How I Removed AWS Access Keys from GitLab CI/CD with OIDC

When I first connected my GitLab CI/CD pipelines to AWS, I used the simplest solution: an IAM user with an Access Key and Secret Access Key stored as GitLab CI/CD variables. It worked. But there was one problem: those credentials were permanent. They had to be stored, protected and eventually rotated. If they were accidentally exposed in logs or compromised, they could remain valid until manually revoked. I wanted a cleaner solution. So I replaced permanent AWS credentials with OIDC federation between GitLab and AWS . The result is simple: GitLab pipelines can access AWS without storing any permanent AWS credentials. In this post, I'll explain how I implemented it, how the authentication flow works, and one important issue I faced when using it with EKS and Terraform. The architecture The authentication flow looks like this: ┌──────────────┐ │ GitLab CI │ └──────┬───────┘ │ │ OIDC token ▼ ┌──────────────┐ │ AWS STS │ └──────┬───────┘ │ │ Temporary credentials ▼ ┌──────────────┐ │ IAM Role │ └──────┬───────┘ │ ├──────────► Terraform │ ├──────────► ECR │ └──────────► EKS Instead of GitLab storing an AWS Access Key, it proves its identity to AWS using a short-lived OIDC token. AWS verifies the token and returns temporary credentials. How does OIDC authentication work? The process can be summarized in five steps: GitLab creates an OIDC token for the CI/CD job. The pipeline sends this token to AWS. AWS verifies that the token really comes from GitLab. AWS checks that the project is allowed to assume the requested IAM role. AWS STS returns temporary credentials. These credentials expire automatically. So there is nothing permanent to store or rotate inside GitLab. Step 1 — Register GitLab as an OIDC provider AWS first needs to trust GitLab as an identity provider. I configured the OIDC provider using Terraform: data "tls_certificate" "gitlab" { url = "${var.gitlab_url}/.well-known/openid-configuration" } resource "aws_iam_openid_connect_provider" "gitlab" { url = var . gi