mcp-postgres

A comprehensive PostgreSQL MCP (Model Context Protocol) server providing 27 tools for database management and administration.

Features

• Connection Management — connect, disconnect, pool health monitoring
• Query Execution — parameterized queries, EXPLAIN ANALYZE, prepared statements
• Schema Introspection — tables, indexes, constraints, views, functions, enums, extensions
• CRUD Operations — type-safe insert, update, delete, upsert with injection protection
• Server Management — version, settings, config reload, uptime
• Database Sizing — database and table sizes with index/toast breakdown

Installation

npm install @itunified.io/mcp-postgres

Or run directly:

npx @itunified.io/mcp-postgres

Configuration

Set one of the following environment variables:

# Option 1: Connection string (preferred)
export POSTGRES_CONNECTION_STRING="postgresql://myuser:[email protected]:5432/mydb"

# Option 2: Individual variables
export PGHOST="your-database.example.com"
export PGPORT="5432"
export PGUSER="myuser"
export PGPASSWORD="mypassword"
export PGDATABASE="mydb"
export PGSSLMODE="require"  # optional

Multi-Database Configuration

Create a config file at ~/.config/mcp-postgres/databases.yaml:

databases:
  production:
    host: db.example.com
    port: 5432
    user: admin
    password: ${DB_PROD_PASSWORD}
    database: myapp
    ssl: true
  staging:
    host: staging-db.example.com
    port: 5432
    user: admin
    password: ${DB_STAGING_PASSWORD}
    database: myapp
default: production

Environment variables in ${VAR_NAME} syntax are automatically expanded.

Config file discovery order:

1. POSTGRES_CONFIG_FILE env var (explicit path)
2. ~/.config/mcp-postgres/databases.yaml or databases.json
3. POSTGRES_CONNECTION_STRING env var (single database)
4. Individual PG* env vars (single database)

Override the config path with POSTGRES_CONFIG_FILE env var:

{
  "mcpServers": {
    "postgres": {
      "command": "npx",
      "args": ["@itunified.io/mcp-postgres"],
      "env": {
        "POSTGRES_CONFIG_FILE": "/path/to/databases.yaml"
      }
    }
  }
}

Use pg_list_connections to see all configured databases, pg_switch_database to change the active one.

HashiCorp Vault Integration (Optional)

mcp-postgres supports opportunistic secret loading from HashiCorp Vault via AppRole authentication. When configured, it fetches PostgreSQL credentials from a KV v2 path — so you never need to put database passwords in environment variables or config files.

How it works:

1. On startup, the server checks for NAS_VAULT_ADDR, NAS_VAULT_ROLE_ID, and NAS_VAULT_SECRET_ID in the environment
2. If all three are set, it logs in via AppRole and reads the configured KV v2 path
3. It populates POSTGRES_CONNECTION_STRING and PG* env vars from the Vault secret — but only for vars not already set
4. If Vault is not configured or unreachable, the server silently falls back to env vars

Precedence: Explicit env vars → Vault → config file fallback → (error if nothing set)

| Variable | Required | Description | |----------|----------|-------------| | NAS_VAULT_ADDR | Yes* | Vault server address (e.g., https://vault.example.com:8200) | | NAS_VAULT_ROLE_ID | Yes* | AppRole role ID for this server | | NAS_VAULT_SECRET_ID | Yes* | AppRole secret ID for this server | | NAS_VAULT_KV_MOUNT | No | KV v2 mount path (default: kv) |

* Only required if using Vault. Without these, the server uses env vars / config files directly.

Vault KV v2 secret structure:

# Path: kv/your/postgres/secret
{
  "connection_string": "postgresql://myuser:[email protected]:5432/mydb",
  "host": "your-database.example.com",
  "port": "5432",
  "user": "myuser",
  "password": "mypassword",
  "database": "mydb"
}

Key mapping: connection_string → POSTGRES_CONNECTION_STRING, host → PGHOST, port → PGPORT, user → PGUSER, password → PGPASSWORD, database → PGDATABASE

Tip: You can store either connection_string (for single-database setups) or individual fields (host/port/user/password/database), or both. The loader maps whatever keys are present.

Vault setup steps:

1. Write PG credentials to a KV v2 path:

   vault kv put kv/your/postgres/secret \
     connection_string="postgresql://myuser:[email protected]:5432/mydb" \
     host="your-database.example.com" \
     port="5432" \
     user="myuser" \
     password="mypassword" \
     database="mydb"

2. Create a read-only policy:

   path "kv/data/your/postgres/secret" {
     capabilities = ["read"]
   }

3. Create an AppRole and get credentials:

   vault write auth/approle/role/mcp-postgres \
     token_policies="mcp-postgres" token_ttl=1h
   vault read auth/approle/role/mcp-postgres/role-id
   vault write -f auth/approle/role/mcp-postgres/secret-id

4. Configure the server with Vault env vars (no PG creds needed):

   {
     "mcpServers": {
       "postgres": {
         "command": "npx",
         "args": ["@itunified.io/mcp-postgres"],
         "env": {
           "NAS_VAULT_ADDR": "https://vault.example.com:8200",
           "NAS_VAULT_ROLE_ID": "your-role-id",
           "NAS_VAULT_SECRET_ID": "your-secret-id"
         }
       }
     }
   }

Note: Config file options (POSTGRES_CONFIG_FILE, databases.yaml) and PGSSLMODE are not loaded from Vault — set them via env vars if needed.

