For others non AWS credentials, just use environment variables
Repo should have a `README` that says the secrets are in the team 1password account, talk to <team member> to get a 1password account, and get added to the group that has access to the vault with the creds.
The repo should have a source script that will pull the credentials[1] and `export` them to your ENV. `direnv` can make that happen automatically[2], or you can run that script from your `.bashrc` or similar.
You can do something similar with your favorite secrets manager. I've used a similar approach before, with good results.
[1] https://support.1password.com/command-line-getting-started/
Have your code fetch any secrets it needs from AWS Secrets manager, using the name of the secret (which does not have to be kept secret, so it can be in your source repo)
That way, you don’t have to put secrets in your environment, with the risk of leaking them.
I'm just pointing out that AWS Secrets Manager is not at automatic, no-brainer win
The other solutions don’t integrate with AWS IAM. Something has to grant access to the password vault. In the case of Secrets Manager/Parameter Store you just grant access to the role attached to your EC2 instance/ECS cluster/Lambda.