Support TF_CLI_* Arguments (#3)

* Update makefile * Export mode * Update README.yaml Co-Authored-By: osterman <[email protected]>
cloudposse-archives · Jan 13, 2019 · 211cd58 · 211cd58
1 parent e6ec168
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diff --git a/Makefile b/Makefile
@@ -2,14 +2,8 @@ SHELL = /bin/bash
 
 PATH:=$(PATH):$(GOPATH)/bin
 
-include $(shell curl --silent -o .build-harness "https://raw.githubusercontent.com/cloudposse/build-harness/master/templates/Makefile.build-harness"; echo .build-harness)
+-include $(shell curl -sSL -o .build-harness "https://git.io/build-harness"; echo .build-harness)
 
+build: go/build
+	@exit 0
 
-.PHONY : go-get
-go-get:
-	go get
-
-
-.PHONY : go-build
-go-build: go-get
-	CGO_ENABLED=0 go build -v -o "./dist/bin/tfenv" *.go
diff --git a/README.md b/README.md
@@ -6,9 +6,12 @@
 # tfenv [![Build Status](https://travis-ci.org/cloudposse/tfenv.svg?branch=master)](https://travis-ci.org/cloudposse/tfenv) [![Latest Release](https://img.shields.io/github/release/cloudposse/tfenv.svg)](https://github.com/cloudposse/tfenv/releases/latest) [![Slack Community](https://slack.cloudposse.com/badge.svg)](https://slack.cloudposse.com)
 
 
-Command line utility to transform environment variables for use with Terraform (e.g. `HOSTNAME` → `TF_VAR_hostname`)
+Command line utility to transform environment variables for use with Terraform.
+(e.g. `HOSTNAME` → `TF_VAR_hostname`)
 
-__NOTE__: `tfenv` is **not** a [terraform version manager](https://github.com/tfutils/tfenv).
+It can also intelligently map environment variables to terraform command line arguments (e.g. `TF_CLI_INIT_BACKEND_CONFIG_BUCKET=example` → `TF_CLI_ARGS_init=-backend-config=bucket=example`).
+
+__NOTE__: `tfenv` is **not** a [terraform version manager](https://github.com/tfutils/tfenv). It strictly manages environment variables.
 
 
 ---
@@ -45,6 +48,7 @@ If you answer "yes" to any of these questions, then look no further!
 * Have you ever wished you could easily pass environment variables to terraform *without* adding the `TF_VAR_` prefix?
 * Do you use [`chamber`](https://github.com/segmentio/chamber) and get annoyed when it transforms environment variables to uppercase?
 * Would you like to use common environment variables names with terraform? (e.g. `USER` or `AWS_REGION`)
+* Is there some argument to `terraform init` you want to specify with an environment variable? (e.g. a `-backend-config` property)
 
 **Yes?** Great! Then this utility is for you.
 
@@ -57,6 +61,11 @@ The `tfenv` utility will perform the following transformations:
 
 __NOTE__: `tfenv` will preserve the existing environment and add the new environment variables with `TF_VAR_`. This is because some terraform providers expect non-`TF_VAR_*` prefixed environment variables. Additionally, when using the `local-exec` provisioner, it's convenient to use regular environment variables. See our [`terraform-null-smtp-mail`](https://github.com/cloudposse/terraform-null-smtp-mail) module for an example of using this pattern.
 
+
+**But wait, there's more!**
+
+With `tfenv` we can surgically assign a value to any terraform argument using per-argument environment variables.
+
 ## Usage
 
 
@@ -75,9 +84,58 @@ The basic usage looks like this. We're going to run some `command` and pass it `
 So for example, we can pass our current environment to terraform by simply running:
 
 ```sh
-    tfenv terraform plan
+tfenv terraform plan
+```
+
+### Direnv
+
+You can use `tfenv` with direnv very easily. Running `tfenv` without any arguments will emit `export` statements.
+
+Example `.envrc`:
+
+```sh
+# Export terraform environment
+tfenv
+```
+
+### Bash
+
+Load the terraform environment into your shell.
+
+Just add the following into your shell script:
+
+```sh
+source <(tfenv)
 ```
 
