc("AWS_SECRET_KEY"),
+				DefaultFunc: schema.EnvDefaultFunc("AWS_SECRET_KEY", nil),
 				Description: descriptions["secret_key"],
 			},
 
 			"region": &schema.Schema{
 				Type:         schema.TypeString,
 				Required:     true,
-				DefaultFunc:  envDefaultFunc("AWS_REGION"),
+				DefaultFunc:  schema.EnvDefaultFunc("AWS_REGION", nil),
 				Description:  descriptions["region"],
 				InputDefault: "us-east-1",
 			},
@@ -79,16 +77,6 @@ func init() {
 	}
 }
 
-func envDefaultFunc(k string) schema.SchemaDefaultFunc {
-	return func() (interface{}, error) {
-		if v := os.Getenv(k); v != "" {
-			return v, nil
-		}
-
-		return nil, nil
-	}
-}
-
 func providerConfigure(d *schema.ResourceData) (interface{}, error) {
 	config := Config{
 		AccessKey: d.Get("access_key").(string),

builtin/providers/cloudflare/provider.go

@@ -1,8 +1,6 @@
 package cloudflare
 
 import (
-	"os"
-
 	"github.com/hashicorp/terraform/helper/schema"
 	"github.com/hashicorp/terraform/terraform"
 )
@@ -14,14 +12,14 @@ func Provider() terraform.ResourceProvider {
 			"email": &schema.Schema{
 				Type:        schema.TypeString,
 				Required:    true,
-				DefaultFunc: envDefaultFunc("CLOUDFLARE_EMAIL"),
+				DefaultFunc: schema.EnvDefaultFunc("CLOUDFLARE_EMAIL", nil),
 				Description: "A registered CloudFlare email address.",
 			},
 
 			"token": &schema.Schema{
 				Type:        schema.TypeString,
 				Required:    true,
-				DefaultFunc: envDefaultFunc("CLOUDFLARE_TOKEN"),
+				DefaultFunc: schema.EnvDefaultFunc("CLOUDFLARE_TOKEN", nil),
 				Description: "The token key for API operations.",
 			},
 		},
@@ -34,16 +32,6 @@ func Provider() terraform.ResourceProvider {
 	}
 }
 
-func envDefaultFunc(k string) schema.SchemaDefaultFunc {
-	return func() (interface{}, error) {
-		if v := os.Getenv(k); v != "" {
-			return v, nil
-		}
-
-		return nil, nil
-	}
-}
-
 func providerConfigure(d *schema.ResourceData) (interface{}, error) {
 	config := Config{
 		Email: d.Get("email").(string),

builtin/providers/cloudstack/provider.go

@@ -1,8 +1,6 @@
 package cloudstack
 
 import (
-	"os"
-
 	"github.com/hashicorp/terraform/helper/schema"
 	"github.com/hashicorp/terraform/terraform"
 )
@@ -14,25 +12,25 @@ func Provider() terraform.ResourceProvider {
 			"api_url": &schema.Schema{
 				Type:        schema.TypeString,
 				Required:    true,
-				DefaultFunc: envDefaultFunc("CLOUDSTACK_API_URL", nil),
+				DefaultFunc: schema.EnvDefaultFunc("CLOUDSTACK_API_URL", nil),
 			},
 
 			"api_key": &schema.Schema{
 				Type:        schema.TypeString,
 				Required:    true,
-				DefaultFunc: envDefaultFunc("CLOUDSTACK_API_KEY", nil),
+				DefaultFunc: schema.EnvDefaultFunc("CLOUDSTACK_API_KEY", nil),
 			},
 
 			"secret_key": &schema.Schema{
 				Type:        schema.TypeString,
 				Required:    true,
-				DefaultFunc: envDefaultFunc("CLOUDSTACK_SECRET_KEY", nil),
+				DefaultFunc: schema.EnvDefaultFunc("CLOUDSTACK_SECRET_KEY", nil),
 			},
 
 			"timeout": &schema.Schema{
 				Type:        schema.TypeInt,
 				Required:    true,
-				DefaultFunc: envDefaultFunc("CLOUDSTACK_TIMEOUT", 180),
+				DefaultFunc: schema.EnvDefaultFunc("CLOUDSTACK_TIMEOUT", 180),
 			},
 		},
 
