For the latest stable version, please use Korvet 0.19!

Configuration Reference

Complete configuration reference for Korvet.

All korvet properties have sensible defaults. You can override them via application.yml, environment variables (e.g. KORVET_BROKER_PORT), or command-line arguments (e.g. --korvet.broker.port=9092). Unknown korvet properties fail startup (strict binding) — a typo is caught immediately rather than silently ignored.

General

Top-level Korvet runtime settings: namespace and the entry points into each sub-system.

`korvet.namespace`

Env var: KORVET_NAMESPACE · Type: string · Default: korvet

Logical namespace applied to all storage and registry state this Korvet instance owns. Must not contain whitespace or the : delimiter — colons are appended internally to compose sub-namespaces.

Admin

HTTP Admin API bootstrap credentials.

`korvet.admin.bootstrap`

Env var: KORVET_ADMIN_BOOTSTRAP · Type: boolean · Default: true

Create the default admin credential at startup when it does not already exist.

`korvet.admin.password`

Env var: KORVET_ADMIN_PASSWORD · Type: string · Default: admin

Password for the bootstrapped admin credential. Change this before exposing the Admin API.

`korvet.admin.username`

Env var: KORVET_ADMIN_USERNAME · Type: string · Default: admin

Username for the bootstrapped admin credential.

Jwt

JWT session settings for the Admin API cookie auth.

`korvet.admin.jwt.expiry`

Env var: KORVET_ADMIN_JWT_EXPIRY · Type: duration · Default: 8h

Lifetime of an admin session JWT. Defaults to 8 hours.

`korvet.admin.jwt.secret`

Env var: KORVET_ADMIN_JWT_SECRET · Type: string

HMAC-SHA256 signing secret for admin session JWTs. Must be at least 32 characters. If not set, a random key is generated at startup (all sessions are invalidated on restart).

Broker

Kafka-wire broker listener and group coordinator: bind address, TLS, request limits, backpressure, and rebalance tuning.

`korvet.broker.advertised-host`

Env var: KORVET_BROKER_ADVERTISED_HOST · Type: string

Hostname advertised to clients via the Kafka metadata response. Leave unset (null) to fall back to host, or to localhost when host binds to all interfaces (0.0.0.0); blank/whitespace values are rejected.

`korvet.broker.advertised-port`

Env var: KORVET_BROKER_ADVERTISED_PORT · Type: integer

Port advertised to clients via the Kafka metadata response. Defaults to port when unset.

`korvet.broker.boss-threads`

Env var: KORVET_BROKER_BOSS_THREADS · Type: integer · Default: 1

Netty boss (accept) thread count.

`korvet.broker.cert-file`

Env var: KORVET_BROKER_CERT_FILE · Type: file path

PEM-encoded server certificate (or chain). Required when tls=true.

`korvet.broker.client-auth-required`

Env var: KORVET_BROKER_CLIENT_AUTH_REQUIRED · Type: boolean · Default: false

Require clients to present a certificate (mTLS).

`korvet.broker.enabled`

Env var: KORVET_BROKER_ENABLED · Type: boolean · Default: true

Enable the broker listener.

`korvet.broker.fetch-max-wait`

Env var: KORVET_BROKER_FETCH_MAX_WAIT · Type: duration · Default: 500ms

Maximum time a fetch request will block waiting for fetch.min.bytes to be satisfied.

`korvet.broker.fetch-partition-max-bytes`

Env var: KORVET_BROKER_FETCH_PARTITION_MAX_BYTES · Type: data size · Default: 1MB

Default upper bound on per-partition bytes returned by a fetch.

`korvet.broker.host`

Env var: KORVET_BROKER_HOST · Type: string · Default: 0.0.0.0

Listener host (interface to bind to).

`korvet.broker.id`

Env var: KORVET_BROKER_ID · Type: integer · Default: 0

Numeric broker id advertised to Kafka clients. Must be unique across a multi-node deployment.

`korvet.broker.key-file`

Env var: KORVET_BROKER_KEY_FILE · Type: file path

PEM-encoded server private key. Required when tls=true.

