Finding out where to go
When we make a web request to a service, we need to know which Uniform Resource Locator (URL) to use. Most of the examples in this book use hardcoded URLs—that is, they are written into the source code. This is nice and easy to read for an example, but can be a problem when maintaining software. What happens when a service gets a new URI, and its hostname or IP address changes? It might move between AWS regions due to a failure or be migrated from Google Cloud Platform to Microsoft Azure. An API update can make the path to a resource change, even if the hostname or IP address has not updated.
We want to pass in data about which URLs to use as configuration to our application. There are several options to manage more configuration options without adding them directly to the code, such as environment variables and service discovery.
Environment variables
Container-based environments are common these days, and we will discuss them in more...