CometBFT 可以通过位于 $CMTHOME/config/config.toml 的 TOML 文件进行配置。其中一些参数可以通过命令行标志覆盖。对大多数用户来说,##### main base configuration options ##### 这一节中的选项才是通常需要修改的,而下面更靠后的配置项则面向高级用户。

选项

cometbft init 创建的默认配置文件会把所有参数都设置为默认值。它大致会像下面这样;不过,仍请以你当前安装的 cometbft 版本生成的 config.toml 为准:
# This is a TOML config file.
# For more information, see https://github.com/toml-lang/toml

# NOTE: Any path below can be absolute (e.g. "/var/myawesomeapp/data") or
# relative to the home directory (e.g. "data"). The home directory is
# "$HOME/.cometbft" by default, but could be changed via $CMTHOME env variable
# or --home cmd flag.

# The version of the CometBFT binary that created or
# last modified the config file. Do not modify this.
version = "0.38.0"

#######################################################################
###                   Main Base Config Options                      ###
#######################################################################

# TCP or UNIX socket address of the ABCI application,
# or the name of an ABCI application compiled in with the CometBFT binary
proxy_app = "tcp://127.0.0.1:26658"

# A custom human readable name for this node
moniker = "anonymous"

# Database backend: goleveldb | cleveldb | boltdb | rocksdb | badgerdb
# * goleveldb (github.com/syndtr/goleveldb)
#   - UNMAINTAINED
#   - stable
#   - pure go
#   - stable
# * cleveldb (uses levigo wrapper)
#   - fast
#   - requires gcc
#   - use cleveldb build tag (go build -tags cleveldb)
# * boltdb (uses etcd's fork of bolt - github.com/etcd-io/bbolt)
#   - EXPERIMENTAL
#   - may be faster in some use-cases (random reads - indexer)
#   - use boltdb build tag (go build -tags boltdb)
# * rocksdb (uses github.com/tecbot/gorocksdb)
#   - EXPERIMENTAL
#   - requires gcc
#   - use rocksdb build tag (go build -tags rocksdb)
# * badgerdb (uses github.com/dgraph-io/badger)
#   - EXPERIMENTAL
#   - use badgerdb build tag (go build -tags badgerdb)
db_backend = "goleveldb"

# Database directory
db_dir = "data"

# Output level for logging, including package level options
log_level = "info"

# Output format: 'plain' (colored text) or 'json'
log_format = "plain"

##### additional base config options #####

# Path to the JSON file containing the initial validator set and other meta data
genesis_file = "config/genesis.json"

# Path to the JSON file containing the private key to use as a validator in the consensus protocol
priv_validator_key_file = "config/priv_validator_key.json"

# Path to the JSON file containing the last sign state of a validator
priv_validator_state_file = "data/priv_validator_state.json"

# TCP or UNIX socket address for CometBFT to listen on for
# connections from an external PrivValidator process
priv_validator_laddr = ""

# Path to the JSON file containing the private key to use for node authentication in the p2p protocol
node_key_file = "config/node_key.json"

# Mechanism to connect to the ABCI application: socket | grpc
abci = "socket"

# If true, query the ABCI app on connecting to a new peer
# so the app can decide if we should keep the connection or not
filter_peers = false


#######################################################################
###                 Advanced Configuration Options                  ###
#######################################################################

#######################################################
###       RPC Server Configuration Options          ###
#######################################################
[rpc]

# TCP or UNIX socket address for the RPC server to listen on
laddr = "tcp://127.0.0.1:26657"

# A list of origins a cross-domain request can be executed from
# Default value '[]' disables cors support
# Use '["*"]' to allow any origin
cors_allowed_origins = []

# A list of methods the client is allowed to use with cross-domain requests
cors_allowed_methods = ["HEAD", "GET", "POST", ]

# A list of non simple headers the client is allowed to use with cross-domain requests
cors_allowed_headers = ["Origin", "Accept", "Content-Type", "X-Requested-With", "X-Server-Time", ]

# TCP or UNIX socket address for the gRPC server to listen on
# NOTE: This server only supports /broadcast_tx_commit
grpc_laddr = ""

# Maximum number of simultaneous connections.
# Does not include RPC (HTTP&WebSocket) connections. See max_open_connections
# If you want to accept a larger number than the default, make sure
# you increase your OS limits.
# 0 - unlimited.
# Should be < {ulimit -Sn} - {MaxNumInboundPeers} - {MaxNumOutboundPeers} - {N of wal, db and other open files}
# 1024 - 40 - 10 - 50 = 924 = ~900
grpc_max_open_connections = 900

# Activate unsafe RPC commands like /dial_seeds and /unsafe_flush_mempool
unsafe = false

# Maximum number of simultaneous connections (including WebSocket).
# Does not include gRPC connections. See grpc_max_open_connections
# If you want to accept a larger number than the default, make sure
# you increase your OS limits.
# 0 - unlimited.
# Should be < {ulimit -Sn} - {MaxNumInboundPeers} - {MaxNumOutboundPeers} - {N of wal, db and other open files}
# 1024 - 40 - 10 - 50 = 924 = ~900
max_open_connections = 900

# Maximum number of unique clientIDs that can /subscribe
# If you're using /broadcast_tx_commit, set to the estimated maximum number
# of broadcast_tx_commit calls per block.
max_subscription_clients = 100

# Maximum number of unique queries a given client can /subscribe to
# If you're using GRPC (or Local RPC client) and /broadcast_tx_commit, set to
# the estimated maximum number of broadcast_tx_commit calls per block.
max_subscriptions_per_client = 5

