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var GoSumFile string // path to go.sum; set by package modload
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var HelpGoproxy = &base.Command{
	UsageLine: "goproxy",
	Short:     "module proxy protocol",
	Long: `
A Go module proxy is any web server that can respond to GET requests for
URLs of a specified form. The requests have no query parameters, so even
a site serving from a fixed file system (including a file:/// URL)
can be a module proxy.

For details on the GOPROXY protocol, see
View Source
var HelpModuleAuth = &base.Command{
	UsageLine: "module-auth",
	Short:     "module authentication using go.sum",
	Long: `
When the go command downloads a module zip file or go.mod file into the
module cache, it computes a cryptographic hash and compares it with a known
value to verify the file hasn't changed since it was first downloaded. Known
hashes are stored in a file in the module root directory named go.sum. Hashes
may also be downloaded from the checksum database depending on the values of

For details, see
View Source
var HelpPrivate = &base.Command{
	UsageLine: "private",
	Short:     "configuration for downloading non-public code",
	Long: `
The go command defaults to downloading modules from the public Go module
mirror at It also defaults to validating downloaded modules,
regardless of source, against the public Go checksum database at
These defaults work well for publicly available source code.

The GOPRIVATE environment variable controls which modules the go command
considers to be private (not available publicly) and should therefore not use
the proxy or checksum database. The variable is a comma-separated list of
glob patterns (in the syntax of Go's path.Match) of module path prefixes.
For example,


causes the go command to treat as private any module with a path prefix
matching either pattern, including,,

For fine-grained control over module download and validation, the GONOPROXY
and GONOSUMDB environment variables accept the same kind of glob list
and override GOPRIVATE for the specific decision of whether to use the proxy
and checksum database, respectively.

For example, if a company ran a module proxy serving private modules,
users would configure go using:


The GOPRIVATE variable is also used to define the "public" and "private"
patterns for the GOVCS variable; see 'go help vcs'. For that usage,
GOPRIVATE applies even in GOPATH mode. In that case, it matches import paths
instead of module paths.

The 'go env -w' command (see 'go help env') can be used to set these variables
for future go command invocations.

For more details, see


func CachePath

func CachePath(m module.Version, suffix string) (string, error)

func Download

func Download(ctx context.Context, mod module.Version) (dir string, err error)

    Download downloads the specific module version to the local download cache and returns the name of the directory corresponding to the root of the module's file tree.

    func DownloadDir

    func DownloadDir(m module.Version) (string, error)

      DownloadDir returns the directory to which m should have been downloaded. An error will be returned if the module path or version cannot be escaped. An error satisfying errors.Is(err, fs.ErrNotExist) will be returned along with the directory if the directory does not exist or if the directory is not completely populated.

      func DownloadZip

      func DownloadZip(ctx context.Context, mod module.Version) (zipfile string, err error)

        DownloadZip downloads the specific module version to the local zip cache and returns the name of the zip file.

        func GoMod

        func GoMod(path, rev string) ([]byte, error)

          GoMod is like Lookup(path).GoMod(rev) but avoids the repository path resolution in Lookup if the result is already cached on local disk.

          func GoModFile

          func GoModFile(path, version string) (string, error)

            GoModFile is like GoMod but returns the name of the file containing the cached information.

            func GoModSum

            func GoModSum(path, version string) (string, error)

              GoModSum returns the go.sum entry for the module version's go.mod file. (That is, it returns the entry listed in go.sum as "path version/go.mod".)

              func HaveSum

              func HaveSum(mod module.Version) bool

                HaveSum returns true if the go.sum file contains an entry for mod. The entry's hash must be generated with a known hash algorithm. mod.Version may have a "/go.mod" suffix to distinguish sums for .mod and .zip files.

                func ImportRepoRev

                func ImportRepoRev(path, rev string) (Repo, *RevInfo, error)

                  ImportRepoRev returns the module and version to use to access the given import path loaded from the source code repository that the original "go get" would have used, at the specific repository revision (typically a commit hash, but possibly also a source control tag).

                  func InfoFile

                  func InfoFile(path, version string) (string, error)

                    InfoFile is like Lookup(path).Stat(version) but returns the name of the file containing the cached information.

                    func IsPseudoVersion

                    func IsPseudoVersion(v string) bool

                      IsPseudoVersion reports whether v is a pseudo-version.

                      func IsZeroPseudoVersion

                      func IsZeroPseudoVersion(v string) bool

                        IsZeroPseudoVersion returns whether v is a pseudo-version with a zero base, timestamp, and revision, as returned by ZeroPseudoVersion.

                        func PseudoVersion

                        func PseudoVersion(major, older string, t time.Time, rev string) string

                          PseudoVersion returns a pseudo-version for the given major version ("v1") preexisting older tagged version ("" or "v1.2.3" or "v1.2.3-pre"), revision time, and revision identifier (usually a 12-byte commit hash prefix).

                          func PseudoVersionBase

                          func PseudoVersionBase(v string) (string, error)

                            PseudoVersionBase returns the canonical parent version, if any, upon which the pseudo-version v is based.

                            If v has no parent version (that is, if it is "vX.0.0-[…]"), PseudoVersionBase returns the empty string and a nil error.

                            func PseudoVersionRev

                            func PseudoVersionRev(v string) (rev string, err error)

                              PseudoVersionRev returns the revision identifier of the pseudo-version v. It returns an error if v is not a pseudo-version.

