Use latest cargo-local-registry (from git)

[dhovart]

This fixes #34.

Make sure to pull rust:latest if it's not compiling locally (build needs cargo >= 1.56).

Sorry for the long resolution time, I had to resolve a few issues related to cargo-local-registry.
In this PR, we're building cargo-local-registry from its git source instead of pulling a binary release.
I'll update the Dockerfile once a binary is available to shorten build time.

I've made a test with the gigasecond exercise and it worked properly.

[ErikSchierboom]

@dhovart I can confirm that the build failure is fixed. When I try to run the test runner though, I get an error:

slug:          gigasecond
solution path: /solution
output path:   /output
   Unpacking libc v0.2.108 (registry `/opt/test-runner/local-registry`)
error: failed to download `libc v0.2.108`

Caused by:
  unable to get packages from source

Caused by:
  failed to download replaced source registry `crates-io`

Caused by:
  failed to unpack package `libc v0.2.108 (registry `/opt/test-runner/local-registry`)`

Caused by:
  failed to create directory `/usr/local/cargo/registry/src/-0177ef2a2962ff86/libc-0.2.108`

Caused by:
  Read-only file system (os error 30)

Is that something that happens on your side too?

[dhovart]

@ErikSchierboom it doesn't work with a read-only filesystem. You need to run the docker image without the read-only option.

[ErikSchierboom]

@dhovart Ah right. That's okay for now.

It does now work:

slug:          gigasecond
solution path: /solution
output path:   /output
   Unpacking libc v0.2.108 (registry `/opt/test-runner/local-registry`)
   Unpacking time v0.3.5 (registry `/opt/test-runner/local-registry`)
   Compiling libc v0.2.108
   Compiling time v0.3.5
   Compiling gigasecond v2.0.0 (/solution)
    Finished test [unoptimized + debuginfo] target(s) in 6.06s
     Running unittests (target/debug/deps/gigasecond-71d09f45297ab0ff)
     Running tests/gigasecond.rs (target/debug/deps/gigasecond-67509d699a3b6632)
   Doc-tests gigasecond

It looks like the test runner was compiling libc and time. Is there any way to pre-compile these?

[dhovart]

Yes! I plan to work on this with #35.

[ErikSchierboom]

Thanks!