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title: 'Runtime' sidebar_label: 'Runtime' description: 'Runtime YAML reference'

The runtime section specifies configuration settings for the Spice runtime.

runtime.auth

runtime.auth.api-key

Spice supports adding optional authentication to its API endpoints via configurable API keys. Learn more.

API key authentication supports the following configuration parameters:

Parameter name	Optional	Default	Description
enabled	Yes	false	Defaults to false. Whether API key authentication is enabled
keys	Yes	[]	A list of API keys used to authenticate requests.

runtime.dataset_load_parallelism

This setting specifies the maximum number of datasets that can be loaded in parallel during startup. By default, the number of parallel datasets is unlimited.

runtime.caching

This setting specifies cache settings for supported Runtime components:

• sql_results: Specifies cache settings for results from SQL queries.
• search_results: Specifies cache settings for results from searches.
• embeddings: Specifies cache settings for embeddings requests.

Runtime caches support common configuration parameters:

Parameter name	Optional	Default	Description
enabled	Yes	true	Defaults to true.
max_size	Yes	128MiB	Maximum cache size. Defaults to 128MiB.
eviction_policy	Yes	lru	Cache replacement policy when the cache reaches max_size. Defaults to lru. Supports lru (Least Recently Used) and tiny_lfu (Tiny Least Frequently Used, higher hit rate for skewed access patterns).
item_ttl	Yes	1s	Cache entry expiration duration (Time to Live). Defaults to 1 second.
hashing_algorithm

runtime.caching.search_results

The search results cache section specifies runtime search cache configuration. Learn more.

The search results cache supports the common cache configuration parameters.

runtime.caching.embeddings

The embeddings cache section specifies runtime embeddings requests cache configuration. Learn more.

The embeddings cache supports the common cache configuration parameters.

runtime.caching.sql_results

The SQL results cache section specifies runtime SQL query cache configuration. Learn more.

In addition to the common cache configuration parameters, sql_results also supports the following parameters:

Parameter name	Optional	Default	Description
cache_key_type	Yes	plan	Determines how cache keys are generated. Defaults to plan. plan uses the query's logical plan, while sql uses the raw SQL query string.
encoding	Yes	none	Compression algorithm for cached results. Defaults to none. Supports none or zstd.
stale_while_revalidate_ttl	Yes	0s	Duration to serve stale cache entries while revalidating in the background. When set to a non-zero value, expired cache entries continue to be served while a background refresh occurs. Defaults to 0s (disabled).

:::info

runtime.results_cache has been deprecated and will be removed in a future release. If runtime.results_cache is specifed in the spicepod it will override the runtime.caching.sql_results settings if it is not defined.

:::

Choosing a cache_key_type

• plan (Default): Uses the query's logical plan as the cache key. Matches semantically equivalent queries but requires query parsing.
• sql: Uses the raw SQL string as the cache key. Provides faster lookups but requires exact string matches. Queries with dynamic functions, such as NOW(), may produce unexpected results. Use sql only when results are predictable.

Use sql for the lowest latency with identical queries that do not include dynamic functions. Use plan for greater flexibility.

Choosing a hashing_algorithm

• xxh3 (Default): Uses the XXH3 algorithm for hashing the cache keys. XXH3 is a fast, non-cryptographic hash algorithm that provides high performance and good distribution. It is suitable for scenarios where speed is critical and cryptographic security is not required.
• siphash: Uses the SipHash1-3 algorithm for hashing the cache keys, the default hashing algorithm of Rust. This hashing algorithm is a secure algorithm that implements verified protections against "hash flooding" denial of service (DoS) attacks. Reasonably performant, and provides a high level of security.
• ahash: Uses the AHash algorithm for hashing the cache keys. The AHash algorithm is a high quality hashing algorithm, and has claimed resistance against hashing DoS attacks. AHash has higher performance than SipHash1-3, especially when used with cache_key_type: plan.
• blake3: Uses the BLAKE3 cryptographic hash function. BLAKE3 is a fast, parallelizable hash function that provides cryptographic security while maintaining high performance. It is suitable for scenarios requiring both speed and cryptographic guarantees.
• xxh32, xxh64, : Variants of the XXH hashing algorithm with different output sizes. These algorithms offer a balance between speed and collision resistance, with larger hash sizes providing better collision resistance at the cost of performance.

Use xxh3 (the default) for its superior speed in most scenarios. Use ahash, xxh64 or xxh128 for reduced collision probability when caching a large number of queries. Use blake3 when cryptographic security is required. Use siphash when protection against hash flooding attacks is a priority.

runtime.shutdown_timeout

Controls how long Spice waits for connections to be gracefully drained and for components to shut down cleanly during runtime termination. Defaults to 30 seconds.

runtime.tls

The TLS section specifies the configuration for enabling Transport Layer Security (TLS) for all endpoints exposed by the runtime. Learn more about enabling TLS.

In addition to configuring TLS via the manifest, TLS can also be configured via spiced command line arguments using the --tls-enabled true flag along with --tls-certificate/--tls-certificate-file and --tls-key/--tls-key-file.

runtime.tls.enabled

Enables or disables TLS for the runtime endpoints.

runtime.tls.certificate

The TLS certificate to use for securing the runtime endpoints. The certificate can also come from secrets.

runtime.tls.certificate_file

The path to the TLS PEM-encoded certificate file. Only one of certificate or certificate_file must be used.

runtime.tls.key

The TLS key to use for securing the runtime endpoints. The key can also come from secrets.

runtime.tls.key_file

The path to the TLS PEM-encoded key file. Only one of key or key_file must be used.

runtime.task_history

The task history section specifies runtime task history configuration. For more details, see the Task History documentation.

