Refine the default behaviour for "wasmer run"

[Michael-F-Bryan]

Currently, when the user runs wasmer run ls, the behaviour is as follows...

• If the command has already been installed (i.e. wasmer install user/some-package where the package contains a ls command),
  • Execute it
• Otherwise,
  • Ask the WAPM backend which packages include a ls command (query)
  • Automatically install the package that was most recently published
  • Execute it

This mostly works, but there’s no guarantee which package you are installing if someone else publishes a package with the same command name (not good for ergonomics or security).

One idea @syrusakbary raised is that we could use the [dependencies] section in wapm.toml (soon to be renamed wasmer.toml) to figure out which commands are available.

For example:

#  wapm.toml
[package]
name = "..."

[[command]]
name = "ls"
package = "markj/coreutils"

[dependencies]
"mark/coreutils" = ".."
"sharrattj/coreutils:ls" = "1.2.3"

To help users, the wapm install mark/coreutils command could automatically update the "closest" wapm.toml file, and running wasmer run ls without an ls command in your wapm.toml would give you a suggestion like this:

$ wasmer run ls
ERROR: The "ls" command isn't currently installed. 

You might want to install one of the following packages:
- sharrattj/coreutils
- mark2/coreutils

If we behave similar to git and npm by recursively searching parent files for a wapm.toml, this effectively gives us a "global install" command for free - if no wapm.toml is found, add it to $HOME/.wapm.toml (or $WASMER_HOME/wapm.toml or $HOME/.config/wasmer/wapm.toml or wherever).

[Michael-F-Bryan]

It sounds like this broke webassembly.sh - wasmerio/webassembly.sh#116.

[Michael-F-Bryan]

I'm closing this because it's no longer relevant.

There is no longer the concept of "installing" commands. Instead, since merging the wapm and wasmer CLIs and re-implementing wasmer run (#3924), wasmer run will now accept

• a URL or file path pointing to a *.webc file
• the name (and version) of a package that we'll fetch from the current registry, or
• the path to a directory containing a wasmer.toml file