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Why is this a given? Because of the potential of Raft failovers blocking reads from Consul?
by techman9 10y ago
Why is this a given? Because of the potential of Raft failovers blocking reads from Consul?
- zackelan 10y agoBy default[0] a Raft failover will block DNS reads, since Consul forwards all DNS queries to the master, making it a single-point-of-failure. However, Consul can be configured[1] to serve "eventually consistent" DNS queries, allowing follower nodes to respond with possibly outdated information, during the few seconds of a Raft failover. Where I work, we've also set it up so that BIND acts as a front-end, caching responses from Consul for up to 60 seconds. 0: This apparently changed in 0.7, released last month, to make eventually consistent reads the default. I assume the version of Consul that Stripe is using predates this, as does the version my company runs in production. 1: https://www.consul.io/docs/agent/options.html#dns_config https://www.consul.io/docs/agent/options.html#dns_config