# Experimental parameter to specify the maximum number of events a node will
# buffer, per subscription, before returning an error and closing the
# subscription. Must be set to at least 100, but higher values will accommodate
# higher event throughput rates (and will use more memory).
experimental_subscription_buffer_size = 200

# Experimental parameter to specify the maximum number of RPC responses that
# can be buffered per WebSocket client. If clients cannot read from the
# WebSocket endpoint fast enough, they will be disconnected, so increasing this
# parameter may reduce the chances of them being disconnected (but will cause
# the node to use more memory).
#
# Must be at least the same as "experimental_subscription_buffer_size",
# otherwise connections could be dropped unnecessarily. This value should
# ideally be somewhat higher than "experimental_subscription_buffer_size" to
# accommodate non-subscription-related RPC responses.
experimental_websocket_write_buffer_size = 200

# If a WebSocket client cannot read fast enough, at present we may
# silently drop events instead of generating an error or disconnecting the
# client.
#
# Enabling this experimental parameter will cause the WebSocket connection to
# be closed instead if it cannot read fast enough, allowing for greater
# predictability in subscription behavior.
experimental_close_on_slow_client = false

# How long to wait for a tx to be committed during /broadcast_tx_commit.
# WARNING: Using a value larger than 10s will result in increasing the
# global HTTP write timeout, which applies to all connections and endpoints.
# See https://github.com/tendermint/tendermint/issues/3435
timeout_broadcast_tx_commit = "10s"

# Maximum number of requests that can be sent in a JSON-RPC batch request.
# Possible values: number greater than 0.
# If the number of requests sent in a JSON-RPC batch exceed the maximum batch
# size configured, an error will be returned.
# The default value is set to `10`, which will limit the number of requests
# to 10 requests per JSON-RPC batch request.
# If you don't want to enforce a maximum number of requests for a batch
# request, set this value to `0`.
max_request_batch_size = 10

# Maximum size of request body, in bytes
max_body_bytes = 1000000

# Maximum size of request header, in bytes
max_header_bytes = 1048576

# The path to a file containing certificate that is used to create the HTTPS server.
# Might be either absolute path or path related to CometBFT's config directory.
# If the certificate is signed by a certificate authority,
# the certFile should be the concatenation of the server's certificate, any intermediates,
# and the CA's certificate.
# NOTE: both tls_cert_file and tls_key_file must be present for CometBFT to create HTTPS server.
# Otherwise, HTTP server is run.
tls_cert_file = ""

# The path to a file containing matching private key that is used to create the HTTPS server.
# Might be either absolute path or path related to CometBFT's config directory.
# NOTE: both tls_cert_file and tls_key_file must be present for CometBFT to create HTTPS server.
# Otherwise, HTTP server is run.
tls_key_file = ""

# pprof listen address (https://golang.org/pkg/net/http/pprof)
pprof_laddr = ""

#######################################################
###           P2P Configuration Options             ###
#######################################################
[p2p]

# Address to listen for incoming connections
laddr = "tcp://0.0.0.0:26656"

# Address to advertise to peers for them to dial. If empty, will use the same
# port as the laddr, and will introspect on the listener to figure out the
# address. IP and port are required. Example: 159.89.10.97:26656
external_address = ""

# Comma separated list of seed nodes to connect to
seeds = ""

# Comma separated list of nodes to keep persistent connections to
persistent_peers = ""

# Path to address book
addr_book_file = "config/addrbook.json"

# Set true for strict address routability rules
# Set false for private or local networks
addr_book_strict = true

# Maximum number of inbound peers
max_num_inbound_peers = 40

# Maximum number of outbound peers to connect to, excluding persistent peers
max_num_outbound_peers = 10

# List of node IDs, to which a connection will be (re)established ignoring any existing limits
unconditional_peer_ids = ""

# Maximum pause when redialing a persistent peer (if zero, exponential backoff is used)
persistent_peers_max_dial_period = "0s"

# Time to wait before flushing messages out on the connection
flush_throttle_timeout = "100ms"

# Maximum size of a message packet payload, in bytes
max_packet_msg_payload_size = 1024

# Rate at which packets can be sent, in bytes/second
send_rate = 5120000

# Rate at which packets can be received, in bytes/second
recv_rate = 5120000

# Set true to enable the peer-exchange reactor
pex = true

# Seed mode, in which node constantly crawls the network and looks for
# peers. If another node asks it for addresses, it responds and disconnects.
#
# Does not work if the peer-exchange reactor is disabled.
seed_mode = false

# Comma separated list of peer IDs to keep private (will not be gossiped to other peers)
private_peer_ids = ""

# Toggle to disable guard against peers connecting from the same ip.
allow_duplicate_ip = false

# Peer connection configuration.
handshake_timeout = "20s"
dial_timeout = "3s"

#######################################################
###          Mempool Configuration Option          ###
#######################################################
[mempool]

# The type of mempool for this node to use.
#
#  Possible types:
#  - "flood" : concurrent linked list mempool with flooding gossip protocol
#  (default)
#  - "nop"   : nop-mempool (short for no operation; the ABCI app is responsible
#  for storing, disseminating and proposing txs). "create_empty_blocks=false" is
#  not supported.
type = "flood"

# Recheck (default: true) defines whether CometBFT should recheck the
# validity for all remaining transaction in the mempool after a block.
# Since a block affects the application state, some transactions in the
# mempool may become invalid. If this does not apply to your application,
# you can disable rechecking.
recheck = true

# Broadcast (default: true) defines whether the mempool should relay
# transactions to other peers. Setting this to false will stop the mempool
# from relaying transactions to other peers until they are included in a
# block. In other words, if Broadcast is disabled, only the peer you send
# the tx to will see it until it is included in a block.
broadcast = true

