type definition for the AWS policy - aws-sdk-go

Question

Where can i find the type (structure) definition of an AWS policy? For eg, for a policy like this
firstly := "{
"Version": "2012-10-17",
"Statement": [
{
"Sid": "VisualEditor0",
"Effect": "Allow",
"Action": "s3:ListBucket",
"Resource": "arn:aws:s3:::amit",
"Condition": {
"StringLike": {
"s3:prefix": "Development/*"
}
}
},
{
"Sid": "VisualEditor1",
"Effect": "Allow",
"Action": [
"s3:PutObject",
"s3:GetObject"
],
"Resource": "arn:aws:s3:::amit/Development/*"
}
]
}
I am currently doing the following to access the field inside:
var temp interface{}
json.Unmarshal([]byte(firstKey), &temp)
c := temp.(map[string]interface{})
fmt.Println(c)
#
map[Version:2012-10-17 Statement:[map[Resource:arn:aws:s3:::amit Condition:map[StringLike:map[s3:prefix:Development/*]] Sid:VisualEditor0 Effect:Allow Action:s3:ListBucket] map[Sid:VisualEditor1 Effect:Allow Action:[s3:PutObject s3:GetObject] Resource:arn:aws:s3:::amit/Development/*]]]
I would like to have a struct like
type Policy {
Version string,
Statement []blah
}
and on unmarshaling, able to access like Policy.Version.

Answer 1

Check out https://mholt.github.io/json-to-go/. Using your example, it gave me (I changed the struct name to Policy; forgive the formatting) :
type Policy struct {
Version string `json:"Version"`
Statement []struct {
Sid string `json:"Sid"`
Effect string `json:"Effect"`
Action string `json:"Action"`
Resource string `json:"Resource"`
Condition struct {
StringLike struct {
S3Prefix string `json:"s3:prefix"`
} `json:"StringLike"`
} `json:"Condition,omitempty"`
} `json:"Statement"`
}
I saved your policy in a file, policy.json, and ran:
contents, err := ioutil.ReadFile("policy.json")
if err != nil {
os.Exit(1)
}
var thePolicy Policy
json.Unmarshal(contents, &thePolicy)
fmt.Println("Version: ", thePolicy.Version)
And got:
Version: 2012-10-17

Answer 2

Use separated structs to keep your code more organized.
condition := struct {
StringLike map[string]string
}
statement := []struct {
Sid string
Effect string
Action []string
Resource []string
Condition interface{}
}
policyStruct, _ := json.Marshal(struct {
Version string
Statement interface{}
}
UPDATE: If you need to document it on Swagger, I strongly recommend using OpenAPi. It generates the server/client code and also the struct definition.
Example:
---
openapi: 3.0.3
info:
version: "1.0.0"
title: OpenAPI AWS Policy Map
security:
- bearerAuth: []
paths:
/policy-statements:
get:
operationId: listPolicyStatements
description: Returns all existing policy statements
responses:
"200":
description: A list of policy statements
content:
application/json:
schema:
type: array
items:
$ref: "#/components/schemas/PolicyStatement"
components:
schemas:
PolicyStatement:
type: object
required:
- sid
- effect
- action
- resource
properties:
sid:
type: string
effect:
type: string
action:
type: array
items:
type: string
resource:
type: array
items:
type: string
example:
sid: bucketWrite
effect: Allow
action:
- s3:List*
- s3:Get*
- s3:Put*
resource:
- arn:aws:s3:::xxxxxx/*
- arn:aws:s3:::yyyyyy/*