Configuration

All options are available as command-line flags. Run moon --help for the full list.

Server

Flag	Default	Description
--bind	127.0.0.1	Bind address
--port / -p	6379	Port to listen on
--shards	0 (auto)	Number of shards (0 = CPU count)
--databases	16	Number of databases
--requirepass	(none)	Require password authentication
--protected-mode	yes	Reject non-loopback when no password set

Persistence

Flag	Default	Description
--appendonly	no	Enable AOF persistence (yes/no)
--appendfsync	everysec	AOF fsync policy (always/everysec/no)
--appendfilename	appendonly.aof	AOF filename
--save	(none)	RDB auto-save rules (e.g., "3600 1 300 100")
--dir	.	Directory for persistence files
--dbfilename	dump.rdb	RDB snapshot filename

Memory and eviction

Flag	Default	Description
--maxmemory	0	Max memory in bytes (0 = unlimited)
--maxmemory-policy	noeviction	Eviction policy
--maxmemory-samples	5	Keys to sample for eviction

Eviction policies: noeviction, allkeys-lru, allkeys-lfu, allkeys-random, volatile-lru, volatile-lfu, volatile-random, volatile-ttl

TLS

Flag	Default	Description
--tls-port	0 (disabled)	TLS listener port
--tls-cert-file	(none)	PEM certificate file
--tls-key-file	(none)	PEM private key file
--tls-ca-cert-file	(none)	CA cert for mTLS client auth
--tls-ciphersuites	(default)	TLS 1.3 cipher suites

Cluster

Flag	Default	Description
--cluster-enabled	false	Enable cluster mode
--cluster-node-timeout	15000	Node timeout in ms

ACL

Flag	Default	Description
--aclfile	(none)	Path to ACL file (Redis-compatible format)
--acllog-max-len	128	Max ACL log entries

Example: production configuration

./target/release/moon \
  --bind 0.0.0.0 \
  --port 6379 \
  --tls-port 6380 \
  --tls-cert-file /etc/moon/server.crt \
  --tls-key-file /etc/moon/server.key \
  --admin-port 9100 \
  --console-auth-required \
  --console-auth-secret "$ADMIN_SECRET" \
  --shards 8 \
  --requirepass "$REDIS_PASSWORD" \
  --appendonly yes \
  --appendfsync everysec \
  --dir /var/lib/moon \
  --maxmemory 8589934592 \
  --maxmemory-policy allkeys-lfu \
  --aclfile /etc/moon/users.acl

Web console

Flag	Default	Description
--admin-port	0 (disabled)	Admin/metrics HTTP port. Serves /metrics, /healthz, /readyz, and web console at /ui/
--console-auth-required	false	Require Bearer/HMAC auth on the admin/console HTTP port
--console-auth-secret	(ephemeral)	HMAC-SHA256 secret for token verification. Empty = auto-generated at startup
--console-cors-origin	localhost:5173	CORS origin allowlist (repeatable). * only allowed without auth
--console-rate-limit	1000	Per-IP rate limit in requests/sec on the admin port
--console-rate-burst	2000	Token-bucket burst capacity for the rate limiter

Performance tuning

Flag	Default	Description
--maxclients	10000	Maximum simultaneous client connections (0 = unlimited)
--timeout	0 (disabled)	Close idle connections after N seconds
--tcp-keepalive	300	TCP keepalive interval in seconds (0 = disabled)
--slowlog-log-slower-than	10000	Slowlog threshold in microseconds
--slowlog-max-len	128	Maximum slowlog entries
--uring-sqpoll	(disabled)	io_uring SQPOLL idle timeout in ms. Requires CAP_SYS_NICE. Linux only

Disk offload (tiered storage)

Flag	Default	Description
--disk-offload	enable	Enable disk offload (RAM → mmap → NVMe)
--disk-offload-dir	(same as --dir)	Directory for disk offload files
--disk-offload-threshold	0.85	RAM pressure threshold to trigger offload (0.0-1.0)
--segment-warm-after	3600	Seconds before sealed segments transition to warm tier

WAL (Write-Ahead Log)

Flag	Default	Description
--wal-fpi	enable	Enable Full Page Images for torn page defense
--wal-compression	lz4	FPI compression codec
--wal-segment-size	16mb	WAL segment file size
--max-wal-size	256mb	Max WAL size before triggering checkpoint
--checkpoint-timeout	300	Checkpoint timeout in seconds
--checkpoint-completion	0.9	Fraction of checkpoint interval for dirty page flush (0.0-1.0)
--pagecache-size	(25% maxmemory)	PageCache memory budget (e.g., 256mb, 1gb)

Vector search tuning

Flag	Default	Description
--vec-codes-mlock	enable	mlock vector code pages into RAM
--vec-diskann-beam-width	8	DiskANN beam width for disk-resident search (reserved)
--vec-diskann-cache-levels	3	HNSW upper levels cached for DiskANN hybrid (reserved)
--segment-cold-after	86400	Seconds before warm segments transition to cold tier (reserved)
--segment-cold-min-qps	0.1	QPS threshold for cold candidates (reserved)

Tips

Note

Use --shards 0 to auto-detect CPU count. Use --shards 1 for benchmarking or when comparing per-key memory against Redis.

Tip

Hash tags like {tag} in key names (e.g., user:{1234}:name) route all tagged keys to the same shard, eliminating cross-shard dispatch for MGET/MSET operations.

Warning

Testing with more than 1,000 concurrent clients may require ulimit -n 65536. At 5,000 clients with pipelining, connection drops can occur without it.