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 (Etsy.com, 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.
Good info on how Etsy use their Deployinator tool, end-to-end. Slide 11: git SHA is visible for each env, allowing easy verification of what code is deployed. Slide 14: Code is deployed to “princess” staging env while CI tests are running; no need to wait for unit/CI tests to complete. Slide 23: smoke tests of pre-prod “princess” (complete after 8 mins elapsed). Slide 31: dashboard link for deployed code is posted during deploy; post-release prod smoke tests are run by Jenkins. (short ones! they complete in 42 seconds)
I’ve been speaking to a few people [at Makerbot] who prefer to remain anonymous and most of my contacts there are gone (the head of PR was apparently fired) and don’t want to talk. But the new from inside is troubling. The mass-layoffs are blamed on low revenue and one former employee wrote “Company was failing. Couldn’t pay vendors, had to downsize.” Do I think Makerbot will sink? At this point I don’t know.
‘CredStash is a very simple, easy to use credential management and distribution system that uses AWS Key Management System (KMS) for key wrapping and master-key storage, and DynamoDB for credential storage and sharing.’
Links for 2015-04-22
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