Parameter name	Optional	Description
enabled	Yes	Defaults to true.
captured_output	Yes	Specifies the level of output captured by the task history table. Defaults to none.
captured_plan	Yes	Controls SQL query plan capture. Options: none (default), explain, or explain analyze. Query plans are captured asynchronously after query completion.
min_sql_duration	Yes	Minimum query execution duration before a plan is captured. Only queries exceeding this threshold are captured. Example: 5s.
min_plan_duration	Yes	Minimum plan execution duration before a plan is captured. This threshold applies to the execution time of the EXPLAIN operation itself. Example: 10s.
retention_period

runtime.cors

The CORS section specifies the configuration for enabling Cross-Origin Resource Sharing (CORS) for the HTTP endpoint. By default, CORS is disabled.

Default configuration:

runtime.cors.enabled

Enables or disables CORS for the HTTP endpoint. Defaults to false.

runtime.cors.allowed_origins

A list of allowed origins for CORS requests. Defaults to ["*"], which permits all origins.

Example:

This configuration permits requests only from the https://example.com origin.

runtime.query.memory_limit

The memory_limit parameter sets a memory usage cap for the Spice runtime query engine. This limit applies only to the query engine and should be used in addition to other memory configuration options, such as duckdb_memory_limit. When memory_limit is specified, the value of runtime.query.temp_directory determines the directory DataFusion uses for spilling intermediate data to disk.

Specify the value as a size, for example 4GiB or 1024MiB.

For detailed memory information, see Memory.

runtime.query.spill_compression

The spill_compression parameter configures compression for spill files generated during large query execution in the Spice runtime.

Supported values:

• zstd (default): Enables high compression ratios for spill files, reducing disk usage but with moderate (de)compression speed.
• lz4_frame: Provides faster (de)compression, resulting in larger spill files and potentially higher disk usage.
• uncompressed: Disables compression. Spill files will be the largest, but with no (de)compression overhead.

This setting controls the trade-off between disk space usage and query performance for large-scale analytics workloads.

runtime.query.temp_directory

The path to a temporary directory that Spice uses for query and acceleration operations that spill to disk. For more details, see the Managing Memory Usage documentation and the DuckDB Data Accelerator documentation.

runtime.output_level

Controls verbosity in addition to the existing CLI and environment variable support.. Supported values are info, verbose, and very_verbose. The value is applied in the following priority: CLI, environment variables, then YAML configuration.

runtime.telemetry

The telemetry section configures runtime telemetry collection and export. Learn more.

runtime.telemetry.enabled

Enables or disables runtime telemetry collection. Defaults to true.

runtime.telemetry.otel_exporter

Configures an OpenTelemetry metrics exporter to push metrics to an OpenTelemetry collector. The exporter automatically infers the protocol (gRPC or HTTP) based on the endpoint configuration.

Parameter name	Optional	Default	Description
enabled	Yes	true	Whether the OpenTelemetry exporter is enabled.
endpoint	No	-	The OpenTelemetry collector endpoint. Protocol is inferred from the format (see examples below).
push_interval	Yes	60s	How frequently metrics are pushed to the collector. Specify as a duration.
metrics	Yes	[]	List of metric names to export. When empty (default), all metrics are exported.

Protocol inference:

• gRPC (default): Use a bare host:port endpoint without a scheme (e.g., localhost:4317). gRPC uses port 4317 by default.
• HTTP: Include the http:// or https:// scheme and the /v1/metrics path (e.g., http://localhost:4318/v1/metrics). HTTP uses port 4318 by default.

Examples:

gRPC configuration:

HTTP configuration:

With metric filtering (export only specific metrics):

runtime.metrics

Specifies metrics that are disabled by default.

Following metrics are disabled by default:

• dataset_acceleration_max_timestamp_before_refresh_ms
• dataset_acceleration_max_timestamp_after_refresh_ms
• dataset_acceleration_refresh_lag_ms
• dataset_acceleration_ingestion_lag_ms

For details about these metrics, see Observability.

runtime.flight

Configures Arrow Flight protocol settings for the runtime.

Parameter name	Optional	Default	Description
max_message_size	Yes	-	Maximum size of a single Arrow Flight message.
do_put_rate_limit_enabled	Yes	true	Whether rate limiting is applied to DoPut Arrow Flight operations.

runtime.ready_state

Controls when the runtime readiness probe (/v1/ready) reports the runtime as ready. This is particularly useful for Kubernetes readiness probes.

Value	Description
on_load (default)	The runtime reports ready after all components (datasets, models, etc.) have loaded successfully.
on_registration	The runtime reports ready as soon as all components have been registered, before they finish loading.

runtime.scheduler

Configures the cluster scheduler when running Spice in cluster mode. This section is relevant only when using --role scheduler.

Parameter name	Optional	Default	Description
state_location	No	-	Root URI for shared cluster state storage (e.g. s3://bucket/path/).
params	Yes	-	Object store parameters (e.g. aws_region).
partition_management.interval	Yes	30s	How often the scheduler runs partition assignment cycles.
partition_management.max_assignments_per_cycle	Yes	100	Maximum number of partition assignments per cycle.
partition_management.max_partitions_per_executor	Yes	1000	Maximum number of partitions assigned to a single executor.
partition_management.discovery_timeout	Yes	60s	How long the scheduler waits for executor discovery before timing out.