[erlang-questions] Including erl_call in the release tarball

Ulf Wiger ulf@REDACTED
Thu Jan 3 22:15:07 CET 2013

Hi Michal,

Not sure if it helps, but here is a first draft of an escript that works roughly like erl_call.


I've had great difficulty getting the Distributed Erlang bootstrap to work nicely on MacOS (haven't tried it elsewhere). Thus, the quirky method of deleting the net_sup child and re-adding it with specified arguments (also, the call to inet_db:set_hostname/1 is absolutely necessary on my machine - I can't explain why).

Some of the issues I've run into:

- When calling net_kernel:start(…) from within an escript, the host name is apparently determined differently from when a %%! line with a node name is given at the top of the escript. For it to work on my laptop, I have to give a fully qualified name, which the script then splits and uses for set_hostname.

- The times I was able to make it work at all with net_kernel:start(), connection took forever. After replacing it with the delete_child/start_child gymnastics, this problem went away.

Anyway, if it helps anyone, have at it.

OTP team - this shouldn't be so hard. Perhaps someone could take a look at the issues?

Ulf W

On 3 Jan 2013, at 19:23, Michał Ptaszek wrote:

> Hey, 
> I'm running my system in the embedded mode, and trying to apply live upgrades using release_handler. Nonetheless, in order to automate the process, I would like to interface with the running Erlang node via 'erl_call' command and pass the release_handler instructions as arguments (I would love to avoid writing escripts or playing with 'erl -eval "rpc:call(...)"' mumbo-jumbo). 
> Unfortunately, it seems like erl_call is not included in the release package generated by rebar, and to make things worse - is not even put in the standard erlang bin/ directory. Instead, by default, it's located under $ERL_ROOT/lib/erlang/lib/erl_interface-$VERSION/bin/erl_call. 
> Also, trying to add erl_interface application to the released apps does not work, as erl_interface is not an OTP application (does not have .app file).
> What would be the best way to make sure that the target release package contains erl_call binary? How do you usually make it accessible/available on the target system? 
> Thanks, 
> Michal 
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Ulf Wiger, Co-founder & Developer Advocate, Feuerlabs Inc.

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