Support installing pre-built releases

[tsloughter]

We should start by pulling builds from https://github.com/wojtekmach/otp_releases/releases

The main question I have at this point is what command to use/create?

My initial thinking is we add a command erlup install <version>. The user can then use that instead of erlup build <tag> if they want to use a binary release. I sort of want install to also set the new version as the default, simply because install just sounds like it would do that -- of course with a --no-default option to not change the default.

But if install does update the default then there should also be a way to use it to build a tag and set it as default. I suppose it could be as simple as erlup install --tag <tag> will do a build and erlup install <version> will always do binary releases.

Oh and install should probably still support --repo to make it easy to test pointing at different repos for fetching the releases., esp since they'll eventually be moving to the erlang/otp repo.

[lrascao]

Maybe we should try and first streamline the current interface and see where this would fit, i still get a bit confused with default/switch and build/fetch/report

[lrascao]

The way i see it, people want to:

• build an Erlang from source, any repo that they choose, defaults to OTP's
• fetch a pre-compiled Erlang from somewhere, defaults to Wojteck's (or OTP's)
• switch around between any of the above

I envision the following:

• erlup repo ls/add/rm --[source, binary]: adds source/binary repos with a given name, both default to OTP's
• erlup build <id> <repo>, builds an Erlang and makes it available somewhere through the id
• erlup install <id> <repo>, install a pre-compiled Erlang from
• erlup default <id>, as is
• erlup delete <id>, as is
• erlup show, rename of erlup list

[tsloughter]

And you think we should rename switch to use?

[lrascao]

rustup only has one command to switch around between toolchains, i think default, switch or use are all fine names, i just think it should be a single one

[tsloughter]

@lrascao hm? But you need a command that can set the global Erlang to use and one to set the Erlang to use for the cwd.

[lrascao]

Maybe i'm missing something then, i've never had a need for that. If i had i'd probably look for some other tool that switches Erlangs on the cwd kinda like direnv does.

[tsloughter]

If you used direnv but didn't have this feature to set it per cwd then it would be still global. So you'd change to a directory in one terminal and now even in any other terminal you have the Erlang used is changed.

We could just copy rustup's commands for this: https://doc.rust-lang.org/nightly/edition-guide/rust-2018/rustup-for-managing-rust-versions.html#managing-versions

They use default like erlup does but instead of switch <vsn> it has override set <vsn> to do the same thing (per-directory version to use).

[lrascao]

nah, if it's just naming then this way is fine

[tsloughter]

Can also configure overrides the way they do. Right now it creates a file in the cwd, ./erlup.config. rustup adds the override to the global config, like:

[overrides]
"/home/tristan/Devel/erlup" = "nightly-x86_64-unknown-linux-gnu"

But you can also manually create the file rust-toolchain in the cwd so you can check it in.

I think I like that better than always creating the file in the cwd. But getting off topic at this point :), I can make issues for that stuff.

[tsloughter]

The nice thing I see now about using override instead of switch is the other commands that it has:

SUBCOMMANDS:
    list     List directory toolchain overrides
    set      Set the override toolchain for a directory
    unset    Remove the override toolchain for a directory

So maybe override is a better name than switch.

[tsloughter]

And yea, show instead of list sounds good.