Setting service-specific configuration in the profile or an env var

[Velfi]

Users may set service-specific configuration in the environment, either as profile configuration or as an environment variable.

NOTE: Only a restricted set of configuration is currently supported.

• Endpoint URL

If your use case requires support for an currently-unsupported config value, please file an issue.

Setting service-specific configuration with an environment variable

Environment variable names are constructed like so:

"AWS_" + <setting name in CONST case> + "_" + <service id in CONST case>

As an example, you can set an endpoint URL that will only be used when making requests with the AWS Health APIs and Notifications service client like this:

export AWS_ENDPOINT_URL_HEALTH="us-east-1"

Setting service-specific configuration with AWS profile config

Profile config variables for specific services must be defined in a special services section, like so:

[default]
endpoint_url = "http://localhost:7070"
services = service-config

[services service-config]
s3 =
  endpoint_url = "http://localhost:8080"
ec2 =
  endpoint_url = "http://localhost:9090"

The config above would produce an S3 client that sends requests to http://localhost:8080 and an EC2 client that sends requests to http://localhost:9090. All other SDK clients would use the http://localhost:7070 URL.

Service-specific profile config may only be defined in a services section. For example, if the profile above was instead defined like this:

[default]
endpoint_url = "http://localhost:7070"
# his endpoint URL would be IGNORED
s3 =
  endpoint_url = "http://invalid:8080"

Then the http://invalid:8080 endpoint URL would be silently ignored! This is an intentional part of the design which simplifies our internal implementation.

Configuration precedence

Configuration precedence is almost identical to how it was before this change. In order of descending precedence:

1. Client configuration i.e. setting a config value in your Rust program.
2. Service-specific environment variables.
3. Non-specific environment variables.
4. Service-specific profile configuration.
5. Non-specific profile configuration.

In other words, client configuration overrules all other configuration and specific configuration overrides non-specific configuration.

How to find a service's service ID

Every SDK crate we publish includes the service id in its name. Here are a few examples:

Service Name	SDK Crate	service ID
AWSServerlessApplicationRepository	aws-sdk-serverlessapplicationrepository	serverlessapplicationrepository
Amazon DynamoDB	aws-sdk-dynamodb	dynamodb
Firewall Management Service	aws-sdk-fms	fms

You can see the list of all SDK crates we publish here.