# WalPath (default: "") configures the location of the Write Ahead Log
# (WAL) for the mempool. The WAL is disabled by default. To enable, set
# wal_dir to where you want the WAL to be written (e.g.
# "data/mempool.wal").
wal_dir = ""

# Maximum number of transactions in the mempool
size = 5000

# Limit the total size of all txs in the mempool.
# This only accounts for raw transactions (e.g. given 1MB transactions and
# max_txs_bytes=5MB, mempool will only accept 5 transactions).
max_txs_bytes = 1073741824

# Size of the cache (used to filter transactions we saw earlier) in transactions
cache_size = 10000

# Do not remove invalid transactions from the cache (default: false)
# Set to true if it's not possible for any invalid transaction to become valid
# again in the future.
keep-invalid-txs-in-cache = false

# Maximum size of a single transaction.
# NOTE: the max size of a tx transmitted over the network is {max_tx_bytes}.
max_tx_bytes = 1048576

# Maximum size of a batch of transactions to send to a peer
# Including space needed by encoding (one varint per transaction).
# XXX: Unused due to https://github.com/tendermint/tendermint/issues/5796
max_batch_bytes = 0

#######################################################
###         State Sync Configuration Options        ###
#######################################################
[statesync]
# State sync rapidly bootstraps a new node by discovering, fetching, and restoring a state machine
# snapshot from peers instead of fetching and replaying historical blocks. Requires some peers in
# the network to take and serve state machine snapshots. State sync is not attempted if the node
# has any local state (LastBlockHeight > 0). The node will have a truncated block history,
# starting from the height of the snapshot.
enable = false

# RPC servers (comma-separated) for light client verification of the synced state machine and
# retrieval of state data for node bootstrapping. Also needs a trusted height and corresponding
# header hash obtained from a trusted source, and a period during which validators can be trusted.
#
# For Cosmos SDK-based chains, trust_period should usually be about 2/3 of the unbonding time (~2
# weeks) during which they can be financially punished (slashed) for misbehavior.
rpc_servers = ""
trust_height = 0
trust_hash = ""
trust_period = "168h0m0s"

# Time to spend discovering snapshots before initiating a restore.
discovery_time = "15s"

# Temporary directory for state sync snapshot chunks, defaults to the OS tempdir (typically /tmp).
# Will create a new, randomly named directory within, and remove it when done.
temp_dir = ""

# The timeout duration before re-requesting a chunk, possibly from a different
# peer (default: 1 minute).
chunk_request_timeout = "10s"

# The number of concurrent chunk fetchers to run (default: 1).
chunk_fetchers = "4"

#######################################################
###       Block Sync Configuration Options          ###
#######################################################
[blocksync]

# Block Sync version to use:
#
# In v0.37, v1 and v2 of the block sync protocols were deprecated.
# Please use v0 instead.
#
#   1) "v0" - the default block sync implementation
version = "v0"

#######################################################
###         Consensus Configuration Options         ###
#######################################################
[consensus]

wal_file = "data/cs.wal/wal"

# How long we wait for a proposal block before prevoting nil
timeout_propose = "3s"
# How much timeout_propose increases with each round
timeout_propose_delta = "500ms"
# How long we wait after receiving +2/3 prevotes for "anything" (ie. not a single block or nil)
timeout_prevote = "1s"
# How much the timeout_prevote increases with each round
timeout_prevote_delta = "500ms"
# How long we wait after receiving +2/3 precommits for "anything" (ie. not a single block or nil)
timeout_precommit = "1s"
# How much the timeout_precommit increases with each round
timeout_precommit_delta = "500ms"
# How long we wait after committing a block, before starting on the new
# height (this gives us a chance to receive some more precommits, even
# though we already have +2/3).
timeout_commit = "1s"

# How many blocks to look back to check existence of the node's consensus votes before joining consensus
# When non-zero, the node will panic upon restart
# if the same consensus key was used to sign {double_sign_check_height} last blocks.
# So, validators should stop the state machine, wait for some blocks, and then restart the state machine to avoid panic.
double_sign_check_height = 0

# Make progress as soon as we have all the precommits (as if TimeoutCommit = 0)
skip_timeout_commit = false

# EmptyBlocks mode and possible interval between empty blocks
create_empty_blocks = true
create_empty_blocks_interval = "0s"

# Reactor sleep duration parameters
peer_gossip_sleep_duration = "100ms"
peer_query_maj23_sleep_duration = "2s"

#######################################################
###         Storage Configuration Options           ###
#######################################################
[storage]

# Set to true to discard ABCI responses from the state store, which can save a
# considerable amount of disk space. Set to false to ensure ABCI responses are
# persisted. ABCI responses are required for /block_results RPC queries, and to
# reindex events in the command-line tool.
discard_abci_responses = false

#######################################################
###   Transaction Indexer Configuration Options     ###
#######################################################
[tx_index]

# What indexer to use for transactions
#
# The application will set which txs to index. In some cases a node operator will be able
# to decide which txs to index based on configuration set in the application.
#
# Options:
#   1) "null"
#   2) "kv" (default) - the simplest possible indexer, backed by key-value storage (defaults to levelDB; see DBBackend).
# 		- When "kv" is chosen "tx.height" and "tx.hash" will always be indexed.
#   3) "psql" - the indexer services backed by PostgreSQL.
# When "kv" or "psql" is chosen "tx.height" and "tx.hash" will always be indexed.
indexer = "kv"

# The PostgreSQL connection configuration, the connection format:
#   postgresql://<user>:<password>@<host>:<port>/<db>?<opts>
psql-conn = ""