+### Terraform Args
+
+With `tfenv` we can populate the [`TF_CLI_ARGS` and `TF_CLI_ARGS_*` environment variables](https://www.terraform.io/docs/configuration/environment-variables.html#tf_cli_args-and-tf_cli_args_name) automatically. This makes it easy to toggle settings. 
+
+For example, if you want to pass `-backend-config=bucket=terraform-state-bucket` to `terraform init`, then you would do the following:
+
+```sh
+export TF_CLI_INIT_BACKEND_CONFIG_BUCKET=terraform-state-bucket
+```
+
+Running `tfenv` will populate the `TF_CLI_ARGS_init=-backend-config=bucket=terraform-state-bucket`
+
+Multiple arguments can be specified and they will be properly concatenated.
+
+### Initializing Modules
+
+Terraform as the built-in capability to initialize "root modules" from a remote sources by passing the `-from-module` argument to `terraform init`.
+
+We can turn this into a 12-factor style invocation using `tfenv`.
+
+```sh
+export TF_CLI_INIT_FROM_MODULE=git::[email protected]:ImpactHealthio/terraform-root-modules.git//aws/$(SERVICE)?ref=tags/0.5.7
+source <(tfenv)
+terraform init
+```
+
+Learn more about `TF_CLI_ARGS` and `TF_CLI_ARGS_*` in the [official documentation](https://www.terraform.io/docs/configuration/environment-variables.html#tf_cli_args-and-tf_cli_args_name).
+
 
 
 
@@ -207,7 +265,7 @@ In general, PRs are welcome. We follow the typical "fork-and-pull" Git workflow.
 
 ## Copyright
 
-Copyright © 2017-2018 [Cloud Posse, LLC](https://cpco.io/copyright)
+Copyright © 2017-2019 [Cloud Posse, LLC](https://cpco.io/copyright)
 
 
 

diff --git a/README.yaml b/README.yaml
@@ -30,9 +30,12 @@ badges:
 
 # Short description of this project
 description: |-
-  Command line utility to transform environment variables for use with Terraform (e.g. `HOSTNAME` → `TF_VAR_hostname`)
+  Command line utility to transform environment variables for use with Terraform.
+  (e.g. `HOSTNAME` → `TF_VAR_hostname`)
+ 
+  It can also intelligently map environment variables to terraform command line arguments (e.g. `TF_CLI_INIT_BACKEND_CONFIG_BUCKET=example` → `TF_CLI_ARGS_init=-backend-config=bucket=example`).
 
-  __NOTE__: `tfenv` is **not** a [terraform version manager](https://github.com/tfutils/tfenv).
+  __NOTE__: `tfenv` is **not** a [terraform version manager](https://github.com/tfutils/tfenv). It strictly manages environment variables.
 
 introduction: |-
 
@@ -41,6 +44,7 @@ introduction: |-
   * Have you ever wished you could easily pass environment variables to terraform *without* adding the `TF_VAR_` prefix?
   * Do you use [`chamber`](https://github.com/segmentio/chamber) and get annoyed when it transforms environment variables to uppercase?
   * Would you like to use common environment variables names with terraform? (e.g. `USER` or `AWS_REGION`)
+  * Is there some argument to `terraform init` you want to specify with an environment variable? (e.g. a `-backend-config` property)
 
   **Yes?** Great! Then this utility is for you.
 
@@ -54,6 +58,11 @@ introduction: |-
   __NOTE__: `tfenv` will preserve the existing environment and add the new environment variables with `TF_VAR_`. This is because some terraform providers expect non-`TF_VAR_*` prefixed environment variables. Additionally, when using the `local-exec` provisioner, it's convenient to use regular environment variables. See our [`terraform-null-smtp-mail`](https://github.com/cloudposse/terraform-null-smtp-mail) module for an example of using this pattern.
 
 
+  **But wait, there's more!**
+
+  With `tfenv` we can surgically assign a value to any terraform argument using per-argument environment variables.
+
+
 # How to use this project
 usage: |-
 
@@ -72,9 +81,59 @@ usage: |-
   So for example, we can pass our current environment to terraform by simply running:
 
   ```sh
-      tfenv terraform plan
+  tfenv terraform plan
+  ```
+
+  ### Direnv
+  
+  You can use `tfenv` with direnv very easily. Running `tfenv` without any arguments will emit `export` statements.
+
+  Example `.envrc`:
+
+  ```sh
+  # Export terraform environment
+  tfenv
   ```
 
