# Changing default interface for Julia worker

**URL:** <https://discourse.julialang.org/t/changing-default-interface-for-julia-worker/101746>\
**Category:** Julia at Scale\
**Tags:** distributed, network\
**Created:** [July 18, 2023, 5:36pm UTC](https://discourse.julialang.org/t/changing-default-interface-for-julia-worker/101746 "2023-07-18T17:36:42Z")\
**Posts on this page:** 2\
**Page:** 1

<div class="post-metadata">

**Author:** ![JasperW99](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/jasperw99/32/50665_2.png) [@JasperW99](https://discourse.julialang.org/u/JasperW99)\
**Post date:** [July 18, 2023, 5:36pm UTC](https://discourse.julialang.org/t/changing-default-interface-for-julia-worker/101746/1 "2023-07-18T17:36:42Z")

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I am running a distributed workload using Distributed.jl on a cluster that has set up IP over Infiniband (IPoIB). However, when the workers are created, they automatically return the IP address of the slow ethernet interface. A workaround I found is to edit [line 1279](https://github.com/JuliaLang/julia/blob/master/stdlib/Distributed/src/cluster.jl#L1279) of cluster.jl in stdlib/Distributed where the bind address is set from the _getipaddr()_ function to the IP address of the Infiniband. I am aware that you can change the bind-address of a worker via the _–bind-to_ flag, however, this is just for a single worker and is complicated if you can only access a cluster through a reservation system. Now my question is, is there a way to set a preferred interface for Julia workers without having to compile a custom Julia version?

Alternative solutions using for example the ClusterManager are also very welcome.

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<div class="post-metadata">

**Author:** ![raminammour](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/raminammour/32/13572_2.png) [@raminammour](https://discourse.julialang.org/u/raminammour)\
**Post date:** [July 18, 2023, 9:20pm UTC](https://discourse.julialang.org/t/changing-default-interface-for-julia-worker/101746/2 "2023-07-18T21:20:09Z")

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Hello,

I had similar problems in the past and solved them by adding these lines in [lsf](https://github.com/JuliaParallel/ClusterManagers.jl/pull/74) `ClusterManager`:

```julia
cmd = `cd $dir ";" hostname -i "|" xargs $exename $exeflags $(worker_arg) --bind-to `
bsub_cmd = `bsub -I -x $(manager.flags) -cwd $dir -J $jobname "$cmd"`

```

That way the worker was getting its correct ip address and passing to `--bind-to`. There may be a cleaner solution (I was much less familiar with julia back then, and there appears to be some cleaner options in the chat YMMV :)); but since then, that system was decommissioned and I thankfully didn’t need that workaround anymore.

A general point about “compiling a custom julia version”. Julia is a dynamic language so if you only needed to edit one line to make this work you can do

```julia
@eval Distributed function init_bind_addr()
....
your_edits
....
end

```

And that would replace the function and should recompile a bunch of code automatically as needed at runtime.

Hope this helps,

Cheers!