问题
今天使用go get下载安装hugo的时候遇到如下网络连接失败的问题，
原因是部分网络资源在中国无法直接访问。
$ go get -v github.com/gohugoio/hugo
github.com/gohugoio/hugo (download)
...
github.com/spf13/nitro (download)
Fetching https://golang.org/x/sync/errgroup?go-get=1
https fetch failed: Get https://golang.org/x/sync/errgroup?go-get=1: dial tcp 216.239.37.1:443: connectex: A connection attempt failed because the connected party did not properly respond after a period of time, or established connection failed because connected host has failed to respond.
package golang.org/x/sync/errgroup: unrecognized import path "golang.org/x/sync/errgroup" (https fetch: Get https://golang.org/x/sync/errgroup?go-get=1: dial tcp 216.239.37.1:443: connectex: A connection attempt failed because the connected party did not properly respond after a period of time, or established connection failed because connected host has failed to respond.)
github.com/cpuguy83/go-md2man (download)
github.com/spf13/fsync (download)
解决思路
在$GOPATH/src路径下创建golang/x文件夹并下载想要的包。以Windows为例，下面的报错信息提示无法获取https://golang.org/x/sync，现在我们来手动获取。
命令
执行如下命令，手动下载golang.org sync package.
mkidr -p ~/go/src/golang.org/x
cd ~/go/src/golang.org/x
git clone https://github.com/golang/sync.git
go get -v github.com/gohugoio/hugo
安装完毕，可以执行hugo，查看安装时候成功。
casperl@CasperLiu MINGW64 ~/go/src/golang.org/x
$ hugo -h
hugo is the main command, used to build your Hugo site.
Hugo is a Fast and Flexible Static Site Generator
built with love by spf13 and friends in Go.
Complete documentation is available at http://gohugo.io/.
Usage:
hugo [flags]
hugo [command]
Available Commands:
config Print the site configuration
convert Convert your content to different formats
env Print Hugo version and environment info
gen A collection of several useful generators.
help Help about any command
import Import your site from others.
list Listing out various types of content
new Create new content for your site
server A high performance webserver
version Print the version number of Hugo
Flags:
-b, --baseURL string hostname (and path) to the root, e.g. http://spf13.com/
-D, --buildDrafts include content marked as draft
-E, --buildExpired include expired content
-F, --buildFuture include content with publishdate in the future
--cacheDir string filesystem path to cache directory. Defaults: $TMPDIR/hugo_cache/
--cleanDestinationDir remove files from destination not found in static directories
--config string config file (default is path/config.yaml|json|toml)
--configDir string config dir (default "config")
-c, --contentDir string filesystem path to content directory
--debug debug output
-d, --destination string filesystem path to write files to
--disableKinds strings disable different kind of pages (home, RSS etc.)
--enableGitInfo add Git revision, date and author info to the pages
-e, --environment string build environment
--forceSyncStatic copy all files when static is changed.
--gc enable to run some cleanup tasks (remove unused cache files) after the build
-h, --help help for hugo
--i18n-warnings print missing translations
--ignoreCache ignores the cache directory
-l, --layoutDir string filesystem path to layout directory
--log enable Logging
--logFile string log File path (if set, logging enabled automatically)
--minify minify any supported output format (HTML, XML etc.)
--noChmod don't sync permission mode of files
--noTimes don't sync modification time of files
--quiet build in quiet mode
--renderToMemory render to memory (only useful for benchmark testing)
-s, --source string filesystem path to read files relative from
--stepAnalysis display memory and timing of different steps of the program
--templateMetrics display metrics about template executions
--templateMetricsHints calculate some improvement hints when combined with --templateMetrics
-t, --theme strings themes to use (located in /themes/THEMENAME/)
--themesDir string filesystem path to themes directory
-v, --verbose verbose output
--verboseLog verbose logging
-w, --watch watch filesystem for changes and recreate as needed
Additional help topics:
hugo check Contains some verification checks
Use "hugo [command] --help" for more information about a command.