`korvet.broker.key-password`

Env var: KORVET_BROKER_KEY_PASSWORD · Type: secret

Passphrase protecting keyFile, if encrypted.

`korvet.broker.max-pending-bytes`

Env var: KORVET_BROKER_MAX_PENDING_BYTES · Type: data size · Default: 100MB

Backpressure threshold: pause reads from the wire once this many bytes are pending outbound.

`korvet.broker.max-request-bytes`

Env var: KORVET_BROKER_MAX_REQUEST_BYTES · Type: data size · Default: 100MB

Maximum size of a single inbound Kafka request. Requests larger than this are rejected.

`korvet.broker.port`

Env var: KORVET_BROKER_PORT · Type: integer · Default: 9092

Listener TCP port.

`korvet.broker.produce-timeout`

Env var: KORVET_BROKER_PRODUCE_TIMEOUT · Type: duration · Default: 5s

Server-side cap on how long a single partition’s storage write may run before it is surfaced as REQUEST_TIMED_OUT. Because produce responses are sent in request order per connection, a stalled write would otherwise hold the head of the in-order response queue (and every pipelined request behind it) for the client’s full timeoutMs — collapsing throughput on the connection. The effective bound per partition is the smaller of this value and the client-supplied request timeout. Set to zero to disable the server-side cap.

`korvet.broker.rebalance-delay`

Env var: KORVET_BROKER_REBALANCE_DELAY · Type: duration · Default: 3s

Grace period before triggering a consumer-group rebalance after a member joins or leaves.

`korvet.broker.rebalance-threads`

Env var: KORVET_BROKER_REBALANCE_THREADS · Type: integer · Default: max(2, available CPU cores)

Scheduler thread-pool size for the group coordinator.

`korvet.broker.response-queue-timeout`

Env var: KORVET_BROKER_RESPONSE_QUEUE_TIMEOUT · Type: duration · Default: 10s

Upper bound on how long a single request may hold the head of the per-connection, in-order response queue before it is failed with REQUEST_TIMED_OUT. Prevents a request whose handler never completes from stalling every later request on the connection. Fetch requests additionally get their fetchMaxWait long-poll budget on top of this.

`korvet.broker.resume-pending-bytes`

Env var: KORVET_BROKER_RESUME_PENDING_BYTES · Type: data size · Default: 50MB

Backpressure release threshold: resume reads once pending bytes drop below this. Must be < maxPendingBytes.

`korvet.broker.tls`

Env var: KORVET_BROKER_TLS · Type: boolean · Default: false

Enable TLS on the listener. When true, certFile and keyFile are required.

`korvet.broker.trust-cert-file`

Env var: KORVET_BROKER_TRUST_CERT_FILE · Type: file path

PEM-encoded CA trust store for verifying client certificates (mTLS). Required when clientAuthRequired=true.

`korvet.broker.worker-threads`

Env var: KORVET_BROKER_WORKER_THREADS · Type: integer · Default: 0

Netty worker (IO) thread count. 0 lets Netty pick a default based on CPU count.

Acl

`korvet.broker.acl.enabled`

Env var: KORVET_BROKER_ACL_ENABLED · Type: boolean · Default: false

Enable topic ACL enforcement. Requires SASL authentication to be enabled.

Metrics

`korvet.broker.metrics.offset-cardinality-cap`

Env var: KORVET_BROKER_METRICS_OFFSET_CARDINALITY_CAP · Type: integer · Default: 10000

Maximum number of (topic, partition) pairs published as offset gauges. When the live topic-partition count exceeds this cap, the publisher skips the refresh and logs a warning to prevent unbounded time-series cardinality.

`korvet.broker.metrics.offset-refresh-interval`

Env var: KORVET_BROKER_METRICS_OFFSET_REFRESH_INTERVAL · Type: duration · Default: 15s

Interval between refreshes of per-topic-partition offset gauges (korvet.broker.max_offset, korvet.broker.log_start_offset).

