Add MySQL topology server implementation#1
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morgo merged 4 commits intorelease-23.0from Mar 12, 2026
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Adds a MySQL-based topology backend (mysqltopo) for Vitess, allowing MySQL to be used as the topology store instead of etcd/zk/consul. This is useful in environments where MySQL is already available and adding etcd/zk would increase operational complexity. New files: - go/vt/topo/mysqltopo/ - Full topo.Factory implementation using MySQL including server, elections, locking, watches, and notifications - Plugin registrations for vtctld, vtgate, vttablet, vtorc, topo2topo, and vtctldclient - Example scripts for local development with MySQL topo Modified files: - go/vt/topo/server.go - Reuse global connection for cells when the factory supports HasGlobalReadOnlyCell (shared DB backends) - go/flags/endtoend/*.txt - Register --topo-mysql-election-ttl and --topo-mysql-lock-ttl flags - .github/workflows/local_example.yml - Add mysql to CI matrix Based on vitess v23.0.3.
Signed-off-by: Morgan Tocker <mtocker@squareup.com>
…count Server.Close() unconditionally called releaseNotificationSystem, but the notification system is only acquired when Watch/WatchRecursive is called. This caused unbalanced refcounts: servers that never watched would decrement without incrementing, and servers that watched multiple times would increment multiple times but only decrement once. Fix by tracking whether each Server has acquired a reference via a hasNotificationSystem flag. getNotificationSystemForServer now only increments the refcount on the first call, and Close() only releases if a reference was actually acquired. Also fix TestMySQLTopo to close the topo.Server, which owns additional mysqltopo.Server instances for globalCell and local cell connections. Signed-off-by: Morgan Tocker <mtocker@squareup.com>
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🤖 These comments are Claude-generated (prompted by @armand-block for observability review).
Focused on logging gaps that would help debug production issues in downstream consumers that rely heavily on Watch, WatchRecursive, and CRUD operations.
Address review feedback from @aparajon focused on production debuggability: - Mark notification system as dead after exhausting retries and warn callers that watches will not receive updates - Add 5s timeout for slow consumers in notifyChange/notifyDeletion to prevent a single blocked watcher from stalling all binlog processing - Add lifecycle logging for watch/recursive watch registration and deregistration - Log server Close() with root/schema context, and warn on db.Close() errors instead of discarding them - Log notification system refcount transitions (increment/decrement/zero) - Log rollback errors in file.go CRUD operations instead of discarding (filtering out expected sql.ErrTxDone) - Log GTID extraction failures instead of silently swallowing them - Log topo change and deletion detection in checkForTopoDataChanges - Add Docker command example to mysql-up.sh error message
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* Add MySQL topology server implementation Adds a MySQL-based topology backend (mysqltopo) for Vitess, allowing MySQL to be used as the topology store instead of etcd/zk/consul. This is useful in environments where MySQL is already available and adding etcd/zk would increase operational complexity. New files: - go/vt/topo/mysqltopo/ - Full topo.Factory implementation using MySQL including server, elections, locking, watches, and notifications - Plugin registrations for vtctld, vtgate, vttablet, vtorc, topo2topo, and vtctldclient - Example scripts for local development with MySQL topo Modified files: - go/vt/topo/server.go - Reuse global connection for cells when the factory supports HasGlobalReadOnlyCell (shared DB backends) - go/flags/endtoend/*.txt - Register --topo-mysql-election-ttl and --topo-mysql-lock-ttl flags - .github/workflows/local_example.yml - Add mysql to CI matrix Based on vitess v23.0.3. * Fix ConnForCell to create cell-specific connections with correct root Signed-off-by: Morgan Tocker <mtocker@squareup.com> * mysqltopo: fix goroutine leak from unbalanced notification system refcount Server.Close() unconditionally called releaseNotificationSystem, but the notification system is only acquired when Watch/WatchRecursive is called. This caused unbalanced refcounts: servers that never watched would decrement without incrementing, and servers that watched multiple times would increment multiple times but only decrement once. Fix by tracking whether each Server has acquired a reference via a hasNotificationSystem flag. getNotificationSystemForServer now only increments the refcount on the first call, and Close() only releases if a reference was actually acquired. Also fix TestMySQLTopo to close the topo.Server, which owns additional mysqltopo.Server instances for globalCell and local cell connections. Signed-off-by: Morgan Tocker <mtocker@squareup.com> * Improve observability for mysqltopo Address review feedback from @aparajon focused on production debuggability: - Mark notification system as dead after exhausting retries and warn callers that watches will not receive updates - Add 5s timeout for slow consumers in notifyChange/notifyDeletion to prevent a single blocked watcher from stalling all binlog processing - Add lifecycle logging for watch/recursive watch registration and deregistration - Log server Close() with root/schema context, and warn on db.Close() errors instead of discarding them - Log notification system refcount transitions (increment/decrement/zero) - Log rollback errors in file.go CRUD operations instead of discarding (filtering out expected sql.ErrTxDone) - Log GTID extraction failures instead of silently swallowing them - Log topo change and deletion detection in checkForTopoDataChanges - Add Docker command example to mysql-up.sh error message --------- Signed-off-by: Morgan Tocker <mtocker@squareup.com>
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What's this?
A MySQL-based topology backend (
mysqltopo) for Vitess, so we can use MySQL (including RDS) as the topology store instead of etcd/zk/consul.This reduces operational complexity in environments where MySQL is already available.
How it works
topo.Factoryinterface backed by a MySQL databaseGET_LOCK()with configurable TTLsHasGlobalReadOnlyCellWhat's changed
New files (19):
go/vt/topo/mysqltopo/— full implementation: server, elections, locking, watches, notifications, testsexamples/common/scripts/mysql-up.sh— local dev setup scriptModified files (10):
go/vt/topo/server.go— reuse global connection for cells when factory supports itgo/cmd/vtctldclient/command/root.go— register mysqltopo importgo/flags/endtoend/*.txt— register--topo-mysql-election-ttland--topo-mysql-lock-ttlflagsBase
This is one commit on top of vitess
v23.0.3. Therelease-23.0branch points at the unmodified tag.Ported from the
mysql-topo-wipbranch — squashed into a single commit for review.