Allow doppler secrets substitute to use environment variables

pkg/cmd/secrets.go

@@ -23,6 +23,7 @@ import (
 	"io/ioutil"
 	"os"
 	"path/filepath"
+	"slices"
 	"strings"
 
 	"github.com/DopplerHQ/cli/pkg/configuration"
@@ -130,6 +131,8 @@ $ doppler secrets download --format=env --no-file`,
 	Run:  downloadSecrets,
 }
 
+var validUseEnvSettings = []string{"false", "true", "override", "only"}
+var validUseEnvSettingsList = strings.Join(validUseEnvSettings, ", ")
 var secretsSubstituteCmd = &cobra.Command{
 	Use:   "substitute <filepath>",
 	Short: "Substitute secrets into a template file",
@@ -151,7 +154,15 @@ $ doppler secrets substitute template.yaml
 host: 127.0.0.1
 port: 8080
 Multiline: "Line one\r\nLine two"
-JSON Secret: "{\"logging\": \"info\"}"`,
+JSON Secret: "{\"logging\": \"info\"}"
+----------------------------------
+
+The '--use-env' flag can be used to expose environment variables to templates:
+  - 'false' (default) will not expose environment variables to templates
+  - 'true' will expose both environment variables and Doppler secrets to templates. If there is a collision, the Doppler secret will take precedence.
+  - 'override' will expose both environment variables and Doppler secrets to templates. If there is a collision, the environment variable will take precedence.
+  - 'only' will only expose environment variables to templates (and will not fetch Doppler secrets)
+`,
 	Args: cobra.ExactArgs(1),
 	Run:  substituteSecrets,
 }
@@ -575,7 +586,15 @@ func downloadSecrets(cmd *cobra.Command, args []string) {
 func substituteSecrets(cmd *cobra.Command, args []string) {
 	localConfig := configuration.LocalConfig(cmd)
 
-	utils.RequireValue("token", localConfig.Token.Value)
+	useEnv := cmd.Flag("use-env").Value.String()
+	if !slices.Contains(validUseEnvSettings, useEnv) {
+		utils.HandleError(fmt.Errorf("invalid use-env option. Valid options are %s", validUseEnvSettingsList))
+	}
+
+	if useEnv != "only" {
+		// No need to require a token for env-only substitution
+		utils.RequireValue("token", localConfig.Token.Value)
+	}
 
 	var outputFilePath string
 	var err error
@@ -586,23 +605,38 @@ func substituteSecrets(cmd *cobra.Command, args []string) {
 			utils.HandleError(err, "Unable to parse output file path")
 		}
 	}
+	secretsMap := map[string]string{}
+	env := utils.ParseEnvStrings(os.Environ())
 
-	dynamicSecretsTTL := utils.GetDurationFlag(cmd, "dynamic-ttl")
-	response, responseErr := http.GetSecrets(localConfig.APIHost.Value, utils.GetBool(localConfig.VerifyTLS.Value, true), localConfig.Token.Value, localConfig.EnclaveProject.Value, localConfig.EnclaveConfig.Value, nil, true, dynamicSecretsTTL)
-	if !responseErr.IsNil() {
-		utils.HandleError(responseErr.Unwrap(), responseErr.Message)
+	if useEnv != "false" {
+		// If use-env is not disabled entirely, include them from the beginning
+		for k, v := range env {
+			secretsMap[k] = v
+		}
 	}
 
-	secrets, parseErr := models.ParseSecrets(response)
-	if parseErr != nil {
-		utils.HandleError(parseErr, "Unable to parse API response")
-	}
+	if useEnv != "only" {
+		dynamicSecretsTTL := utils.GetDurationFlag(cmd, "dynamic-ttl")
+		response, responseErr := http.GetSecrets(localConfig.APIHost.Value, utils.GetBool(localConfig.VerifyTLS.Value, true), localConfig.Token.Value, localConfig.EnclaveProject.Value, localConfig.EnclaveConfig.Value, nil, true, dynamicSecretsTTL)
+		if !responseErr.IsNil() {
+			utils.HandleError(responseErr.Unwrap(), responseErr.Message)
+		}
 