#######################################################
###       Instrumentation Configuration Options     ###
#######################################################
[instrumentation]

# When true, Prometheus metrics are served under /metrics on
# PrometheusListenAddr.
# Check out the documentation for the list of available metrics.
prometheus = false

# Address to listen for Prometheus collector(s) connections
prometheus_listen_addr = ":26660"

# Maximum number of simultaneous connections.
# If you want to accept a larger number than the default, make sure
# you increase your OS limits.
# 0 - unlimited.
max_open_connections = 3

# Instrumentation namespace
namespace = "cometbft"

空块与非空块

create_empty_blocks = true

如果在配置中将 create_empty_blocks 设为 true,则大约每秒会创建一个区块(使用默认共识参数时)。你可以通过修改 timeout_commit 来调节区块之间的延迟。例如,timeout_commit = "10s" 应该会生成大约 10 秒一个区块。

create_empty_blocks = false

在这种设置下,区块会在收到交易时创建。 请注意,在区块 H 之后,CometBFT 会创建一个我们称之为“证明区块”的东西 H+1(仅当应用哈希发生变化时)。这样做是为了支持证明。如果你在区块 H 中有一笔交易将状态改为 X,那么新的应用哈希只会包含在区块 H+1 中。也就是说,如果在交易提交后,你想为新状态(X)获取轻客户端证明,就需要先提交新区块,因为新区块包含了状态 X 的新应用哈希。这就是为什么当应用哈希发生变化时,我们会创建一个新的(空)区块。否则,你将无法为新状态生成证明。 另外,如果你将 create_empty_blocks_interval 设为非默认值(0)以外的其他值,那么即使没有交易,CometBFT 也会每隔 create_empty_blocks_interval 创建空区块。例如,当 create_empty_blocks = false 且 create_empty_blocks_interval = "30s" 时,CometBFT 只会在有交易时创建区块,或者在连续 30 秒没有收到任何交易后创建区块。

共识超时说明

关于超时有很多信息可以在 生产环境运行 中找到。你也可以在描述 Tendermint 共识算法、并被 CometBFT 采用的论文中找到更详细的解释:The latest gossip on BFT consensus。
[consensus]
...

timeout_propose = "3s"
timeout_propose_delta = "500ms"
timeout_prevote = "1s"
timeout_prevote_delta = "500ms"
timeout_precommit = "1s"
timeout_precommit_delta = "500ms"
timeout_commit = "1s"
请注意,在成功轮次中,无论如何我们都会等待的唯一超时是 timeout_commit。 下面简要总结这些超时:
  • timeout_propose = 验证人等待提议区块并在超时后对 nil 进行预投票的时长
  • timeout_propose_delta = 每一轮中 timeout_propose 增加的幅度
  • timeout_prevote = 验证人在收到 +2/3 预投票后,等待“任何内容”(即既不是单个区块也不是 nil)的时长
  • timeout_prevote_delta = 每一轮中 timeout_prevote 增加的幅度
  • timeout_precommit = 验证人在收到 +2/3 预提交后,等待“任何内容”(即既不是单个区块也不是 nil)的时长
  • timeout_precommit_delta = 每一轮中 timeout_precommit 增加的幅度
  • timeout_commit = 验证人在提交区块后、开始处理新区块高度之前等待的时长(这让我们即使已经拥有 +2/3,也还有机会收到更多预提交)

在网络中使用不一致的 timeout_propose 的负面影响

这里有个有趣的问题:如果某个特定验证人把 timeout_propose 设得比网络其他节点小很多,会发生什么? 假设你的网络里只有两个验证人:Alice 和 Bob。Bob 把 timeout_propose 设为 0s。Alice 使用默认值 3s。假设他们的投票权相同。由于提议者选择算法是加权轮转,你可能会期望 Alice 和 Bob 轮流提议区块,结果像这样:
#1 block - Alice
#2 block - Bob
#3 block - Alice
#4 block - Bob
...
但现实中的情况要稍微不同一些:
#1 block - Bob
#2 block - Bob
#3 block - Bob
#4 block - Bob
这是因为 Bob 不会等待 Alice 的提议(会对 nil 进行预投票)。这让 Alice 没有机会提交区块。请注意,Bob 创建的每个区块都需要 Alice 的投票才能构成 2/3+。Bob 总能拿到这一票,因为 Alice 的 timeout_propose 设为 3s;而 Alice 从来拿不到,因为 Bob 的设为 0s。 再想象一下,网络里有十个地理上分散的验证人。其中一个(Bob)把 timeout_propose 设为 0s,其他人设为 3s。此时,Bob 也无法按自己的速度推进,因为他仍然需要其他验证人中 2/3 的投票,而这些投票需要时间传播。换句话说,网络的推进速度取决于聚集 2/3+ 票数(预投票和预提交)所需的时间,而不是最快提议者的速度。
区块生产不是由投票权决定的吗?
如果仅由投票权决定,就无法保证活性。之所以存在超时,是因为网络不能依赖某个单一提议者始终可用;如果该提议者没有响应,网络就必须继续推进。
我们该如何应对某人任意调整出块时间以获取优势的情况?
在充分去中心化的去中心化网络中,上面展示的影响可以忽略不计。

在网络中使用不一致的 timeout_commit 的负面影响

我们来看一个和前面相同的场景。网络里有十个地理上分散的验证人。其中一个(Bob)把 timeout_commit 设为 0s。其他人使用 1s(默认值)。这时,Bob 会成为最快的出块者,因为他在创建区块后不会等待额外的预提交。如果等待预提交(timeout_commit)没有激励,Bob 相比其他 9 个验证人将获得更多奖励。 这是因为 Bob 能够更早广播自己的提议(比其他人早 1 秒)。但这也意味着,由于他更早开始 timeout_propose,Bob 可能会错过其他验证人的提议,并因为进入 nil 预投票。换句话说,如果 Bob 的 timeout_commit 相比其他验证人过低,那么他可能会错过一些提议,并因不活跃而被罚没。
CometBFT can be configured via a TOML file in $CMTHOME/config/config.toml. Some of these parameters can be overridden by command-line flags. For most users, the options in the ##### main base configuration options ##### section are intended to be modified, while config options further below are intended for advanced power users.