Sasl

`korvet.broker.sasl.enabled`

Env var: KORVET_BROKER_SASL_ENABLED · Type: boolean · Default: false

Enable SASL authentication on the listener.

`korvet.broker.sasl.mechanisms`

Env var: KORVET_BROKER_SASL_MECHANISMS · Type: list of string · Default: SCRAM-SHA-256

SASL mechanisms advertised to clients. Must be a non-empty subset of SUPPORTED. Defaults to SCRAM-SHA-256 only — PLAIN must be opted in explicitly and requires TLS.

Redis

Primary Redis client used by the broker, registries, and (unless overridden) storage.

`korvet.redis.cluster`

Env var: KORVET_REDIS_CLUSTER · Type: boolean · Default: false

Treat the target as a Redis Cluster (uses Lettuce RedisClusterClient).

`korvet.redis.host`

Env var: KORVET_REDIS_HOST · Type: string · Default: localhost

Redis host. Ignored when uri is set.

`korvet.redis.io-threads`

Env var: KORVET_REDIS_IO_THREADS · Type: integer · Default: available CPU cores

Size of the Lettuce IO (event-loop) thread pool.

`korvet.redis.password`

Env var: KORVET_REDIS_PASSWORD · Type: secret

Password for AUTH.

`korvet.redis.port`

Env var: KORVET_REDIS_PORT · Type: integer · Default: 6379

Redis port. Ignored when uri is set.

`korvet.redis.timeout`

Env var: KORVET_REDIS_TIMEOUT · Type: duration · Default: 1m

Default per-command timeout.

`korvet.redis.uri`

Env var: KORVET_REDIS_URI · Type: string

Redis URI (redis://… or rediss://…). When set, supersedes host/port/username/password.

`korvet.redis.username`

Env var: KORVET_REDIS_USERNAME · Type: string

Username for ACL authentication. Leave unset for password-only AUTH.

Circuit Breaker

Fail-fast circuit breaker around Redis stream operations on the primary client.

`korvet.redis.circuit-breaker.enabled`

Env var: KORVET_REDIS_CIRCUIT_BREAKER_ENABLED · Type: boolean · Default: true

Enable the stream-operation circuit breaker.

`korvet.redis.circuit-breaker.log-interval`

Env var: KORVET_REDIS_CIRCUIT_BREAKER_LOG_INTERVAL · Type: duration · Default: 30s

Minimum interval between breaker-state log lines (rate-limit for repeated open events).

`korvet.redis.circuit-breaker.open-duration`

Env var: KORVET_REDIS_CIRCUIT_BREAKER_OPEN_DURATION · Type: duration · Default: 30s

How long the breaker stays open before allowing a probe call.

Metrics

Client-side latency metrics published by Lettuce for the primary Redis client.

`korvet.redis.metrics.enabled`

Env var: KORVET_REDIS_METRICS_ENABLED · Type: boolean · Default: false

Enable command-latency metrics collection.

`korvet.redis.metrics.histogram`

Env var: KORVET_REDIS_METRICS_HISTOGRAM · Type: boolean · Default: false

Publish per-command histograms in addition to summary statistics.

`korvet.redis.metrics.local-distinction`

Env var: KORVET_REDIS_METRICS_LOCAL_DISTINCTION · Type: boolean · Default: false

Split metrics by local (client) socket address — useful in pooled deployments.

`korvet.redis.metrics.max-latency`

Env var: KORVET_REDIS_METRICS_MAX_LATENCY · Type: duration · Default: 5m

Upper bound used when bucketing latency samples.

`korvet.redis.metrics.min-latency`

Env var: KORVET_REDIS_METRICS_MIN_LATENCY · Type: duration · Default: 1ms

Lower bound used when bucketing latency samples.

Pool

Connection-pool sizing for the primary Redis client.

`korvet.redis.pool.max-wait`

Env var: KORVET_REDIS_POOL_MAX_WAIT · Type: duration · Default: 3s

Maximum time a caller will block waiting to borrow a connection from a saturated pool.

`korvet.redis.pool.size`

Env var: KORVET_REDIS_POOL_SIZE · Type: integer · Default: 8

Maximum number of pooled connections.

