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Configuration: malloy-config.json

VSCode document

Both the VS Code Extension and the Malloy CLI use a malloy-config.json file to configure database connections. This page documents the shared file format, connection types, and environment variable options.

Config File Format

The file contains a connections object where each key is a connection name and each value specifies the connection type and its parameters. The first connection listed is the default.

{
  "connections": {
    "my_duckdb": {
      "is": "duckdb",
      "databasePath": "./data.db"
    },
    "my_bq": {
      "is": "bigquery",
      "projectId": "my-project"
    }
  }
}

The is field identifies the connection type. All other fields are type-specific parameters documented below.

Where the config file lives

  • VS Code Extension — place malloy-config.json in your workspace root. The extension detects it automatically and picks up changes on save. In multi-root workspaces, each root can have its own file. You can also set a global fallback directory via the malloy.globalConfigDirectory setting (e.g. ~/.config/malloy) — this is used when no workspace config file exists.

  • Malloy CLI — ~/.config/malloy/malloy-config.json. See the CLI setup for details.

Connection Types

duckdb — DuckDB / MotherDuck

Parameter Type Description
databasePath file Path to .db file (default: :memory:)
workingDirectory string Working directory for relative paths
motherDuckToken secret MotherDuck auth token. Default: {env: "MOTHERDUCK_TOKEN"}
additionalExtensions string Comma-separated DuckDB extensions to load (e.g. "spatial,fts"). Built-in: json, httpfs, icu
readOnly boolean Open database read-only
setupSQL text Connection setup SQL (see below)

bigquery — Google BigQuery

Parameter Type Description
projectId string GCP project ID
serviceAccountKeyPath file Path to service account JSON key
location string Dataset location
maximumBytesBilled string Byte billing cap
timeoutMs string Query timeout in ms
billingProjectId string Billing project (if different)
setupSQL text Connection setup SQL (see below)

postgres — PostgreSQL

Parameter Type Description
host string Server host
port number Server port
username string Username
password password Password
databaseName string Database name
connectionString string Full connection string (alternative)
setupSQL text Connection setup SQL (see below)

mysql — MySQL

Parameter Type Description
host string Server host. Default: {env: "MYSQL_HOST"}
port number Server port. Default: {env: "MYSQL_PORT"} or 3306
database string Database name. Default: {env: "MYSQL_DATABASE"}
user string Username. Default: {env: "MYSQL_USER"}
password password Password. Default: {env: "MYSQL_PASSWORD"}
setupSQL text Connection setup SQL (see below)

snowflake — Snowflake

Parameter Type Description
account string Snowflake account identifier (required). Default: {env: "SNOWFLAKE_ACCOUNT"}
username string Username. Default: {env: "SNOWFLAKE_USER"}
password password Password. Default: {env: "SNOWFLAKE_PASSWORD"}
role string Role
warehouse string Warehouse. Default: {env: "SNOWFLAKE_WAREHOUSE"}
database string Database. Default: {env: "SNOWFLAKE_DATABASE"}
schema string Schema. Default: {env: "SNOWFLAKE_SCHEMA"}
privateKeyPath file Path to private key (.pem/.key)
privateKeyPass password Private key passphrase
timeoutMs number Query timeout in ms
setupSQL text Connection setup SQL (see below)

Snowflake also supports TOML configuration at ~/.snowflake/connections.toml. See Snowflake connection configuration for details.

trino — Trino

Parameter Type Description
server string Server hostname. Default: {env: "TRINO_SERVER"}
port number Server port
catalog string Catalog name. Default: {env: "TRINO_CATALOG"}
schema string Schema name. Default: {env: "TRINO_SCHEMA"}
user string Username. Default: {env: "TRINO_USER"}
password password Password. Default: {env: "TRINO_PASSWORD"}
setupSQL text Connection setup SQL (see below)

presto — Presto

Parameter Type Description
server string Server hostname. Default: {env: "PRESTO_HOST"}
port number Server port (default: 8080). Default: {env: "PRESTO_PORT"}
catalog string Catalog name. Default: {env: "PRESTO_CATALOG"}
schema string Schema name. Default: {env: "PRESTO_SCHEMA"}
user string Username. Default: {env: "PRESTO_USER"}
password password Password. Default: {env: "PRESTO_PASSWORD"}
setupSQL text Connection setup SQL (see below)

Setup SQL

All connection types support a setupSQL parameter. This is a multi-line text field containing SQL statements to execute each time the connection is established.

Each statement must end with ; at the end of a line. Statements can span multiple lines. Only one statement-ending ; is allowed per line.

Legal — each statement ends with ; on its own line:

SET search_path TO analytics;
CREATE TEMP TABLE foo
  AS SELECT 1;

Illegal — two statements on the same line:

SET search_path TO analytics; CREATE TEMP TABLE foo AS SELECT 1;

Environment Variables

Any property value can be replaced with an environment variable reference. This is especially useful for sensitive values like passwords and API tokens, so they don't need to appear directly in your config file:

{
  "connections": {
    "my_motherduck": {
      "is": "duckdb",
      "databasePath": "md:my_database",
      "motherDuckToken": {"env": "MOTHERDUCK_TOKEN"}
    },
    "my_postgres": {
      "is": "postgres",
      "host": "db.example.com",
      "password": {"env": "PG_PASSWORD"}
    }
  }
}

The {"env": "VAR_NAME"} syntax looks up the value from the named environment variable at connection time. If the variable is not set, the field is omitted and the connection proceeds without it.

You can also provide a plain string value directly — this is useful for testing but not recommended for shared or committed config files.