main: load CLI config files from ~/.terraform.d/*.tfrc

Now that we are looking into the CLI config file for service host
credentials, it's important to support multiple separate files so that
users can keep credentials separate from other settings and credentials
for different hosts separate from one another.

There is no restriction on which settings can appear in which locations.
This is up to the user to decide, depending on their security needs and
e.g. on whether certain files are generated vs. manually-edited.

commands.go

@@ -1,6 +1,7 @@
 package main
 
 import (
+	"log"
 	"os"
 	"os/signal"
 
@@ -361,9 +362,11 @@ func credentialsSource(config *Config) auth.CredentialsSource {
 	}
 
 	for helperType, helperConfig := range config.CredentialsHelpers {
+		log.Printf("[DEBUG] Searching for credentials helper named %q", helperType)
 		available := pluginDiscovery.FindPlugins("credentials", globalPluginDirs())
 		available = available.WithName(helperType)
 		if available.Count() == 0 {
+			log.Printf("[ERROR] Unable to find credentials helper %q; ignoring", helperType)
 			break
 		}
 

config.go

@@ -6,6 +6,7 @@ import (
 	"io/ioutil"
 	"log"
 	"os"
+	"path/filepath"
 
 	"github.com/hashicorp/hcl"
 
@@ -79,6 +80,14 @@ func LoadConfig() (*Config, tfdiags.Diagnostics) {
 		}
 	}
 
+	if configDir, err := ConfigDir(); err == nil {
+		if info, err := os.Stat(configDir); err == nil && info.IsDir() {
+			dirConfig, dirDiags := loadConfigDir(configDir)
+			diags = diags.Append(dirDiags)
+			config = config.Merge(dirConfig)
+		}
+	}
+
 	if envConfig := EnvConfig(); envConfig != nil {
 		// envConfig takes precedence
 		config = envConfig.Merge(config)
@@ -94,6 +103,8 @@ func loadConfigFile(path string) (*Config, tfdiags.Diagnostics) {
 	var diags tfdiags.Diagnostics
 	result := &Config{}
 
+	log.Printf("Loading CLI configuration from %s", path)
+
 	// Read the HCL file and prepare for parsing
 	d, err := ioutil.ReadFile(path)
 	if err != nil {
@@ -129,6 +140,35 @@ func loadConfigFile(path string) (*Config, tfdiags.Diagnostics) {
 	return result, diags
 }
 
+func loadConfigDir(path string) (*Config, tfdiags.Diagnostics) {
+	var diags tfdiags.Diagnostics
+	result := &Config{}
+
+	entries, err := ioutil.ReadDir(path)
+	if err != nil {
+		diags = diags.Append(fmt.Errorf("Error reading %s: %s", path, err))
+		return result, diags
+	}
+
+	for _, entry := range entries {
+		name := entry.Name()
+		// Ignoring errors here because it is used only to indicate pattern
+		// syntax errors, and our patterns are hard-coded here.
+		hclMatched, _ := filepath.Match("*.tfrc", name)
+		jsonMatched, _ := filepath.Match("*.tfrc.json", name)
+		if !(hclMatched || jsonMatched) {
+			continue
+		}
+
+		filePath := filepath.Join(path, name)
+		fileConfig, fileDiags := loadConfigFile(filePath)
+		diags = diags.Append(fileDiags)
+		result = result.Merge(fileConfig)
+	}
+
+	return result, diags
+}
+
 // EnvConfig returns a Config populated from environment variables.
 //
 // Any values specified in this config should override those set in the