Schema Registry

Embedded Confluent-compatible schema-registry HTTP endpoint.

`korvet.schema-registry.default-compatibility`

Env var: KORVET_SCHEMA_REGISTRY_DEFAULT_COMPATIBILITY · Type: none, backward, backward_transitive, forward, forward_transitive, full, full_transitive · Default: backward

Default compatibility level applied to newly-created subjects.

`korvet.schema-registry.enabled`

Env var: KORVET_SCHEMA_REGISTRY_ENABLED · Type: boolean · Default: true

Enable the embedded schema-registry HTTP endpoint.

`korvet.schema-registry.validate-produce`

Env var: KORVET_SCHEMA_REGISTRY_VALIDATE_PRODUCE · Type: boolean · Default: true

Reject produce requests whose payload doesn’t validate against the subject’s latest schema.

Storage

Storage settings split by tier: a Redis-backed local tier and optional object-store remote tier.

Local

Redis-backed local tier settings.

Compression

`korvet.storage.local.compression.codec`

Env var: KORVET_STORAGE_LOCAL_COMPRESSION_CODEC · Type: none, gzip, snappy, lz4, zstd · Default: none

Default compression codec for values at rest in Redis, applied to topics that do not pin their own storage.compression.type at creation. none stores values uncompressed and directly readable; any other codec compresses the value into its standard frame format. Compression trades codec CPU for lower Redis I/O and memory usage. Use zstd for JSON/log storage efficiency, snappy when CPU cost matters more, and none when payloads must stay directly readable from Redis or are random/already compressed. Values: none, gzip, snappy, lz4, zstd.

Redis

Sparse overrides for the local storage Redis client. Each unset field inherits the corresponding value from korvet.redis.

`korvet.storage.local.redis.cluster`

Env var: KORVET_STORAGE_LOCAL_REDIS_CLUSTER · Type: boolean

Treat the storage Redis target as a Redis Cluster.

`korvet.storage.local.redis.host`

Env var: KORVET_STORAGE_LOCAL_REDIS_HOST · Type: string

Storage Redis host. Ignored when uri is set.

`korvet.storage.local.redis.io-threads`

Env var: KORVET_STORAGE_LOCAL_REDIS_IO_THREADS · Type: integer

Storage Redis Lettuce IO thread-pool size.

`korvet.storage.local.redis.password`

Env var: KORVET_STORAGE_LOCAL_REDIS_PASSWORD · Type: secret

Storage Redis password.

`korvet.storage.local.redis.port`

Env var: KORVET_STORAGE_LOCAL_REDIS_PORT · Type: integer

Storage Redis port. Ignored when uri is set.

`korvet.storage.local.redis.timeout`

Env var: KORVET_STORAGE_LOCAL_REDIS_TIMEOUT · Type: duration

Storage Redis per-command timeout.

`korvet.storage.local.redis.uri`

Env var: KORVET_STORAGE_LOCAL_REDIS_URI · Type: string

Storage Redis URI. When set, overrides the primary Redis URI for storage traffic.

`korvet.storage.local.redis.username`

Env var: KORVET_STORAGE_LOCAL_REDIS_USERNAME · Type: string

Storage Redis ACL username.

Circuit Breaker

Sparse circuit-breaker overrides for the local storage Redis client.

`korvet.storage.local.redis.circuit-breaker.enabled`

Env var: KORVET_STORAGE_LOCAL_REDIS_CIRCUIT_BREAKER_ENABLED · Type: boolean

Enable the storage Redis stream-operation circuit breaker.

`korvet.storage.local.redis.circuit-breaker.log-interval`

Env var: KORVET_STORAGE_LOCAL_REDIS_CIRCUIT_BREAKER_LOG_INTERVAL · Type: duration

Minimum interval between storage Redis breaker-state log lines.

`korvet.storage.local.redis.circuit-breaker.open-duration`

Env var: KORVET_STORAGE_LOCAL_REDIS_CIRCUIT_BREAKER_OPEN_DURATION · Type: duration

How long the storage Redis circuit breaker stays open before allowing a probe call.

