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Configuration

Nexir loads configuration at startup. Change TOML or environment variables, then restart the node; runtime CONFIG SET is not supported.

Loading and precedence

Load a local .env file if present.
Load config/default.toml if present relative to the working directory.
Apply NEXIR__* environment variables.

Environment variables override TOML. Existing shell variables override values from .env. Nested names use double underscores:

NEXIR__SERVER__REDIS_BIND=127.0.0.1:16379
NEXIR__SERVER__TLS__CLIENT__MODE=require
NEXIR__STORAGE__PATH=/var/lib/nexir

Essential settings

TOML field	Environment variable	Default
`server.redis_bind`	`NEXIR__SERVER__REDIS_BIND`	`127.0.0.1:6379`
`server.grpc_bind`	`NEXIR__SERVER__GRPC_BIND`	`127.0.0.1:50051`
`server.default_read_mode`	`NEXIR__SERVER__DEFAULT_READ_MODE`	`LINEARIZABLE`
`server.enable_admin_commands`	`NEXIR__SERVER__ENABLE_ADMIN_COMMANDS`	`true`
`raft.node_id`	`NEXIR__RAFT__NODE_ID`	`1`
`storage.path`	`NEXIR__STORAGE__PATH`	`./data/nexir`
`prometheus.bind`	`NEXIR__PROMETHEUS__BIND`	`127.0.0.1:9090`

Identity is durableSet a unique node ID and storage path before first start. Never change the node ID for an existing data directory or let two processes share one storage path.

TLS settings

Both TLS surfaces default to disabled. require means mutual TLS and requires a certificate, matching private key, and CA bundle.

Surface	Fields under `server.tls`	Environment prefix
RESP clients	`client.mode`, `cert_file`, `key_file`, `ca_bundle`	`NEXIR__SERVER__TLS__CLIENT__*`
Raft peers	`cluster.mode`, `cert_file`, `key_file`, `ca_bundle`	`NEXIR__SERVER__TLS__CLUSTER__*`

Use separate client and cluster CA bundles. Startup rejects the same resolved CA file for both required surfaces. TLS files are read at startup; rotation requires restart.

Server resource defaults

Field	Default	Purpose
`max_connections`	10,000	Concurrent RESP clients
`max_inflight_commands_global`	100,000	Unfinished commands across clients
`max_inflight_commands_per_connection`	1,000	Per-client command budget
`max_inflight_bytes_global`	512 MiB	Global in-flight request payload budget
`max_inflight_bytes_per_connection`	64 MiB	Per-client payload budget
`max_client_buffer_bytes`	64 MiB	Unread input per socket
`max_buffered_client_bytes_global`	512 MiB	Buffered input across clients
`client_idle_timeout_secs`	300	Idle RESP socket timeout
`max_concurrent_reads_per_connection`	16	Concurrent reads for one client
`max_buffered_response_bytes_per_connection`	64 MiB	Queued output per client
`max_buffered_response_bytes_global`	512 MiB	Queued output globally

Storage defaults

Field	Default	Notes
`block_cache_size_mb`	0 (auto)	25% of system memory, minimum 64 MiB
`write_buffer_size_mb`	128	State DB buffer; log DB uses twice this
`max_write_buffers`	4	Storage-engine write buffers
`enable_bloom_filters`	true	Point lookup filters
`read_io_threads`	0 (auto)	Available cores clamped to 4–64
`scan_io_threads`	0 (auto)	Available cores clamped to 2–8
`write_io_threads`	2	Blocking write workers
`cleanup_io_threads`	1	Background cleanup worker
`max_read_reply_bytes`	0 → 64 MiB	Resolves to per-client response limit
`max_reader_pin_ms`	300,000	Five-minute maximum read lifetime
`max_snapshot_files`	10,000	Accepted snapshot file count
`max_snapshot_size_bytes`	5 GiB	Extracted snapshot cap
`max_archive_bytes`	5 GiB	Snapshot archive cap
`max_retained_snapshot_bytes`	20 GiB	Retained archive budget
`min_free_disk_bytes`	1 GiB	Snapshot free-space reserve

Raft defaults

Field	Default
`snapshot_policy_logs`	100,000
`max_pending_write_tasks`	10,000
`max_pending_write_bytes`	256 MiB
`max_inflight_read_barriers`	10
`max_queued_linearizable_reads`	100,000
`membership_preflight_timeout_ms`	3,000
`membership_change_timeout_ms`	30,000
`add_learner_catchup_timeout_ms`	300,000
`transfer_leader_timeout_ms`	10,000
`heartbeat_interval_ms`	1,000
`election_timeout_min_ms` / `max_ms`	3,000 / 5,000

Logging

RUST_LOG controls tracing output and defaults to info. Use warn for quieter operation or debug temporarily while diagnosing a problem.

Startup validation

Nexir rejects invalid addresses and modes, zero required limits, inconsistent global/per-connection budgets, request budgets below 60 MiB, invalid I/O queue sizes, unsafe snapshot limits, invalid Raft timing relationships, and missing or mismatched TLS files. It exits with a useful startup error rather than silently altering invalid settings.

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