Lua recipes

Lua scripts define on_request and/or on_response hooks. Return a modified table to continue, return nil to pass through unchanged, or return a response table from on_request to short-circuit the upstream request.

Add a request header

function on_request(request)
    request.headers["X-Proxied-By"] = "proxelar"
    return request
end

Remove cookies

function on_request(request)
    request.headers["cookie"] = nil
    return request
end

Add CORS response headers

function on_response(request, response)
    response.headers["Access-Control-Allow-Origin"] = "*"
    response.headers["Access-Control-Allow-Methods"] = "GET, POST, PUT, DELETE, OPTIONS"
    response.headers["Access-Control-Allow-Headers"] = "Content-Type, Authorization"
    return response
end

Block a domain

local blocked = { "ads%.example%.com", "tracker%.example%.com" }

function on_request(request)
    for _, pattern in ipairs(blocked) do
        if string.find(request.url, pattern) then
            return {
                status = 403,
                headers = { ["Content-Type"] = "text/plain" },
                body = "Blocked by Proxelar",
            }
        end
    end
end

Modify a JSON response

function on_response(request, response)
    local ct = response.headers["content-type"] or ""
    if not string.find(ct, "application/json") then return end

    if string.sub(response.body, 1, 1) == "{" then
        response.body = '{"proxied":true,' .. string.sub(response.body, 2)
    end
    return response
end

Use the checked-in examples

The repository includes complete scripts in examples/scripts/:

• add_header.lua
• auth_inject.lua
• block_domain.lua
• filter_by_method.lua
• inject_cors.lua
• log_traffic.lua
• mock_api.lua
• modify_json_response.lua
• redirect.lua
• request_body_modify.lua
• rewrite_html.lua
• strip_cookies.lua

See the Lua API reference for all fields and return values.