IAM tutorial: Use an AWS CloudFormation template to create a SAML Identity Provider (IdP)
To set up SAML federation for your AWS account, you need to create a SAML Identity Provider (IdP). This tutorial shows you how to use an AWS CloudFormation template to create a SAML IdP that establishes trust between AWS and your external IdP.
The template creates a SAML IdP configured with your IdP's metadata document. Federated IAM roles can then reference this IdP to allow authenticated users from your external IdP to access AWS resources.
The deployed resource consists of a SAML IdP configured with your IdP's metadata document and optional encryption settings.
Prerequisites
This tutorial assumes that you have the following already in place:
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Python 3.6 or later installed on your local machine to run the Python command used in this tutorial for formatting your IdP's SAML metadata XML file.
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A SAML metadata document from your external IdP saved as an XML file.
Create a SAML IdP using AWS CloudFormation
To create the SAML IdP, you'll create an CloudFormation template and use it to create a stack containing the IdP resource.
Create the template
First, create the CloudFormation template.
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In the Template section, click the copy icon on the JSON or YAML tab to copy the template contents.
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Paste the template contents into a new file.
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Save the file locally.
Create the stack
Next, use the template you've saved to provision a CloudFormation stack.
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Open the AWS CloudFormation console at https://console.aws.amazon.com/cloudformation
. -
On the Stacks page, from the Create stack menu, choose with new resources (standard).
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Specify the template:
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Under Prerequisite, choose Choose an existing template.
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Under Specify template, choose Upload a template file.
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Choose Choose file, navigate to the template file, and choose it.
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Choose Next.
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Specify the following stack details:
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Enter a stack name.
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For IdentityProviderName, you can leave this empty to auto-generate a name based on the stack name, or enter a custom name for your SAML IdP. Custom names must contain only alphanumeric characters, periods, underscores, and hyphens.
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For IdentityProviderSAMLMetadataDocument, you need to format your SAML metadata XML file as a single line before pasting it into this field. This is necessary because the CloudFormation console requires XML content to be formatted as a single line when passed through console parameters.
Use the following Python command to reformat your XML file:
python3 -c "import sys, re; content=open(sys.argv[1]).read(); print(re.sub(r'>\s+<', '><', content.replace('\n', '').replace('\r', '').strip()))"
saml-metadata.xml
Note
The IdP's SAML metadata document must be formatted as a single line for console parameter input. The Python command removes line breaks and extra whitespace to create the required format while maintaining all original content and structure.
Copy the output from the Python command and paste it into the IdentityProviderSAMLMetadataDocument field.
Example of formatted SAML metadata document (abbreviated):
<?xml version="1.0" encoding="UTF-8"?><md:EntityDescriptor xmlns:md="urn:oasis:names:tc:SAML:2.0:metadata" entityID="https://portal.sso.example.com/saml/assertion/CompanyIdP"><md:IDPSSODescriptor WantAuthnRequestsSigned="false" protocolSupportEnumeration="urn:oasis:names:tc:SAML:2.0:protocol"><md:KeyDescriptor use="signing"><ds:KeyInfo xmlns:ds="http://www.w3.org/2000/09/xmldsig#"><ds:X509Data><ds:X509Certificate>MIIDXTCCAkWgAwIBAgIJAJC1HiIAZAiIMA0GCSqGSIb3DQEBBQUAMEUxCzAJBgNV...</ds:X509Certificate></ds:X509Data></ds:KeyInfo></md:KeyDescriptor><md:SingleLogoutService Binding="urn:oasis:names:tc:SAML:2.0:bindings:HTTP-POST" Location="https://portal.sso.example.com/saml/logout/CompanyIdP"/><md:NameIDFormat>urn:oasis:names:tc:SAML:2.0:nameid-format:persistent</md:NameIDFormat><md:SingleSignOnService Binding="urn:oasis:names:tc:SAML:2.0:bindings:HTTP-POST" Location="https://portal.sso.example.com/saml/assertion/CompanyIdP"/></md:IDPSSODescriptor></md:EntityDescriptor>
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For other parameters, accept the default values or enter your own based on your requirements:
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IdentityProviderAddPrivateKey - Optional private key for decrypting SAML assertions
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IdentityProviderAssertionEncryptionMode - Optional, sets encryption mode for SAML assertions (Allowed, Required, or empty)
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Choose Next.
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Configure the stack options:
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Under Stack failure options, choose Delete all newly created resources.
Note
Choosing this option prevents you from possibly being billed for resources whose deletion policy specifies they be retained even if the stack creation fails.
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Accept all other default values.
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Under Capabilities, check the box to acknowledge that CloudFormation might create IAM resources in your account.
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Choose Next.
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Review the stack details and choose Submit.
AWS CloudFormation creates the stack. Once the stack creation is complete, the stack resources are ready to use. You can use the Resources tab on the stack detail page to view the resources that were provisioned in your account.
The stack will output the following values, which you can view on the Outputs tab:
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ProviderARN: The ARN of the created SAML IdP (for example,
arn:aws:iam::123456789012:saml-provider/CompanyIdP
). You'll need this ARN when creating roles that trust this provider. -
ProviderName: The name of the created SAML IdP (for example,
CompanyIdP
if you specified a custom name, ormy-saml-stack-saml-provider
if you used the default naming).
These outputs are also exported, allowing them to be imported by other AWS CloudFormation
stacks using the Fn::ImportValue
function.
Verify the SAML IdP
Once the SAML IdP has been created, you can verify its configuration and note its ARN for use with federated roles.
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Open the IAM console at https://console.aws.amazon.com/iam/
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In the navigation pane, choose Identity providers.
You should see your newly created SAML IdP in the list.
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Choose the IdP name to view its details.
On the IdP detail page, you can see the SAML metadata document and other configuration details.
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Note the Provider ARN displayed on the details page.
You will need this ARN when creating federated IAM roles that trust this IdP.
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Review the metadata document to ensure it matches what you provided from your external IdP.
Your SAML IdP is now ready to be used by federated IAM roles. You can create roles that trust this IdP to allow authenticated users from your external IdP to assume those roles and access AWS resources.
Clean up: delete resources
As a final step, you'll delete the stack and the resources it contains.
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Open the AWS CloudFormation console.
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On the Stacks page, choose the stack created from the template, and choose Delete, then confirm Delete.
CloudFormation initiates deletion of the stack and all resources it includes.
CloudFormation template details
Resources
The AWS CloudFormation template for this tutorial will create the following resource in your account:
AWS::IAM::SAMLProvider
: A SAML IdP that establishes
trust between AWS and your external IdP.
Configuration
The template includes the following configurable parameters:
-
IdentityProviderName - The name for your SAML IdP (leave empty for auto-generated name)
Example:
CompanyIdP
orEnterpriseSSO
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IdentityProviderSAMLMetadataDocument - The SAML metadata document from your external IdP (formatted as a single line)
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IdentityProviderAddPrivateKey - Optional private key for decrypting SAML assertions
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IdentityProviderAssertionEncryptionMode - Optional, sets encryption mode for SAML assertions
CloudFormation template
Save the following JSON or YAML code as a separate file to use as the CloudFormation template for this tutorial.