vishal-h
Find Elixir process running on a box given it's name
We have used https://github.com/BlakeWilliams/Elixir-Slack to write a slack-bot. The question is not about the library but about Elixir. The bot is run as a worker with name :slack_bot under a supervisor.
During tests, the bot was run from multiple nodes (boxes). Now we have a situation where 2 bots respond whenever a message is sent. Unfortunately we don’t know where the second bot is running from.
The question is given the process name (:slack_bot), can we check if an Elixir process with that name is running on a box?
Marked As Solved
rvirding
Actually if the node is up and running then Node.ping/1 should return :pong .
Yes, getting the cookies right is critical. I had assumed that this part of the handling of distribution had been solved. How have you started the nodes with “sname” or with “name”? They have to be done in the same way, and it does affect the node names.
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rvirding
Process.whereis/1 can be called from any function but it does need to be run on the node which it is checking. You could do something like:
:rpc.call(node_name, Process, :whereis, [:slack_bot])
which would tell you if there is a process with the registered name :slack_bot running on it and return its pid. I don’t know of an Elixir equivalent module to :rpc.
NobbZ
The cookies are different, the right one has a colon at the start, the left doesn’t have that.
idi527
You can probably use https://hexdocs.pm/elixir/Process.html?#whereis/1.
vishal-h
OMG How did that happen?
I copied the result of Node.get_cookie - including the colon - while starting the other node.
It works fine and apologies to the good people here who had to rake their brains over a silly mistake.
Well, the colon killed my weekend
vishal-h
And :rpc.call(node_name, Process, :whereis, [:slack_bot]) works just fine
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