One GOPROXY setting for go get and go mod download. Modules come through a pull-through cache that verifies every checksum, and the checksum database is proxied too, so GOSUMDB stays at its default.
go env -w persists the setting in Go's own environment file. Mark internal modules with GOPRIVATE on an air-gapped instance.
The placeholders are your base URL and a token from the web UI. The guide covers the same steps for a single project, plain HTTP, verifying the change, and reverting it.
go env -w GOPROXY=https://repo.example.com/go,direct
# the checksum database is proxied too: leave GOSUMDB at its defaultThe client sees a registry. Behind it, Dependably Packages stages each upstream artefact and refuses the ones that fail a check you configured.
The Go guide continues with a verification step and reverting the configuration. Go is served as a mirror: it proxies and caches, and does not accept uploads.