Options

The default configuration file created by cometbft init has all the parameters set with their default values. It will look something like the file below; however, double-check by inspecting the config.toml created with your version of cometbft installed:
# This is a TOML config file.
# For more information, see https://github.com/toml-lang/toml

# NOTE: Any path below can be absolute (e.g. "/var/myawesomeapp/data") or
# relative to the home directory (e.g. "data"). The home directory is
# "$HOME/.cometbft" by default, but could be changed via $CMTHOME env variable
# or --home cmd flag.

# The version of the CometBFT binary that created or
# last modified the config file. Do not modify this.
version = "0.38.0"

#######################################################################
###                   Main Base Config Options                      ###
#######################################################################

# TCP or UNIX socket address of the ABCI application,
# or the name of an ABCI application compiled in with the CometBFT binary
proxy_app = "tcp://127.0.0.1:26658"

# A custom human readable name for this node
moniker = "anonymous"

# Database backend: goleveldb | cleveldb | boltdb | rocksdb | badgerdb
# * goleveldb (github.com/syndtr/goleveldb)
#   - UNMAINTAINED
#   - stable
#   - pure go
#   - stable
# * cleveldb (uses levigo wrapper)
#   - fast
#   - requires gcc
#   - use cleveldb build tag (go build -tags cleveldb)
# * boltdb (uses etcd's fork of bolt - github.com/etcd-io/bbolt)
#   - EXPERIMENTAL
#   - may be faster in some use-cases (random reads - indexer)
#   - use boltdb build tag (go build -tags boltdb)
# * rocksdb (uses github.com/tecbot/gorocksdb)
#   - EXPERIMENTAL
#   - requires gcc
#   - use rocksdb build tag (go build -tags rocksdb)
# * badgerdb (uses github.com/dgraph-io/badger)
#   - EXPERIMENTAL
#   - use badgerdb build tag (go build -tags badgerdb)
db_backend = "goleveldb"

# Database directory
db_dir = "data"

# Output level for logging, including package level options
log_level = "info"

# Output format: 'plain' (colored text) or 'json'
log_format = "plain"

##### additional base config options #####

# Path to the JSON file containing the initial validator set and other meta data
genesis_file = "config/genesis.json"

# Path to the JSON file containing the private key to use as a validator in the consensus protocol
priv_validator_key_file = "config/priv_validator_key.json"

# Path to the JSON file containing the last sign state of a validator
priv_validator_state_file = "data/priv_validator_state.json"

# TCP or UNIX socket address for CometBFT to listen on for
# connections from an external PrivValidator process
priv_validator_laddr = ""

# Path to the JSON file containing the private key to use for node authentication in the p2p protocol
node_key_file = "config/node_key.json"

# Mechanism to connect to the ABCI application: socket | grpc
abci = "socket"

# If true, query the ABCI app on connecting to a new peer
# so the app can decide if we should keep the connection or not
filter_peers = false


#######################################################################
###                 Advanced Configuration Options                  ###
#######################################################################

#######################################################
###       RPC Server Configuration Options          ###
#######################################################
[rpc]

# TCP or UNIX socket address for the RPC server to listen on
laddr = "tcp://127.0.0.1:26657"

# A list of origins a cross-domain request can be executed from
# Default value '[]' disables cors support
# Use '["*"]' to allow any origin
cors_allowed_origins = []

# A list of methods the client is allowed to use with cross-domain requests
cors_allowed_methods = ["HEAD", "GET", "POST", ]

# A list of non simple headers the client is allowed to use with cross-domain requests
cors_allowed_headers = ["Origin", "Accept", "Content-Type", "X-Requested-With", "X-Server-Time", ]

# TCP or UNIX socket address for the gRPC server to listen on
# NOTE: This server only supports /broadcast_tx_commit
grpc_laddr = ""

# Maximum number of simultaneous connections.
# Does not include RPC (HTTP&WebSocket) connections. See max_open_connections
# If you want to accept a larger number than the default, make sure
# you increase your OS limits.
# 0 - unlimited.
# Should be < {ulimit -Sn} - {MaxNumInboundPeers} - {MaxNumOutboundPeers} - {N of wal, db and other open files}
# 1024 - 40 - 10 - 50 = 924 = ~900
grpc_max_open_connections = 900

# Activate unsafe RPC commands like /dial_seeds and /unsafe_flush_mempool
unsafe = false

# Maximum number of simultaneous connections (including WebSocket).
# Does not include gRPC connections. See grpc_max_open_connections
# If you want to accept a larger number than the default, make sure
# you increase your OS limits.
# 0 - unlimited.
# Should be < {ulimit -Sn} - {MaxNumInboundPeers} - {MaxNumOutboundPeers} - {N of wal, db and other open files}
# 1024 - 40 - 10 - 50 = 924 = ~900
max_open_connections = 900

# Maximum number of unique clientIDs that can /subscribe
# If you're using /broadcast_tx_commit, set to the estimated maximum number
# of broadcast_tx_commit calls per block.
max_subscription_clients = 100

