AWS Secrets Manager Agent

AWS Secrets Manager Agent

What is the AWS Secrets Manager Agent?

When building applications, you often need to provide developers with access to sensitive information such as database credentials, API keys, or authentication tokens. However, you do not want these secrets shared insecurely (for example, via email or hardcoded in source code).

AWS Secrets Manager allows you to securely store and manage secrets. Your application can then retrieve these secrets at runtime to connect to services such as:

• Amazon RDS
• Amazon DocumentDB
• Third-party APIs
• Internal services

Typically, the application calls AWS Secrets Manager directly to retrieve the secret whenever it needs it.

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The Scaling Problem

For applications with a small user base, retrieving secrets directly from AWS Secrets Manager works well.

However, as your system scales, this approach can become inefficient:

• If your application retrieves a secret on every request
• And your system handles a large number of requests (for example, hundreds of thousands or millions)

You may end up making an extremely high number of API calls to Secrets Manager.

This can lead to:

• Increased latency
• Higher costs
• API rate limiting
• Potential throttling

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How the AWS Secrets Manager Agent Solves This

The AWS Secrets Manager Agent addresses this issue by acting as a local caching layer.

According to the official documentation:

“The AWS Secrets Manager Agent is a local HTTP service that you can install and use in your compute environments to read secrets from Secrets Manager and cache them in memory.”

Instead of your application calling AWS Secrets Manager directly:

1. The application makes a request to a local HTTP endpoint (for example, localhost).
2. The agent retrieves the secret from AWS Secrets Manager.
3. The agent caches the secret in memory.
4. Subsequent requests are served from the in-memory cache.

This significantly reduces the number of direct calls to AWS Secrets Manager and helps prevent rate limiting.

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Where It Can Be Used

The Secrets Manager Agent is a client-side HTTP service that standardizes secret retrieval across compute environments, including:

• AWS EC2
• Amazon ECS
• Amazon EKS
• AWS Lambda

Because it exposes an HTTP interface, it is language-agnostic and works with any application stack.

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Configuration Options

The Secrets Manager Agent can be configured with:

• Maximum number of connections
• Cache time-to-live (TTL)
• Localhost HTTP port
• Cache size

This allows you to control performance, memory usage, and secret refresh behavior.

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Benefits of Using the Secrets Manager Agent

• Client-side HTTP caching layer
• Standardized secret consumption across compute types
• Works with EC2, ECS, EKS, and Lambda
• Language-agnostic and open source
• Can fetch live credentials, reducing the need for container restarts when using static environment variables
• Built-in protection against server-side request forgery (SSRF)
• Post-quantum TLS enabled by default

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When Should You Use the Secrets Manager Agent?

Use the Secrets Manager Agent when:

• Your application frequently retrieves secrets
• You are operating at scale and want to avoid rate limiting
• You want to reduce latency caused by repeated API calls
• You want a standardized way to consume secrets across multiple compute environments
• You want to avoid restarting containers when secrets rotate

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When You May Not Need It

You may not need the Secrets Manager Agent if:

• Your application retrieves secrets only once at startup
• Your traffic is low and rate limits are not a concern
• You are already using another secure caching mechanism
• You inject secrets at deployment time and do not require runtime retrieval

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Example Usage Scenario

Imagine an application running on Amazon ECS that connects to an RDS database.

Without the Agent

• Each container retrieves database credentials directly from AWS Secrets Manager.
• Under high load, this can result in excessive API calls.

With the Agent

• The container queries the local Secrets Manager Agent endpoint.
• The agent retrieves and caches the database credentials.
• Subsequent requests are served from memory.
• API calls to AWS Secrets Manager are significantly reduced.

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Summary

The AWS Secrets Manager Agent is a local HTTP caching service that improves scalability, reduces latency, and helps prevent rate limiting when retrieving secrets from AWS Secrets Manager.

It is particularly useful for high-traffic, distributed systems where secrets are accessed frequently and must be securely managed without compromising performance.