+  ### Bash
+  
+  Load the terraform environment into your shell.
+
+  Just add the following into your shell script:
+
+  ```sh
+  source <(tfenv)
+  ```
+
+  ### Terraform Args
+  
+  With `tfenv` we can populate the [`TF_CLI_ARGS` and `TF_CLI_ARGS_*` environment variables](https://www.terraform.io/docs/configuration/environment-variables.html#tf_cli_args-and-tf_cli_args_name) automatically. This makes it easy to toggle settings. 
+
+  For example, if you want to pass `-backend-config=bucket=terraform-state-bucket` to `terraform init`, then you would do the following:
+
+  ```sh
+  export TF_CLI_INIT_BACKEND_CONFIG_BUCKET=terraform-state-bucket
+  ```
+
+  Running `tfenv` will populate the `TF_CLI_ARGS_init=-backend-config=bucket=terraform-state-bucket`
+
+  Multiple arguments can be specified and they will be properly concatenated.
+
+  ### Initializing Modules
+  
+  Terraform has the built-in capability to initialize "root modules" from a remote sources by passing the `-from-module` argument to `terraform init`.
+
+  We can turn this into a 12-factor style invocation using `tfenv`.
+
+  ```sh
+  export TF_CLI_INIT_FROM_MODULE=git::[email protected]:ImpactHealthio/terraform-root-modules.git//aws/$(SERVICE)?ref=tags/0.5.7
+  source <(tfenv)
+  terraform init
+  ```
+
+  Learn more about `TF_CLI_ARGS` and `TF_CLI_ARGS_*` in the [official documentation](https://www.terraform.io/docs/configuration/environment-variables.html#tf_cli_args-and-tf_cli_args_name).
+
+
 related:
   - name: "Packages"
     description: "Cloud Posse installer and distribution of native apps"

diff --git a/main.go b/main.go
@@ -1,7 +1,8 @@
 package main
 
 import (
-	//	"fmt"
+	"fmt"
+	"github.com/taskcluster/shell"
 	"log"
 	"os"
 	"os/exec"
@@ -44,8 +45,16 @@ func main() {
 	// Blacklist of excluded environment variables. Processed *before* whitelist.
 	var tfenvBlacklist = getEnv("TFENV_BLACKLIST", "^(AWS_ACCESS_KEY_ID|AWS_SECRET_ACCESS_KEY)$")
 
-	// The command that was executed
-	cmd := os.Args[0]
+	// Args that we pass to TF_CLI_ARGS_init
+	var tfCliArgsInit []string
+	var tfCliArgsPlan []string
+	var tfCliArgsApply []string
+	var tfCliArgsDestroy []string
+	var tfCliArgs []string
+
+	reTfCliInitBackend := regexp.MustCompile("^TF_CLI_INIT_BACKEND_CONFIG_(.*)")
+	reTfCliCommand := regexp.MustCompile("^TF_CLI_(INIT|PLAN|APPLY|DESTROY)_(.*)")
+	reTfCliDefault := regexp.MustCompile("^TF_CLI_DEFAULT_(.*)")
 
 	reTfVar := regexp.MustCompile("^" + tfenvPrefix)
 	reTrim := regexp.MustCompile("(^_+|_+$)")
@@ -58,10 +67,45 @@ func main() {
 		env = append(env, e)
 
 		// Begin normalization of environment variable
-		pair := strings.Split(e, "=")
-
-		// Process the blacklist for exclusions, then the whitelist for inclusions
-		if !reBlacklist.MatchString(pair[0]) && reWhitelist.MatchString(pair[0]) {
+		pair := strings.SplitN(e, "=", 2)
+
+		originalEnvName := pair[0]
+
+		// `TF_CLI_ARGS_init`: Map `TF_CLI_INIT_BACKEND_CONFIG_FOO=value` to `-backend-config=foo=value`
+		if reTfCliInitBackend.MatchString(pair[0]) {
+			match := reTfCliInitBackend.FindStringSubmatch(pair[0])
+			arg := reDedupe.ReplaceAllString(match[1], "-")
+			arg = strings.ToLower(arg)
+			arg = "-backend-config=" + arg + "=" + pair[1]
+			tfCliArgsInit = append(tfCliArgsInit, arg)
+		} else if reTfCliCommand.MatchString(pair[0]) {
+			// `TF_CLI_ARGS_plan`: Map `TF_CLI_PLAN_SOMETHING=value` to `-something=value`
+			match := reTfCliCommand.FindStringSubmatch(pair[0])
+			cmd := reDedupe.ReplaceAllString(match[1], "-")
+			cmd = strings.ToLower(cmd)
+
+			param := reDedupe.ReplaceAllString(match[2], "-")
+			param = strings.ToLower(param)
+			arg := "-" + param + "=" + pair[1]
+			switch cmd {
+			case "init":
+				tfCliArgsInit = append(tfCliArgsInit, arg)
+			case "plan":
+				tfCliArgsPlan = append(tfCliArgsPlan, arg)
+			case "apply":
+				tfCliArgsApply = append(tfCliArgsApply, arg)
+			case "destroy":
+				tfCliArgsDestroy = append(tfCliArgsDestroy, arg)
+			}
+		} else if reTfCliDefault.MatchString(pair[0]) {
+			// `TF_CLI_ARGS`: Map `TF_CLI_DEFAULT_SOMETHING=value` to `-something=value`
+			match := reTfCliDefault.FindStringSubmatch(pair[0])
+			param := reDedupe.ReplaceAllString(match[1], "-")
+			param = strings.ToLower(param)
+			arg := "-" + param + "=" + pair[1]
+			tfCliArgs = append(tfCliArgs, arg)
+		} else if !reBlacklist.MatchString(pair[0]) && reWhitelist.MatchString(pair[0]) {
+			// Process the blacklist for exclusions, then the whitelist for inclusions
 			// Strip off TF_VAR_ prefix so we can simplify normalization
 			pair[0] = reTfVar.ReplaceAllString(pair[0], "")
 
