Configuring the server
Configuring the server
KurrentDB has a number of configuration options that are described in detail in the sections to the left.
The options have sensible defaults, but those might not suit your specific needs and can be customised.
There are multiple ways to configure KurrentDB. They are described below in order of increasing precedence:
Version and help
Use the --version parameter in the command line to check the installed version of KurrentDB. For example:
$ kurrentd --version
KurrentDB version 25.0.0.1673-build.1 ee (0de5e4be-c415-4230-95d4-0f0d3b1d4a18/80248a9214b3412d5051bac58168ee5666e6cb97)> KurrentDB.exe --version
KurrentDB version 25.0.0.1673-build.1 ee (0de5e4be-c415-4230-95d4-0f0d3b1d4a18/80248a9214b3412d5051bac58168ee5666e6cb97)The full list of available options is available from the currently installed server by using the --help option in the command line.
Configuration files
YAML
The default configuration file name is kurrentdb.conf, and it is located in:
- Linux:
/etc/kurrentdb/ - Windows: KurrentDB installation directory
This configuration file has a YAML format. Options can be set as follows:
---
Db: "/volumes/data"
Log: "/kurrentdb/logs"
ReaderThreadsCount: 4Nested configuration options are expressed in the natural way:
UserCertificates:
Enabled: trueTips
You need to use the three dashes at the top of the YAML file, and spaces for indentation.
The path to the configuration file can be changed with the KURRENTDB_CONFIG environment variable, or on the command line with --config=path-to-file.
JSON
KurrentDB looks for JSON configuration files in the <installation-directory>/config/ directory, and on Linux and OS X, the server additionally looks in /etc/kurrentdb/config/. JSON configuration may be split across multiple files or combined into a single file. Apart from the json extension, the names of the files is not important.
All configuration options are nested under the KurrentDB key.
{
"KurrentDB": {
"Db": "/volumes/data",
"Log": "/kurrentdb/logs",
"ReaderThreadsCount": 4,
"UserCertificates": {
"Enabled": true
}
}
}An option set in the JSON configuration overrides the same option set in the YAML configuration.
Environment variables
When setting options via environment variables, prefix the option with KURRENTDB_ and use double underscores __ to indicate nesting.
For example:
KURRENTDB_DB
KURRENTDB_LOG
KURRENTDB_READER_THREADS_COUNT
KURRENTDB_USER_CERTIFICATES__ENABLEDAn option set via an environment variables overrides the same option set in the configuration files.
Command line
For example, starting KurrentDB with the --log option will override the default log files location:
kurrentd --log /tmp/kurrentdb/logsKurrentDB.exe --log C:\Temp\KurrentDB\LogsUse double underscores __ to indicate nesting, as with environment variables.
Additional examples:
--db
--log
--reader-threads-count
--user-certificates__enabledCommand line options override the configuration files and environment variables.
Testing the configuration
If more than one method is used to configure the server, it may be difficult to discern the effective configuration when the server starts. You can use the --what-if option to better understand the configuration details.
When you run KurrentDB with the --what-if option, it will print out the effective configuration applied from all available sources (default and custom configuration file, environment variables, and command line parameters) to the console.