@@ -64,13 +62,3 @@ func providerConfigure(d *schema.ResourceData) (interface{}, error) {
 
 	return config.NewClient()
 }
-
-func envDefaultFunc(k string, dv interface{}) schema.SchemaDefaultFunc {
-	return func() (interface{}, error) {
-		if v := os.Getenv(k); v != "" {
-			return v, nil
-		}
-
-		return dv, nil
-	}
-}

builtin/providers/digitalocean/provider.go

@@ -1,8 +1,6 @@
 package digitalocean
 
 import (
-	"os"
-
 	"github.com/hashicorp/terraform/helper/schema"
 	"github.com/hashicorp/terraform/terraform"
 )
@@ -14,7 +12,7 @@ func Provider() terraform.ResourceProvider {
 			"token": &schema.Schema{
 				Type:        schema.TypeString,
 				Required:    true,
-				DefaultFunc: envDefaultFunc("DIGITALOCEAN_TOKEN"),
+				DefaultFunc: schema.EnvDefaultFunc("DIGITALOCEAN_TOKEN", nil),
 				Description: "The token key for API operations.",
 			},
 		},
@@ -29,16 +27,6 @@ func Provider() terraform.ResourceProvider {
 	}
 }
 
-func envDefaultFunc(k string) schema.SchemaDefaultFunc {
-	return func() (interface{}, error) {
-		if v := os.Getenv(k); v != "" {
-			return v, nil
-		}
-
-		return nil, nil
-	}
-}
-
 func providerConfigure(d *schema.ResourceData) (interface{}, error) {
 	config := Config{
 		Token: d.Get("token").(string),

builtin/providers/dnsimple/provider.go

@@ -1,8 +1,6 @@
 package dnsimple
 
 import (
-	"os"
-
 	"github.com/hashicorp/terraform/helper/schema"
 	"github.com/hashicorp/terraform/terraform"
 )
@@ -14,14 +12,14 @@ func Provider() terraform.ResourceProvider {
 			"email": &schema.Schema{
 				Type:        schema.TypeString,
 				Required:    true,
-				DefaultFunc: envDefaultFunc("DNSIMPLE_EMAIL"),
+				DefaultFunc: schema.EnvDefaultFunc("DNSIMPLE_EMAIL", nil),
 				Description: "A registered DNSimple email address.",
 			},
 
 			"token": &schema.Schema{
 				Type:        schema.TypeString,
 				Required:    true,
-				DefaultFunc: envDefaultFunc("DNSIMPLE_TOKEN"),
+				DefaultFunc: schema.EnvDefaultFunc("DNSIMPLE_TOKEN", nil),
 				Description: "The token key for API operations.",
 			},
 		},
@@ -34,16 +32,6 @@ func Provider() terraform.ResourceProvider {
 	}
 }
 
-func envDefaultFunc(k string) schema.SchemaDefaultFunc {
-	return func() (interface{}, error) {
-		if v := os.Getenv(k); v != "" {
-			return v, nil
-		}
-
-		return nil, nil
-	}
-}
-
 func providerConfigure(d *schema.ResourceData) (interface{}, error) {
 	config := Config{
 		Email: d.Get("email").(string),

builtin/providers/google/provider.go

@@ -1,8 +1,6 @@
 package google
 
 import (
-	"os"
-
 	"github.com/hashicorp/terraform/helper/schema"
 	"github.com/hashicorp/terraform/terraform"
 )
@@ -14,25 +12,25 @@ func Provider() terraform.ResourceProvider {
 			"account_file": &schema.Schema{
 				Type:        schema.TypeString,
 				Required:    true,
-				DefaultFunc: envDefaultFunc("GOOGLE_ACCOUNT_FILE"),
+				DefaultFunc: schema.EnvDefaultFunc("GOOGLE_ACCOUNT_FILE", nil),
 			},
 
 			"client_secrets_file": &schema.Schema{
 				Type:        schema.TypeString,
 				Required:    true,
-				DefaultFunc: envDefaultFunc("GOOGLE_CLIENT_FILE"),
+				DefaultFunc: schema.EnvDefaultFunc("GOOGLE_CLIENT_FILE", nil),
 			},
 
 			"project": &schema.Schema{
 				Type:        schema.TypeString,
 				Required:    true,
-				DefaultFunc: envDefaultFunc("GOOGLE_PROJECT"),
+				DefaultFunc: schema.EnvDefaultFunc("GOOGLE_PROJECT", nil),
 			},
 
 			"region": &schema.Schema{
 				Type:        schema.TypeString,
 				Required:    true,
-				DefaultFunc: envDefaultFunc("GOOGLE_REGION"),
+				DefaultFunc: schema.EnvDefaultFunc("GOOGLE_REGION", nil),
 			},
 		},
 
