AWS Certificate Manager vs AWS Secrets Manager: What are the differences?

Introduction

AWS Certificate Manager (ACM) and AWS Secrets Manager are two services provided by Amazon Web Services. While both services are used for managing sensitive data, they have distinct differences in terms of their functionality and use cases.

1. Certificate Management: The key difference between ACM and Secrets Manager lies in their primary functions. ACM is primarily used for managing SSL/TLS certificates, making it easier to deploy, manage, and renew certificates for applications running on AWS. On the other hand, Secrets Manager is designed to manage sensitive secrets like database passwords, API keys, and other credentials, providing a secure way to store and retrieve such secrets.

2. Automation and Integration: ACM allows for seamless integration with other AWS services like Elastic Load Balancer (ELB), CloudFront, and API Gateway. It simplifies the process of provisioning and configuring SSL certificates for these services, auto-renewing them, and handling the complexity of certificate management. Secrets Manager, on the other hand, integrates well with services like Amazon RDS, Amazon DocumentDB, and ECS, enabling automated retrieval and rotation of secrets, reducing the operational overhead of managing credentials.

3. Granularity of Access Control: ACM provides basic access control through IAM policies, allowing you to control who can manage and utilize SSL certificates within your AWS account. However, the access control is limited to the AWS account level. In contrast, Secrets Manager enables finer-grained access control through resource-based policies and IAM permissions. You can grant or restrict access to individual secrets, making it more suitable for multi-tenant environments or scenarios where different applications require access to different secrets.

4. Encryption at Rest: ACM automatically encrypts SSL/TLS certificates at rest using AWS Key Management Service (KMS). This ensures that the data is encrypted and protected even if stored in the ACM service. On the other hand, Secrets Manager encrypts secret values using KMS as well, ensuring that the secrets are encrypted both at rest and in transit.

5. Secret Rotation: Secrets Manager provides built-in support for secret rotation, enabling you to automatically rotate secrets on schedules or triggers. This ensures that credentials are regularly updated, reducing the risk of compromised or outdated credentials being used. ACM, on the other hand, does not offer automatic rotation for SSL/TLS certificates. Certificate rotation needs to be manually performed, which might require additional effort and careful planning.

6. Integration with Third-Party Tools: Since ACM is designed specifically for managing SSL/TLS certificates within AWS, its integration with third-party tools and platforms may be limited. On the other hand, Secrets Manager offers more flexibility in terms of integration, allowing you to easily retrieve secrets for non-AWS applications or services. This makes Secrets Manager a suitable choice for managing credentials across different environments or hybrid cloud setups.

In summary, AWS Certificate Manager (ACM) primarily focuses on managing SSL/TLS certificates and simplifies their deployment and management within AWS services. On the other hand, AWS Secrets Manager is designed for managing sensitive secrets, enabling secure storage, automated retrieval, and rotation of credentials. While ACM offers integration with AWS services and automated certificate management, Secrets Manager provides finer-grained access control, secret rotation, and broader integration options.