Exec instead of formatting environment variables to eval

README.md

@@ -19,10 +19,10 @@ $ wget https://github.com/Droplr/aws-env/raw/master/bin/aws-env-linux-amd64 -O a
 ```
 
 3. Start your application with aws-env
- * `AWS_ENV_PATH` - path of parameters. If it won't be provided, aws-env will exit immediately. That way, you can run your Dockerfiles locally.
+ * `AWS_ENV_PATH` - path of parameters. If it isn't be provided, aws-env will not make requests to SSM. That way, you can run your Dockerfiles locally.
  * `AWS_REGION` and AWS Credentials - [configuring credentials](https://github.com/aws/aws-sdk-go#configuring-credentials)
 ```
-$ eval $(AWS_ENV_PATH=/prod/my-app/ AWS_REGION=us-west-2 ./aws-env) && node -e "console.log(process.env)"
+$ AWS_ENV_PATH=/prod/my-app/ AWS_REGION=us-west-2 ./aws-env node -e "console.log(process.env)"
 ```
 
 
@@ -45,7 +45,7 @@ RUN apk update && apk upgrade && \
 RUN wget https://github.com/Droplr/aws-env/raw/master/bin/aws-env-linux-amd64 -O /bin/aws-env && \
   chmod +x /bin/aws-env
 
-CMD eval $(aws-env) && node -e "console.log(process.env)"
+CMD aws-env node -e "console.log(process.env)"
 ```
 
 ```
@@ -69,13 +69,6 @@ $ docker run -t my-app
 $ wget https://github.com/Droplr/aws-env/raw/befe6fa44ea508508e0bcd2c3f4ac9fc7963d542/bin/aws-env-linux-amd64
 ```
 
-* Many Docker images (e.g. ruby) are using /bin/sh as a default shell. It crashes `$'string'`
-  notation that enables multi-line variables export. For this reason, to use aws-env, it's
-  required to switch shell to /bin/bash:
-```
-CMD ["/bin/bash", "-c", "eval $(aws-env) && rails s Puma"]
-```
-
 * You should never pass AWS credentials inside the containers, instead use IAM Roles for that -
 [Managing Secrets for Amazon ECS Applications Using Parameter Store and IAM Roles for Tasks](
 https://aws.amazon.com/blogs/compute/managing-secrets-for-amazon-ecs-applications-using-parameter-store-and-iam-roles-for-tasks/)

aws-env.go

@@ -1,22 +1,35 @@
 package main
 
 import (
-	"fmt"
+	"log"
+	"os"
+	"os/exec"
+	"path"
+	"syscall"
+
 	"github.com/aws/aws-sdk-go/aws"
 	"github.com/aws/aws-sdk-go/aws/session"
 	"github.com/aws/aws-sdk-go/service/ssm"
-	"log"
-	"os"
-	"strings"
 )
 
 func main() {
 	if os.Getenv("AWS_ENV_PATH") == "" {
 		log.Println("aws-env running locally, without AWS_ENV_PATH")
-		return
+	} else {
+		ExportVariables(os.Getenv("AWS_ENV_PATH"), "")
 	}
 
-	ExportVariables(os.Getenv("AWS_ENV_PATH"), "")
+	binary, lookErr := exec.LookPath(os.Args[1])
+	if lookErr != nil {
+		panic(lookErr)
+	}
+
+	env := os.Environ()
+	args := os.Args[1:]
+	execErr := syscall.Exec(binary, args, env)
+	if execErr != nil {
+		panic(execErr)
+	}
 }
 
 func CreateClient() *ssm.SSM {
@@ -43,20 +56,18 @@ func ExportVariables(path string, nextToken string) {
 	}
 
 	for _, element := range output.Parameters {
-		PrintExportParameter(path, element)
+		SetExportParameter(element)
 	}
 
 	if output.NextToken != nil {
 		ExportVariables(path, *output.NextToken)
 	}
 }
 
-func PrintExportParameter(path string, parameter *ssm.Parameter) {
+func SetExportParameter(parameter *ssm.Parameter) {
 	name := *parameter.Name
 	value := *parameter.Value
 
-	env := strings.Trim(name[len(path):], "/")
-	value = strings.Replace(value, "\n", "\\n", -1)
-
-	fmt.Printf("export %s=$'%s'\n", env, value)
+	_, envName := path.Split(name)
+	os.Setenv(envName, value)
 }