Click here to see a WhatIf example
$ KurrentDB.exe --what-if
[13816, 1,12:02:34.627,INF] KurrentDB DB VERSION: 25.0.0.1673-build.1 ee (0de5e4be-c415-4230-95d4-0f0d3b1d4a18/80248a9214b3412d5051bac58168ee5666e6cb97, 2025-02-03 15:57:19.547253)
[13816, 1,12:02:34.630,INF] KurrentDB OS ARCHITECTURE: X64
[13816, 1,12:02:34.631,INF] KurrentDB OS: Windows (Microsoft Windows NT 10.0.22631.0)
[13816, 1,12:02:34.631,INF] KurrentDB RUNTIME: .NET 8.0.12/89ef51c5d (64-bit)
[13816, 1,12:02:34.631,INF] KurrentDB GC: 3 GENERATIONS IsServerGC: False Latency Mode: Interactive
[13816, 1,12:02:34.632,INF] KurrentDB LOGS: C:\Users\hayle\Downloads\kurrentdb.25.0.0-build.1\logs
[13816, 1,12:02:34.635,INF] KurrentDB
MODIFIED OPTIONS:
APPLICATION OPTIONS:
WHAT IF: true (Command Line)
DEFAULT OPTIONS:
APPLICATION OPTIONS:
ALLOW ANONYMOUS ENDPOINT ACCESS: False (<DEFAULT>)
ALLOW ANONYMOUS STREAM ACCESS: False (<DEFAULT>)
ALLOW UNKNOWN OPTIONS: False (<DEFAULT>)
CONFIG: C:\kurrentdb.25.0.0-build.1 (<DEFAULT>)
DISABLE HTTP CACHING: False (<DEFAULT>)
ENABLE HISTOGRAMS: False (<DEFAULT>)
HELP: False (<DEFAULT>)
INSECURE: False (<DEFAULT>)
LOG FAILED AUTHENTICATION ATTEMPTS: False (<DEFAULT>)
LOG HTTP REQUESTS: False (<DEFAULT>)
MAX APPEND SIZE: 1048576 (<DEFAULT>)
OVERRIDE ANONYMOUS ENDPOINT ACCESS FOR GOSSIP: True (<DEFAULT>)
SKIP INDEX SCAN ON READS: False (<DEFAULT>)
STATS PERIOD SEC: 30 (<DEFAULT>)
TELEMETRY OPTOUT: False (<DEFAULT>)
VERSION: False (<DEFAULT>)
WORKER THREADS: 0 (<DEFAULT>)
AUTHENTICATION/AUTHORIZATION OPTIONS:
AUTHENTICATION CONFIG: (<DEFAULT>)
AUTHENTICATION TYPE: internal (<DEFAULT>)
AUTHORIZATION CONFIG: (<DEFAULT>)
AUTHORIZATION TYPE: internal (<DEFAULT>)
DISABLE FIRST LEVEL HTTP AUTHORIZATION: False (<DEFAULT>)
CERTIFICATE OPTIONS:
CERTIFICATE RESERVED NODE COMMON NAME: (<DEFAULT>)
TRUSTED ROOT CERTIFICATES PATH: (<DEFAULT>)
CERTIFICATE OPTIONS (FROM FILE):
CERTIFICATE FILE: (<DEFAULT>)
CERTIFICATE PASSWORD: ******** (<DEFAULT>)
CERTIFICATE PRIVATE KEY FILE: (<DEFAULT>)
CERTIFICATE PRIVATE KEY PASSWORD: ******** (<DEFAULT>)
CERTIFICATE OPTIONS (FROM STORE):
CERTIFICATE STORE LOCATION: (<DEFAULT>)
CERTIFICATE STORE NAME: (<DEFAULT>)
CERTIFICATE SUBJECT NAME: (<DEFAULT>)
CERTIFICATE THUMBPRINT: (<DEFAULT>)
TRUSTED ROOT CERTIFICATE STORE LOCATION: (<DEFAULT>)
TRUSTED ROOT CERTIFICATE STORE NAME: (<DEFAULT>)
TRUSTED ROOT CERTIFICATE SUBJECT NAME: (<DEFAULT>)
TRUSTED ROOT CERTIFICATE THUMBPRINT: (<DEFAULT>)
CLUSTER OPTIONS:
ARCHIVER: False (<DEFAULT>)
CLUSTER DNS: fake.dns (<DEFAULT>)
CLUSTER GOSSIP PORT: 2113 (<DEFAULT>)
CLUSTER SIZE: 1 (<DEFAULT>)
DEAD MEMBER REMOVAL PERIOD SEC: 1800 (<DEFAULT>)
DISCOVER VIA DNS: True (<DEFAULT>)
GOSSIP ALLOWED DIFFERENCE MS: 60000 (<DEFAULT>)
GOSSIP INTERVAL MS: 2000 (<DEFAULT>)
GOSSIP SEED: (<DEFAULT>)
GOSSIP TIMEOUT MS: 2500 (<DEFAULT>)
LEADER ELECTION TIMEOUT MS: 1000 (<DEFAULT>)
NODE PRIORITY: 0 (<DEFAULT>)
QUORUM SIZE: 1 (<DEFAULT>)
READ ONLY REPLICA: False (<DEFAULT>)
STREAM INFO CACHE CAPACITY: 0 (<DEFAULT>)
UNSAFE ALLOW SURPLUS NODES: False (<DEFAULT>)
DATABASE OPTIONS:
CACHED CHUNKS: -1 (<DEFAULT>)
CHUNK INITIAL READER COUNT: 5 (<DEFAULT>)
CHUNK SIZE: 268435456 (<DEFAULT>)
CHUNKS CACHE SIZE: 536871424 (<DEFAULT>)
COMMIT TIMEOUT MS: 2000 (<DEFAULT>)
