sap-mcp-config 0.0.2

Shared configuration models for MCP servers that connect to SAP systems

sap-mcp-config

The standard way to manage SAP credentials for MCP servers.

If you're building an MCP server that connects to SAP, use this package. It gives you validated, type-safe configuration in both Go and Python with a single shared config file. No more reinventing credential loading, no more inconsistent formats between projects.

Both mcp-server-abap (Go) and sapwebgui.mcp (Python) use this package.

The default config path (~/.config/sap-mcp/systems.json) follows the XDG Base Directory Specification.

Features

• One config file, two languages — Go and Python read the same JSON, guaranteed by shared test fixtures
• Validates eagerly — reports all errors at once so users fix everything in one pass
• Passwords never leak in print/log output — masked in str()/repr()/fmt.Println()/fmt.Sprintf("%+v") (Go: fmt.Formatter; Python: pydantic.SecretStr)
• Immutable after loading — frozen Pydantic models in Python; in Go, use the returned structs as read-only
• .env file support — SAP_CONFIG_FILE can be set in a .env file
• Easy to extend — subclass SAPSystem in Python or embed the struct in Go to add project-specific fields

MCP JSON Configuration

This package integrates naturally with the MCP JSON configuration standard. Point your MCP server to the shared config file via the SAP_CONFIG_FILE environment variable:

{
  "mcpServers": {
    "sap-abap": {
      "command": "mcp-server-abap",
      "env": {
        "SAP_CONFIG_FILE": "/home/user/.config/sap-mcp/systems.json"
      }
    },
    "sap-webgui": {
      "command": "sapwebgui-mcp",
      "env": {
        "SAP_CONFIG_FILE": "/home/user/.config/sap-mcp/systems.json"
      }
    }
  }
}

Both servers read the same config file with the same credentials — no duplication.

Installation

Go

go get github.com/Hochfrequenz/sap-mcp-config

Python

pip install sap-mcp-config

Configuration File

Create ~/.config/sap-mcp/systems.json:

{
  "default_system": "dev",
  "systems": {
    "dev": {
      "host": "https://your-sap-system:44300",
      "client": "100",
      "user": "YOUR_USER",
      "password": "YOUR_PASSWORD",
      "language": "DE"
    },
    "prod": {
      "host": "https://prod-sap:44300",
      "client": "200",
      "user": "PROD_USER",
      "password": "PROD_PASSWORD",
      "language": "EN"
    }
  }
}

Override the config file location via the SAP_CONFIG_FILE environment variable:

export SAP_CONFIG_FILE=/path/to/my/config.json

This also works from a .env file in the current directory.

Fields

Field	Type	Required	Default	Description
host	string	yes		SAP system base URL (must start with http:// or https://)
client	string	no	""	SAP client/mandant, must be exactly 3 digits (e.g. "100")
user	string	conditional	""	SAP username (omit for OAuth2)
password	string	conditional	""	SAP password (omit for OAuth2)
language	string	no	"EN"	Login language: "DE" or "EN"
tls_skip_verify	bool	no	false	Skip TLS certificate verification
oauth2_client_id	string	no	""	OAuth2 client ID for token-based auth

Validation rules:

• At least one system must be defined
• default_system must reference an existing system
• host is required and must start with http:// or https://
• client, if set, must be exactly 3 digits
• language, if set, must be "DE" or "EN"
• Either both user and password must be set, or neither (for OAuth2)

Usage

Go

package main

import (
    "fmt"
    "os"

    sapmcpconfig "github.com/Hochfrequenz/sap-mcp-config"
)

func main() {
    // Load from SAP_CONFIG_FILE env var or ~/.config/sap-mcp/systems.json
    cfg, err := sapmcpconfig.LoadDefault()
    if err != nil {
        fmt.Fprintf(os.Stderr, "Configuration error:\n%s\n", err)
        os.Exit(1)
    }

    // Access the default system
    dev := cfg.GetDefault()
    fmt.Println(dev.Host, dev.Client, dev.User)

    // Access a specific system
    prod := cfg.Systems["prod"]
    fmt.Println(prod.Host, prod.Client, prod.User)

    // Password is safe to print — it won't leak
    fmt.Println(dev) // Output: SAPSystem{Host:https://... Client:100 User:DEV_USER Password:*** Language:DE}
}

Python

import sys

from pydantic import ValidationError

from sap_mcp_config import load_default

try:
    # Load from SAP_CONFIG_FILE env var or ~/.config/sap-mcp/systems.json
    cfg = load_default()
except FileNotFoundError:
    print("Config file not found. Create ~/.config/sap-mcp/systems.json")
    sys.exit(1)
except ValidationError as e:
    print(f"Configuration error:\n{e}")
    sys.exit(1)

# Access the default system
dev = cfg.get_default()
print(dev.host, dev.client, dev.user)

# Access a specific system
prod = cfg.systems["prod"]
print(prod.host, prod.client, prod.user)

# Password is a SecretStr — it won't leak in print/logs
print(dev)  # password=SecretStr('**********')

# Access the actual password value when needed
password = dev.password.get_secret_value()

Error Messages

Both implementations validate eagerly and return all errors at once. A misconfigured file like this:

{
  "default_system": "missing",
  "systems": {
    "dev": { "host": "ftp://wrong", "client": "1", "user": "u" }
  }
}

...will report all problems in a single error:

invalid configuration:
  - default_system "missing" not found in systems
  - system "dev": host must start with http:// or https://, got "ftp://wrong"
  - system "dev": client must be a 3-digit string (e.g. "100"), got "1"
  - system "dev": must have both user and password, or neither (for OAuth2)

This way users fix everything in one pass instead of playing whack-a-mole.

Extending the Configuration

Both languages make it easy to add project-specific fields on top of the shared base.

Python

Subclass SAPSystem to add your own fields:

from pydantic import ConfigDict
from sap_mcp_config import SAPSystem

class MySAPSystem(SAPSystem):
    model_config = ConfigDict()  # unfreeze for subclass

    connection_name: str = ""
    custom_timeout: int = 30

Go

Embed SAPSystem in your own struct:

type MySAPSystem struct {
    sapmcpconfig.SAPSystem
    ConnectionName string `json:"connection_name"`
    CustomTimeout  int    `json:"custom_timeout"`
}

Development

Go

go test ./...

Python

pip install -e ".[tests]"
PYTHONPATH=src pytest unittests

Or via tox:

pip install tox
tox -e tests       # unit tests
tox -e linting     # pylint
tox -e type_check  # mypy --strict
tox -e coverage    # coverage with 80% minimum

License

MIT