| Title | Planning for change in a formal verification of the Raft consensus protocol |
| Publication Type | Conference Paper |
| Year of Publication | 2016 |
| Authors | Woos D, Wilcox JR, Anton S, Tatlock Z, Ernst MD, Anderson T |
| Conference Name | CPP 2016: 5th ACM SIGPLAN Conference on Certified Programs and Proofs |
| Pagination | 154-165 |
| Date or Month Published | January |
| Conference Location | St. Petersburg, FL, USA |
| Abstract | We present the first formal verification of state machine safety for the Raft consensus protocol, a critical component of many distributed systems. We connected our proof to previous work to establish an end-to-end guarantee that our implementation provides linearizable state machine replication. This proof required iteratively discovering and proving 90 system invariants. Our verified implementation is extracted to OCaml and runs on real networks. \par The primary challenge we faced during the verification process was proof maintenance, since proving one invariant often required strengthening and updating other parts of our proof. To address this challenge, we propose a methodology of planning for change during verification. Our methodology adapts classical information hiding techniques to the context of proof assistants, factors out common invariant-strengthening patterns into custom induction principles, proves higher-order lemmas that show any property proved about a particular component implies analogous properties about related components, and makes proofs robust to change using structural tactics. We also discuss how our methodology may be applied to systems verification more broadly. |
| Downloads | https://verdi.uwplse.org/ Verdi website
https://github.com/uwplse/verdi Verdi implementation
https://github.com/uwplse/verdi/tree/cpp2015 Raft implementation and proofs
https://homes.cs.washington.edu/~mernst/pubs/raft-proof-cpp2016.pdf PDF
https://homes.cs.washington.edu/~mernst/pubs/raft-proof-cpp2016-slides.pdf slides (PDF)
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| Citation Key | WoosWATEA2016 |
