DevOps unifies development and operations through shared responsibility, automation, and rapid feedback. The CALMS model - Culture, Automation, Lean, Measurement, Sharing - is the textbook frame.
11.2 The Principles of DevOps
The CALMS frame
Letter
Meaning
Example practice
C
Culture
Shared ownership; blameless post-mortems
A
Automation
Everything from build to deploy
L
Lean
Reduce batch size; flow; eliminate waste
M
Measurement
Lead time, deploy freq, MTTR, CFR
S
Sharing
Tools, knowledge, runbooks across teams
DORA's four key metrics
Metric
Elite team baseline
Deployment frequency
Many per day
Lead time for changes
Less than one day
Change failure rate (CFR)
Less than 15 %
Time to restore service
Less than 1 hour
You build it, you run it
Dev teams operate what they ship. Pager goes to the team that wrote it. This aligns incentives - poor code wakes the author up.
Platform engineering shape
Layer
Provider
Consumer
Golden paths
Platform team
Product teams
CI/CD template
Platform team
Product teams
Observability
Platform team
Product teams
Cost guardrails
Platform team
Product teams
Worked example - bank from quarterly to weekly deploys
Item
Before
After
Cadence
Quarterly batched
Weekly production deploys
Branching
Long-lived feature
Trunk-based + flags
Testing
Manual QA window
Automated; staging in prod-like env
CFR
18 %
6 %
On-call
Ops team only
Balanced across product teams
Common pitfalls
Pitfall
Why it backfires
DevOps as a team
Should be a practice, not a silo
Automation without observability
Faster but blind
DORA scores as targets
Goodhart's law; gamed
No platform team
Every product reinvents pipelines
Mentor’s tip: CALMS + DORA + platform thinking. You build it, you run it. Treat the internal platform as a product. DORA metrics inform; they are not targets.
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