                              func PseudoVersionTime

                              func PseudoVersionTime(v string) (time.Time, error)

                                PseudoVersionTime returns the time stamp of the pseudo-version v. It returns an error if v is not a pseudo-version or if the time stamp embedded in the pseudo-version is not a valid time.

                                func RemoveAll

                                func RemoveAll(dir string) error

                                  RemoveAll removes a directory written by Download or Unzip, first applying any permission changes needed to do so.

                                  func SideLock

                                  func SideLock() (unlock func(), err error)

                                    SideLock locks a file within the module cache that that previously guarded edits to files outside the cache, such as go.sum and go.mod files in the user's working directory. If err is nil, the caller MUST eventually call the unlock function.

                                    func SortVersions

                                    func SortVersions(list []string)

                                    func Sum

                                    func Sum(mod module.Version) string

                                      Sum returns the checksum for the downloaded copy of the given module, if present in the download cache.

                                      func TrimGoSum

                                      func TrimGoSum(keep map[module.Version]bool)

                                        TrimGoSum trims go.sum to contain only the modules needed for reproducible builds.

                                        keep is used to check whether a sum should be retained in go.mod. It should have entries for both module content sums and go.mod sums (version ends with "/go.mod").

                                        func TryProxies

                                        func TryProxies(f func(proxy string) error) error

                                          TryProxies iterates f over each configured proxy (including "noproxy" and "direct" if applicable) until f returns no error or until f returns an error that is not equivalent to fs.ErrNotExist on a proxy configured not to fall back on errors.

                                          TryProxies then returns that final error.

                                          If GOPROXY is set to "off", TryProxies invokes f once with the argument "off".

                                          func WriteGoSum

                                          func WriteGoSum(keep map[module.Version]bool)

                                            WriteGoSum writes the go.sum file if it needs to be updated.

                                            keep is used to check whether a newly added sum should be saved in go.sum. It should have entries for both module content sums and go.mod sums (version ends with "/go.mod"). Existing sums will be preserved unless they have been marked for deletion with TrimGoSum.

                                            func ZeroPseudoVersion

                                            func ZeroPseudoVersion(major string) string

                                              ZeroPseudoVersion returns a pseudo-version with a zero timestamp and revision, which may be used as a placeholder.


                                              type DownloadDirPartialError

                                              type DownloadDirPartialError struct {
                                              	Dir string
                                              	Err error

                                                DownloadDirPartialError is returned by DownloadDir if a module directory exists but was not completely populated.

                                                DownloadDirPartialError is equivalent to fs.ErrNotExist.

                                                func (*DownloadDirPartialError) Error

                                                func (e *DownloadDirPartialError) Error() string

                                                func (*DownloadDirPartialError) Is

                                                func (e *DownloadDirPartialError) Is(err error) bool

                                                type Repo

                                                type Repo interface {
                                                	// ModulePath returns the module path.
                                                	ModulePath() string
                                                	// Versions lists all known versions with the given prefix.
                                                	// Pseudo-versions are not included.
                                                	// Versions should be returned sorted in semver order
                                                	// (implementations can use SortVersions).
                                                	// Versions returns a non-nil error only if there was a problem
                                                	// fetching the list of versions: it may return an empty list
                                                	// along with a nil error if the list of matching versions
                                                	// is known to be empty.
                                                	// If the underlying repository does not exist,
                                                	// Versions returns an error matching errors.Is(_, os.NotExist).
                                                	Versions(prefix string) ([]string, error)
                                                	// Stat returns information about the revision rev.
                                                	// A revision can be any identifier known to the underlying service:
                                                	// commit hash, branch, tag, and so on.
                                                	Stat(rev string) (*RevInfo, error)
                                                	// Latest returns the latest revision on the default branch,
                                                	// whatever that means in the underlying source code repository.
                                                	// It is only used when there are no tagged versions.
                                                	Latest() (*RevInfo, error)
                                                	// GoMod returns the go.mod file for the given version.
                                                	GoMod(version string) (data []byte, err error)
                                                	// Zip writes a zip file for the given version to dst.
                                                	Zip(dst io.Writer, version string) error

                                                  A Repo represents a repository storing all versions of a single module. It must be safe for simultaneous use by multiple goroutines.

                                                  func Lookup

                                                  func Lookup(proxy, path string) Repo

                                                    Lookup returns the module with the given module path, fetched through the given proxy.

                                                    The distinguished proxy "direct" indicates that the path should be fetched from its origin, and "noproxy" indicates that the patch should be fetched directly only if GONOPROXY matches the given path.

                                                    For the distinguished proxy "off", Lookup always returns a non-nil error.

                                                    A successful return does not guarantee that the module has any defined versions.

                                                    type RevInfo

                                                    type RevInfo struct {
                                                    	Version string    // suggested version string for this revision
                                                    	Time    time.Time // commit time
                                                    	// These fields are used for Stat of arbitrary rev,
                                                    	// but they are not recorded when talking about module versions.
                                                    	Name  string `json:"-"` // complete ID in underlying repository
                                                    	Short string `json:"-"` // shortened ID, for use in pseudo-version

                                                      A Rev describes a single revision in a module repository.


                                                      Path Synopsis
                                                      Package codehost defines the interface implemented by a code hosting source, along with support code for use by implementations.
                                                      Package codehost defines the interface implemented by a code hosting source, along with support code for use by implementations.