Installing opam does not seem to install switch

[Zarickan]

Hi,

I am trying to install opam on Debian, to install I run:

sudo apt install opam
opam init
eval $(opam env)

All complete without errors or warnings, the output from opam init is:

$ opam init

<><> Required setup - please read <><><><><><><><><><><><><><><><><><><><><><><>

  In normal operation, opam only alters files within ~/.opam.

  However, to best integrate with your system, some environment variables
  should be set. If you allow it to, this initialisation step will update
  your bash configuration by adding the following line to ~/.profile:

    test -r /home/X/.opam/opam-init/init.sh && . /home/X/.opam/opam-init/init.sh > /dev/null 2> /dev/null || true

  Otherwise, every time you want to access your opam installation, you will
  need to run:

    eval $(opam env)

  You can always re-run this setup with 'opam init' later.

Do you want opam to modify ~/.profile? [N/y/f]
(default is 'no', use 'f' to choose a different file) y
A hook can be added to opam's init scripts to ensure that the shell remains in sync with the opam environment when they are loaded. Set that up? [y/N] y

User configuration:
  ~/.profile is already up-to-date.
[NOTE] Make sure that ~/.profile is well sourced in your ~/.bashrc.

However, if I try to install something with opam install ... I get the following error:

$ opam install opam-depext
[ERROR] No switch is currently set. Please use 'opam switch' to set or install a switch

Is opam not supposed to create a switch on install?

I tried to create a switch, but it seems I have hundreds of different compilers to choose from, which one should I select for the switch?

Opam config report:

# opam config report
# opam-version      2.0.3
# self-upgrade      no
# system            arch=x86_64 os=linux os-distribution=debian os-version=10
[ERROR] No switch is currently set. Please use 'opam switch' to set or install a switch
# read-state        OpamStd.OpamSys.Exit(50)

[dra27]

Assuming you haven't trimmed anything from that log, is OPAMBARE set in your environment? The log you've given above is exactly expect to see with opam init --bare or OPAMBARE=true opam init.

[dra27]

Oh no, hang on - even with opam init --bare you should still see the initial repo sync. Have you used opam previously - it looks more like ~/.opam already existed. Assuming you're happy to start again, you can either rm -rf ~/.opam or rename it to something else and re-run opam init.

[Zarickan]

After doing rm -rf ~/.opam I get this instead:

$ opam init
[NOTE] Will configure from built-in defaults.
Checking for available remotes: rsync and local, git, mercurial, darcs. Perfect!

<><> Fetching repository information ><><><><><><><><><><><><><><><><><><><><><>
[default] Initialised

<><> Required setup - please read <><><><><><><><><><><><><><><><><><><><><><><>

  In normal operation, opam only alters files within ~/.opam.

  However, to best integrate with your system, some environment variables
  should be set. If you allow it to, this initialisation step will update
  your bash configuration by adding the following line to ~/.profile:

    test -r /home/X/.opam/opam-init/init.sh && . /home/X/.opam/opam-init/init.sh > /dev/null 2> /dev/null || true

  Otherwise, every time you want to access your opam installation, you will
  need to run:

    eval $(opam env)

  You can always re-run this setup with 'opam init' later.

Do you want opam to modify ~/.profile? [N/y/f]
(default is 'no', use 'f' to choose a different file) y
A hook can be added to opam's init scripts to ensure that the shell remains in sync with the opam environment when they are loaded. Set that up? [y/N] y

User configuration:
  ~/.profile is already up-to-date.
[NOTE] Make sure that ~/.profile is well sourced in your ~/.bashrc.


<><> Creating initial switch (ocaml-system>=4.02.3) <><><><><><><><><><><><><><>


<><> Gathering sources ><><><><><><><><><><><><><><><><><><><><><><><><><><><><>

<><> Processing actions <><><><><><><><><><><><><><><><><><><><><><><><><><><><>
∗ installed base-bigarray.base
∗ installed base-threads.base
∗ installed base-unix.base
[ERROR] The compilation of ocaml-system failed at "/home/X/.opam/opam-init/hooks/sandbox.sh build ocaml gen_ocaml_config.ml".

#=== ERROR while compiling ocaml-system.4.05.0 ================================#
# context     2.0.3 | linux/x86_64 |  | https://opam.ocaml.org#5c5a526e
# path        ~/.opam/default/.opam-switch/build/ocaml-system.4.05.0
# command     ~/.opam/opam-init/hooks/sandbox.sh build ocaml gen_ocaml_config.ml
# exit-code   1
# env-file    /tmp/opam-xxx-2354/ocaml-system-2354-6aa130.env
# output-file /tmp/opam-xxx-2354/ocaml-system-2354-6aa130.out
### output ###
# bwrap: Creating new namespace failed: Permission denied



<><> Error report <><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><>
┌─ The following actions failed
│ λ build ocaml-system 4.05.0
└─
┌─ The following changes have been performed (the rest was aborted)
│ ∗ install base-bigarray base
│ ∗ install base-threads  base
│ ∗ install base-unix     base
└─
# Run eval $(opam env) to update the current shell environment
Switch initialisation failed: clean up? ('n' will leave the switch partially installed) [Y/n] y

[kit-ty-kate]

Are you running this inside of a docker container or similar container/sandbox?

[Zarickan]

This is in Debian on WSL2 on Windows 10 version 20H2

[dra27]

Are you certain that's WSL2 and not WSL1? (wsl -l -v from a command prompt)

[Zarickan]

You are right it was still running on version 1. After upgrading to version 2 it seems to work, is opam not compatible with WSL1?

[kit-ty-kate]

is opam not compatible with WSL1?

opam itself should be. It's just its sandboxing mecanism (bubblewrap) that is not. See ocaml/opam-repository#12050 for more info.

I'm guessing this issue can now be closed. Please reopen if I'm mistaken. I've opened #4821 to make opam init less confusing per your setup in your original comment.

Using opam install ... to setup a switch would be a bit surprising in my opinion as opam would have to guess what the user wants (global switch vs. local switch, and with which OCaml version, OCaml system vs. ocaml-base-compiler, etc..)

Thanks for your time!

[Zarickan]

Thank you for helping.

Perhaps this would be a candidate for something to include somewhere in the installation documentation (perhaps on the website). At least it wasn't clear to me that this error was because of WSL1 and I couldn't find any documentation anywhere stating that opam is not compatible with WSL1.

[kit-ty-kate]

Mmh, that's fair. I've opened #4822 for that purpose. Thanks for the suggestion.

I believe more recent versions of opam (2.0.3 is 2 and a half years old) would have caught that in the opam init step as it tests if the sandbox works and shown a useful error message:

opam/src/client/opamAuxCommands.ml

Line 524 in 295e273

"Do you want to disable it? Note that this will result in \