Learn how to get started with Amazon Web Services (AWS) APIs in Postman. If you are using AWS APIs for the first time, you can follow the steps in this guide to call the APIs using requests sent through the Postman client. You can use these requests to experiment with an API before you develop your application, or programmatically run a sequence of API calls to create and manage your infrastructure on AWS.

Prerequisites

What You'll Learn

What You'll Need

What You'll Build

Create a new administrative user in AWS

IAM (Identity and Access Management) enables you to manage users and user permissions in AWS. You can create multiple IAM users with different roles and permissions as an added layer of security for your AWS account. In this tutorial we will create an IAM user to enable programmatic access to the AWS APIs.

  1. From the AWS console, create a new User on your AWS team. create new user
  2. You can optionally set permissions now following your team's procedures and preferences. Or in the subsequent steps, we will add permissions before working with each AWS service.

Input AWS data into Postman

  1. Click the orange Run in Postman button below to fork this example collection to your own Postman workspace.
    Run in Postman
  2. In the Postman app, enter a label for your fork and select the workspace to fork the collection: fork label
  3. Select the Postman collection that you forked to your workspace. Find the Variables tab, and paste your new User's information into each variable value.

Authentication is a process of verifying the identity of the requester trying to access an Amazon Web Services (AWS) product. Authenticated requests must include a signature value that authenticates the request sender. The signature value is generated from the requester's AWS access keys that we will generate next.

Get AWS credentials from AWS console

  1. In the AWS IAM console, click Users in the Details pane, click the IAM user we created in the previous steps, and then click Create Access Key on the Security Credentials tab. create access key in AWS console
  2. Step through the configuration details, such as selecting the use case "Application running outside AWS". Generate your Access key and Secret access key, which we will need for the next step. Keys in AWS console

For more information about getting access keys, see the AWS General Reference.

Set AWS credentials in Postman

In Postman, we can use an authorization helper to compute an AWS signature to include with each request. To authenticate requests using AWS Signature Version 4, add your AWS credentials to Postman:

  1. In Postman, select the collection that you previously forked to your own workspace. Navigate to the Authorization tab, and select AWS Signature as the authorization type. We are setting up authorization for the collection, so that every request within this collection can inherit and use these authorization credentials.
  2. Scroll down to fill in the following details.
    • AccessKey: This is the Access key from the AWS IAM console in the previous steps.
    • SecretKey: This is the Secret access key from the AWS IAM console. select aws signature
  3. Instead of pasting those values directly in the fields, we used double curly braces to reference a collection or environment variable to keep sensitive data secure. Input keys in Postman
  4. Once all the data has been provided to the respective fields, Save your updates. Postman will add the required headers to every request within this collection.

In the following sections, let's explore some of the most popular APIs on Amazon Web Services.

What is IAM?

As previously mentioned, IAM (Identity and Access Management) enables you to manage users and user permissions in AWS as an added layer of security for your AWS account.

You manage access in AWS by creating policies and attaching them to IAM identities (users, groups of users, or roles) or AWS resources. A policy is an object in AWS that, when associated with an identity or resource, defines their permissions.

You can change the permissions for an IAM user in your AWS account by changing its group memberships, by copying permissions from an existing user, or by attaching policies directly to a user. You can do this from the IAM console in the AWS Management Console, the AWS Command Line Interface (AWS CLI), or the AWS API.

Let's attach an existing IAM policy using the IAM console.

Attach policy with console

In the next steps, we will work with an Amazon S3 cloud storage resource called a bucket. To grant the user permissions on a bucket, the AWS account can use a bucket policy, a user policy, or both. Let's attach an IAM policy to our new user.

  1. Open the IAM console in the AWS Management Console, and choose Policies. Search for AmazonS3FullAccess. Click on the policy, toggle over to JSON, and review the details. The AmazonS3FullAccess managed policy provides full access to all buckets. 
    {
  "Version": "2012-10-17",
  "Statement": [
    {
      "Effect": "Allow",
      "Action": ["s3:*", "s3-object-lambda:*"],
      "Resource": "*"
    }
  ]
}
  2. Return to the previous page, once again search for AmazonS3FullAccess, and select the radio button next to the name of the policy to attach. Choose Actions, and then choose Attach. filter for IAM policy
  3. Select the IAM user we created in the previous steps, and choose Attach policy. attach IAM policy

Now that we've granted our new user access to all S3 buckets, let's create a new bucket.

What is Amazon S3?

Amazon Simple Storage Service (Amazon S3) is an object storage service that offers scalability, data availability, security, and performance. Customers can use Amazon S3 to store and protect data for a range of use cases, such as data lakes, websites, mobile applications, backup and restore, archive, enterprise applications, IoT devices, and big data analytics. You can optimize, organize, and configure access to your data to meet your specific requirements.

Get started with Amazon S3

To get started with Amazon S3 APIs, we will rely on the API reference as well as common error codes to help with troubleshooting.

