Revert "refactor(cmd): use resty.signal for process signaling (#11382)…

…" (#11620)

This reverts commit bbdda0b.

For posterity's sake, there are actually _two_ reasons for us to merge this:

1. commit history cleanup (as noted in the PR desc for #11620)
2. we discovered a subtle bug in the way that `resty.signal` traverses `LUA_CPATH` in order to discover and load its shared object dependency ([link](https://github.com/openresty/lua-resty-signal/blob/7834226610e2df36f8e69641c4ca0d5ea75a9535/lib/resty/signal.lua#L21-L58)) and _need_ to revert this to un-break master

bin/kong-health

@@ -3,7 +3,7 @@
 setmetatable(_G, nil)
 package.path = (os.getenv("KONG_LUA_PATH_OVERRIDE") or "") .. "./?.lua;./?/init.lua;" .. package.path
 
-local process = require "kong.cmd.utils.process"
+local kill = require "kong.cmd.utils.kill"
 local kong_default_conf = require "kong.templates.kong_defaults"
 local pl_app = require "pl.lapp"
 local pl_config = require "pl.config"
@@ -42,7 +42,8 @@ local function execute(args)
 
   print("")
   local pid_file = pl_path.join(prefix, "pids", "nginx.pid")
-  assert(process.exists(pid_file), "Kong is not running at " .. prefix)
+  kill.is_running(pid_file)
+  assert(kill.is_running(pid_file), "Kong is not running at " .. prefix)
   print("Kong is healthy at ", prefix)
 end
 

kong-3.5.0-0.rockspec

@@ -116,7 +116,7 @@ build = {
     ["kong.cmd.version"] = "kong/cmd/version.lua",
     ["kong.cmd.hybrid"] = "kong/cmd/hybrid.lua",
     ["kong.cmd.utils.log"] = "kong/cmd/utils/log.lua",
-    ["kong.cmd.utils.process"] = "kong/cmd/utils/process.lua",
+    ["kong.cmd.utils.kill"] = "kong/cmd/utils/kill.lua",
     ["kong.cmd.utils.env"] = "kong/cmd/utils/env.lua",
     ["kong.cmd.utils.migrations"] = "kong/cmd/utils/migrations.lua",
     ["kong.cmd.utils.tty"] = "kong/cmd/utils/tty.lua",

kong/cmd/health.lua

@@ -1,5 +1,5 @@
 local log = require "kong.cmd.utils.log"
-local process = require "kong.cmd.utils.process"
+local kill = require "kong.cmd.utils.kill"
 local pl_path = require "pl.path"
 local pl_tablex = require "pl.tablex"
 local pl_stringx = require "pl.stringx"
@@ -26,7 +26,7 @@ local function execute(args)
 
   local count = 0
   for k, v in pairs(pids) do
-    local running = process.exists(v)
+    local running = kill.is_running(v)
     local msg = pl_stringx.ljust(k, 12, ".") .. (running and "running" or "not running")
     if running then
       count = count + 1

kong/cmd/quit.lua

@@ -1,7 +1,7 @@
 local nginx_signals = require "kong.cmd.utils.nginx_signals"
 local conf_loader = require "kong.conf_loader"
 local pl_path = require "pl.path"
-local process = require "kong.cmd.utils.process"
+local kill = require "kong.cmd.utils.kill"
 local log = require "kong.cmd.utils.log"
 
 local function execute(args)
@@ -24,7 +24,7 @@ local function execute(args)
     log.verbose("waiting %s seconds before quitting", args.wait)
     while twait > ngx.now() do
       ngx.sleep(0.2)
-      if not process.exists(conf.nginx_pid) then
+      if not kill.is_running(conf.nginx_pid) then
         log.error("Kong stopped while waiting (unexpected)")
         return
       end
@@ -41,7 +41,7 @@ local function execute(args)
   local texp, running = tstart + math.max(args.timeout, 1) -- min 1s timeout
   repeat
     ngx.sleep(0.2)
-    running = process.exists(conf.nginx_pid)
+    running = kill.is_running(conf.nginx_pid)
     ngx.update_time()
   until not running or ngx.now() >= texp
 

kong/cmd/restart.lua

@@ -1,6 +1,6 @@
 local log = require "kong.cmd.utils.log"
 local stop = require "kong.cmd.stop"
-local process = require "kong.cmd.utils.process"
+local kill = require "kong.cmd.utils.kill"
 local start = require "kong.cmd.start"
 local pl_path = require "pl.path"
 local conf_loader = require "kong.conf_loader"
@@ -27,7 +27,7 @@ local function execute(args)
   local running
   repeat
     ngx.sleep(0.1)
-    running = process.exists(conf.nginx_pid)
+    running = kill.is_running(conf.nginx_pid)
   until not running or ngx.time() >= texp
 
