Run Livebook Desktop without EPMD #2591
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| @@ -393,6 +418,8 @@ defmodule Livebook.Application do | |||
| }) | |||
| end | |||
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| # ELIXIR_ERL_OPTIONS used to configure EPMD module in releases. | |||
| defp config_env_var?("ELIXIR_ERL_OPTIONS"), do: true | |||
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We need to delete this, otherwise any Elixir executable invoked within the runtime will have the custom EPMD configuration.
On the flip side, this means if the user has set ELIXIR_ERL_OPTIONS somewhere, it will no longer propagate to the runtime (like ERL_AFLAGS and ERL_ZFLAGS currently propagate). Is this acceptable?
Another option is to not delete ELIXIR_ERL_OPTIONS here, then it will be also available in the runtime (so we don't need to set it by hand), and then we delete it from the runtime instead.
So overall, we need to answer which of ERL_AFLAGS, ERL_ZFLAGS and ELIXIR_ERL_OPTIONS we want to pass all the way down, from Livebook -> Runtime -> Executable, or if we want to delete some (or all) of them along the way (and if so, where).
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@josevalim we can set ELIXIR_ERL_OPTIONS_WAS or similar, and just revert the value here, so whatever the user sets gets propagated as expected, wdyt?
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I thought about that but I also think it is useful to have a value that only applies to Livebook but not the runtimes and ELIXIR_ERL_OPTIONS sounds like a good candidate. We just have to document it?
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useful to have a value that only applies to Livebook but not the runtimes
We don't expect users to set it for Livebook specifically though? So if anything they want to set it for the runtime. Whatever you think is best :)
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We don't expect ERL_AFLAGS to be set it either, but it just works by the nature of things, it that makes any sense.
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What I mean is that Livebook-specific env var is probably not interesting for the end user, only us, so we can replicate that without affecting how envs work for the user. Again, no strong opinion though.
lib/livebook/application.ex
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| ensure_distribution!() | ||
| validate_hostname_resolution!() | ||
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| if Livebook.Config.boolean!("LIVEBOOK_EPMDLESS", false) do |
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I think for consistency we should parse this in lib/livebook.ex and put in config.
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I was thinking about this... but the app env var is not really used anywhere else and I wanted to avoid us reading it (we should use Livebook.EPMD.dist_port instead to detect the status). Do you prefer the app env var anyway?
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I would put it in config, even if used in this single place. I think we env -> config -> access almost everywhere and that makes it more centralized :)
lib/livebook/epmd.ex
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| File.mkdir_p!("priv/epmd") | ||
| File.write!("priv/epmd/Elixir.Livebook.EPMD.beam", binary) |
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Can we put this in __after_compile__?
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Good call, I will try :)
Co-authored-by: Jonatan Kłosko <[email protected]>
rel/app/env.sh.eex
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| if [[ "$hostname" =~ " " ]]; then | ||
| echo "[error] system hostname ($hostname) cannot contain whitespaces" | ||
| exit 1 | ||
| if [[ "$LIVEBOOK_EPMDLESS" != "false" && "$LIVEBOOK_EPMDLESS" != "0" ]]; then |
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I think we need to set the env var:
| if [[ "$LIVEBOOK_EPMDLESS" != "false" && "$LIVEBOOK_EPMDLESS" != "0" ]]; then | |
| export LIVEBOOK_EPMDLESS=${LIVEBOOK_EPMDLESS:-false} | |
| if [[ "$LIVEBOOK_EPMDLESS" != "false" && "$LIVEBOOK_EPMDLESS" != "0" ]]; then |
so that in Elixir land this can be executed:
if Livebook.Config.boolean!("LIVEBOOK_EPMDLESS", false) do
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💚 💙 💜 💛 ❤️ |
If EPMD is running, we will register ourselves within EPMD, otherwise we don't bother starting it. This works by passing the parent port to the runtime which then matches against it when trying to connect back. We also patch the epmd module to keep the distribution port (which otherwise we wouldn't know).
To test this, you can
killall epmd(orepmd -kill), start Livebook, and double check running a notebook works as expected. There are some pending features which I will need the power of friendship to solve: