Deployment strategies
Recreate, rolling, blue-green, canary and feature flags: what each costs, what it guarantees, and why two versions living together must be compatible.
- 21 cards
- 5 topics
- Free
The outline, topic by topic
Each topic is weighted the way the exam weighs it.
- Concepts
- Questions
- Sort and link
- The numbers
- Scenarios
A few cards from the deck
Recreate deployment: what is it?
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A strategy that stops every instance of the old version, then starts those of the new one.
The simplest: no coexisting versions and no extra cost, but the service is down while restarting.
During a blue-green switch, the blue group serves v1. What is the right sequence of actions?
- Deploy and check v2 on green, switch, keep blue
- Switch the load balancer to green, then deploy and check v2
- Stop blue, deploy v2 on green, restart traffic
- Deploy v2 on blue and green, then switch
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Deploy and check v2 on green, switch, keep blue
The classic mistake is switching before green is verified: users become the testers. Blue stays intact until green has proven itself, which enables rollback.
In blue-green, … means switching the load balancer back to the old environment, left intact.
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In blue-green, rollback means switching the load balancer back to the old environment, left intact.
Nothing is rebuilt: only the traffic moves, hence the speed, as long as the old environment has not been removed.
Rolling update: what is it?
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A strategy that replaces instances in batches, a few at a time, while the others keep serving.
No downtime and no extra machines, but capacity drops during the operation and both versions answer at the same time.