DB: C:\kurrentdb.25.0.0-build.1\data (<DEFAULT>)
DB LOG FORMAT: V2 (<DEFAULT>)
DISABLE SCAVENGE MERGING: False (<DEFAULT>)
HASH COLLISION READ LIMIT: 100 (<DEFAULT>)
INDEX: (<DEFAULT>)
INDEX CACHE DEPTH: 16 (<DEFAULT>)
INDEX CACHE SIZE: 0 (<DEFAULT>)
INITIALIZATION THREADS: 1 (<DEFAULT>)
MAX AUTO MERGE INDEX LEVEL: 2147483647 (<DEFAULT>)
MAX MEM TABLE SIZE: 1000000 (<DEFAULT>)
MAX TRUNCATION: 268435456 (<DEFAULT>)
MEM DB: False (<DEFAULT>)
MIN FLUSH DELAY MS: 2 (<DEFAULT>)
PREPARE TIMEOUT MS: 2000 (<DEFAULT>)
READER THREADS COUNT: 0 (<DEFAULT>)
REDUCE FILE CACHE PRESSURE: False (<DEFAULT>)
SCAVENGE BACKEND CACHE SIZE: 67108864 (<DEFAULT>)
SCAVENGE BACKEND PAGE SIZE: 16384 (<DEFAULT>)
SCAVENGE HASH USERS CACHE CAPACITY: 100000 (<DEFAULT>)
SCAVENGE HISTORY MAX AGE: 30 (<DEFAULT>)
SKIP DB VERIFY: False (<DEFAULT>)
SKIP INDEX VERIFY: False (<DEFAULT>)
STATS STORAGE: File (<DEFAULT>)
STREAM EXISTENCE FILTER SIZE: 256000000 (<DEFAULT>)
TRANSFORM: identity (<DEFAULT>)
UNBUFFERED: False (<DEFAULT>)
UNSAFE DISABLE FLUSH TO DISK: False (<DEFAULT>)
UNSAFE IGNORE HARD DELETE: False (<DEFAULT>)
USE INDEX BLOOM FILTERS: True (<DEFAULT>)
WRITE STATS TO DB: False (<DEFAULT>)
WRITE THROUGH: False (<DEFAULT>)
WRITE TIMEOUT MS: 2000 (<DEFAULT>)
DEFAULT USER OPTIONS:
DEFAULT ADMIN PASSWORD: ******** (<DEFAULT>)
DEFAULT OPS PASSWORD: ******** (<DEFAULT>)
DEV MODE OPTIONS:
DEV: False (<DEFAULT>)
REMOVE DEV CERTS: False (<DEFAULT>)
GRPC OPTIONS:
KEEP ALIVE INTERVAL: 10000 (<DEFAULT>)
KEEP ALIVE TIMEOUT: 10000 (<DEFAULT>)
INTERFACE OPTIONS:
ADVERTISE HOST TO CLIENT AS: (<DEFAULT>)
ADVERTISE NODE PORT TO CLIENT AS: 0 (<DEFAULT>)
CONNECTION PENDING SEND BYTES THRESHOLD: 10485760 (<DEFAULT>)
CONNECTION QUEUE SIZE THRESHOLD: 50000 (<DEFAULT>)
DISABLE ADMIN UI: False (<DEFAULT>)
DISABLE GOSSIP ON HTTP: False (<DEFAULT>)
DISABLE STATS ON HTTP: False (<DEFAULT>)
ENABLE ATOM PUB OVER HTTP: False (<DEFAULT>)
ENABLE TRUSTED AUTH: False (<DEFAULT>)
ENABLE UNIX SOCKET: False (<DEFAULT>)
NODE HOST ADVERTISE AS: (<DEFAULT>)
NODE IP: 127.0.0.1 (<DEFAULT>)
NODE PORT: 2113 (<DEFAULT>)
NODE PORT ADVERTISE AS: 0 (<DEFAULT>)
REPLICATION HEARTBEAT INTERVAL: 700 (<DEFAULT>)
REPLICATION HEARTBEAT TIMEOUT: 700 (<DEFAULT>)
REPLICATION HOST ADVERTISE AS: (<DEFAULT>)
REPLICATION IP: 127.0.0.1 (<DEFAULT>)
REPLICATION PORT: 1112 (<DEFAULT>)
REPLICATION TCP PORT ADVERTISE AS: 0 (<DEFAULT>)
LOGGING OPTIONS:
DISABLE LOG FILE: False (<DEFAULT>)
LOG: C:\kurrentdb.25.0.0-build.1\logs (<DEFAULT>)
LOG CONFIG: logconfig.json (<DEFAULT>)
LOG CONSOLE FORMAT: Plain (<DEFAULT>)
LOG FILE INTERVAL: Day (<DEFAULT>)
LOG FILE RETENTION COUNT: 31 (<DEFAULT>)
LOG FILE SIZE: 1073741824 (<DEFAULT>)
LOG LEVEL: Default (<DEFAULT>)
PROJECTION OPTIONS:
FAULT OUT OF ORDER PROJECTIONS: False (<DEFAULT>)
PROJECTION COMPILATION TIMEOUT: 500 (<DEFAULT>)
PROJECTION EXECUTION TIMEOUT: 250 (<DEFAULT>)
PROJECTION THREADS: 3 (<DEFAULT>)
PROJECTIONS QUERY EXPIRY: 5 (<DEFAULT>)
RUN PROJECTIONS: None (<DEFAULT>)
START STANDARD PROJECTIONS: False (<DEFAULT>)Note
The server will not start when an unknown configuration option is passed in the configuration file, environment variable, or command line.
As an example, the following will prevent the server from starting:
