AWS Credentials for Docker and Rails Application

Greetings,

I'd like to discuss what's the best way for passing aws credentials

My application is Ruby on Rails

So far my Dockerfile uses:

```ssh
# https://docs.aws.amazon.com/xray/latest/devguide/xray-daemon-ecs.html
RUN apt-get update && apt-get install -y --force-yes --no-install-recommends apt-transport-https curl ca-certificates wget && apt-get clean && apt-get autoremove && rm -rf /var/lib/apt/lists/*
RUN wget https://s3.ap-southeast-1.amazonaws.com/aws-xray-assets.ap-southeast-1/xray-daemon/aws-xray-daemon-3.x.deb
RUN dpkg -i aws-xray-daemon-3.x.deb
ENTRYPOINT ["/usr/bin/xray", "--bind=0.0.0.0:2000", "--bind-tcp=0.0.0.0:2000"]
EXPOSE 2000/udp
EXPOSE 2000/tcp
```

Application setup:

```ssh
# Gemfile
gem "aws-xray-sdk", "~> 0.13.0"

# config/initializers/aws_xray.rb
Rails.application.config.xray = {
# default segment name generated by XRay middleware
name: "webportal",
patch: %I[net_http aws_sdk],
# record db transactions as subsegments
active_record: true
}
```

What's the best way to pass my aws credentials ?

Start by reading the Dockerfile setup, Gemfile entry, and config/initializers/aws_xray.rb configuration shown in the issue, then review the linked AWS X-Ray ECS documentation. Determine what credential-passing guidance is missing for this Dockerized Rails application and document the supported approach; done means the recommendation is clear and reproducible.

Written by the indexing model from the issue text.