Explain like I'm five · SRE

What is Orchestration?

Orchestration, told as a story about an operations center that decides how many of each ride to run.

ride ANOTEBOOKride A: keep 2 runningride B: 1ride C: how many was it...for every ride, someone decides how many to run — by hand, in a notebook

For every ride, someone decides how many to run, by hand.And when one breaks, a person decides on the spot whether to stand up a new one.

dozens of ride types, hundreds of units... I can't keep up alonewith dozens of ride types and hundreds of units, no one person can keep up

With dozens of ride types and hundreds of units, no one person can keep up.One notebook runs out of room fast once things grow.

RULE BOARDride A: always 3brokenjust restarted!give it one rule board, and it restarts a dead one and places it — automaticallyall a person does is change the rule

Give it one rule board, and it restarts a dead one and places it — automatically.All a person does is change the rule.

Just set the "how many" ruleone number is enough
Restarts a dead one automaticallyeven without anyone watching
Places it automatically, toopicks which spot it goes in
A person just turns the dialthe center handles the rest
RULEride A: always keep 3just diednew one takes the open spotwhen one dies, the operations center stands up a new one in the open spot right away

When one dies, the operations center stands up a new one in the open spot right away.It keeps going until the number in the rule is met again.

with only 2 rides, a person is fasterfirst I have to learn the center itself...the operations center is itself a complex system

The operations center is itself a complex system.For a small park it's overkill — with just a few rides, a person is faster.

In one breath

Orchestration = an operations center that, once you set a "keep this many running" rule, restarts a dead one automatically and places it for you, too.

Refers to container orchestration — Kubernetes being the best-known example. You write down only the "desired state" as declarative config, and the orchestrator keeps nudging reality toward that goal. Auto-restart, scheduling, autoscaling, and rolling updates all run on top of this.

When grown-ups say it

Orchestration
The operations center managing rides on its own. Give it a rule, and it handles the rest.
Container
One ride, packaged identically every time. In the castle world, this is called a crate. → crates from the same mold
Declarative config
A rule board like "ride A: 3". You write the desired result, not the steps to get there.
Auto-restart
Standing up a dead ride automatically. Cuts down on how often a person needs to be paged.
Scheduling
Deciding which spot a new ride goes in. The center picks the open spot on its own.
Autoscaling
Adding more units when the line grows. It's just the number on the rule board changing itself.
Rolling update
Swapping rides to a new version one at a time. If it goes wrong, it rolls back to the old version.
Health check
Periodically poking a ride to see if it's still alive. Fail this, and the center decides the ride is broken.
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