Update README.md

README.md

@@ -1,8 +1,34 @@
 # aws-ssm-env
-Simple utility to print parameters from Amazon EC2 Systems Manager Parameter Store as environment variables. This is useful for injecting secure secrets into the environment of a docker container.
+Simple utility to print parameters from Amazon EC2 Systems Manager Parameter Store as environment variables. This is useful for injecting secure secrets into the environment of a docker container process.
 
 ### Usage
-TODO
+Create secret parameters on AWS Parameter Store for your application using [hierarchies](http://docs.aws.amazon.com/systems-manager/latest/userguide/sysman-paramstore-working.html#sysman-paramstore-su-organize)  :
+```
+> aws ssm put-parameter --name /production/app-1/SECRET_1 --value "123456" --type SecureString --key-id <your-key-id> --region <aws-region>
+> aws ssm put-parameter --name /production/app-1/secret_2 --value "abcdef" --type SecureString --key-id <your-key-id> --region <aws-region>
+```
+Use `export` with `aws-ssm-env` to inject secrets from Parameter Store into the environment:
+```
+> export $(AWS_REGION=<aws-region> aws-ssm-env -paths /production/app-1/)
+> env
+...
+...
+SECRET_1=123456
+SECRET_2=abcdef
+```
+Notice that parameter names are automatically capitalized
+
+Multiple hierarchy paths can be passed in vis `-paths` (comma separated):
+```
+> aws ssm put-parameter --name /production/common/common_secret --value "foobarbaz" --type SecureString --key-id <your-key-id> --region <aws-region>
+> export $(AWS_REGION=<aws-region> aws-ssm-env -paths /production/app-1/,/production/common/)
+> env
+...
+...
+SECRET_1=123456
+SECRET_2=abcdef
+COMMON_SECRET=foobarbaz
+```
 
 ### Author
 Jamie Tsao