raft-boltdb

This repository provides the raftboltdb package. The package exports the BoltStore which is an implementation of both a LogStore and StableStore.

It is meant to be used as a backend for the raft package here.

This implementation uses BoltDB. BoltDB is a simple key/value store implemented in pure Go, and inspired by LMDB.

Metrics Emission and Compatibility

This library can emit metrics using either github.com/armon/go-metrics or github.com/hashicorp/go-metrics. Choosing between the libraries is controlled via build tags.

Build Tags

• armonmetrics - Using this tag will cause metrics to be routed to armon/go-metrics
• hashicorpmetrics - Using this tag will cause all metrics to be routed to hashicorp/go-metrics

If no build tag is specified, the default behavior is to use armon/go-metrics.

Deprecating armon/go-metrics

Emitting metrics to armon/go-metrics is officially deprecated. Usage of armon/go-metrics will remain the default until mid-2025 with opt-in support continuing to the end of 2025.

Migration To migrate an application currently using the older armon/go-metrics to instead use hashicorp/go-metrics the following should be done.

1. Upgrade libraries using armon/go-metrics to consume hashicorp/go-metrics/compat instead. This should involve only changing import statements. All repositories in the hashicorp namespace
2. Update an applications library dependencies to those that have the compatibility layer configured.
3. Update the application to use hashicorp/go-metrics for configuring metrics export instead of armon/go-metrics
   • Replace all application imports of github.com/armon/go-metrics with github.com/hashicorp/go-metrics
   • Instrument your build system to build with the hashicorpmetrics tag.

Eventually once the default behavior changes to use hashicorp/go-metrics by default (mid-2025), you can drop the hashicorpmetrics build tag.

Metrics

The following table details all the metrics emitted by this library. One note is that the application which pulls in this library may add its own prefix to the metric names. For example within Consul, the metrics will be prefixed with consul..

Metric	Unit	Type	Description
raft.boltdb.freelistBytes	bytes	gauge	Represents the number of bytes necessary to encode the freelist metadata. When raft_boltdb.NoFreelistSync is set to false these metadata bytes must also be written to disk for each committed log.
raft.boltdb.freePageBytes	bytes	gauge	Represents the number of bytes of free space within the raft.db file.
raft.boltdb.getLog	ms	timer	Measures the amount of time spent reading logs from the db.
raft.boltdb.logBatchSize	bytes	sample	Measures the total size in bytes of logs being written to the db in a single batch.
raft.boltdb.logsPerBatch	logs	sample	Measures the number of logs being written per batch to the db.
raft.boltdb.logSize	bytes	sample	Measures the size of logs being written to the db.
raft.boltdb.numFreePages	pages	gauge	Represents the number of free pages within the raft.db file.
raft.boltdb.numPendingPages	pages	gauge	Represents the number of pending pages within the raft.db that will soon become free.
raft.boltdb.openReadTxn	transactions	gauge	Represents the number of open read transactions against the db
raft.boltdb.storeLogs	ms	timer	Measures the amount of time spent writing logs to the db.
raft.boltdb.totalReadTxn	transactions	gauge	Represents the total number of started read transactions against the db
raft.boltdb.txstats.cursorCount	cursors	counter	Counts the number of cursors created since Consul was started.
raft.boltdb.txstats.nodeCount	allocations	counter	Counts the number of node allocations within the db since Consul was started.
raft.boltdb.txstats.nodeDeref	dereferences	counter	Counts the number of node dereferences in the db since Consul was started.
raft.boltdb.txstats.pageAlloc	bytes	gauge	Represents the number of bytes allocated within the db since Consul was started. Note that this does not take into account space having been freed and reused. In that case, the value of this metric will still increase.
raft.boltdb.txstats.pageCount	pages	gauge	Represents the number of pages allocated since Consul was started. Note that this does not take into account space having been freed and reused. In that case, the value of this metric will still increase.
raft.boltdb.txstats.rebalance	rebalances	counter	Counts the number of node rebalances performed in the db since Consul was started.
raft.boltdb.txstats.rebalanceTime	ms	timer	Measures the time spent rebalancing nodes in the db.
raft.boltdb.txstats.spill	spills	counter	Counts the number of nodes spilled in the db since Consul was started.
raft.boltdb.txstats.spillTime	ms	timer	Measures the time spent spilling nodes in the db.
raft.boltdb.txstats.split	splits	counter	Counts the number of nodes split in the db since Consul was started.
raft.boltdb.txstats.write	writes	counter	Counts the number of writes to the db since Consul was started.
raft.boltdb.txstats.writeTime	ms	timer	Measures the amount of time spent performing writes to the db.
raft.boltdb.writeCapacity	logs/second	sample	Theoretical write capacity in terms of the number of logs that can be written per second. Each sample outputs what the capacity would be if future batched log write operations were similar to this one. This similarity encompasses 4 things: batch size, byte size, disk performance and boltdb performance. While none of these will be static and its highly likely individual samples of this metric will vary, aggregating this metric over a larger time window should provide a decent picture into how this BoltDB store can perform