Epic: Improved support for user-defined shells (e.g. fish / zsh, etc)

[axonasif]

Improve the support for user-defined shells such as zsh, fish, etc.

Includes, but not limited to:

• Improve documentation around SHELL environment variable
• Update Gitpod compatibility matrix
• Update default workspaces images
• Update any other parts of the product that assume bash (where possible)

Relates to:

• Epic: Persisted Terminal History #9019
• tasks: Fail on error by default (run with bash -e) #13558
• Python pip doesn't work properly in zsh workspace-images#984
• VSCODE terminals are automatically created without any visible reason #9531

Original issue description

Is your feature request related to a problem? Please describe

It would be nice to have Gitpod switch to the user defined(terminal.integrated.defaultProfile.linux ) SHELL after processing the task commands in bash.

Describe the behaviour you'd like

• Imagine I have this on my .gitpod.yml:

tasks:
  - name: combined tasks
    command: echo "this is a command (combined)"
    before: echo "this is a before (combined)"

• Upon workspace IDE start, I would see this on my task terminal:

Proposed solution

So, I think we could just put ; exec <user-shell>(only if the user is not using bash as default) at the end of the script that we're sending to the task terminal, which could look like:

 HISTFILE=/workspace/.gitpod/cmd-0 history -r; {
echo "this is a before (combined)"
} && {
echo "this is a command (combined)"
}; exec /usr/bin/fish # This here mainly

We might also need to consider having an option for .gitpod.yml to disable the switching behavior as someone might not want it to switch on some specific use case.

Describe alternatives you've considered

There are two ways I know of at this moment:

1. Set SHELL env var in https://gitpod.io/variables or set in dockerfile to make the defined SHELL globally be used across the workspace, @akosyakov shared this trick 👍
   However, this will cause issues since many of the bash builtins are either not present in other shells or behaves differently. On the other hand, we also have non POSIX shells like fish.
2. Append some custom logic(hijacking PROMPT_COMMAND) into $HOME/.bashrc to run exec <shell> upon detection of a task terminal and to switch only after the commands have been run. This is done via utilizing the dotfiles feature of Gitpod ¹
   However, this is not a neat or straightforward method of doing this.

Additional context

Internal discussion on Slack.

Footnotes

1. https://github.com/axonasif/dotfiles/blob/5d50fdc8a6fd171ecf3ddeed6443ca45e1f817f3/src/main.sh#L61 ↩

[loujaybee]

Agree, as I have this issue/challenge with using fish terminal, however terminal.integrated.defaultProfile.linux is VS Code specific, so would be good to have the configuration done somewhere that's IDE agnostic 🙏

[akosyakov]

Yes, I think SHELL emv var is a still way to go. Honestly even if supervisor reads from terminal.integrated.defaultProfile.linux I doubt it will resolve issues with fish.

So the focus should be to resolve:

However, this will cause issues since many of the bash builtins are either not present in other shells or behaves differently. On the other hand, we also have non POSIX shells like fish.

[axonasif]

Yes, I think SHELL emv var is a still way to go. Honestly even if supervisor reads from terminal.integrated.defaultProfile.linux I doubt it will resolve issues with fish.

Yep, I think we should cover both cases(imagine someone set from their dockerfile), can we add ; exec /your/shell/here at the end of a task script that we send to the terminal(detailed in the main issue)? That would potentially solve this.

[axonasif]

Just noticed after daily driving SHELL=/usr/bin/zsh for a while, if you set your shell to something else other than bash with SHELL variable, you miss out on all the workspace customization we do (e.g environment variables, bashrc.d hooks).

Perhaps we should switch to other shells from bash env.

[loujaybee]

Hey folks, I have broadened the scope of this issue (the original description is in the toggle) to be an epic to contain other sub issues about improved support for user defined shells. I will start to update the description with other related issues. If you have issues with any shell when using Gitpod, please raise an issue with the specific issue you are facing, and we can then link it here to track general progress towards improved user-defined shell support 🙏