AppScale Talk at SBonRails
- 1. The AppScale Project Presented by Chris Bunch (on behalf of the AppScale team) March 7, 2011 @ sbonrails meetup Thursday, March 10, 2011
- 2. Thursday, March 10, 2011
- 3. Overview • Google App Engine • AppScale - now with 50% Ruby! • Research Directions • Neptune - A Ruby DSL for the cloud Thursday, March 10, 2011
- 4. Google App Engine • A web framework introduced in 2008 • Python and Java supported • Offers a Platform-as-a-Service: Use Google’s APIs to achieve scale • Upload your app to Google Thursday, March 10, 2011
- 5. Quotas Thursday, March 10, 2011
- 6. Data Model • Not relational - semi-structured schema • Compare to models in Rails • Exposes a get / put / delete / query interface Thursday, March 10, 2011
- 7. Storing Data • Datastore API - Persistent storage • Memcache API - Transient storage • User can set expiration times • Blobstore API - Store large files • need to enable billing to use it Thursday, March 10, 2011
- 8. Be Social! • Mail API - Send and receive e-mail • XMPP API - Send and receive IMs • Channel API - Creating persistent connections via XMPP • Use for chat rooms, games, etc. Thursday, March 10, 2011
- 9. Background Tasks • Cron API - Access a URL periodically • Descriptive language: “every 5 minutes”, “every 1st Sun of Jan, Mar, Dec”, etc. • Uses a separate cron.yaml file • Taskqueue API - Within your app, fire off tasks to be done later Thursday, March 10, 2011
- 10. Dealing with Users • Users API: Uses Google Accounts • Don’t write that ‘forgot password’ page ever again! • Authorization: via app.yaml: • anyone, must login, or admin only Thursday, March 10, 2011
- 11. When Services Fail • Originally: failures throw exceptions • Just catch them all! • Capabilities API: Check if a service is available • Datastore, Memcache, and so on Thursday, March 10, 2011
- 12. Deploying Your App • Develop locally on SDK • Stub implementations of most APIs • Then deploy to Google Thursday, March 10, 2011
- 13. How to Scale • Limitations on the programming model: • No filesystem interaction • 30 second limit per web request • Language libraries must be on whitelist • Sandboxed execution Thursday, March 10, 2011
- 14. Enter AppScale • App Engine is easy to use • but we really want to tinker with the internals! • Need an open platform to experiment on • test API implementations • add new APIs Thursday, March 10, 2011
- 15. Enter AppScale • Lots of NoSQL DBs out there • Hard to compare DBs • Configuration and deployment can be complex • Need one-button deployment Thursday, March 10, 2011
- 16. Storing Data • Datastore API - AppServers use a database agnostic layer - sends requests to PBServer • Named for data format: Protocol Buffers • Memcache API - memcached • Blobstore API - Custom server Thursday, March 10, 2011
- 17. Be Social! • Mail API - sendmail (disabled by default) • XMPP API - ejabberd • Channel API - strophejs Thursday, March 10, 2011
- 18. Background Tasks • Cron API - Uses Vixie Cron • Taskqueue - Separate thread fetches web page • Both make a single attempt • Will replace with distributed, fault- tolerant versions Thursday, March 10, 2011
- 19. Dealing with Users • Users API: Defers users to AppLoadBalancer • Password reset via command-line tools • Authorization: no major changes here Thursday, March 10, 2011
- 20. Deploying Your App • Develop locally on SDK • Stub implementations of most APIs • Then deploy to AppScale! • Use your own cluster or via Amazon • Command-line tools mirror Amazon’s Thursday, March 10, 2011
- 21. Deploying Your App • run-instances: Start AppScale • describe-instances:View cloud metadata • upload-app: Deploy an App Engine app • remove-app: Un-deploy an App Engine app • terminate-instances: Stop AppScale Thursday, March 10, 2011
- 22. Deployment Models • Cloud deployment: Amazon EC2 or Eucalyptus (the open source implementation of the EC2 APIs) • Just specify how many machines you need • Non-cloud deployment via Xen or KVM Thursday, March 10, 2011
- 23. Thursday, March 10, 2011
- 24. AppController • The brains of the outfit • Runs on every node • Handles configuration and deployment of all services (including other AppControllers) • Written in Ruby Thursday, March 10, 2011
- 25. Load balancer • Routes users to their app via nginx • haproxy makes sure app servers are live • Can’t assume the user has DNS: • Thus we wrote the AppLoadBalancer • Rails app that routes users to apps • Performs authentication as well Thursday, March 10, 2011