# Maximum number of unique queries a given client can /subscribe to
# If you're using GRPC (or Local RPC client) and /broadcast_tx_commit, set to
# the estimated maximum number of broadcast_tx_commit calls per block.
max_subscriptions_per_client = 5

# Experimental parameter to specify the maximum number of events a node will
# buffer, per subscription, before returning an error and closing the
# subscription. Must be set to at least 100, but higher values will accommodate
# higher event throughput rates (and will use more memory).
experimental_subscription_buffer_size = 200

# Experimental parameter to specify the maximum number of RPC responses that
# can be buffered per WebSocket client. If clients cannot read from the
# WebSocket endpoint fast enough, they will be disconnected, so increasing this
# parameter may reduce the chances of them being disconnected (but will cause
# the node to use more memory).
#
# Must be at least the same as "experimental_subscription_buffer_size",
# otherwise connections could be dropped unnecessarily. This value should
# ideally be somewhat higher than "experimental_subscription_buffer_size" to
# accommodate non-subscription-related RPC responses.
experimental_websocket_write_buffer_size = 200

# If a WebSocket client cannot read fast enough, at present we may
# silently drop events instead of generating an error or disconnecting the
# client.
#
# Enabling this experimental parameter will cause the WebSocket connection to
# be closed instead if it cannot read fast enough, allowing for greater
# predictability in subscription behavior.
experimental_close_on_slow_client = false

# How long to wait for a tx to be committed during /broadcast_tx_commit.
# WARNING: Using a value larger than 10s will result in increasing the
# global HTTP write timeout, which applies to all connections and endpoints.
# See https://github.com/tendermint/tendermint/issues/3435
timeout_broadcast_tx_commit = "10s"

# Maximum number of requests that can be sent in a JSON-RPC batch request.
# Possible values: number greater than 0.
# If the number of requests sent in a JSON-RPC batch exceed the maximum batch
# size configured, an error will be returned.
# The default value is set to `10`, which will limit the number of requests
# to 10 requests per JSON-RPC batch request.
# If you don't want to enforce a maximum number of requests for a batch
# request, set this value to `0`.
max_request_batch_size = 10

# Maximum size of request body, in bytes
max_body_bytes = 1000000

# Maximum size of request header, in bytes
max_header_bytes = 1048576

# The path to a file containing certificate that is used to create the HTTPS server.
# Might be either absolute path or path related to CometBFT's config directory.
# If the certificate is signed by a certificate authority,
# the certFile should be the concatenation of the server's certificate, any intermediates,
# and the CA's certificate.
# NOTE: both tls_cert_file and tls_key_file must be present for CometBFT to create HTTPS server.
# Otherwise, HTTP server is run.
tls_cert_file = ""

# The path to a file containing matching private key that is used to create the HTTPS server.
# Might be either absolute path or path related to CometBFT's config directory.
# NOTE: both tls_cert_file and tls_key_file must be present for CometBFT to create HTTPS server.
# Otherwise, HTTP server is run.
tls_key_file = ""

# pprof listen address (https://golang.org/pkg/net/http/pprof)
pprof_laddr = ""

#######################################################
###           P2P Configuration Options             ###
#######################################################
[p2p]

# Address to listen for incoming connections
laddr = "tcp://0.0.0.0:26656"

# Address to advertise to peers for them to dial. If empty, will use the same
# port as the laddr, and will introspect on the listener to figure out the
# address. IP and port are required. Example: 159.89.10.97:26656
external_address = ""

# Comma separated list of seed nodes to connect to
seeds = ""

# Comma separated list of nodes to keep persistent connections to
persistent_peers = ""

# Path to address book
addr_book_file = "config/addrbook.json"

# Set true for strict address routability rules
# Set false for private or local networks
addr_book_strict = true

# Maximum number of inbound peers
max_num_inbound_peers = 40

# Maximum number of outbound peers to connect to, excluding persistent peers
max_num_outbound_peers = 10

# List of node IDs, to which a connection will be (re)established ignoring any existing limits
unconditional_peer_ids = ""

# Maximum pause when redialing a persistent peer (if zero, exponential backoff is used)
persistent_peers_max_dial_period = "0s"

# Time to wait before flushing messages out on the connection
flush_throttle_timeout = "100ms"

# Maximum size of a message packet payload, in bytes
max_packet_msg_payload_size = 1024

# Rate at which packets can be sent, in bytes/second
send_rate = 5120000

# Rate at which packets can be received, in bytes/second
recv_rate = 5120000

# Set true to enable the peer-exchange reactor
pex = true

# Seed mode, in which node constantly crawls the network and looks for
# peers. If another node asks it for addresses, it responds and disconnects.
#
# Does not work if the peer-exchange reactor is disabled.
seed_mode = false

# Comma separated list of peer IDs to keep private (will not be gossiped to other peers)
private_peer_ids = ""

# Toggle to disable guard against peers connecting from the same ip.
allow_duplicate_ip = false

# Peer connection configuration.
handshake_timeout = "20s"
dial_timeout = "3s"

#######################################################
###          Mempool Configuration Option          ###
#######################################################
[mempool]

# The type of mempool for this node to use.
#
#  Possible types:
#  - "flood" : concurrent linked list mempool with flooding gossip protocol
#  (default)
#  - "nop"   : nop-mempool (short for no operation; the ABCI app is responsible
#  for storing, disseminating and proposing txs). "create_empty_blocks=false" is
#  not supported.
type = "flood"

# Recheck (default: true) defines whether CometBFT should recheck the
# validity for all remaining transaction in the mempool after a block.
# Since a block affects the application state, some transactions in the
# mempool may become invalid. If this does not apply to your application,
# you can disable rechecking.
recheck = true

