Silhouette of a man is seen in front of the logos of Amazon Online Shopping Website and Apple Technology Company. Aytac Unal | Anadolu Agency | Getty Images

As Apple and Amazon compete for a greater share of consumer dollars and attention, they also have a particularly intimate business relationship: Apple is spending more than $30 million a month on Amazon's cloud, according to people familiar with the arrangement. Apple's cloud expenditure reflects the company's determination to deliver online services like iCloud quickly and reliably, even if it must depend on a rival to do so.

As Apple's top product, the iPhone, approaches market saturation, the company has begun pointing more to online services as a key contributor. Recently, the company stopped disclosing unit sales for iPhones and other hardware products and started disclosing the profit margin for its services business, which includes the iOS App Store, AppleCare, Apple Pay and iCloud. Apple also introduced new subscription services for video and magazines last month. People use more than 1 billion Apple devices each month, and accordingly, Apple has considerable computing and storage requirements. The company is investing heavily to build its own infrastructure: In January 2018, Apple announced plans to spend $10 billion on data centers in the U.S. within five years. In December, Apple said it would spend $4.5 billion of that amount through 2019. The company also depends on smaller third-party cloud providers. But it also relies on the big cloud providers, including Amazon Web Services and Alphabet subsidiary Google. Microsoft has also provided cloud tools to Apple in the past. The company has said in the past that it uses AWS for iCloud storage but has not disclosed whether any other Apple services use AWS or other third-party clouds.

A growing AWS footprint