Server Configuration Flags

Dragonfly can be tuned and configured by a set of config flags. These flags can be:

1. Passed to a Dragonfly as command line arguments. E.g, dragonfly --port=6379.
2. Loaded from a file. E.g. dragonfly --flagfile=path_to_flags/flags.txt
3. Can be set via env variables by adding the prefix DFLY_ followed by the flag name. E.g. export DFLY_port=6379 (note it's case sensitive)
4. At runtime via CONFIG SET command. Not all flags can be configured at runtime.

You can try dragonfly --helpfull to get a list of all flags or --help=substring shows help for flags which include specified substring in either in the name, description or path.

Available flags

--port

Redis port. 0 disables the port, -1 will bind on a random available port.

default: 6379

--cache_mode

If true, the backend behaves like a cache, by evicting entries when getting close to maxmemory limit

default: false

--cluster_mode

Set cluster mode. Available options are: yes, emulated and empty "".

default: ""

--maxmemory

Limit on maximum-memory that is used by the database. 0 - means the program will automatically determine its maximum memory usage.

default: 0

--dbnum

Number of databases.

default: 16

--bind

Bind address. If empty - binds on all interfaces. It's not advised due to security implications.

default: ""

--requirepass

Password for AUTH authentication.

default: ""

--dbfilename

The filename to save/load the DB.

default: "dump-{timestamp}"

--snapshot_cron

Cron expression for the time to save a snapshot, crontab style.

default:

--use_set2

If true use DenseSet for an optimized set data structure.

default: true

--use_zset_tree

If true use b+tree for zset implementation.

default: true

--admin_bind

If set, the admin console TCP connection would be bind to the given address. This supports both HTTP and RESP protocols.

default: ""

--admin_port

If set, would enable admin access to console on the assigned port. This supports both HTTP and RESP protocols.

default: 0

--max_client_iobuf_len

Maximum io buffer length that is used to read client requests.

default: 65536

--max_multi_bulk_len

Maximum multi-bulk (array) length that is allowed to be accepted when parsing RESP protocol

default: 65536

--migrate_connections

When enabled, Dragonfly will try to migrate connections to the target thread on which they operate. Currently this is only supported for Lua script invocations, and can happen at most once per connection.

default: true

--no_tls_on_admin_port

Allow non-tls connections on admin port.

default: false

--subscriber_thread_limit

Amount of memory to use for storing pub commands in bytes - per IO thread.

default: 134217728

--pipeline_squash

Number of queued pipelined commands above which squashing is enabled, 0 means disabled.

default: 10

--primary_port_http_enabled

If true allows accessing http console on main TCP port.

default: true

--request_cache_limit

Amount of memory to use for request cache in bytes per IO thread.

default: 67108864

--tcp_nodelay

Configures dragonfly connections with socket option TCP_NODELAY.

default: true

--conn_io_thread_start

Starting thread id for handling server connections.

default: 0

--conn_io_threads

Number of threads used for handing server connections.

default: 0

--conn_use_incoming_cpu

If true uses incoming cpu of a socket in order to distribute incoming connections.

default: false

--tcp_keepalive

The period in seconds of inactivity after which keep-alives are triggerred, the duration until an inactive connection is terminated is twice the specified time.

default: 300

--tls

Enable tls.

default: false

--tls_ca_cert_dir

Certified authority signed certificates directory. Use c_rehash on the directory before specifying this flag.

default: ""

--tls_ca_cert_file

Certified authority signed certificate to validate tls connections.

default: ""

--tls_cert_file

Cert file(public key) for tls connections.

default: ""

--tls_key_file

Private Key file for tls connections.

default: ""

--rename_command

Change the name of commands, format is: <cmd1_name>=<cmd1_new_name>, <cmd2_name>=<cmd2_new_name>)

default:

--restricted_commands

Commands restricted to connections on the admin port.

default:

--lock_on_hashtags

When true, locks are done in the {hashtag} level instead of key level. Only use this with --cluster_mode=emulated|yes.

default: false

--enable_heartbeat_eviction

Enable eviction during heartbeat when memory is under pressure.

default: true

--max_eviction_per_heartbeat

The maximum number of key-value pairs that will be deleted in each eviction when heartbeat based eviction is triggered under memory pressure.

default: 100

--max_segment_to_consider

The maximum number of dashtable segments to scan in each eviction when heartbeat based eviction is triggered under memory pressure.

default: 4

--force_epoll

If true - uses linux epoll engine underneath. Can fit for kernels older than 5.10.

default: false

--pidfile

If not empty - server writes its pid into the file).

default: ""

--unixsocket

If not empty - specifies path for the Unix socket that will be used for listening for incoming connections.

default: ""

--unixsocketperm

Set permissions for unixsocket, in octal value.

default: ""

--version_check

If true, Will monitor for new releases on Dragonfly servers once a day.

default: true

--hz

Base frequency at which the server performs other background tasks. Warning: not advised to decrease in production.

default: 100

--mem_defrag_page_utilization_threshold

Memory page under utilization threshold. Ratio between used and committed size, below this, memory in this page will defragmented.

default: 0.8

--mem_defrag_threshold

Minimum percentage of used memory relative to maxmemory cap before running defragmentation.

default: 0.7

--mem_defrag_waste_threshold

The ratio of wasted/committed memory above which we run defragmentation.

