Add management of TF_APPEND_USER_AGENT

Fixes #9

.vscode/launch.json

@@ -0,0 +1,17 @@
+{
+    // Use IntelliSense to learn about possible attributes.
+    // Hover to view descriptions of existing attributes.
+    // For more information, visit: https://go.microsoft.com/fwlink/?linkid=830387
+    "version": "0.2.0",
+    "configurations": [
+        {
+            "name": "Launch",
+            "type": "go",
+            "request": "launch",
+            "mode": "auto",
+            "program": "${fileDirname}",
+            "env": {},
+            "args": []
+        }
+    ]
+}

internal/version/version.go

@@ -0,0 +1,9 @@
+package version
+
+const version = "0.4.0"
+
+// ModuleVersion returns the current version of the github.com/hashicorp/terraform-exec Go module.
+// This is a function to allow for future possible enhancement using debug.BuildInfo.
+func ModuleVersion() string {
+	return version
+}

scripts/release/release.sh

@@ -6,7 +6,7 @@ set -x
 # release.sh will:
 # 1. Modify changelog
 # 2. Run changelog links script
-# 3. Modify version in tfinstall/version.go
+# 3. Modify version in internal/version/version.go
 # 4. Commit and push changes
 # 5. Create a Git tag
 
@@ -59,13 +59,13 @@ function changelogMain {
 }
 
 function modifyVersionFiles {
-  sed -i "s/const Version =.*/const Version = \"${TARGET_VERSION}\"/" tfinstall/version.go
+  sed -i "s/const version =.*/const version = \"${TARGET_VERSION}\"/" internal/version/version.go
 }
 
 function commitChanges {
   git add CHANGELOG.md
   modifyVersionFiles
-  git add tfinstall/version.go
+  git add internal/version/version.go
 
   if [ "$CI" = true ] ; then
       git commit --gpg-sign="${GPG_KEY_ID}" -m "v${TARGET_VERSION} [skip ci]"

tfexec/cmd.go

@@ -2,9 +2,12 @@ package tfexec
 
 import (
 	"context"
+	"fmt"
 	"os"
 	"os/exec"
 	"strings"
+
+	"github.com/hashicorp/terraform-exec/internal/version"
 )
 
 const (
@@ -14,6 +17,7 @@ const (
 	automationEnvVar        = "TF_IN_AUTOMATION"
 	logPathEnvVar           = "TF_LOG_PATH"
 	reattachEnvVar          = "TF_REATTACH_PROVIDERS"
+	appendUserAgentEnvVar   = "TF_APPEND_USER_AGENT"
 
 	varEnvVarPrefix = "TF_VAR_"
 )
@@ -24,6 +28,7 @@ var prohibitedEnvVars = []string{
 	logPathEnvVar,
 	logEnvVar,
 	reattachEnvVar,
+	appendUserAgentEnvVar,
 }
 
 func envMap(environ []string) map[string]string {
@@ -74,6 +79,14 @@ func (tf *Terraform) buildEnv(mergeEnv map[string]string) []string {
 		env[checkpointDisableEnvVar] = os.Getenv(checkpointDisableEnvVar)
 	}
 
+	// always override user agent
+	ua := mergeUserAgent(
+		os.Getenv(appendUserAgentEnvVar),
+		tf.appendUserAgent,
+		fmt.Sprintf("HashiCorp-terraform-exec/%s", version.ModuleVersion()),
+	)
+	env[appendUserAgentEnvVar] = ua
+
 	// always override logging
 	if tf.logPath == "" {
 		// so logging can't pollute our stderr output
@@ -100,3 +113,22 @@ func (tf *Terraform) buildTerraformCmd(ctx context.Context, args ...string) *exe
 
 	return cmd
 }
+
+func mergeUserAgent(uas ...string) string {
+	included := map[string]bool{}
+	merged := []string{}
+	for _, ua := range uas {
+		parts := strings.Split(ua, " ")
+		for _, p := range parts {
+			if p == "" {
+				continue
+			}
+			if included[p] {
+				continue
+			}
+			included[p] = true
+			merged = append(merged, p)
+		}
+	}
+	return strings.Join(merged, " ")
+}

tfexec/cmd_test.go

@@ -1,16 +1,44 @@
 package tfexec
 
 import (
+	"fmt"
 	"os/exec"
 	"strings"
 	"testing"
+
+	"github.com/hashicorp/terraform-exec/internal/version"
 )
 
