XDS "backend" is based on go language and up to now glide tool is used to manage dependencies with other packages.
But glide tool is now deprecated (1) and must be replace by Go modules (2) that is coming the new "official" way to manage package dependencies in go.

After a quick test it's seem not working as expected in some cases due to AGL tagging workflow. AGL tags added in xds repositories seems not compatible with go module versioning (3), and I suspect that there are 2 problems :

• 'v' letter is missing in tags
• major.minor.patch semantic doesn't respect semver (4) definition

More investigation is mandatory