Optimize build size

[MarinPostma]

Remove debug symbols from the release build, and strip the binaries.

We used to need to debug symbols for sentry, but since it was removed with #1616, we don't need them anymore.

Shrinks the binary size from ~300MB to ~50MB on linux.

[Kerollmops]

Hum... I am not sure about that but the backtrace i.e. RUST_BACKTRACE=1 will not work anymore, am I right? If I'm wrong and the backtrace can always be displayed correctly without having to specify the debug = true in the Cargo.toml file, I would gladly approve this PR.

[irevoire]

Yeah not sure either we want to remove the debug symbol; when a user encounters an unknown panic, the symbols/backtrace can give us a hint at what is going wrong 😬

[MarinPostma]

@Kerollmops none of the distribution of meilisearch comes with the RUST_BACKTRACE=1 enabled, and we never ever collect them anyway. The backtrace is rendered correctly without the debug symbols:

but not when the binary is stripped. I think we can put aside stripping for now.

[irevoire]

Since we can still see the panics I'm ok with this change

[Kerollmops]

Same, as we see the panic backtraces, I approve this!

[irevoire]

Here is a screenshot of a panic before this PR:

Now a screenshot with this PR:

And finally, a screenshot of what we would have if we stripped + compressed the binary with upx as shown in #1782:

@Kerollmops do you still think this is ok?
We lost all the line numbers of the backtrace in this PR.
For me, the only line we can use if we merge this PR is the only line kept when stripping the binary. So why not strip everything as well? 🤔

thread 'actix-rt|system:0|arbiter:0' panicked at 'Hello', meilisearch-http/src/routes/indexes/search.rs:140:5

(I took every screenshot with the option RUST_BACKTRACE=1)

[Kerollmops]

For me, the only line we can use if we merge this PR is the only line kept when stripping the binary. So why not strip everything as well? 🤔

That's no true, sometimes it panics in a function that is not quite useful (inside of [T]::split_at, <[T] as Index>::index) and sometimes not even in a function of the standard library.

[irevoire]

So are we sure we want to merge this PR as-is?

[Kerollmops]

What is the size gain for this PR, already?

[irevoire]

On my computer, without this PR, the binary weight 326MB, and with this PR it's only 35MB

[Kerollmops]

That's a lot! maybe we can merge this. I think that the backtrace we got without all of the line numbers is enough to debug.

[irevoire]

bors merge

[bors]

Build succeeded:

• Run Clippy
• Run Rustfmt
• Tests on macos-latest
• Tests on ubuntu-18.04
• Tests on windows-latest