See "go help modules". Modules and vendoring When using modules, the go command completely ignores vendor directories. By default, the go command satis

See "go help modules". Modules and vendoring When using modules, the go command completely ignores vendor directories. By default, the go command satisfies dependencies by downloading modules from their sources and using those downloaded copies (after verification, as described in the previous section). To allow interoperation with older versions of Go, or to ensure that all files used for a build are stored together in a single file tree, 'go mod -vendor' creates a directory named vendor in the root directory of the main module and stores there all the packages from dependency modules that are needed to support builds and tests of packages in the main module. To build using the main module's top-level vendor directory to satisfy dependencies (disabling use of the usual network sources and local caches), use 'go build -getmode=vendor'. Note that only the main module's top-level vendor directory is used; vendor directories in other locations are still ignored.