ReductStore Settings

ReductStore can be configured using environment variables. The following sections describe the available settings and how to use them.

Remote Backend Settings

ReductStore supports using a remote object storage as a backend to store data. You can configure the remote backend using the following environment variables:

Name	Default	Description
RS_REMOTE_BACKEND_TYPE	File system	If it is set to S3, the storage uses an S3-compatible object storage as a backend
RS_REMOTE_ENDPOINT		URL of the S3-compatible object storage endpoint. It's ignored for the AWS S3 service.
RS_REMOTE_REGION		Region of the S3-compatible object storage. It's ignored for on-premises storage like MinIO.
RS_REMOTE_ACCESS_KEY		Access key for the S3-compatible object storage. Set it together with RS_REMOTE_SECRET_KEY, or leave both unset to use the default AWS credential provider chain.
RS_REMOTE_SECRET_KEY		Secret key for the S3-compatible object storage. Set it together with RS_REMOTE_ACCESS_KEY, or leave both unset to use the default AWS credential provider chain.
RS_REMOTE_SESSION_TOKEN		Optional session token for temporary S3 credentials. Use it together with RS_REMOTE_ACCESS_KEY and RS_REMOTE_SECRET_KEY.
RS_REMOTE_BUCKET		Name of the bucket to store data. The bucket must be created before starting ReductStore.
RS_REMOTE_CACHE_PATH		Path to a folder where the storage caches data before uploading it to the remote backend.
RS_REMOTE_CACHE_SIZE	1GB	Maximum size of the cache folder. When the limit is reached, the oldest data is removed.
RS_REMOTE_SYNC_INTERVAL	0.1, 60 for S3	Synchronization interval with the remote backend in seconds.
RS_REMOTE_DEFAULT_STORAGE_CLASS	STANDARD	Default storage class for data blocks. See the list of supported S3 storage classes.

By default, ReductStore uses the local file system to store data. To use a remote backend, set the RS_REMOTE_BACKEND_TYPE variable to S3 and configure the other variables accordingly. When the remote backend is enabled, ReductStore caches data in the folder specified by the RS_REMOTE_CACHE_PATH variable, thereby reducing the number of requests made to the remote backend. The RS_DATA_PATH variable is ignored when the remote backend is enabled.

Default AWS Credentials

For Amazon S3, you can omit RS_REMOTE_ACCESS_KEY and RS_REMOTE_SECRET_KEY entirely and let the AWS SDK resolve credentials from its default provider chain. In this case, you can use any supported authentication method (e.g., environment variables starting with AWS_, EC2 instance roles, or ECS task roles) without needing to configure ReductStore specifically for AWS.

For end-to-end deployment examples (standalone, active-passive, and read-only replicas) using S3, see the S3 integration guide.

Supported S3 Storage Classes

A user can specify default storage class for data blocks stored in the S3-compatible object storage using the RS_REMOTE_DEFAULT_STORAGE_CLASS environment variable. The following storage classes are supported:

Name	Description
STANDARD	Standard storage class. Suitable for frequently accessed data.
STANDARD_IA	Standard-Infrequent Access storage class. Suitable for data that is infrequently accessed but requires rapid access when needed.
INTELLIGENT_TIERING	Intelligent-Tiering storage class. Automatically moves data to the most cost-effective access tier based on usage patterns.
ONEZONE_IA	One Zone-Infrequent Access storage class. Suitable for data that is infrequently accessed and stored in a single availability zone.
EXPRESS_ONEZONE	Express-One Zone storage class. Suitable for data that requires low latency access and is stored in a single availability zone.
GLACIER_IR	Glacier Instant Retrieval storage class. Suitable for data that is rarely accessed and requires immediate access when needed.
GLACIER	Glacier storage class. Suitable for data that is rarely accessed and can be retrieved within a few hours.
DEEP_ARCHIVE	Deep Archive storage class. Suitable for data that is rarely accessed and can be retrieved within 12 hours.
OUTPOSTS	Outposts storage class. Suitable for data that needs to be stored on AWS Outposts.

For more information about S3 storage classes, see the Amazon S3 Storage Classes documentation.

Zenoh API Settings

ReductStore includes an optional Zenoh API that lets you ingest and retrieve data using the Zenoh pub/sub and query protocol alongside the existing HTTP API. The following environment variables configure it:

Name	Default	Description
RS_ZENOH_ENABLED	false	Set to true, 1, yes, or on to enable the Zenoh API
RS_ZENOH_CONFIG		Inline Zenoh session config string, e.g. mode=client;connect/endpoints=[tcp/127.0.0.1:7447]. Takes precedence over RS_ZENOH_CONFIG_PATH
RS_ZENOH_CONFIG_PATH		Path to a Zenoh JSON5 config file
RS_ZENOH_BUCKET	zenoh	Target ReductStore bucket. Created automatically if it does not exist.
RS_ZENOH_SUB_KEYEXPRS		Key expression for the subscriber (write path). Disabled if unset.
RS_ZENOH_QUERY_KEYEXPRS		Key expression for the queryable (read path). Disabled if unset.
RS_ZENOH_QUERY_LOCALITY	Any	Allowed origin for query replies. One of SessionLocal, Remote, or Any.

