Which three defining moments shaped DevOps as a discipline?

• 2003: Google institutionalises Site Reliability Engineering.
• 2009: Patrick Debois brings agile methods and version control to infrastructure ("Agile Infrastructure").
• 2009: John Allspaw and Paul Hammond's talk on Dev and Ops jointly enabling the business.

DevOps grew in several places at once, but these three moments stand out:

1. SRE at Google (2003). Operations run as a software-engineering discipline.
2. Patrick Debois and Agile Infrastructure. Debois, a Belgian consultant, argued for automating virtual and physical infrastructure using version control and agile methods, the same way software is built. He organised the first DevOpsDays in Ghent in 2009, which gave the movement its name.
3. Allspaw and Hammond (Velocity 2009). In "10+ Deploys per Day: Dev and Ops Cooperation at Flickr", the two showed a set of best practices based on one idea: development and operations together enable the business, rather than one producing change and the other resisting it.

Go deeper:

• John Allspaw & Paul Hammond — 10+ Deploys per Day (Velocity 2009) — the talk itself: Dev and Ops cooperation at Flickr.
• devopsdays — About — how the 2009 Ghent conference gave the movement its name.