--UnknownConfigon the command lineKURRENTDB_UnknownConfigthrough environment variableUnknownConfig: valuein the config file
And will output on stdout only: Error while parsing options: The option UnknownConfig is not a known option. (Parameter 'UnknownConfig').
Autoconfigured options
Some options are configured at startup to make better use of the available resources on larger instances or machines.
These options are StreamInfoCacheCapacity, ReaderThreadsCount, and WorkerThreads.
Autoconfiguration does not apply in containerized environments.
StreamInfoCacheCapacity
This option sets the maximum number of entries in the stream info cache. This lookup contains information on any stream that has recently been read or written. Having entries in this cache significantly improves the write and read performance to cached streams on larger databases.
By default, the cache dynamically resizes based on the amount of free memory. The minimum it can be set to is 100,000 entries.
| Format | Syntax |
|---|---|
| Command line | --stream-info-cache-capacity |
| YAML | StreamInfoCacheCapacity |
| Environment variable | KURRENTDB_STREAM_INFO_CACHE_CAPACITY |
The option is set to 0 by default, which enables dynamic resizing. The default on previous versions of KurrentDB was 100,000 entries.
Note
The default value of 0 for StreamInfoCacheCapacity might not always be the best value for optimal performance. Ideally, it should be set to double the number of streams in the anticipated working set.
Check the event count in the $streams system stream to obtain the total number of streams. This stream is created by the $streams system projection.
It should be noted that the total number of streams does not necessarily provide you with the anticipated working set. The working set of streams is the one you intend to read, write, and/or subscribe to actively. This can be much lower than the total number of streams in some instances, especially in systems with many short-lived streams.
ReaderThreadsCount
This option configures the number of reader threads available to KurrentDB. Increased reader threads enables more concurrent reads to be processed.
Warning
Increasing the reader threads count too high can cause read timeouts if your disk cannot handle the increased load.
The reader threads count will be set at startup to twice the number of available processors, with a minimum of four and a maximum of sixteen threads.
| Format | Syntax |
|---|---|
| Command line | --reader-threads-count |
| YAML | ReaderThreadsCount |
| Environment variable | KURRENTDB_READER_THREADS_COUNT |
The option is set to 0 by default, which enables autoconfiguration. The default on previous versions of KurrentDB was four threads.
WorkerThreads
The WorkerThreads option configures the number of threads available to the pool of worker services.
At startup, the number of worker threads will be set to ten if there are more than four reader threads. Otherwise, it will be set to have five threads available.
| Format | Syntax |
|---|---|
| Command line | --worker-threads |
| YAML | WorkerThreads |
| Environment variable | KURRENTDB_WORKER_THREADS |
The option is set to 0 by default, which enables autoconfiguration. The default on previous versions of KurrentDB was five threads.