Unable to build the rust-simple example

[roberthbailey]

What happened: Unable to build the rust-simple example.

What you expected to happen: Build completes successfully.

How to reproduce it (as minimally and precisely as possible): cd examples/rust-simple; make build-image

Anything else we need to know?: Here's the last bit of output from docker where the build fails:

Step 9/22 : COPY sdk/Cargo.toml /home/builder/agones/sdks/rust/
 ---> Using cache
 ---> bd867547e2cc
Step 10/22 : COPY sdk/Cargo.lock /home/builder/agones/sdks/rust/
COPY failed: stat /var/lib/docker/tmp/docker-builder692801886/sdk/Cargo.lock: no such file or directory
make: *** [build-image] Error 1

This may be related to #912 -- should Cargo.lock be committed into the repo?

I could probably create the file by running build before running build-image, but I don't have cargo installed on my Mac and the point of doing the build in the docker container is to have as few tools installed locally as possible.

Environment:

• Agones version: master branch
• Kubernetes version (use kubectl version): n/a
• Cloud provider or hardware configuration: Mac 10.14.5
• Install method (yaml/helm): n/a
• Troubleshooting guide log(s):
• Others:

/cc @aLekSer @Kuqd

[aLekSer]

I found this documentation.
It seems that we need to add Cargo.lock as we use docker with a binary https://doc.rust-lang.org/cargo/guide/cargo-toml-vs-cargo-lock.html
Also I will prepare a fix of rust version in a rust-simple/Dockerfile.