- 26. AppLoadBalancer Thursday, March 10, 2011
- 27. App Server • We modified the App Engine SDK • Easier for Python (source included) • Harder for Java (had to decompile) • Removed non-scalable API implementations • Goal: Use open source whenever possible Thursday, March 10, 2011
- 28. A Common Feature Request Thursday, March 10, 2011
- 29. Database Options • Open source / open APIs / proprietary • Master / slave v. peer-to-peer • Differences in query languages • Data model (key/val, semi-structured) • In-memory or persistent • Data consistency model • Interfaces - REST / Thrift / libraries Thursday, March 10, 2011
- 30. In AppScale: • BigTable clones: • Master / slave relationship • Master stores metadata • Slaves store data • Fault-tolerant to slave failure • Partially tolerant to master failure Thursday, March 10, 2011
- 31. In AppScale: • Variably consistent DBs • Voldemort and • Both are peer-to-peer: no SPOF • Voldemort: Specify consistency per table • Cassandra: Specify consistency per request Thursday, March 10, 2011
- 32. In AppScale: • Relational: • Not NoSQL but used like NoSQL • Document-oriented: • Targets append-heavy workloads Thursday, March 10, 2011
- 33. In AppScale: • Key-value datastores: • MemcacheDB: like memcached but persistent and replicated • Scalaris: in-memory, no persistence • SimpleDB: semi-structured but used as key-value (will update this in the future) Thursday, March 10, 2011
- 34. Research Ideas • Placement support • Monitoring • Shared memory • Cost modeling • Hybrid cloud • Active Cloud DB • Disaster Recovery • Neptune Thursday, March 10, 2011
- 35. Placement Support Thursday, March 10, 2011
- 36. Monitr Thursday, March 10, 2011
- 37. Shared memory • Since AppServer + DB are co-located, reduce message overhead • no serialization • Leverage CoLoRs to do so across languages • AS is in Python or Java, DBS is Python • Can be orders-of-magnitude faster Thursday, March 10, 2011
- 38. Cost modeling • Can we reproduce Google’s cost model? • We can reproduce memory, network bandwidth in / out, size and types of data • Can’t reproduce CPU - it’s based on Google’s load, which we can’t capture • varies based on placement and time of day Thursday, March 10, 2011
- 39. Hybrid Cloud Thursday, March 10, 2011
- 40. Database Agnostic Transactions • Want to support disparate DBs with ACID • Leverage ZooKeeper for versioning • And PBServer as the DB agnostic layer • Needs strong consistency from DB itself • And row-level atomicity on updates Thursday, March 10, 2011
- 41. Active Cloud DB • Need a common interface to DBs • But not just for Java / Python • Named after Rails’ ActiveRecord • Exposes REST interface for DB • Included in AppScale 1.3 Thursday, March 10, 2011
- 42. Disaster Recovery • People are using App Engine as a production level environment • Need a way to automatically back up data • Can leverage this data for data analytics • Need to also seamlessly switch to AppScale version if App Engine version goes down Thursday, March 10, 2011
- 43. Neptune • Need a simple way to run compute-intensive jobs • We have the code from the ‘net • We have the resources - the cloud • But the average user does not have the know how • Our solution: create a domain specific language for configuring cloud apps • Based on Ruby Thursday, March 10, 2011
- 44. Syntax • It’s as easy as: neptune :type => “mpi”, :code => “MpiNQueens”, :nodes_to_use => 8, :output => “/mpi/output-1.txt” Thursday, March 10, 2011
- 45. Neptune Supports: • Message Passing Interface (MPI) • MapReduce • Unified Parallel C (UPC) • X10 • Erlang Thursday, March 10, 2011
- 46. Extensibility • Experts can add support for other computational jobs • Biochemists can run simulations via DFSP and dwSSA • Embarassingly parallel Monte Carlo simulations Thursday, March 10, 2011
- 47. Compiling Code • You may not have the binaries, so compile from source! • Auto-generates makefiles for beginners neptune :type => “compile”, :code => “/home/appscale/mpi_nqueens” Thursday, March 10, 2011
- 48. Installing Neptune • Just use good old ‘gem’: • gem install neptune • Current version is 0.0.4, fully compatible with AppScale 1.5 • More info at our web page: • http://neptune-lang.org Thursday, March 10, 2011
- 49. Wrapping It Up • Thanks to the AppScale team, especially: • Co-lead Navraj Chohan and advisor Professor Chandra Krintz • Check us out on the web: • http://appscale.cs.ucsb.edu • http://code.google.com/p/appscale Thursday, March 10, 2011