Configuration: malloy-config.json

VSCode

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

bigquery — Google BigQuery

databricks — Databricks

Authentication: provide either token or the oauthClientId + oauthClientSecret pair.

postgres — PostgreSQL

mysql — MySQL

snowflake — Snowflake

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

trino — Trino

The ssl, session, extraCredential, and extraHeaders properties accept JSON objects that are passed directly to the underlying trino-client library. For example, to connect to a Trino server with a self-signed certificate:

{
  "connections": {
    "my_trino": {
      "is": "trino",
      "server": "https://trino.example.com",
      "catalog": "hive",
      "user": "analyst",
      "password": {"env": "TRINO_PASSWORD"},
      "ssl": {"rejectUnauthorized": false}
    }
  }
}

Because these properties use the json type, {"env": "..."} inside them is treated as literal data, not as an environment variable reference.

presto — Presto

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.

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

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

Incorrect — two statements on the same line:

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

Manifest Path

The config file can specify where persistence manifests are stored:

{
  "connections": { ... },
  "manifestPath": "MANIFESTS"
}

The manifestPath property is optional and defaults to "MANIFESTS". The manifest file is <manifestPath>/malloy-manifest.json, relative to the config file's location. Both the builder (malloy-cli build) and the VS Code extension read the manifest from this path.

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.