Configuration

All configuration is YAML-based and lives in the config directory (~/.adb-link/conf/ by default).

Config Directory

Variable	Default	Description
ADB_LINK_CONFIG_DIR	~/.adb-link/conf	Config directory path

Environment Variables

Variable	Default	Description
ADB_LINK_API_HOST	0.0.0.0	API bind address
ADB_LINK_API_PORT	8000	API bind port
ADB_LINK_LOG_LEVEL	INFO	Log level (DEBUG, INFO, WARN, ERROR)
ADB_LINK_LOG_DIR	~/.adb-link/logs	Log directory
ADB_LINK_RELOAD	true	Enable hot-reload
ADB_LINK_ASYNC_QUERY_TTL	3600	Async result TTL in seconds

Config File Types

Each YAML file uses a kind: discriminator:

Kind	Purpose	Example File
datasource	Database connection definitions	datasource.yaml
users	API keys and user accounts	auth.yaml
permission	RBAC access control rules	permission.yaml
tool	Custom query tool definitions	tool-reports.yaml
metadata	Column/table comment annotations	metadata-mydb.yaml

---

Datasource Configuration

kind: datasource
name: my-postgres
type: postgresql
description: "Production PostgreSQL"
connection:
  host: 127.0.0.1
  port: 5432
  username: app_user
  password: ${PG_PASSWORD}
  default_database: mydb
options:
  pool_size: 10

Supported Types

mysql, postgresql, clickhouse, sqlite, mssql, hive, oracle, gaussdb, tidb, redis, mongodb, milvus, elasticsearch

Connection Fields

Field	Description
host	Database host
port	Database port
username	Connection username
password	Connection password (supports ${ENV_VAR})
default_database	Default database to connect to
dsn	Full DSN string (alternative to individual fields)

Options

Option	Description
pool_size	Connection pool size
max_idle	Maximum idle connections
max_lifetime	Maximum connection lifetime

---

Authentication (Users)

kind: users
users:
  - name: admin
    api_key: "your-secret-api-key"
    group: admin
    email: "admin@example.com"
    description: "Administrator"
  - name: readonly
    api_key: "readonly-key"
    group: viewer
  - name: mcp_stdio_user
    group: mcp
    description: "Default user for MCP stdio transport"

Fields

Field	Required	Description
name	Yes	Username
api_key	No	Bearer token for API auth (supports ${ENV_VAR})
group	Yes	Permission group membership
email	No	User email
description	No	User description

---

Permission Rules

kind: permission
groups: ["admin"]
enable: true
rules:
  - datasource: "*"
    databases: ["*"]
    tables: ["*"]
    fields: ["*"]
tools: ["*"]

Fields

Field	Description
groups	List of groups this permission applies to
enable	Whether this permission set is active
rules	List of access rules
rules[].datasource	Datasource glob pattern
rules[].databases	Database glob patterns
rules[].tables	Table glob patterns
rules[].fields	Field glob patterns
tools	Tool glob patterns

Glob patterns support * (match any) and exact names.

---

Custom Tools

kind: tool
name: get_user_orders
description: "Get recent orders for a user"
datasource: my-postgres
database: mydb
sql: "SELECT * FROM orders WHERE user_id = :user_id ORDER BY created_at DESC LIMIT :limit"
parameters:
  - name: user_id
    type: integer
    description: "User ID"
    required: true
  - name: limit
    type: integer
    description: "Max results"
    default: 10

Tool Fields

Field	Description
name	Tool name (used in MCP tools/call)
description	Tool description shown to agents
datasource	Target datasource
database	Target database
sql	SQL template with named parameters (:param)
parameters	Parameter definitions with JSON Schema types

---

Metadata Annotations

kind: metadata
datasource: my-postgres
database: mydb
tables:
  - name: users
    comment: "Application users"
    columns:
      - name: id
        comment: "Primary key"
      - name: status
        comment: "0=inactive, 1=active, 2=banned"

Metadata annotations enrich schema discovery with human-readable comments.

---

Hot Reload

Configuration changes are automatically detected via filesystem notifications (fsnotify). Changes take effect within seconds without restarting the server.

Supported hot-reload operations:

• Add/remove/modify datasources
• Update users and permissions
• Add/remove custom tools
• Update metadata annotations

---

Environment Variable Interpolation

All YAML config values support ${ENV_VAR} syntax:

connection:
  password: ${DB_PASSWORD}
  host: ${DB_HOST}

If the environment variable is not set, the literal ${VAR} string is preserved.

---

MCP Stdio Combined Config

For MCP stdio mode, a single file can contain all config kinds:

kind: users
users:
  - name: mcp_stdio_user
    group: admin
---
kind: permission
groups: ["admin"]
enable: true
rules:
  - datasource: "*"
    databases: ["*"]
    tables: ["*"]
    fields: ["*"]
tools: ["*"]
---
kind: datasource
name: local-sqlite
type: sqlite
connection:
  dsn: "/path/to/database.db"

Multi-document YAML (separated by ---) is supported.