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Chapter 4: Volume 1 Recap

4.1 The pictures to keep

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Four ways to build, from the code city:

  1. Waterfall is a giant stone bridge. Twelve months of design can hide a mistake until month 11, and the span comes down.
  2. Agile is small weekly brickwork. A two-week sprint gets feedback sooner. Operations may still deploy by hand.
  3. DevOps is an automated conveyor belt. Dev and Ops ship daily. In the tale, safety checks were left off.
  4. DevSecOps is the safe high-speed belt. Security scans ride on the belt.

Operations means the server-side people. If that sentence still sounds like a buzzword, say it again in your own words: the people who run the servers.

Three chairs:

  1. Dev wants speed and features.
  2. Sec wants risk and compliance under control.
  3. Ops wants uptime.

Friction is expected. After a bad change, a blameless note asks what the system made easy, then changes the belt. It does not hunt a name for sport.

One payment sheet:

  1. External entity: the mobile app user.
  2. Process: the payment API.
  3. Data store: Postgres, holding balances.
  4. Data flow: the request over HTTPS.
  5. The feared change, in one sentence: the amount goes from 5000 to 1.
  6. The fixes: enforce TLS in transit, sign payloads with HMAC, re-check the amount on the server.

This is for learning only, and only inside a system you are allowed to test. The recap does not relax that line.