-	secretsMap := map[string]string{}
-	for _, secret := range secrets {
-		if secret.ComputedValue != nil {
-			// By not providing a default value when ComputedValue is nil (e.g. it's a restricted secret), we default
-			// to the same behavior the substituter provides if the template file contains a secret that doesn't exist.
+		secrets, parseErr := models.ParseSecrets(response)
+		if parseErr != nil {
+			utils.HandleError(parseErr, "Unable to parse API response")
+		}
+
+		for _, secret := range secrets {
+			if _, ok := env[secret.Name]; useEnv == "override" && ok {
+				// This secret collides with an environment variable and the env var is supposed to take precedence
+				continue
+			}
+			if secret.ComputedValue == nil {
+				// By not providing a default value when ComputedValue is nil (e.g. it's a restricted secret), we default
+				// to the same behavior the substituter provides if the template file contains a secret that doesn't exist.
+				continue
+			}
 			secretsMap[secret.Name] = *secret.ComputedValue
 		}
 	}
@@ -739,6 +773,7 @@ func init() {
 	if err := secretsSubstituteCmd.RegisterFlagCompletionFunc("config", configNamesValidArgs); err != nil {
 		utils.HandleError(err)
 	}
+	secretsSubstituteCmd.Flags().String("use-env", "false", fmt.Sprintf("setting for how to use environment variables passed to 'doppler secrets substitute'. One of: %s (see help ext for details)", validUseEnvSettingsList))
 	secretsSubstituteCmd.Flags().String("output", "", "path to the output file. by default the rendered text will be written to stdout.")
 	secretsSubstituteCmd.Flags().Duration("dynamic-ttl", 0, "(BETA) dynamic secrets will expire after specified duration, (e.g. '3h', '15m')")
 	secretsCmd.AddCommand(secretsSubstituteCmd)

pkg/controllers/secrets.go

@@ -380,14 +380,7 @@ func PrepareSecrets(dopplerSecrets map[string]string, originalEnv []string, pres
 			}
 		}
 
-		existingEnvKeys := map[string]string{}
-		for _, envVar := range originalEnv {
-			// key=value format
-			parts := strings.SplitN(envVar, "=", 2)
-			key := parts[0]
-			value := parts[1]
-			existingEnvKeys[key] = value
-		}
+		existingEnvKeys := utils.ParseEnvStrings(originalEnv)
 
 		if preserveEnv != "false" {
 			secretsToPreserve := strings.Split(preserveEnv, ",")

pkg/utils/env.go

@@ -0,0 +1,32 @@
+/*
+Copyright © 2024 Doppler <[email protected]>
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+	http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+package utils
+
+import "strings"
+
+// ParseEnvStrings returns a new map[string]string created by parsing env strings (in `key=value` format).
+func ParseEnvStrings(envStrings []string) map[string]string {
+	env := map[string]string{}
+	for _, envVar := range envStrings {
+		// key=value format
+		parts := strings.SplitN(envVar, "=", 2)
+		key := parts[0]
+		value := parts[1]
+		env[key] = value
+	}
+
+	return env
+}

tests/e2e/secrets-substitute.sh

@@ -40,11 +40,31 @@ beforeAll
 
 beforeEach
 
-# verify template substitution behavior
-config="$("$DOPPLER_BINARY" secrets substitute /dev/stdin <<<'{{.DOPPLER_CONFIG}}')"
+export MY_ENV_VAR="123"
+export TEST="foo"
+
+# DOPPLER_ENVIRONMENT is used here because it isn't specified as an environment variable for the purposes of configuration
+
+# verify default template substitution behavior
+config="$("$DOPPLER_BINARY" secrets substitute /dev/stdin <<<'{{.DOPPLER_ENVIRONMENT}}')"
 [[ "$config" == "e2e" ]] || error "ERROR: secrets substitute output was incorrect"
 
-"$DOPPLER_BINARY" secrets substitute nonexistent-file.txt && \
+"$DOPPLER_BINARY" secrets substitute nonexistent-file.txt &&
   error "ERROR: secrets substitute did not fail on nonexistent file"
 
+output="$("$DOPPLER_BINARY" secrets substitute /dev/stdin --use-env false <<<'{{.DOPPLER_ENVIRONMENT}} {{.MY_ENV_VAR}} {{.TEST}}')"
+[[ "$output" == "e2e <no value> abc" ]] || error "ERROR: secrets substitute output was incorrect (env:false)"
+
+output="$("$DOPPLER_BINARY" secrets substitute /dev/stdin --use-env true <<<'{{.DOPPLER_ENVIRONMENT}} {{.MY_ENV_VAR}} {{.TEST}}')"
+[[ "$output" == "e2e 123 abc" ]] || error "ERROR: secrets substitute output was incorrect (env:true)"
+
+output="$("$DOPPLER_BINARY" secrets substitute /dev/stdin --use-env override <<<'{{.DOPPLER_ENVIRONMENT}} {{.MY_ENV_VAR}} {{.TEST}}')"
+[[ "$output" == "e2e 123 foo" ]] || error "ERROR: secrets substitute output was incorrect (env:override)"
+
+output="$("$DOPPLER_BINARY" secrets substitute /dev/stdin --use-env only <<<'{{.DOPPLER_ENVIRONMENT}} {{.MY_ENV_VAR}} {{.TEST}}')"
+[[ "$output" == "<no value> 123 foo" ]] || error "ERROR: secrets substitute output was incorrect (env:only)"
+
+output="$(DOPPLER_TOKEN="invalid" "$DOPPLER_BINARY" secrets substitute /dev/stdin --use-env only <<<'{{.DOPPLER_ENVIRONMENT}} {{.MY_ENV_VAR}} {{.TEST}}')"
+[[ "$output" == "<no value> 123 foo" ]] || error "ERROR: secrets substitute output was incorrect (env:only token:cleared)"
+
 afterAll