-var defaultEnv = []string{
-	"TF_LOG=",
-	"TF_LOG_PATH=",
-	"TF_IN_AUTOMATION=1",
-	"CHECKPOINT_DISABLE=",
+func TestMergeUserAgent(t *testing.T) {
+	for i, c := range []struct {
+		expected string
+		uas      []string
+	}{
+		{"foo/1 bar/2", []string{"foo/1", "bar/2"}},
+		{"foo/1 bar/2", []string{"foo/1 bar/2"}},
+		{"foo/1 bar/2", []string{"", "foo/1", "bar/2"}},
+		{"foo/1 bar/2", []string{"", "foo/1    bar/2"}},
+		{"foo/1 bar/2", []string{"  ", "foo/1    bar/2"}},
+		{"foo/1 bar/2", []string{"foo/1", "", "bar/2"}},
+		{"foo/1 bar/2", []string{"foo/1", "   ", "bar/2"}},
+	} {
+		t.Run(fmt.Sprintf("%d %s", i, c.expected), func(t *testing.T) {
+			actual := mergeUserAgent(c.uas...)
+			if c.expected != actual {
+				t.Fatalf("expected %q, got %q", c.expected, actual)
+			}
+		})
+	}
+}
+
+func defaultEnv() []string {
+	return []string{
+		"TF_APPEND_USER_AGENT=HashiCorp-terraform-exec/" + version.ModuleVersion(),
+		"TF_LOG=",
+		"TF_LOG_PATH=",
+		"TF_IN_AUTOMATION=1",
+		"CHECKPOINT_DISABLE=",
+	}
 }
 
 func assertCmd(t *testing.T, expectedArgs []string, expectedEnv map[string]string, actual *exec.Cmd) {
@@ -29,7 +57,7 @@ func assertCmd(t *testing.T, expectedArgs []string, expectedEnv map[string]strin
 	}
 
 	// check environment
-	expectedEnv = envMap(append(defaultEnv, envSlice(expectedEnv)...))
+	expectedEnv = envMap(append(defaultEnv(), envSlice(expectedEnv)...))
 
 	// compare against raw slice len incase of duplication or something
 	if len(expectedEnv) != len(actual.Env) {

tfexec/terraform.go

@@ -12,9 +12,10 @@ import (
 )
 
 type Terraform struct {
-	execPath   string
-	workingDir string
-	env        map[string]string
+	execPath        string
+	workingDir      string
+	appendUserAgent string
+	env             map[string]string
 
 	logger  *log.Logger
 	logPath string
@@ -82,6 +83,12 @@ func (tf *Terraform) SetLogPath(path string) error {
 	return nil
 }
 
+// SetAppendUserAgent sets the TF_APPEND_USER_AGENT environment variable for
+// Terraform CLI execution.
+func (tf *Terraform) SetAppendUserAgent(ua string) {
+	tf.appendUserAgent = ua
+}
+
 // WorkingDir returns the working directory for Terraform.
 func (tf *Terraform) WorkingDir() string {
 	return tf.workingDir

tfinstall/tfinstall.go

@@ -15,6 +15,8 @@ import (
 	"github.com/hashicorp/go-getter"
 	"github.com/hashicorp/go-version"
 	"golang.org/x/crypto/openpgp"
+
+	intversion "github.com/hashicorp/terraform-exec/internal/version"
 )
 
 const baseUrl = "https://releases.hashicorp.com/terraform"
@@ -164,7 +166,7 @@ func downloadWithVerification(tfVersion string, installDir string) (string, erro
 
 	// setup: getter client
 	httpHeader := make(http.Header)
-	httpHeader.Set("User-Agent", "HashiCorp-tfinstall/"+Version)
+	httpHeader.Set("User-Agent", "HashiCorp-tfinstall/"+intversion.ModuleVersion())
 	httpGetter := &getter.HttpGetter{
 		Netrc: true,
 	}