# Broadcast (default: true) defines whether the mempool should relay
# transactions to other peers. Setting this to false will stop the mempool
# from relaying transactions to other peers until they are included in a
# block. In other words, if Broadcast is disabled, only the peer you send
# the tx to will see it until it is included in a block.
broadcast = true

# WalPath (default: "") configures the location of the Write Ahead Log
# (WAL) for the mempool. The WAL is disabled by default. To enable, set
# wal_dir to where you want the WAL to be written (e.g.
# "data/mempool.wal").
wal_dir = ""

# Maximum number of transactions in the mempool
size = 5000

# Limit the total size of all txs in the mempool.
# This only accounts for raw transactions (e.g. given 1MB transactions and
# max_txs_bytes=5MB, mempool will only accept 5 transactions).
max_txs_bytes = 1073741824

# Size of the cache (used to filter transactions we saw earlier) in transactions
cache_size = 10000

# Do not remove invalid transactions from the cache (default: false)
# Set to true if it's not possible for any invalid transaction to become valid
# again in the future.
keep-invalid-txs-in-cache = false

# Maximum size of a single transaction.
# NOTE: the max size of a tx transmitted over the network is {max_tx_bytes}.
max_tx_bytes = 1048576

# Maximum size of a batch of transactions to send to a peer
# Including space needed by encoding (one varint per transaction).
# XXX: Unused due to https://github.com/tendermint/tendermint/issues/5796
max_batch_bytes = 0

#######################################################
###         State Sync Configuration Options        ###
#######################################################
[statesync]
# State sync rapidly bootstraps a new node by discovering, fetching, and restoring a state machine
# snapshot from peers instead of fetching and replaying historical blocks. Requires some peers in
# the network to take and serve state machine snapshots. State sync is not attempted if the node
# has any local state (LastBlockHeight > 0). The node will have a truncated block history,
# starting from the height of the snapshot.
enable = false

# RPC servers (comma-separated) for light client verification of the synced state machine and
# retrieval of state data for node bootstrapping. Also needs a trusted height and corresponding
# header hash obtained from a trusted source, and a period during which validators can be trusted.
#
# For Cosmos SDK-based chains, trust_period should usually be about 2/3 of the unbonding time (~2
# weeks) during which they can be financially punished (slashed) for misbehavior.
rpc_servers = ""
trust_height = 0
trust_hash = ""
trust_period = "168h0m0s"

# Time to spend discovering snapshots before initiating a restore.
discovery_time = "15s"

# Temporary directory for state sync snapshot chunks, defaults to the OS tempdir (typically /tmp).
# Will create a new, randomly named directory within, and remove it when done.
temp_dir = ""

# The timeout duration before re-requesting a chunk, possibly from a different
# peer (default: 1 minute).
chunk_request_timeout = "10s"

# The number of concurrent chunk fetchers to run (default: 1).
chunk_fetchers = "4"

#######################################################
###       Block Sync Configuration Options          ###
#######################################################
[blocksync]

# Block Sync version to use:
#
# In v0.37, v1 and v2 of the block sync protocols were deprecated.
# Please use v0 instead.
#
#   1) "v0" - the default block sync implementation
version = "v0"

#######################################################
###         Consensus Configuration Options         ###
#######################################################
[consensus]

wal_file = "data/cs.wal/wal"

# How long we wait for a proposal block before prevoting nil
timeout_propose = "3s"
# How much timeout_propose increases with each round
timeout_propose_delta = "500ms"
# How long we wait after receiving +2/3 prevotes for "anything" (ie. not a single block or nil)
timeout_prevote = "1s"
# How much the timeout_prevote increases with each round
timeout_prevote_delta = "500ms"
# How long we wait after receiving +2/3 precommits for "anything" (ie. not a single block or nil)
timeout_precommit = "1s"
# How much the timeout_precommit increases with each round
timeout_precommit_delta = "500ms"
# How long we wait after committing a block, before starting on the new
# height (this gives us a chance to receive some more precommits, even
# though we already have +2/3).
timeout_commit = "1s"

# How many blocks to look back to check existence of the node's consensus votes before joining consensus
# When non-zero, the node will panic upon restart
# if the same consensus key was used to sign {double_sign_check_height} last blocks.
# So, validators should stop the state machine, wait for some blocks, and then restart the state machine to avoid panic.
double_sign_check_height = 0

# Make progress as soon as we have all the precommits (as if TimeoutCommit = 0)
skip_timeout_commit = false

# EmptyBlocks mode and possible interval between empty blocks
create_empty_blocks = true
create_empty_blocks_interval = "0s"

# Reactor sleep duration parameters
peer_gossip_sleep_duration = "100ms"
peer_query_maj23_sleep_duration = "2s"

#######################################################
###         Storage Configuration Options           ###
#######################################################
[storage]

# Set to true to discard ABCI responses from the state store, which can save a
# considerable amount of disk space. Set to false to ensure ABCI responses are
# persisted. ABCI responses are required for /block_results RPC queries, and to
# reindex events in the command-line tool.
discard_abci_responses = false

#######################################################
###   Transaction Indexer Configuration Options     ###
#######################################################
[tx_index]

# What indexer to use for transactions
#
# The application will set which txs to index. In some cases a node operator will be able
# to decide which txs to index based on configuration set in the application.
#
# Options:
#   1) "null"
#   2) "kv" (default) - the simplest possible indexer, backed by key-value storage (defaults to levelDB; see DBBackend).
# 		- When "kv" is chosen "tx.height" and "tx.hash" will always be indexed.
#   3) "psql" - the indexer services backed by PostgreSQL.
# When "kv" or "psql" is chosen "tx.height" and "tx.hash" will always be indexed.
indexer = "kv"

