jm + deploy + cd   1

'Continuous Deployment: The Dirty Details'
Good slide deck from Etsy's Mike Brittain regarding their CD setup. Some interesting little-known details:

Slide 41: database schema changes are not CD'd -- they go out on "Schema change Thursdays".

Slide 44: only the webapp is CD'd -- PHP, Apache, memcache components (, support and back-office tools, developer API, gearman async worker queues). The external "services" are not -- databases, Solr/JVM search (rolling restarts), photo storage (filters, proxy cache, S3), payments (PCI-DSS, controlled access).

They avoid schema changes and breaking changes using an approach they call "non-breaking expansions" -- expose new version in a service interface; support multiple versions in the consumer. Example from slides 50-63, based around a database schema migration.

Slide 66: "dev flags" (rollout oriented) are promoted to "feature flags" (long lived degradation control).

Slide 71: some architectural philosophies: deploying is cheap; releasing is cheap; gathering data should be cheap too; treat first iterations as experiments.

Slide 102: "Canary pools". They have multiple pools of users for testing in production -- the staff pool, users who have opted in to see prototypes/beta stuff, 0-100% gradual phased rollout.
cd  deploy  etsy  slides  migrations  database  schema  ops  ci  version-control  feature-flags 
april 2015 by jm

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