cannot find package "github.com/gorilla/mux" in any of:

I use command go get github.com/gorilla/mux. I made http server using Golang, and I run this program :

package main

import (
    "fmt"
    "html"
    "log"
    "net/http"

    "github.com/gorilla/mux"
)

func main() {

    router := mux.NewRouter().StrictSlash(true)
    router.HandleFunc("/", Index)
    log.Fatal(http.ListenAndServe(":8080", router))
}

func Index(w http.ResponseWriter, r *http.Request) {
    fmt.Fprintf(w, "Hello, %q", html.EscapeString(r.URL.Path))

But I conflict this error :

/usr/local/go/bin/go build -i [/Users/imac/go/src]
http.go:9:5: cannot find package "github.com/gorilla/mux" in any of:
	/usr/local/go/src/github.com/gorilla/mux (from $GOROOT)
	($GOPATH not set)
Error: process exited with code 1.

My Go environment is here :

GOARCH="amd64"
GOBIN=""
GOEXE=""
GOHOSTARCH="amd64"
GOHOSTOS="darwin"
GOOS="darwin"
GOPATH="/Users/imac/go"
GORACE=""
GOROOT="/usr/local/go"
GOTOOLDIR="/usr/local/go/pkg/tool/darwin_amd64"
CC="clang"
GOGCCFLAGS="-fPIC -m64 -pthread -fno-caret-diagnostics -Qunused-arguments -fmessage-length=0 -fdebug-prefix-map=/var/folders/v9/fkc_t97s5v1g9sr938zzvxvh0000gn/T/go-build096571864=/tmp/go-build -gno-record-gcc-switches -fno-common"
CXX="clang++"
CGO_ENABLED="1"

I fight with this error for a week, But I can't find out solution. Please help me.

Could you try this steps to debug it:

1. ls -l /usr/local/go/src/github.com | grep gorilla

2. cd $GOPATH

   go list ... | grep gorilla

3. if you din't see gorilla in the above two command, then you need to install it:
   go get -v -u github.com/gorilla/mux

Please run this: export PATH=$PATH:$GOPATH/bin

How about running go run main.go ? is that working, if yes you should be able to do go build from your project path.

I wish this helpful.
You may off the 'mod'.

$ export GO111MODULE=off

This works for me...

1. fire command
   > go mod init <your-directoryNane-where-main.go-exits>
2. fire command > go get github.com/gorilla/mux

after firing this both commands you will be able see 2 files :

1. go.mod
2. go.sum

finally, Close VS code and open again, the error will be resolved

Just remove quotes like this:

go get github.com/gorilla/mux

If you are using VS Code as your IDE and facing this problem:

VS Code uses $HOME/go as your default GOPATH - if you export another GOPATH you running into this trouble.

How to solve:

1. Use the VS Code internal terminal and navigate to your project folder: cd prjectFolder. Type go env and check if the GOPATH entry is the same as you get when you use cmd+t and then >Go: Current GOPATH
2. If it doesn't fit, add in your user settings:

"go.gopath": "/some/path"

where /some/path is the same path you export in you shell, zsh and so on.

Hope this helps.

I try to remove github.com/gorilla and github.com/peterbourgon directory, then, retry: make, it works.

<!-- begin snippet: js hide: false console: true babel: false -->

<!-- language: lang-html -->

<pre>
fail log:


mac@user:~/TempPlace/temp/ngrok% make
go fmt ngrok/...
go get github.com/jteeuwen/go-bindata
GOOS="" GOARCH="" go install github.com/jteeuwen/go-bindata/go-bindata
bin/go-bindata -nomemcopy -pkg=assets -tags=debug \
		-debug=true \
		-o=src/ngrok/client/assets/assets_debug.go \
		assets/client/...
go get github.com/jteeuwen/go-bindata
GOOS="" GOARCH="" go install github.com/jteeuwen/go-bindata/go-bindata
bin/go-bindata -nomemcopy -pkg=assets -tags=debug \
		-debug=true \
		-o=src/ngrok/server/assets/assets_debug.go \
		assets/server/...
go get -tags 'debug' -d -v ngrok/...
src/ngrok/server/config.go:16:2: no Go files in /Users/apple/TempPlace/temp/ngrok/src/github.com/gorilla/mux
src/ngrok/server/config.go:17:2: no Go files in /Users/apple/TempPlace/temp/ngrok/src/github.com/peterbourgon/diskv
make: *** [deps] Error 1


success log:


mac@user:~/TempPlace/temp/ngrok% make
go fmt ngrok/...
go get github.com/jteeuwen/go-bindata
GOOS="" GOARCH="" go install github.com/jteeuwen/go-bindata/go-bindata
bin/go-bindata -nomemcopy -pkg=assets -tags=debug \
		-debug=true \
		-o=src/ngrok/client/assets/assets_debug.go \
		assets/client/...
go get github.com/jteeuwen/go-bindata
GOOS="" GOARCH="" go install github.com/jteeuwen/go-bindata/go-bindata
bin/go-bindata -nomemcopy -pkg=assets -tags=debug \
		-debug=true \
		-o=src/ngrok/server/assets/assets_debug.go \
		assets/server/...
go get -tags 'debug' -d -v ngrok/...
github.com/gorilla/websocket (download)
github.com/gorilla/mux (download)
src/ngrok/server/config.go:17:2: no Go files in /Users/apple/TempPlace/temp/ngrok/src/github.com/peterbourgon/diskv
make: *** [deps] Error 1
mac@user:~/TempPlace/temp/ngrok% make
go fmt ngrok/...
go get github.com/jteeuwen/go-bindata
GOOS="" GOARCH="" go install github.com/jteeuwen/go-bindata/go-bindata
bin/go-bindata -nomemcopy -pkg=assets -tags=debug \
		-debug=true \
		-o=src/ngrok/client/assets/assets_debug.go \
		assets/client/...
go get github.com/jteeuwen/go-bindata
GOOS="" GOARCH="" go install github.com/jteeuwen/go-bindata/go-bindata
bin/go-bindata -nomemcopy -pkg=assets -tags=debug \
		-debug=true \
		-o=src/ngrok/server/assets/assets_debug.go \
		assets/server/...
go get -tags 'debug' -d -v ngrok/...
github.com/peterbourgon/diskv (download)
github.com/google/btree (download)
go install -tags 'debug' ngrok/main/ngrok
go install -ldflags "-s" -tags 'debug' ngrok/main/ngrokd

</pre>

<!-- end snippet -->

Try go build /Users/imac/go/src/project

because I see you try to use go build under /Users/imac/go/src

Maybe this can help other users running in Windows.
In my case I had to create two symlinks:

 1. run cmd as administrator  
 2. cd %gopath%  
 3. mklink /D src pkg\mod  
this creates a symlink between src and pkg\mod
 4. cd src\github.com\gorilla

Here you'll notice that the mux package might be listed as mux@v1.8.0

 5. mklink /D mux mux@v1.8.0

With this, go will be able to find github.com/gorilla/mux
under %gopath%\src\github.com\gorilla\mux

Finally, you have to set GO111Module to off
set GO111Module=off

and now you can build your app:

go build app.go