Metrics

Sparse metrics overrides for the local storage Redis client.

`korvet.storage.local.redis.metrics.enabled`

Env var: KORVET_STORAGE_LOCAL_REDIS_METRICS_ENABLED · Type: boolean

Enable command-latency metrics for the storage Redis client.

`korvet.storage.local.redis.metrics.histogram`

Env var: KORVET_STORAGE_LOCAL_REDIS_METRICS_HISTOGRAM · Type: boolean

Publish per-command histograms for the storage Redis client.

`korvet.storage.local.redis.metrics.local-distinction`

Env var: KORVET_STORAGE_LOCAL_REDIS_METRICS_LOCAL_DISTINCTION · Type: boolean

Split storage Redis metrics by local socket address.

`korvet.storage.local.redis.metrics.max-latency`

Env var: KORVET_STORAGE_LOCAL_REDIS_METRICS_MAX_LATENCY · Type: duration

Upper bound used when bucketing storage Redis latency samples.

`korvet.storage.local.redis.metrics.min-latency`

Env var: KORVET_STORAGE_LOCAL_REDIS_METRICS_MIN_LATENCY · Type: duration

Lower bound used when bucketing storage Redis latency samples.

Pool

Sparse pool overrides for the local storage Redis client.

`korvet.storage.local.redis.pool.max-wait`

Env var: KORVET_STORAGE_LOCAL_REDIS_POOL_MAX_WAIT · Type: duration

Maximum time a caller will block waiting to borrow a storage Redis connection.

`korvet.storage.local.redis.pool.size`

Env var: KORVET_STORAGE_LOCAL_REDIS_POOL_SIZE · Type: integer

Maximum number of pooled storage Redis connections.

Write

`korvet.storage.local.write.connections`

Env var: KORVET_STORAGE_LOCAL_WRITE_CONNECTIONS · Type: integer · Default: 8

Number of dedicated Redis connections the produce write path is sharded across, routed by stream key. Each Lettuce connection is pinned to a single event loop thread, so this bounds how many cores one broker’s write path can use (issue #885).

Remote

Optional object-store remote tier settings.

`korvet.storage.remote.path`

Env var: KORVET_STORAGE_REMOTE_PATH · Type: string

Object-store path for the remote Iceberg table (e.g. s3://bucket/korvet/cold). Absent/blank disables the remote tier — Korvet runs local-only on Redis Streams.

Iceberg

`korvet.storage.remote.iceberg.row-group-size`

Env var: KORVET_STORAGE_REMOTE_ICEBERG_ROW_GROUP_SIZE · Type: data size · Default: 128MB

Parquet row-group size for Iceberg data files written by the remote segment store. Maps to Iceberg write.parquet.row-group-size-bytes.

`korvet.storage.remote.iceberg.target-file-size`

Env var: KORVET_STORAGE_REMOTE_ICEBERG_TARGET_FILE_SIZE · Type: data size · Default: 128MB

Target size for Iceberg data files written by the remote segment store. Maps to Iceberg write.target-file-size-bytes.

Metrics

`korvet.storage.remote.metrics.common-tags`

Env var: KORVET_STORAGE_REMOTE_METRICS_COMMON_TAGS · Type: map · Default: [:]

Extra tags attached to remote-tier Iceberg and object-storage SDK meters.

`korvet.storage.remote.metrics.enabled`

Env var: KORVET_STORAGE_REMOTE_METRICS_ENABLED · Type: boolean · Default: true

Enable Iceberg and object-storage SDK metrics for the remote tier when a Micrometer MeterRegistry is available.

S3

S3 connection settings for the remote tier object store. Only consulted when korvet.storage.remote.path starts with s3://.

`korvet.storage.remote.s3.access-key-id`

Env var: KORVET_STORAGE_REMOTE_S3_ACCESS_KEY_ID · Type: string

Access-key id. Maps to Iceberg s3.access-key-id.

