Implement inline declaration of Terraform variables via command-line.

Author: tintoy

CHANGES.md

@@ -2,6 +2,14 @@
 
 ## v0.2
 
+New features:
+
+* You can now choose to specify Terraform variables on the command line using `--terraform-variable` (if reading them from a file using `--terraform-variables-from` is undesirable)
+
+Breaking changes:
+
+* The `--terraform-variables` command-line argument has been renamed to `--terraform-variables-from`.
+
 Bug fixes:
 
 * Fetching source from a directory now works correctly (#1)

README.md

@@ -10,7 +10,9 @@ Well now you do. If you can express it as a Terraform configuration, you can use
 The driver accepts the following arguments:
 
 * `--terraform-config` (Required) - The path (or URL) of the Terraform configuration to use
-* `--terraform-additional-variables` (Optional) - An optional file containing the JSON that represents additional variables for the Terraform configuration
+* `--terraform-variable` (Optional) - One or more items of the form "name=value" representing additional variables for the Terraform configuration  
+For example: `--terraform-variable variable1=foo --terraform-variable variable2=bar`
+* `--terraform-variables-from` (Optional) - An optional file containing the JSON that represents additional variables for the Terraform configuration
 * `--terraform-refresh` (Optional) - A flag which, if specified, will cause the driver to refresh the configuration after applying it
 
 ### Terraform configuration

config_variables.go

@@ -9,6 +9,7 @@ import (
 	"fmt"
 	"os"
 	"path"
+	"strings"
 
 	"github.com/docker/machine/libmachine/log"
 )
@@ -49,8 +50,38 @@ func (driver *Driver) readVariables() error {
 	return nil
 }
 
-// Read Terraform variables from the additional variables file passed in on the command-line.
+// Read all additional variables (from the command line, or from a file)
 func (driver *Driver) readAdditionalVariables() error {
+	err := driver.readAdditionalVariablesInline()
+	if err != nil {
+		return err
+	}
+
+	return driver.readAdditionalVariablesFile()
+}
+
+// Read additional variables passed in on the command-line (--terraform-variable a=b --terraform-variable c=d)
+func (driver *Driver) readAdditionalVariablesInline() error {
+	for _, additionalVariable := range driver.AdditionalVariablesInline {
+		variableNameAndValue := strings.SplitN(additionalVariable, "=", 2)
+		if len(variableNameAndValue) != 2 {
+			return fmt.Errorf("Invalid format for additional variable '%s", additionalVariable)
+		}
+
+		// Don't overwrite existing entries.
+		_, variableExists := driver.ConfigVariables[variableNameAndValue[0]]
+		if variableExists {
+			continue
+		}
+
+		driver.ConfigVariables[variableNameAndValue[0]] = variableNameAndValue[1]
+	}
+
+	return nil
+}
+
+// Read Terraform variables from the file passed in on the command-line.
+func (driver *Driver) readAdditionalVariablesFile() error {
 	if driver.AdditionalVariablesFile == "" {
 		return nil // Nothing to do
 	}

driver.go

@@ -36,6 +36,9 @@ type Driver struct {
 	// An optional file containing the JSON that represents additional variables for the Terraform configuration
 	AdditionalVariablesFile string
 
+	// Optional "name=value" items that represent additional variables for the Terraform configuration
+	AdditionalVariablesInline []string
+
 	// Refresh the configuration after applying it
 	RefreshAfterApply bool
 
@@ -60,9 +63,14 @@ func (driver *Driver) GetCreateFlags() []mcnflag.Flag {
 			Usage: "The path (or URL) of the Terraform configuration",
 			Value: "",
 		},
+		mcnflag.StringSliceFlag{
+			Name:  "terraform-variable",
+			Usage: "Additional variable(s) for the Terraform configuration (in the form name=value)",
+			Value: []string{},
+		},
 		mcnflag.StringFlag{
-			Name:  "terraform-additional-variables",
-			Usage: "An optional file containing the JSON that represents additional variables for the Terraform configuration",
+			Name:  "terraform-variables-from",
+			Usage: "The name of a file containing the JSON that represents additional variables for the Terraform configuration",
 			Value: "",
 		},
 		mcnflag.BoolFlag{
@@ -106,7 +114,10 @@ func (driver *Driver) SetConfigFromFlags(flags drivers.DriverOptions) error {
 
 	driver.ConfigSource = flags.String("terraform-config")
 	driver.ConfigVariables = make(map[string]interface{})
-	driver.AdditionalVariablesFile = flags.String("terraform-additional-variables")
+
+	driver.AdditionalVariablesInline = flags.StringSlice("terraform-variable")
+	driver.AdditionalVariablesFile = flags.String("terraform-variables")
+
 	driver.RefreshAfterApply = flags.Bool("terraform-refresh")
 
 	driver.SSHPort = flags.Int("terraform-ssh-port")

examples/aws/README.md

@@ -25,7 +25,7 @@ export AWS_ACCESS_KEY_ID=my_access_key_id
 export AWS_SECRET_KEY=my_secret_key
 docker-machine create --driver terraform \
 	--terraform-config $PWD/main.tf \
-	--terraform-additional-variables $PWD/additional-variables.json \
+	--terraform-additional-variables-file $PWD/additional-variables.json \
 	hello-aws
 ```
 

examples/ddcloud/private_ip/README.md

@@ -30,7 +30,7 @@ export MCP_USERNAME=my_username
 export MCP_PASSWORD=my_password
 docker-machine create --driver terraform \
 	--terraform-config $PWD/main.tf \
-	--terraform-additional-variables $PWD/additional-variables.json \
+	--terraform-variables-from $PWD/additional-variables.json \
 	hello-ddcloud
 ```
 

examples/ddcloud/public_ip/README.md

@@ -32,7 +32,7 @@ export MCP_USERNAME=my_username
 export MCP_PASSWORD=my_password
 docker-machine create --driver terraform \
 	--terraform-config $PWD/main.tf \
-	--terraform-additional-variables $PWD/additional-variables.json \
+	--terraform-variables-from $PWD/additional-variables.json \
 	hello-ddcloud
 ```
 

examples/digital_ocean/README.md

@@ -21,7 +21,7 @@ export DIGITALOCEAN_TOKEN=my_token
 cd examples/digital_ocean
 docker-machine create --driver terraform \
 	--terraform-config $PWD/main.tf \
-	--terraform-additional-variables $PWD/additional-variables.json \
+	--terraform-variables-from $PWD/additional-variables.json \
 	hello-digital-ocean
 ```