Support custom environment variables in Session configurations

[DanielCardonaRojas]

What would you like sesh to do?

Hey, first of all, thank you for creating this tool!

I would like to suggest a feature enhancement that would allow users to export custom environment variables via the configuration file. The idea is to define environment variables within each session configuration, and when a session is started, these variables should be set in the environment for that session.

Proposed Change:

In addition to the current options available in the TOML configuration (like name, path, startup_command), I propose adding an option for env, where users can define one or more environment variables that will be set when the session is opened.

For example:

[[session]]
name = "Downloads 📥"
path = "~/Downloads"
startup_command = "ls"
env = { MY_CUSTOM_VAR = "downloads", ANOTHER_VAR = "example" }

When the session is started, the specified environment variables should be exported. This would allow external scripts or commands within the tmux session to pick up these environment variables and modify their behavior accordingly.

Benefits:

• This feature would give users more control over their environment per session.
• It allows for more dynamic setups where scripts or tools can behave differently based on the session type or context.
• Users who rely on environment variables in their workflow will find this useful for setting up tmux sessions in a more modular and automated way.

I believe this can be accomplished with:

tmux set-environment MY_CUSTOM_VAR "some_value"

[joshmedeski]

Interesting idea, would this work as-is?

startup_command = "MY_CUSTOM_VAR ='downloads' ANOTHER_VAR='example' ls"

If there are other tools like tmuxp that can do something similar I might be more interested in adding that integration rather than trying to build this kind of feature by hand.

[DanielCardonaRojas]

That doesn't seem to work.

My second attempt was to try the following:

startup_command = "tmux set-environment MY_CUSTOM_VAR 'some_value'"

The previous startup command works but only for subsequently created windows. The window that is initially created for the session does not receive the environment variable.

Investigating a bit more seems like this would allow the first window to receive the environment variable:

tmux new-session -d -s my_session "export MY_CUSTOM_VAR='some_value'; exec $SHELL"

I believe this touches territory of sesh connect.

So the final combination that yields the desired result would be:

tmux new-session -d -s my_session "export MY_CUSTOM_VAR='some_value'; exec $SHELL"
tmux set-environment -t  my_session MY_CUSTOM_VAR 'some_value'

[joshmedeski]

Could you use a tool like direnv?

[DanielCardonaRojas]

I guess that could work for a very project centric workflow, however I think there are still valid escenarios where you would want environment variables tied to sessions, not directories. An obvious benefit is less planning and configuration.

[joshmedeski]

Hmm, I guess I'd like a realistic example. I've never heard anyone mention this scenario, seems overcomplicated to me (without an example).

I'm not opposed to the idea, I just don't want to add complexity to the project if I can't justify it being useful to more than one person, hope you understand that.

[DanielCardonaRojas]

I understand, and perhaps we need more specific use cases to make a solid case for why this might be beneficial. Here are some that I personally would use, though I admit that for each specific case, there might be a workaround, and maybe it’s just convenience that I’m requesting here:

• Configure a specific editor for the session with EDITOR.
• Choose different flavors of CLIs by changing XDG_CONFIG_HOME.
• Choose a different Neovim configuration for the entire session by specifying NVIM_APPNAME.
• Configure a Docker daemon for the entire session with DOCKER_HOST.
• Tweak PATH.

• Source different shell configurations depending on the session.

  just wanted to provide some examples.

[joshmedeski]

Interesting, I think you can solve this with a startup script.

#!/bin/bash
tmux set-environment EDITOR "nano"
tmux set-environment DOCKER_HOST "localhost"

Then, you can call it as a custom configruation

[[session]]
name = "nano custom docker"
path = "~/projects/example"
startup_command = "nano-docker-localhost.sh"

Make sure the script is in your path, or define an absolute path, and make sure the file is exectuable.

I don't see why this wouldn't solve all your problems, and you can reuse the startup scripts. Hope this helps!

[joshmedeski]

The previous startup command works but only for subsequently created windows

I have a feeling you'll have to experiment with the script to get this to work on the first window, seems like you're trying to do something tmux isn't expecting (updating environmental variables on the fly).

[DanielCardonaRojas]

Yes, this almost does it, and is what I'm doing for now. As I mentioned in:

https://github.com/joshmedeski/sesh/issues/182#issuecomment-2378424467

This takes care of any new windows after the session is created but misses on the first window.

But I understand maybe its not worth the extra work. The following startup command does work:

startup_command = "export MY_CUSTOM_VAR='some_value'; tmux set-environment MY_CUSTOM_VAR 'some_value'; clear"

Feel free to close.

[joshmedeski]

I was thinking the same thing (exporting and setting).

Glad we could talk it out, thanks for your feedback.