Cobalt's build tools (CMake, toolchain, ninja, go and protoc-gen-go) and some other developer tools (bigtable tool and cloud SDK) are downloaded pre-builts installed into the sysroot directory using the setup.sh script. Normally this script should be invoked via the command cobaltb.py setup. This causes a single sysroot.tgz file to be downloaded from Google Cloud Storage. The sha1 hash of the downloaded file is verified.
To build and upload a new version of sysroot to Google storage do the following:
rm -fr sysroot./setup.sh -u