Inline Zenoh Credentials

When using TLS or user-password authentication with RS_ZENOH_CONFIG, Zenoh normally requires file paths for certificates and dictionaries. These variables let you supply the file contents directly as environment variables instead. This is useful in Docker or Kubernetes environments where mounting files is inconvenient. Each value is written to a temporary file at startup and its path is injected into the Zenoh session config automatically.

Name	Default	Description
RS_ZENOH_TLS_ROOT_CA		PEM content of the root CA certificate used to verify the Zenoh router or peer (transport/link/tls/root_ca_certificate)
RS_ZENOH_TLS_CONNECT_CERT		PEM content of the client certificate for mutual TLS (transport/link/tls/connect_certificate)
RS_ZENOH_TLS_CONNECT_KEY		PEM content of the client private key for mutual TLS (transport/link/tls/connect_private_key)
RS_ZENOH_AUTH_DICTIONARY		User-password dictionary content, one user:password entry per line (transport/auth/usrpwd/dictionary_file)

For usage examples, deployment patterns, and a full explanation of key expressions, selectors, and encoding, see the Zenoh API integration guide.

I/O Settings

In addition to general settings, you can configure I/O settings to optimize communication over HTTP with the storage engine. The following table describes the available environment variables:

Name	Default	Description
RS_IO_BATCH_MAX_SIZE	8MB	Maximum size of a batch of records sent to the client.
RS_IO_BATCH_MAX_RECORDS	85	Maximum number of records in a batch sent and received from the client.
RS_IO_BATCH_MAX_METADATA_SIZE	8KB	Maximum size of metadata in a batch of records sent and received from the client.
RS_IO_BATCH_TIMEOUT	5	Maximum time in seconds for a batch of records to be prepared and sent to the client. If the batch is not full, it will be sent after the timeout.
RS_IO_BATCH_RECORD_TIMEOUT	1	Maximum time in seconds to wait for a record to be added to a batch. If the record is not added, the unfinished batch will be sent to the client.
RS_IO_OPERATION_TIMEOUT	60	Maximum time in seconds for an I/O operation (e.g., read or write). If the operation takes longer, it will be aborted.

Most of the I/O settings are related to batching and specify the size of the batch, the number of records in the batch, and the timeout for preparing and sending the batch on the server side.

However, if a client is using the HTTP/1.1 protocol, the RS_IO_BATCH_MAX_METADATA_SIZE and RS_IO_BATCH_MAX_RECORDS settings are used to limit the size of the headers in the HTTP request from the client. This means that the client can't send more records in a single batch than specified by the RS_IO_BATCH_MAX_RECORDS and the size of the headers in the request can't exceed the value of the RS_IO_BATCH_MAX_METADATA_SIZE setting.

Read more about batching in the HTTP API Reference.

Lock File Settings

ReductStore uses a lock file to prevent multiple instances from accessing the same data folder. The lock file is created in the data folder specified by the RS_DATA_PATH variable, using the same storage backend as the data. You can configure the lock file settings using the following environment variables:

Name	Default	Description
RS_LOCK_FILE_POLLING_INTERVAL	10	Interval in seconds between attempts to acquire the lock file or rewrite the acquired lock file to update its timestamp.
RS_LOCK_FILE_TTL	30	Time-to-live in seconds for the lock file. If the lock file is not updated within the TTL, it is considered stale and can be overwritten by another instance.
RS_LOCK_FILE_TIMEOUT	60	Timeout in seconds for acquiring the lock file. If the lock file is not acquired within the timeout, the storage will exit. When set to 0, the storage will wait indefinitely.
RS_LOCK_FILE_FAILURE_ACTION	abort	Action to take if the lock file can't be acquired. It can be abort or proceed. If set to abort, the storage will exit. If set to proceed, the storage will overwrite the lock file and continue.

The lock file is enabled when the RS_INSTANCE_ROLE variable is set to PRIMARY or SECONDARY. If the variable is not set, the lock file mechanism is disabled.

Storage Engine Settings

A user can configure storage engine settings to change behavior of data storage and retrieval. The following table describes the available environment variables:

Name	Default	Description
RS_ENGINE_COMPACTION_INTERVAL	60	Interval in seconds between compaction WALs into blocks and synchronization of the storage state to the backend.
RS_ENGINE_REPLICA_UPDATE_INTERVAL	60	Interval in seconds between updates of bucket, entry lists and indexes from the backend in the read-only mode.
RS_ENGINE_ENABLE_INTEGRITY_CHECKS	true	If set to false, the storage engine skips integrity checks at startup to improve performance.

Replication Settings

ReductStore supports data replication between different instances. You can configure replication settings using the following environment variables:

Name	Default	Description
RS_REPLICATION_TIMEOUT	5	Timeout in seconds for attempts to reconnect to the target server.
RS_REPLICATION_LOG_SIZE	1000000	Maximum number of pending records in the replication log. The oldest records are overwritten when the limit is reached.