How do you add a comment to a json IAM policy?

Question

IAM policy are complicated beasts. It would be nice to add a comment when crafting them. For example,

{   "Version": "2012-10-17",   "Statement": [     {       "Sid": "Stmt1422979261000",       "Effect": "Allow",       "Action": [         "route53:ListHostedZones",       ],       "Comment": "Foo"       # or Bar       "Resource": [         "*"       ]     }   ] } 

Neither of these work. Does there exist a way to add comments to these policies?

Answer 1

Hyper Anthony's answer is correct in the strict sense of 'comment' - however, in most situations you can at least use the Sid for pseudo comments to communicate the intent or any constraints etc.:

The Sid (statement ID) is an optional identifier that you provide for the policy statement. You can assign a Sid value to each statement in a statement array. In services that let you specify an ID element, such as SQS and SNS, the Sid value is just a sub-ID of the policy document's ID. In IAM, the Sid value must be unique within a policy. [emphasis mine]

This is e.g. exemplified by the use of TheseActionsSupportResourceLevelPermissions within the (very helpful) AWS blog post Demystifying EC2 Resource-Level Permissions:

{     "Version": "2012-10-17",     "Statement": [         {             "Sid": "TheseActionsSupportResourceLevelPermissions",             "Effect": "Allow",             "Action": [                 "ec2:RunInstances",                 "ec2:TerminateInstances",                 "ec2:StopInstances",                 "ec2:StartInstances"             ],             "Resource": "arn:aws:ec2:us-east-1:accountid:instance/*"         }     ] } 

• As mentioned in Sid some services might require this element and have uniqueness requirements for it, but I haven't experienced resulting naming constraints yet.