jm + feature-flags   3

'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 (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.
cd  deploy  etsy  slides  migrations  database  schema  ops  ci  version-control  feature-flags 
april 2015 by jm
Consul case study from Hootsuite
Hootsuite used Consul for distributed configuration, specifically dark-launch feature flags, with great results:

'Trying out bleeding edge software can be a risky proposition, but in the case of Consul, we’ve found it to be a solid system that works basically as described and was easy to get up and running. We managed to go from initial investigations to production within a month. The value was immediately obvious after looking into the key-value store combined with the events system and it’s DNS features and each of these has worked how we expected. Overall it has been fun to work with and has worked well and based on the initial work we have done with the Dark Launching system we’re feeling confident in Consul’s operation and are looking forward to expanding the scope of it’s use.'
consul  dark-launches  feature-flags  configuration  distributed  hootsuite  notification 
november 2014 by jm
Netflix release new code to production before completing tests
Interesting -- I hadn't heard of this being an official practise anywhere before (although we actually did it ourselves this week)...
If a build has made it [past the 'integration test' phase], it is ready to be deployed to one or more internal environments for user-acceptance testing. Users could be UI developers implementing a new feature using the API, UI Testers performing end-to-end testing or automated UI regression tests. As far as possible, we strive to not have user-acceptance tests be a gating factor for our deployments. We do this by wrapping functionality in Feature Flags so that it is turned off in Production while testing is happening in other environments. 
devops  deployment  feature-flags  release  testing  integration-tests  uat  qa  production  ops  gating  netflix 
october 2014 by jm

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