  1. Set Permissions for User: In the previous step, we attached an IAM policy AmazonS3FullAccess for our new user to access all S3 buckets. If you haven't done this already, do it now from the IAM console.
  2. Configure a bucket: 1. In your Postman workspace, select the collection that you previously forked, and expand the folder called "Storage". Open the "Create bucket" request, and review the following parts of the API request.
    • PUT method
    • Base URL includes two variables. Verify you have a collection or environment variable called serviceName with a value of s3, a variable bucketName with the preferred name for the bucket.
    • Request body includes an XML object containing a variable {{region}} which is previously defined.
  3. Create a bucket: Then Send the request to create a new bucket. create bucket
  4. List buckets: Open the "List buckets" request, and Send the request to inspect all the buckets. The response from the AWS API contains an XML object. Under the Tests tab of Postman, we can use a library called xml2Json to parse the XML object and write a test to programmatically verify our new bucket exists. get buckets
  5. Upload object: Open the "Upload object to bucket" request, and configure the following details.
    • Base URL includes a variable called fileName. Under the Pre-request Scripts tab, we have a line of code to programmatically generate a random word to use as your file name. Postman will generate this random word when the request is run. If you want to manually set the name of your object, comment out this line of code (by inserting // at the beginning of the line), and then add a collection or environment variable called fileName.
    • Under the request body, select Binary and then select a file to upload. Once you add a file, notice Postman automatically updates the Content-type header under the Headers tab.
    • Send the request. upload object
  6. Get object: Open the "Get object from bucket" request, and Send the request. Notice we are using the same fileName from the previous request. get object
  7. Make objects public: Open the "Set bucket policy", and Send the request. Notice we are using the same {{bucketName}} defined previously. Depending on your settings, you may need to go to the S3 console, and navigate to your bucket to uncheck "Block all public access" in order to update the bucket policy. uncheck block all public access

Other related topics:

What is Amazon EC2?

Amazon Elastic Compute Cloud (Amazon EC2) provides scalable computing capacity in the Amazon Web Services (AWS) Cloud. Using Amazon EC2 eliminates your need to invest in hardware up front, so you can develop and deploy applications faster. You can use Amazon EC2 to launch as many or as few virtual servers as you need, configure security and networking, and manage storage. Amazon EC2 enables you to scale up or down to handle changes in requirements or spikes in popularity, reducing your need to forecast traffic.

In this section, you'll learn how to launch, connect to, and use a virtual server in the AWS cloud called an instance.

Get started with Amazon EC2

To get started with Amazon S3 APIs, we will rely on the API reference as well as common error codes to help with troubleshooting. Additionally, we will rely on this guide.

  1. Set Permissions for User: Follow the same process in the IAM console to attach an IAM policy AmazonEC2FullAccess to our new user and provide full access to Amazon EC2.
  2. Describe availability zones: In your Postman workspace, select the collection that you previously forked, and expand the folder called "Compute". Open the "Describe Availability Zones" request, and review the following parts of the API request.
    • GET method
    • Base URL includes a variable serviceName to be defined as ec2 in the folder's pre-request script when the request is sent. To see these details, select the folder Compute and then the Pre-request Scripts tab.
    • Request parameters include a variable Action with a value DescribeAvailabilityZones
    Send the request, and notice the code under the Tests tab parses the server response and sets a collection variable as the first availability zone returned. set availability zone
  3. Describe VPCs: Open the "Describe VPCs" request, and review differences in this API request compared to the previous request.
    • Request parameters include a variable Action with a value DescribeVpcs, and also filters to return only the default VPC.
    Send the request, and once again notice the code under the Tests tab sets a collection variable with the default VPC. set default vpc
  4. Describe Key Pairs: Open the "Describe Key Pairs" request, review and Send this request, and notice the code to set a collection variable with the key pair name. set default key Name
  5. Describe Subnets: Open the "Describe Subnets" request, and Send the request. Notice this request includes filters to find the default subnet given the VPC and availability zone determined in the previous requests. set default subnet
  6. Describe Images: Open the "Describe Images" request. You can add other filter parameters to narrow down the list of results. Send the request. set image Id
  7. Run Instances: It is finally time to launch an instance. Open the "Run Instances" request, and see the query parameters utilize the data collected in the preceding requests. run instances
  8. Describe Instances: Open the "Describe Instances" request which utilizes the instance ID set in the preceding request. This time, let's log the instance state to the Postman console. describe instances

Organize workflows in Postman

Once you explore an API, you understand the basic building blocks of popular services on AWS. Next, organize your work into your own collections and workspaces in Postman.

Automate workflows in Postman

Once you group API requests into collections, there are multiple ways to programmatically run those collections.

Build your own applications

Once you have an API call working the way you want it to in Postman, generate client code to paste into your own applications. code generation

What we've covered

For more hands-on tutorials, check out these resources.

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