Securing Github Webhook Endpoint with Nginx + Lua

validate_signature.lua

-- 多分こんな感じでできる
local x_hub_signature = ngx.hader['X_Hub_Signature']
local body = ngx.req.read_body
local expected_signature = 'sha1=' .. ngx.hmac_sha1(ngx.var.secret_token, body)

if expected_signature ~= x_hub_signature then
  ngx.log(ngx.WARN, 'Invalid access detected')
  ngx.header.content_type = 'text/plain'
  ngx.status = ngx.HTTP_UNAUTHORIZED
  ngx.print('401 Access Denied')
  return
end

-- TODO execでいいのかしら？
ngx.exec('/jenkins')