Gateway Configuration¶

Environment Variables¶

Variable	Description	Example
`MICROMEGAS_FLIGHTSQL_URL`	FlightSQL backend endpoint (required)	`grpc://127.0.0.1:50051`
`MICROMEGAS_GATEWAY_HEADERS`	Header forwarding config (optional)	See below

Header Forwarding¶

Configure which HTTP headers are forwarded to FlightSQL:

export MICROMEGAS_GATEWAY_HEADERS='{
  "allowed_headers": ["Authorization", "X-Request-ID"],
  "allowed_prefixes": ["X-Custom-"],
  "blocked_headers": ["Cookie"]
}'

Field	Description
`allowed_headers`	Exact header names to forward (case-insensitive)
`allowed_prefixes`	Forward all headers matching prefix (e.g., `X-Custom-*`)
`blocked_headers`	Headers to block (overrides allows)

Default headers (if not configured): - Authorization, X-Request-ID, X-User-ID, X-User-Email, User-Agent - Blocks: Cookie, Set-Cookie, X-Client-IP

Security: - X-Client-IP is always blocked (gateway sets from actual connection) - Blocked headers checked first, then exact matches, then prefix matches - All matching is case-insensitive

Origin Tracking¶

Gateway automatically sets these headers:

Header	Description	Example
`x-client-type`	Client type + `+gateway` suffix	`web+gateway`
`x-request-id`	Generated UUID if not provided	`550e8400-...`
`x-client-ip`	Real client IP (prevents spoofing)	`192.168.1.100`

Examples¶

Default configuration:

export MICROMEGAS_FLIGHTSQL_URL=grpc://127.0.0.1:50051
cargo run --bin http-gateway-srv

Custom headers:

export MICROMEGAS_GATEWAY_HEADERS='{
  "allowed_headers": ["Authorization", "X-Tenant-ID"],
  "allowed_prefixes": ["X-Custom-"],
  "blocked_headers": ["Cookie"]
}'
export MICROMEGAS_FLIGHTSQL_URL=grpc://127.0.0.1:50051
cargo run --bin http-gateway-srv

Server Options¶

cargo run --bin http-gateway-srv -- --listen-endpoint-http 0.0.0.0:3000

Default listen address: 0.0.0.0:3000

Request Limits¶

Maximum SQL size: 1 MB
Empty SQL queries rejected (400 Bad Request)

Reference¶

Implementation: rust/http-gateway/src/config.rs
Origin metadata: rust/public/src/servers/http_gateway.rs