@@ -75,35 +119,64 @@ func main() {
 			pair[0] = reDedupe.ReplaceAllString(pair[0], "_")
 
 			// prepend TF_VAR_, if not there already
-			if len(pair[0]) != 0 {
+			if len(pair[0]) > 0 {
 				pair[0] = tfenvPrefix + pair[0]
-				envvar := pair[0] + "=" + pair[1]
-				//fmt.Println(envvar)
-				env = append(env, envvar)
+				if strings.Compare(pair[0], originalEnvName) != 0 {
+					envvar := pair[0] + "=" + pair[1]
+					//fmt.Println(envvar)
+					env = append(env, envvar)
+				}
 			}
 		}
 	}
 
-	sort.Strings(env)
+	if len(tfCliArgsInit) > 0 {
+		env = append(env, "TF_CLI_ARGS_init="+strings.Join(tfCliArgsInit, " "))
+	}
 
-	if len(os.Args) < 2 {
-		log.Fatalf("error: %v command args...", cmd)
+	if len(tfCliArgsPlan) > 0 {
+		env = append(env, "TF_CLI_ARGS_plan="+strings.Join(tfCliArgsPlan, " "))
 	}
 
-	// The command that will be executed
-	exe := os.Args[1]
+	if len(tfCliArgsApply) > 0 {
+		env = append(env, "TF_CLI_ARGS_apply="+strings.Join(tfCliArgsApply, " "))
+	}
 
-	// The command + any arguments
-	args = append(args, os.Args[1:]...)
+	if len(tfCliArgsDestroy) > 0 {
+		env = append(env, "TF_CLI_ARGS_destroy="+strings.Join(tfCliArgsDestroy, " "))
+	}
 
-	// Lookup path for executable
-	binary, binaryPathErr := exec.LookPath(exe)
-	if binaryPathErr != nil {
-		log.Fatalf("error: failed to find executable `%v`: %v", exe, binaryPathErr)
+	if len(tfCliArgs) > 0 {
+		env = append(env, "TF_CLI_ARGS="+strings.Join(tfCliArgs, " "))
 	}
 
-	execErr := syscall.Exec(binary, args, env)
-	if execErr != nil {
-		log.Fatalf("error: exec failed: %v", execErr)
+	sort.Strings(env)
+
+	// The command that was executed
+	cmd := os.Args[0]
+
+	if len(os.Args) < 2 {
+		for _, envvar := range env {
+			// Begin normalization of environment variable
+			pair := strings.SplitN(envvar, "=", 2)
+			fmt.Printf("export %v=%v\n", pair[0], shell.Escape(pair[1]))
+		}
+	} else {
+		// The command that will be executed
+		exe := os.Args[1]
+
+		// The command + any arguments
+		args = append(args, os.Args[1:]...)
+
+		// Lookup path for executable
+		binary, binaryPathErr := exec.LookPath(exe)
+		if binaryPathErr != nil {
+			log.Fatalf("error: %v failed to find executable `%v`: %v", cmd, exe, binaryPathErr)
+		}
+
+		execErr := syscall.Exec(binary, args, env)
+		if execErr != nil {
+			log.Fatalf("error: %v exec failed: %v", cmd, execErr)
+		}
 	}
 }