Claude Desktop / MCP Settings

Add to your settings.json:

{
  "mcpServers": {
    "postgres": {
      "command": "npx",
      "args": ["@itunified.io/mcp-postgres"],
      "env": {
        "POSTGRES_CONNECTION_STRING": "postgresql://myuser:[email protected]:5432/mydb"
      }
    }
  }
}

Tools

Connection (5 tools)

| Tool | Description | |------|-------------| | pg_connect | Connect to a database (default or named) | | pg_disconnect | Disconnect from a database or all | | pg_connection_status | Pool health for active or named database | | pg_list_connections | List all configured databases and status | | pg_switch_database | Switch the active database context |

Query (3 tools)

| Tool | Description | |------|-------------| | pg_query | Execute parameterized SELECT/DML query | | pg_query_explain | Run EXPLAIN ANALYZE on a query | | pg_query_prepared | Manage named prepared statements (PREPARE/EXECUTE/DEALLOCATE) |

Schema Introspection (9 tools)

| Tool | Description | |------|-------------| | pg_schema_list | List all schemas | | pg_table_list | List tables (with optional schema filter) | | pg_table_describe | Describe table columns, types, defaults, constraints | | pg_index_list | List indexes for a table | | pg_constraint_list | List constraints (PK, FK, unique, check) | | pg_view_list | List views with definitions | | pg_function_list | List functions/procedures with signatures | | pg_enum_list | List enum types and values | | pg_extension_list | List installed extensions |

CRUD (4 tools)

| Tool | Description | |------|-------------| | pg_insert | Insert row(s) with parameterized values | | pg_update | Update rows (requires confirm: true) | | pg_delete | Delete rows (requires confirm: true) | | pg_upsert | Insert or update on conflict (requires confirm: true) |

Server (4 tools)

| Tool | Description | |------|-------------| | pg_version | PostgreSQL version | | pg_settings | Show/search server configuration | | pg_reload_config | Reload configuration (requires confirm: true) | | pg_uptime | Server uptime and start time |

HA Monitoring (4 tools)

| Tool | Description | |------|-------------| | pg_replication_status | Streaming replication state and lag | | pg_replication_slots | List replication slots | | pg_wal_status | WAL generation rate and archive status | | pg_standby_status | Primary vs standby detection |

Database Management (2 tools)

| Tool | Description | |------|-------------| | pg_database_size | Size of all databases | | pg_table_sizes | Table sizes with index/toast breakdown |

Enterprise Edition

For advanced PostgreSQL operations, mcp-postgres-enterprise extends this server with:

• DBA Monitoring — VACUUM, ANALYZE, REINDEX, pg_stat_activity, table/index stats, locks, cache hit ratio, bloat detection
• CloudNativePG (CNPG) — K8s cluster management, failover, switchover, backup orchestration
• HA Operations — Replication slot management, PgBouncer pool control
• Backup / PITR — pg_dump/pg_restore orchestration, point-in-time recovery
• RBAC — Role management, privilege grants, row-level security policies
• Audit — Query log analysis, connection audit, permission mapping
• Compliance — SSL enforcement, connection limit checks

Available as a private GitHub package. Contact itunified.io for access.

Security

Query Safety Model

• CRUD tools (pg_insert, pg_update, pg_delete, pg_upsert): All use parameterized queries ($1, $2, ...) — safe from SQL injection. Destructive operations require confirm: true.
• pg_query: Unrestricted raw SQL runner by design — intended for power users who need full SQL flexibility. No injection protection is applied because the tool's purpose is to execute arbitrary SQL.
• pg_query_explain: Defaults to safe plan mode (EXPLAIN only, no execution). mode=analyze always requires confirm: true because EXPLAIN ANALYZE executes the statement.
• pg_query_prepared: Deprecated. Prepared statements are session-local in PostgreSQL and unreliable with connection pools. Statement names are validated as SQL identifiers. Use parameterized pg_query instead.

Destructive Operations

These tools require confirm: true to execute:

• pg_update, pg_delete, pg_upsert — data modification
• pg_reload_config — server configuration
• pg_query_explain (analyze mode) — statement execution

Credentials

• Connection credentials are read from environment variables or JSON/YAML config — never logged or stored
• All identifiers (table, column, schema names) are validated against a strict regex pattern

License

This project is dual-licensed:

1. AGPL-3.0 — Free for open-source and non-commercial use
2. Commercial License — For proprietary and commercial use

See COMMERCIAL_LICENSE.md for details.

Contributing

Contributions are welcome! Please open an issue first to discuss proposed changes.