Text file src/pkg/README.vendor

     1	Vendoring in std and cmd
     2	========================
     3	
     4	The Go command maintains copies of external packages needed by the
     5	standard library in the src/vendor and src/cmd/vendor directories.
     6	
     7	In GOPATH mode, imports of vendored packages are resolved to these
     8	directories following normal vendor directory logic
     9	(see golang.org/s/go15vendor).
    10	
    11	In module mode, std and cmd are modules (defined in src/go.mod and
    12	src/cmd/go.mod). When a package outside std or cmd is imported
    13	by a package inside std or cmd, the import path is interpreted
    14	as if it had a "vendor/" prefix. For example, within "crypto/tls",
    15	an import of "golang.org/x/crypto/cryptobyte" resolves to
    16	"vendor/golang.org/x/crypto/cryptobyte". When a package with the
    17	same path is imported from a package outside std or cmd, it will
    18	be resolved normally. Consequently, a binary may be built with two
    19	copies of a package at different versions if the package is
    20	imported normally and vendored by the standard library.
    21	
    22	Vendored packages are internally renamed with a "vendor/" prefix
    23	to preserve the invariant that all packages have distinct paths.
    24	This is necessary to avoid compiler and linker conflicts. Adding
    25	a "vendor/" prefix also maintains the invariant that standard
    26	library packages begin with a dotless path element.
    27	
    28	The module requirements of std and cmd do not influence version
    29	selection in other modules. They are only considered when running
    30	module commands like 'go get' and 'go mod vendor' from a directory
    31	in GOROOT/src.
    32	
    33	Maintaining vendor directories
    34	==============================
    35	
    36	Before updating vendor directories, ensure that module mode is enabled.
    37	Make sure GO111MODULE=off is not set ('on' or 'auto' should work).
    38	
    39	Requirements may be added, updated, and removed with 'go get'.
    40	The vendor directory may be updated with 'go mod vendor'.
    41	A typical sequence might be:
    42	
    43	    cd src
    44	    go get -m golang.org/x/net@latest
    45	    go mod tidy
    46	    go mod vendor
    47	
    48	Use caution when passing '-u' to 'go get'. The '-u' flag updates
    49	modules providing all transitively imported packages, not just
    50	the target module.
    51	
    52	Note that 'go mod vendor' only copies packages that are transitively
    53	imported by packages in the current module. If a new package is needed,
    54	it should be imported before running 'go mod vendor'.

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