@@ -49,16 +47,6 @@ func Provider() terraform.ResourceProvider {
 	}
 }
 
-func envDefaultFunc(k string) schema.SchemaDefaultFunc {
-	return func() (interface{}, error) {
-		if v := os.Getenv(k); v != "" {
-			return v, nil
-		}
-
-		return nil, nil
-	}
-}
-
 func providerConfigure(d *schema.ResourceData) (interface{}, error) {
 	config := Config{
 		AccountFile:       d.Get("account_file").(string),

builtin/providers/heroku/provider.go

@@ -2,7 +2,6 @@ package heroku
 
 import (
 	"log"
-	"os"
 
 	"github.com/hashicorp/terraform/helper/schema"
 	"github.com/hashicorp/terraform/terraform"
@@ -15,13 +14,13 @@ func Provider() terraform.ResourceProvider {
 			"email": &schema.Schema{
 				Type:        schema.TypeString,
 				Optional:    true,
-				DefaultFunc: envDefaultFunc("HEROKU_EMAIL"),
+				DefaultFunc: schema.EnvDefaultFunc("HEROKU_EMAIL", nil),
 			},
 
 			"api_key": &schema.Schema{
 				Type:        schema.TypeString,
 				Optional:    true,
-				DefaultFunc: envDefaultFunc("HEROKU_API_KEY"),
+				DefaultFunc: schema.EnvDefaultFunc("HEROKU_API_KEY", nil),
 			},
 		},
 
@@ -30,23 +29,13 @@ func Provider() terraform.ResourceProvider {
 			"heroku_addon":  resourceHerokuAddon(),
 			"heroku_domain": resourceHerokuDomain(),
 			"heroku_drain":  resourceHerokuDrain(),
-			"heroku_cert":  resourceHerokuCert(),
+			"heroku_cert":   resourceHerokuCert(),
 		},
 
 		ConfigureFunc: providerConfigure,
 	}
 }
 
-func envDefaultFunc(k string) schema.SchemaDefaultFunc {
-	return func() (interface{}, error) {
-		if v := os.Getenv(k); v != "" {
-			return v, nil
-		}
-
-		return nil, nil
-	}
-}
-
 func providerConfigure(d *schema.ResourceData) (interface{}, error) {
 	config := Config{
 		Email:  d.Get("email").(string),

builtin/providers/mailgun/provider.go

@@ -2,7 +2,6 @@ package mailgun
 
 import (
 	"log"
-	"os"
 
 	"github.com/hashicorp/terraform/helper/schema"
 	"github.com/hashicorp/terraform/terraform"
@@ -15,7 +14,7 @@ func Provider() terraform.ResourceProvider {
 			"api_key": &schema.Schema{
 				Type:        schema.TypeString,
 				Required:    true,
-				DefaultFunc: envDefaultFunc("MAILGUN_API_KEY"),
+				DefaultFunc: schema.EnvDefaultFunc("MAILGUN_API_KEY", nil),
 			},
 		},
 
@@ -27,16 +26,6 @@ func Provider() terraform.ResourceProvider {
 	}
 }
 
-func envDefaultFunc(k string) schema.SchemaDefaultFunc {
-	return func() (interface{}, error) {
-		if v := os.Getenv(k); v != "" {
-			return v, nil
-		}
-
-		return nil, nil
-	}
-}
-
 func providerConfigure(d *schema.ResourceData) (interface{}, error) {
 	config := Config{
 		APIKey: d.Get("api_key").(string),

helper/schema/schema.go

@@ -15,6 +15,7 @@ package schema
 
 import (
 	"fmt"
+	"os"
 	"reflect"
 	"sort"
 	"strconv"
@@ -160,6 +161,19 @@ type Schema struct {
 // a field.
 type SchemaDefaultFunc func() (interface{}, error)
 
+// EnvDefaultFunc is a helper function that returns the value of the
+// given environment variable, if one exists, or the default value
+// otherwise.
+func EnvDefaultFunc(k string, dv interface{}) SchemaDefaultFunc {
+	return func() (interface{}, error) {
+		if v := os.Getenv(k); v != "" {
+			return v, nil
+		}
+
+		return dv, nil
+	}
+}
+
 // SchemaSetFunc is a function that must return a unique ID for the given
 // element. This unique ID is used to store the element in a hash.
 type SchemaSetFunc func(interface{}) int