Request Headers

The Request Headers middleware lets you add, override or remove HTTP headers before your application handler sees the request. You can inject static values or use the full power of String Rewrite to generate header values based on path, query, method, etc.

Configuration

request_headers \
  additions: {
    "X-Correlation-ID" => ["{request_id_full}"],
    "X-Env"            => ["production"]
  },
  removals: ["X-Forwarded-For"]

• additions (Hash(String,Array(StringRewrite))) A map of header names to an array of StringRewrite templates. Each template is rendered after removals.
• removals Array(String) A list of header names to delete outright. If you want to override an existing header, include it in both removals and additions.

Examples

# Add a per‑request UUID and drop any X‑Forwarded‑For header
request_headers \
  additions: { "X-Correlation-ID" => ["{request_id}"] },
  removals:  ["X-Forwarded-For"]

# Inject the full request path and query
request_headers \
  additions: { "X-Full-URL" => ["{path_and_query}"] },
  removals:  []