# The PostgreSQL connection configuration, the connection format:
#   postgresql://<user>:<password>@<host>:<port>/<db>?<opts>
psql-conn = ""

#######################################################
###       Instrumentation Configuration Options     ###
#######################################################
[instrumentation]

# When true, Prometheus metrics are served under /metrics on
# PrometheusListenAddr.
# Check out the documentation for the list of available metrics.
prometheus = false

# Address to listen for Prometheus collector(s) connections
prometheus_listen_addr = ":26660"

# Maximum number of simultaneous connections.
# If you want to accept a larger number than the default, make sure
# you increase your OS limits.
# 0 - unlimited.
max_open_connections = 3

# Instrumentation namespace
namespace = "cometbft"

Empty blocks vs. no empty blocks

create_empty_blocks = true

If create_empty_blocks is set to true in your config, blocks will be created approximately every second (with default consensus parameters). You can regulate the delay between blocks by changing timeout_commit. For example, timeout_commit = "10s" should result in approximately 10-second blocks.

create_empty_blocks = false

In this setting, blocks are created when transactions are received. Note that after block H, CometBFT creates something we call a “proof block” (only if the application hash changed) H+1. The reason for this is to support proofs. If you have a transaction in block H that changes the state to X, the new application hash will only be included in block H+1. If after your transaction is committed, you want to get a light-client proof for the new state (X), you need the new block to be committed in order to do that because the new block has the new application hash for state X. That’s why we create a new (empty) block if the application hash changes. Otherwise, you won’t be able to make a proof for the new state. Additionally, if you set create_empty_blocks_interval to something other than the default (0), CometBFT will create empty blocks even in the absence of transactions every create_empty_blocks_interval. For instance, with create_empty_blocks = false and create_empty_blocks_interval = "30s", CometBFT will only create blocks if there are transactions, or after waiting 30 seconds without receiving any transactions.

Consensus timeouts explained

There’s a variety of information about timeouts in Running in production. You can also find a more detailed explanation in the paper describing the Tendermint consensus algorithm, adopted by CometBFT: The latest gossip on BFT consensus.
[consensus]
...

timeout_propose = "3s"
timeout_propose_delta = "500ms"
timeout_prevote = "1s"
timeout_prevote_delta = "500ms"
timeout_precommit = "1s"
timeout_precommit_delta = "500ms"
timeout_commit = "1s"
Note that in a successful round, the only timeout that we absolutely wait no matter what is timeout_commit. Here’s a brief summary of the timeouts:
  • timeout_propose = how long a validator should wait for a proposal block before prevoting nil
  • timeout_propose_delta = how much timeout_propose increases with each round
  • timeout_prevote = how long a validator should wait after receiving +2/3 prevotes for anything (i.e., not a single block or nil)
  • timeout_prevote_delta = how much timeout_prevote increases with each round
  • timeout_precommit = how long a validator should wait after receiving +2/3 precommits for anything (i.e., not a single block or nil)
  • timeout_precommit_delta = how much timeout_precommit increases with each round
  • timeout_commit = how long a validator should wait after committing a block before starting on the new height (this gives us a chance to receive some more precommits, even though we already have +2/3)

The adverse effect of using inconsistent timeout_propose in a network

Here’s an interesting question: What happens if a particular validator sets a very small timeout_propose, as compared to the rest of the network? Imagine there are only two validators in your network: Alice and Bob. Bob sets timeout_propose to 0s. Alice uses the default value of 3s. Let’s say they both have equal voting power. Given the proposer selection algorithm is a weighted round-robin, you may expect Alice and Bob to take turns proposing blocks, with a result like:
#1 block - Alice
#2 block - Bob
#3 block - Alice
#4 block - Bob
...
What happens in reality is, however, a little bit different:
#1 block - Bob
#2 block - Bob
#3 block - Bob
#4 block - Bob
That’s because Bob doesn’t wait for a proposal from Alice (prevotes nil). This leaves Alice no chance to commit a block. Note that every block Bob creates needs a vote from Alice to constitute 2/3+. Bob always gets one because Alice has timeout_propose set to 3s. Alice never gets one because Bob has it set to 0s. Imagine now there are ten geographically distributed validators. One of them (Bob) sets timeout_propose to 0s. Others have it set to 3s. Now, Bob won’t be able to move at his own speed because it still needs 2/3 votes of the other validators, and it takes time to propagate those. In other words, the network moves at the speed of time to accumulate 2/3+ of votes (prevotes & precommits), not at the speed of the fastest proposer.
Isn’t block production determined by voting power?
If it were determined solely by voting power, it wouldn’t be possible to ensure liveness. Timeouts exist because the network can’t rely on a single proposer being available and must move on if such proposer is not responding.
How can we address situations where someone arbitrarily adjusts their block production time to gain an advantage?
The impact shown above is negligible in a decentralized network with sufficient decentralization.

The adverse effect of using inconsistent timeout_commit in a network

Let’s look at the same scenario as before. There are ten geographically distributed validators. One of them (Bob) sets timeout_commit to 0s. Others have it set to 1s (the default value). Now, Bob will be the fastest producer because he doesn’t wait for additional precommits after creating a block. If waiting for precommits (timeout_commit) is not incentivized, Bob will accrue more rewards compared to the other 9 validators. This is because Bob has the advantage of broadcasting his proposal early (1 second earlier than the others). But it also makes it possible for Bob to miss a proposal from another validator and prevote nil due to him starting timeout_propose earlier. In other words, if Bob’s timeout_commit is too low compared to other validators, then he might miss some proposals and get slashed for inactivity.