[tarantool-patches] [PATCHv2] Detect when instance is run or restarted by tarantoolctl.

[Serge Petrenko]

There are some hacks to know the instance was run by tarantoolctl,
none of them are too reliable, though. This patch introduces 2
environment variables set by tarantoolctl for the instance to
know when it's being run or restarted.

Closes: #3215
---
https://github.com/tarantool/tarantool/tree/sergepetrenko/gh-3215-tarantoolctl-detection
https://github.com/tarantool/tarantool/issues/3215

Changes in v2:
    - scrape all and leave only the environment
      variables setting in tarantoolctl

 extra/dist/tarantoolctl.in | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/extra/dist/tarantoolctl.in b/extra/dist/tarantoolctl.in
index b6b8e09c9..ecab0a0f1 100755
--- a/extra/dist/tarantoolctl.in
+++ b/extra/dist/tarantoolctl.in
@@ -514,6 +514,11 @@ local function start()
         script_name = instance_path,
         __defer_update = true
     }
+
+    -- an env variable to tell when we the
+    -- instance is run under tarantoolctl
+    os.setenv('TARANTOOLCTL', 'true')
+
     shift_argv(arg, 0, 2)
     local success, data = pcall(dofile, instance_path)
     -- if load fails - show last 10 lines of the log file and exit
@@ -593,6 +598,9 @@ local function restart()
     end
     stop()
     fiber.sleep(1)
+    -- an env variable to tell when
+    -- the instance was restarted
+    os.setenv('TARANTOOL_RESTARTED', 'true')
     start()
     return 0
 end
-- 
2.15.2 (Apple Git-101.1)