AWS Token Expired S3: Understanding the Security Token Expiration

AWS Token Expired S3 can be a real headache, but understanding the security token expiration is key to resolving the issue.

Security tokens for S3 are valid for a maximum of 3 hours by default.

The expiration of a security token can occur due to inactivity, which means if your token hasn't been used for a while, it will expire.

This can happen even if the token was generated recently, as long as it's not being used.

The issue of an AWS token expiring on S3 is a common problem, especially when working with temporary, limited-privilege Security Tokens.

These tokens have a limited life or "Expiration" value, which means a new token must be obtained before the active token expires.

S3 Security Tokens can be obtained in several ways, including generating a session token using the aws-cli sts (security token service) api by assuming a role with a least privilege policy.

The aws-cli sts api is a reliable method for obtaining a new token, but it requires proper configuration and setup.

A new token is required every time the active token expires, which can be a challenge when working with automated scripts or continuous integration pipelines.

The alternative method of obtaining credentials using the AWS Instance Metadata Service Version 2 (IMDSv2) is a session-oriented method, but it's not suitable for all use cases.

Most S3 buckets require requests to be authenticated using AWS Signature v4, which adds an extra layer of complexity to the issue of expired tokens.

AWS Signature v4 is a more secure authentication method that's required for newer AWS regions like eu-central-1. This means you must use it when accessing S3 buckets in these regions.

As of January 30, 2014, AWS regions like eu-central-1 require the use of Signature v4 for authentication. To enable v4 signatures, you need to set the name of the S3 region when configuring access to the bucket.

Not setting the S3 region will result in using the older v2 signature method, which may not be supported by all regions. This is why it's essential to set the region when accessing S3 buckets in newer AWS regions.

The S3UseHeaders setting determines how the information is shared, either by adding additional request headers or query arguments.

Security Tokens are a way to access AWS services like S3 with temporary, limited-privilege credentials.

You can create these tokens using AWS's Identity and Access Management (IAM), which allows you to specify a new token before the active one expires.

S3 Security Tokens have a limited life, so you need to obtain a new one before the active token expires.

A session token can be generated by the aws-cli sts (security token service) api by assuming a role with a least privilege policy.

This method is demonstrated in the example, where you can see how to achieve this.

Alternatively, you can use the AWS Instance Metadata Service Version 2 (IMDSv2) to obtain credentials via HTTP request from an AWS EC2 instance.

Most S3 buckets require requests to be authenticated using AWS Signature v4.