   start.execute(args)

kong/cmd/start.lua

@@ -3,7 +3,7 @@ local prefix_handler = require "kong.cmd.utils.prefix_handler"
 local nginx_signals = require "kong.cmd.utils.nginx_signals"
 local conf_loader = require "kong.conf_loader"
 local kong_global = require "kong.global"
-local process = require "kong.cmd.utils.process"
+local kill = require "kong.cmd.utils.kill"
 local log = require "kong.cmd.utils.log"
 local DB = require "kong.db"
 local lfs = require "lfs"
@@ -53,7 +53,7 @@ local function execute(args)
 
   conf.pg_timeout = args.db_timeout -- connect + send + read
 
-  assert(not process.exists(conf.nginx_pid),
+  assert(not kill.is_running(conf.nginx_pid),
          "Kong is already running in " .. conf.prefix)
 
   assert(prefix_handler.prepare_prefix(conf, args.nginx_conf, nil, nil,

kong/cmd/utils/kill.lua

@@ -0,0 +1,32 @@
+local pl_path = require "pl.path"
+local pl_utils = require "pl.utils"
+local log = require "kong.cmd.utils.log"
+
+local cmd_tmpl = [[kill %s `cat %s 2>&1` >/dev/null 2>&1]]
+
+local function kill(pid_file, args)
+  log.debug("sending signal to pid at: %s", pid_file)
+  local cmd = string.format(cmd_tmpl, args or "-0", pid_file)
+  if pl_path.exists(pid_file) then
+    log.debug(cmd)
+    local _, code = pl_utils.execute(cmd)
+    return code
+  else
+    log.debug("no pid file at: %s", pid_file)
+    return 0
+  end
+end
+
+local function is_running(pid_file)
+  -- we do our own pid_file exists check here because
+  -- we want to return `nil` in case of NOT running,
+  -- and not `0` like `kill` would return.
+  if pl_path.exists(pid_file) then
+    return kill(pid_file) == 0
+  end
+end
+
+return {
+  kill = kill,
+  is_running = is_running
+}

kong/cmd/utils/nginx_signals.lua

@@ -1,6 +1,6 @@
 local ffi = require "ffi"
 local log = require "kong.cmd.utils.log"
-local process = require "kong.cmd.utils.process"
+local kill = require "kong.cmd.utils.kill"
 local meta = require "kong.meta"
 local pl_path = require "pl.path"
 local version = require "version"
@@ -55,17 +55,15 @@ end
 
 
 local function send_signal(kong_conf, signal)
-  local pid = process.pid(kong_conf.nginx_pid)
-
-  if not pid or not process.exists(pid) then
+  if not kill.is_running(kong_conf.nginx_pid) then
     return nil, fmt("nginx not running in prefix: %s", kong_conf.prefix)
   end
 
   log.verbose("sending %s signal to nginx running at %s", signal, kong_conf.nginx_pid)
 
-  local ok, err = process.signal(pid, signal)
-  if not ok then
-    return nil, fmt("could not send signal: %s", err or "unknown error")
+  local code = kill.kill(kong_conf.nginx_pid, "-s " .. signal)
+  if code ~= 0 then
+    return nil, "could not send signal"
   end
 
   return true
@@ -145,7 +143,7 @@ function _M.start(kong_conf)
     return nil, err
   end
 
-  if process.exists(kong_conf.nginx_pid) then
+  if kill.is_running(kong_conf.nginx_pid) then
     return nil, "nginx is already running in " .. kong_conf.prefix
   end
 
@@ -207,17 +205,17 @@ end
 
 
 function _M.stop(kong_conf)
-  return send_signal(kong_conf, process.SIG_TERM)
+  return send_signal(kong_conf, "TERM")
 end
 
 
 function _M.quit(kong_conf)
-  return send_signal(kong_conf, process.SIG_QUIT)
+  return send_signal(kong_conf, "QUIT")
 end
 
 
 function _M.reload(kong_conf)
-  if not process.exists(kong_conf.nginx_pid) then
+  if not kill.is_running(kong_conf.nginx_pid) then
     return nil, fmt("nginx not running in prefix: %s", kong_conf.prefix)
   end