Configuration

Arneb loads configuration from three sources with the following precedence (highest wins):

1. CLI arguments (--port, --config, --role)
2. Environment variables (ARNEB_PORT, ARNEB_BIND_ADDRESS, etc.)
3. Configuration file (arneb.toml)
4. Built-in defaults

Configuration File

By default, Arneb looks for arneb.toml in the current directory. Specify a different path with:

cargo run --bin arneb -- --config /path/to/config.toml

Server Settings

Field	Type	Default	Env Var	Description
bind_address	string	"127.0.0.1"	ARNEB_BIND_ADDRESS	Address to bind the server to
port	integer	5432	ARNEB_PORT	PostgreSQL wire protocol port
max_worker_threads	integer	(CPU count)	ARNEB_MAX_WORKER_THREADS	Maximum worker threads for query execution
max_memory_mb	integer	(system dependent)	ARNEB_MAX_MEMORY_MB	Maximum memory in MB

Ports

Service	Port	Roles
pgwire (PostgreSQL protocol)	port	standalone, coordinator
Web UI	port + 1000	standalone, coordinator
Flight RPC	9090	all roles

Table Registration

Register tables directly in the config file:

[[tables]]
name = "lineitem"
path = "/data/lineitem.parquet"
format = "parquet"

[[tables]]
name = "orders"
path = "/data/orders.csv"
format = "csv"

Field	Type	Required	Description
name	string	yes	Table name used in SQL queries
path	string	yes	File path (local or remote s3://, gs://, az://)
format	string	yes	File format: "parquet" or "csv"

Object Store Configuration

S3

[storage.s3]
region = "us-east-1"
endpoint = "http://localhost:9000"   # For MinIO/LocalStack; omit for AWS
allow_http = true                     # Required when endpoint uses HTTP
# access_key_id = "minioadmin"       # Optional: falls back to env/IAM
# secret_access_key = "minioadmin"

Credential precedence: config file → AWS_ACCESS_KEY_ID / AWS_SECRET_ACCESS_KEY env vars → IAM role / instance profile.

GCS

[storage.gcs]
service_account_path = "/path/to/service-account.json"

Catalog Configuration

Register external catalogs (e.g., Hive Metastore):

[[catalogs]]
name = "datalake"
type = "hive"
metastore_uri = "127.0.0.1:9083"
default_schema = "default"

# Per-catalog storage override (merges with global [storage])
[catalogs.storage.s3]
region = "us-east-1"
endpoint = "http://localhost:9000"
allow_http = true

Field	Type	Required	Description
name	string	yes	Catalog name (used as first part of catalog.schema.table)
type	string	yes	Catalog type (currently "hive")
metastore_uri	string	yes	host:port of the Hive Metastore (no scheme prefix)
default_schema	string	no	Default schema within the catalog

Cluster Configuration

For distributed mode (worker nodes):

[cluster]
rpc_port = 9091
coordinator_address = "127.0.0.1:9090"
worker_id = "worker-1"

Field	Type	Required	Description
rpc_port	integer	yes	Flight RPC port for this worker
coordinator_address	string	yes	host:port of the coordinator's Flight RPC
worker_id	string	yes	Unique identifier for this worker

See Distributed Mode for full setup instructions.

CLI Arguments

arneb [OPTIONS]

Options:
  --config <PATH>    Path to configuration file
  --port <PORT>      Override the pgwire port
  --role <ROLE>      Server role: standalone, coordinator, or worker

Example: Standalone with Local Files

bind_address = "127.0.0.1"
port = 5432

[[tables]]
name = "lineitem"
path = "/data/tpch/lineitem.parquet"
format = "parquet"

[[tables]]
name = "orders"
path = "/data/tpch/orders.parquet"
format = "parquet"

Example: Distributed with Hive Catalog

bind_address = "0.0.0.0"
port = 5432

[storage.s3]
region = "us-east-1"
endpoint = "http://minio:9000"
allow_http = true

[[catalogs]]
name = "datalake"
type = "hive"
metastore_uri = "hive-metastore:9083"
default_schema = "default"

[catalogs.storage.s3]
region = "us-east-1"
endpoint = "http://minio:9000"
allow_http = true