MissingAuthenticationToken

**Actual Behaviour**

A work friend has set up serverless dynamodb local, making a GET request to localhost works for her, but it doesn't for me. We have the same code, with the difference that I'm using a new laptop.

Whenever I `curl -v 'http://localhost:5001/users/123'`

I get
```
Connection #0 to host localhost left intact
{"__type":"com.amazonaws.dynamodb.v20120810#MissingAuthenticationToken","message":"Request must contain either a valid (registered) AWS access key ID or X.509 certificate."}* Closing connection 0
```

config.js
```
export const DB_CONFIG = {
region: process.env.AWS_REGION || 'localhost',
endpoint: process.env.DYNAMO_DB_ENDPOINT,
accessKeyId: process.env.AWS_ACCESS_KEY_ID || 'DEFAULT_ACCESS_KEY',
secretAccessKey: process.env.AWS_SECRET_ACCESS_KEY || 'DEFAULT_SECRET',
sessionToken: process.env.AWS_SESSION_TOKEN
}
```

.env.yml
```
local:
AWS_REGION: 'localhost'
DYNAMO_DB_ENDPOINT: 'http://localhost:8000'
AWS_ACCESS_KEY_ID: 'DEFAULT_ACCESS_KEY'
AWS_SECRET_ACCESS_KEY: 'DEFAULT_SECRET'
AWS_SESSION_TOKEN: 'DEFAULT_SESSION_TOKEN'
USERS_TABLE_NAME: 'name-of-our-table-local'

sandbox:
USERS_TABLE_NAME: 'name-of-our-table-sandbox'
```

I don't really know how to solve that issue.

Start with config.js and .env.yml, then reproduce the curl request against the local endpoint while comparing the local configuration with the working setup described in the issue. Done means the GET request to localhost returns the expected user response instead of MissingAuthenticationToken.

Written by the indexing model from the issue text.