use os envs on Makefile

lambda/Makefile

@@ -7,9 +7,9 @@
 # Makefile for generating zip files for lambda functions and then copying them
 # to S3 for deployment. This Makefile will NOT WORK unless you fill in the S3DEST
 # and AWSARGS variables below. Once those parameters are established, simply type
-# 'make' or 'gmake' (depending on your UNIX-like OS) and it will build. 
+# 'make' or 'gmake' (depending on your UNIX-like OS) and it will build.
 #
-# Behaviour: 
+# Behaviour:
 # Creates a file named ._foo.whatever based on foo.whatever.Uploads foo.whatever to
 # the S3 bucket. The ._ file is a hack to figure out whether the file has
 # been modified since the last time we uploaded to s3.
@@ -20,7 +20,7 @@ S3DEST?=[YOUR BUCKET HERE]
 
 # Set these if, for example, you use profiles on the AWS command line
 # or if your 'aws' executable is in a weird place.
-AWSARGS=--region [YOUR REGION] --profile [YOUR PROFILE, or 'default', or remove this]
+AWSARGS=--region ${AWS_REGION} --profile ${AWS_PROFILE}
 AWSCMD=aws
 ZIPCMD=zip
 
@@ -48,4 +48,4 @@ clean:
 # This rule is a BSD make style rule that says "to make foo.zip, call
 # 'zip -jqr foo snapshot_tool_utils.py'"
 %.zip: %
-	$(ZIPCMD) -jqr "$@" "$<" snapshots_tool_utils.py
+	$(ZIPCMD) -jqr "$@" "$<" snapshots_tool_utils.py