default: 0.2

--shard_round_robin_prefix

When non-empty, keys which start with this prefix are not distributed across shards based on their value but instead via round-robin. Use cautiously! This can efficiently support up to a few hundreds of prefixes. Note: prefix is looked inside hash tags when cluster mode is enabled.

default: ""

--singlehop_blocking

Use single hop optimization for blocking commands.

default: true

--spill_file_prefix

Enables tiered storage if set. The string denotes the path and prefix of the files associated with tiered storage. For example, spill_file_prefix=/path/to/file-prefix.

default: ""

--keys_output_limit

Maximum number of keys output by keys command.

default: 8192

--backing_file_direct

If true uses O_DIRECT to open backing files.

default: false

--list_compress_depth

Compress depth of the list. Default is no compression.

default: 0

--list_max_listpack_size

Maximum listpack size, default is 8kb.

default: -2

--admin_nopass

If set, would enable open admin access to console on the assigned port, without authorization needed.

default: false

--memcached_port

Memcached port:

default: 0

--multi_eval_squash_buffer

Max buffer for squashed commands per script:

default: 4096

--multi_exec_mode

Set multi exec atomicity mode: 1 for global, 2 for locking ahead, 3 for non atomic.

default: 2

--multi_exec_squash

Whether multi exec will squash single shard commands to optimize performance.

default: true

--num_shards

Number of database shards, 0 - to choose automatically.

default: 0

--oom_deny_ratio

commands with flag denyoom will return OOM when the ratio between maxmemory and used memory is above this value.

default: 1.1

--masterauth

Password for authentication with master.

default: ""

--replicaof

Specifies a host and port which point to a target master to replicate. Format should be <IPv4>:<PORT> or host:<PORT> or [<IPv6>]:<PORT>.

default:

--tls_replication

Enable TLS on replication.

default: false

--compression_level

The compression level to use on zstd/lz4 compression.

default: 2

--compression_mode

Set 0 for no compression, set 1 for single entry lzf compression,set 2 for multi entry zstd compression on df snapshot and single entry on rdb snapshot, set 3 for multi entry lz4 compression on df snapshot and single entry on rdb snapshot.

default: 3

--enable_multi_shard_sync

Execute multi shards commands on replica synchronized.

default: false

--master_connect_timeout_ms

Timeout for establishing connection to a replication master.

default: 20000

--master_reconnect_timeout_ms

Timeout for re-establishing connection to a replication master.

default: 1000

--replica_partial_sync

Use partial sync to reconnect when a replica connection is interrupted.

default: true

--replication_acks_interval

Interval between acks in milliseconds.

default: 3000

--default_lua_flags

Configure default flags for running Lua scripts:

• Use allow-undeclared-keys to allow accessing undeclared keys,

• Use disable-atomicity to allow running scripts non-atomically.

  Specify multiple values separated by space, for example allow-undeclared-keys disable-atomicity runs scripts non-atomically and allows accessing undeclared keys.

  default: ""

--lua_auto_async

If enabled, call/pcall with discarded values are automatically replaced with acall/apcall.

default: false

--df_snapshot_format

If true, save in dragonfly-specific snapshotting format

default: true

--dir

Working directory

default: ""

--epoll_file_threads

Thread size for file workers when running in epoll mode, default is hardware concurrent threads.

default: 0

--maxclients

Maximum number of concurrent clients allowed.

default: 64000

--s3_ec2_metadata

Whether to load credentials and configuration from EC2 metadata.

default: false

--s3_endpoint

Endpoint for s3 snapshots, default uses aws regional endpoint.

default: ""

--s3_sign_payload

Whether to sign the s3 request payload when uploading snapshots.

default: true

--s3_use_https

Whether to use https for s3 endpoints.

default: true

--slowlog_log_slower_than

Add commands slower than this threshold to slow log. The value is expressed in microseconds and if it's negative disables the slowlog.

default: 10000

--slowlog_max_len

Slow log maximum length.

default: 20

--interpreter_per_thread

Lua interpreters per thread

default: 10

--enable_top_keys_tracking

Enables / disables tracking of hot keys debugging feature.

default: false

--tiered_storage_max_pending_writes

Maximal number of pending writes per thread.

default: 32

--aclfile

Path and name to aclfile.

default: ""

--acllog_max_len

Specify the number of log entries. Logs are kept locally for each thread and therefore the total number of entries are acllog_max_len * threads

default: 32

--cluster_announce_ip

Ip that cluster commands announce to the client.

default: ""

--shard_repl_backlog_len

The length of the circular replication log per shard.

default: 1024

--proactor_affinity_mode

Can be on, off or auto.

default: "on"

--proactor_threads

Number of io threads in the pool.

default: 0

--proactor_register_fd

If true tries to register file descriptors.

default: false

--flagfile

Comma-separated list of files to load flags from.

default:

--alsologtostderr

Log messages go to stderr in addition to logfiles.

default: false

--log_dir

If specified, logfiles are written into this directory instead of the default logging directory.

default: ""

--logtostderr

Log messages go to stderr instead of logfiles.

default: false

--logtostdout

Log messages go to stdout instead of logfiles.

default: false

--max_log_size

Approx. maximum log file size (in MB). A value of 0 will be silently overridden to 1.

default: 1800

--minloglevel

Messages logged at a lower level than this don't actually get logged anywhere.

default: 0

--stderrthreshold

Log messages at or above this level are copied to stderr in addition to logfiles. This flag obsoletes --alsologtostderr

default: 2