`korvet.storage.remote.s3.endpoint`

Env var: KORVET_STORAGE_REMOTE_S3_ENDPOINT · Type: string

Optional endpoint URL for non-AWS S3-compatible stores (e.g. MinIO). Maps to s3.endpoint.

`korvet.storage.remote.s3.path-style-access`

Env var: KORVET_STORAGE_REMOTE_S3_PATH_STYLE_ACCESS · Type: boolean

Use path-style addressing instead of the default virtual-hosted-style. Maps to s3.path-style-access. Required for most non-AWS S3 stores.

`korvet.storage.remote.s3.region`

Env var: KORVET_STORAGE_REMOTE_S3_REGION · Type: string

AWS region (e.g. us-east-1). Maps to Iceberg client.region.

`korvet.storage.remote.s3.secret-access-key`

Env var: KORVET_STORAGE_REMOTE_S3_SECRET_ACCESS_KEY · Type: secret

Secret access key. Maps to s3.secret-access-key.

Worker

Storage worker: leader-locked periodic task that rolls eligible segments, offloads sealed segments, and enforces local and remote retention.

`korvet.storage.worker.enabled`

Env var: KORVET_STORAGE_WORKER_ENABLED · Type: boolean · Default: true

Enable the storage worker. The Redis leader lock ensures at most one enabled instance runs at a time across the cluster.

`korvet.storage.worker.lease-duration`

Env var: KORVET_STORAGE_WORKER_LEASE_DURATION · Type: duration · Default: 2m

Redis leader-lock lease duration. Must exceed tickInterval so a slow tick does not let the lease expire mid-flight.

`korvet.storage.worker.tick-interval`

Env var: KORVET_STORAGE_WORKER_TICK_INTERVAL · Type: duration · Default: 1m

Tick cadence for the storage worker loop.

Ui

`korvet.ui.enabled`

Env var: KORVET_UI_ENABLED · Type: boolean · Default: true

Whether the embedded SPA is served. Defaults to true.

Topic configuration patterns

The korvet.topics list is order-sensitive: each entry is a glob pattern plus optional field overrides, evaluated top-to-bottom with first-non-null-wins semantics. Fields not set by any matching pattern fall back to the built-in defaults. Per-topic admin-set overrides beat patterns.

The per-element fields (korvet.topics[n].partitions, compression, etc.) live on TopicPattern in korvet-server and are not enumerated in the tables above. The full list:

name (required) — glob pattern matched against topic names.
auto-create — whether unknown topics matching this pattern may be auto-created.
partitions, offset-sequence-bits
compression, remote-storage-enabled
retention-time, retention-bytes (*-bytes accepts data sizes such as 10GB)
local-retention-time, local-retention-bytes (*-bytes accepts data sizes such as 512MB)
segment-time, segment-bytes (*-bytes accepts data sizes such as 64MB)

As environment variables, list entries are addressed by index: korvet.topics[0].retention-time becomes KORVET_TOPICS_0_RETENTION_TIME, korvet.topics[1].auto-create becomes KORVET_TOPICS_1_AUTO_CREATE, and so on. Each indexed entry needs at least KORVET_TOPICS_<n>_NAME.

See the configuration guide for examples.

Environment variables

Every property can be set via an environment variable using Spring Boot’s relaxed binding: uppercase the property name, replace . and - with _. For example:

Property Environment variable

Property	Environment variable
`korvet.broker.max-request-bytes`	`KORVET_BROKER_MAX_REQUEST_BYTES`
`korvet.storage.remote.path`	`KORVET_STORAGE_REMOTE_PATH`
`korvet.storage.worker.enabled`	`KORVET_STORAGE_WORKER_ENABLED`

korvet.broker.max-request-bytes

KORVET_BROKER_MAX_REQUEST_BYTES

korvet.storage.remote.path

KORVET_STORAGE_REMOTE_PATH

korvet.storage.worker.enabled

KORVET_STORAGE_WORKER_ENABLED

The exact env-var name for every property is listed in the tables above. For the korvet.topics pattern list, entries are addressed by index, e.g. KORVET_TOPICS_0_NAME and KORVET_TOPICS_0_PARTITIONS.