Configuration

mcpr can be configured three ways. Priority order: CLI args > environment variables > mcpr.toml > defaults.

Config file

mcpr looks for mcpr.toml in the current directory, then parent directories.

MCP server only

mcp = "http://localhost:9000"

MCP server + widgets

mcp = "http://localhost:9000"
widgets = "http://localhost:4444"

Static widgets from disk

mcp = "http://localhost:9000"
widgets = "./widgets/dist"

Local only (no tunnel)

mcp = "http://localhost:9000"
no_tunnel = true
port = 3000

Custom relay

mcp = "http://localhost:9000"
relay_url = "https://relay.yourdomain.com"

CSP configuration

mcp = "http://localhost:9000"
widgets = "http://localhost:4444"
csp = ["cdn.example.com", "api.example.com"]
csp_mode = "extend"   # "extend" (default) or "override"

Cloud sync

mcp = "http://localhost:9000"

[cloud]
token = "mcpr_xxxxxxxx"
server = "my-proxy"

Full example

mcp = "http://localhost:9000"
widgets = "http://localhost:4444"
port = 3000
# no_tunnel = true   # uncomment for production (disables tunnel)
tunnel_token = "tok_abc123..."
csp = ["cdn.example.com"]
csp_mode = "extend"

[cloud]
token = "mcpr_xxxxxxxx"
server = "my-proxy"

Auto-generated fields

On first run, mcpr generates a tunnel_token and appends it to mcpr.toml. This keeps your tunnel URL stable across restarts. You don’t need to set it manually.

Environment variables

Variable	Description
MCPR_RELAY_URL	Custom relay server URL
MCPR_CLOUD_TOKEN	Cloud sync token (from cloud.mcpr.app)
MCPR_AUTH_PROVIDER	Auth provider URL (relay mode)
MCPR_AUTH_PROVIDER_SECRET	Auth provider shared secret (relay mode)

Docker / Kubernetes (production)

mcp = "http://localhost:9000"
no_tunnel = true
no_tui = true
port = 8080
drain_timeout = 25
log_format = "json"
admin_bind = "0.0.0.0:9901"

[cloud]
token = "mcpr_xxxxxxxx"
server = "prod-1"

Validating config

Use mcpr validate to check your config file without starting the proxy:

mcpr validate                        # checks ./mcpr.toml
mcpr validate -c /etc/mcpr/mcpr.toml # checks a specific file

Exit code 0 means the config is valid. Exit code 1 means there are errors.

Config templates

See config_examples/ in the repository for ready-to-use templates:

• tunnel.toml — development with tunnel
• no-tunnel.toml — local or production without tunnel
• relay.toml — running your own relay server

For the full CLI flag reference, see CLI Reference.