Read service specific endpoints from env/config

[trivikr]

Issue

Internal JS-4281

Description

Reads service specific endpoints from environment or configuration

Testing

Test code:

import { DynamoDB, ListTablesCommand } from "@aws-sdk/client-dynamodb";
import { getEndpointFromInstructions } from "@smithy/middleware-endpoint";

const client = new DynamoDB();
const command = new ListTablesCommand({});
const endpoint = await getEndpointFromInstructions(
  command.input,
  ListTablesCommand,
  client.config
);

console.log({ endpoint: endpoint.url.href });

Copied the artifacts from PR into test code:

$ rm -rf node_modules/@smithy/middleware-endpoint

$ cp -R ../smithy-typescript/packages/middleware-endpoint node_modules/@smithy/middleware-endpoint

Configuration:

[default]
region = us-west-2

[profile config]
region = us-west-2
endpoint_url = http://config.custom.endpoint

[profile config-services]
region = us-west-2
services = config
endpoint_url = http://service.config.custom.endpoint
dynamodb =
    endpoint_url = http://invalid.dynamodb.config.custom.endpoint

[services config]
endpoint_url = http://invalid.config.custom.endpoint
dynamodb =
    endpoint_url = http://dynamodb.config.custom.endpoint

Client configuration

The highest preference if one provided during client creation

Code:

const client = new DynamoDB({ endpoint: "http://custom.endpoint" });

Output:

$ node endpoint.mjs
{ endpoint: 'http://custom.endpoint/' }

$ AWS_ENDPOINT_URL=http://env.custom.endpoint \
AWS_ENDPOINT_URL_DYNAMODB=http://dynamodb.env.custom.endpoint \
node endpoint.mjs 
{ endpoint: 'http://custom.endpoint/' }

$ AWS_PROFILE=config \
node endpoint.mjs
{ endpoint: 'http://custom.endpoint/' }

$ AWS_PROFILE=config-services \
node endpoint.mjs
{ endpoint: 'http://custom.endpoint/' }

AWS_ENDPOINT_URL_DYNAMODB

Populates endpoint from AWS_ENDPOINT_URL_DYNAMODB is set.

$ node endpoint.mjs
{ endpoint: 'https://dynamodb.us-west-2.amazonaws.com/' }

$ AWS_ENDPOINT_URL=http://env.custom.endpoint \
AWS_ENDPOINT_URL_DYNAMODB=http://dynamodb.env.custom.endpoint \
node endpoint.mjs 
{ endpoint: 'http://dynamodb.env.custom.endpoint/' }

$ AWS_ENDPOINT_URL_DYNAMODB=http://dynamodb.env.custom.endpoint \
AWS_PROFILE=config \
node endpoint.mjs 
{ endpoint: 'http://dynamodb.env.custom.endpoint/' }

$ AWS_ENDPOINT_URL_DYNAMODB=http://dynamodb.env.custom.endpoint \
AWS_PROFILE=config-services \
node endpoint.mjs 
{ endpoint: 'http://dynamodb.env.custom.endpoint/' }

AWS_ENDPOINT_URL

Populates endpoint from AWS_ENDPOINT_URL is set.

$ node endpoint.mjs                                                                               
{ endpoint: 'https://dynamodb.us-west-2.amazonaws.com/' }

$ AWS_ENDPOINT_URL=http://env.custom.endpoint \
node endpoint.mjs
{ endpoint: 'http://env.custom.endpoint/' }

$ AWS_ENDPOINT_URL=http://env.custom.endpoint \
AWS_PROFILE=config \
node endpoint.mjs
{ endpoint: 'http://env.custom.endpoint/' }

$ AWS_ENDPOINT_URL=http://env.custom.endpoint \
AWS_PROFILE=config-services \
node endpoint.mjs
{ endpoint: 'http://env.custom.endpoint/' }

config dynamodb.endpoint_url

$ AWS_PROFILE=config-services \
node endpoint.mjs
{ endpoint: 'http://dynamodb.config.custom.endpoint/' }

config endpoint_url

$ AWS_PROFILE=config \         
node endpoint.mjs
{ endpoint: 'http://config.custom.endpoint/' }

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[syall]

Would adding @internal to every export make sense? I don't think customers should use these directly.

[trivikr]

Would adding @internal to every export make sense?

None of the utilities added in this PR are exported at top level. We don't need to add @internal.