Hi,
Using plugins with modules has become very restrictive. All common
dependencies between plugins and binary that loads them, must be exactly at
the same version.
With GOPATH, to avoid that, we can use vendoring because import paths are
rewritten. (Ex: gopkg.yaml.v2 is rewritten to
package/sub/vendor/gopkg.in/yaml.v2)
But with modules and vendoring, import paths are preserved.
Is this the desired behavior? If so, then the plugins are difficult to use
by other users.
Maybe it would be possible to accept that module import paths are rewritten
for better modularity, even if it increases the number of dependencies?
In addition, if the vendoring is removed, this feature will be removed too.
Example:
main/main.go : to load plugins
p1/p1.go : plugin
p2/p2.go : like p1.go (only print differs)
script.sh : builds plugins using GOPATH, or modules, and prints import path
of gopkg.in/yaml.v2 dependency.
p1/p1.go
package main
import (
"fmt"
yaml "gopkg.in/yaml.v2"
)
var e = yaml.Encoder{}
func init() { fmt.Printf("p1: Type: %T\n", e) }
func main() {}
main/main.go
package main
import "plugin"
func main() {
if _, err := plugin.Open("../p1/p1.so"); err != nil {
panic(err)
}
if _, err := plugin.Open("../p2/p2.so"); err != nil {
panic(err)
}
}
script.sh
#!/bin/bash
set -e
GOPATH=~/go
p1=$PWD/p1
p2=$PWD/p2
main=$PWD/main
rm -f $p1/p1.so $p2/p2.so
GO111MODULE=on go clean -modcache
go clean -cache
# init vendoring
cd $p1 && GO111MODULE=on go mod vendor
cd $p2 && GO111MODULE=on go mod vendor
echo -e "package yaml\n\nimport \"fmt\"\nfunc init() { fmt.Println(\"Init
yaml (p1)\") }" > $p1/vendor/gopkg.in/yaml.v2/init.go
echo -e "package yaml\n\nimport \"fmt\"\nfunc init() { fmt.Println(\"Init
yaml (p2)\") }" > $p2/vendor/gopkg.in/yaml.v2/init.go
# GOPATH + vendoring
echo -n "GOPATH+vendoring:"
cd $p1 && GO111MODULE=off go build -buildmode=plugin -n 2>&1 | grep '#' |
grep gopkg.in/yaml
cd $p1 && GO111MODULE=off go build -buildmode=plugin 2>/dev/null >/dev/null
cd $p2 && GO111MODULE=off go build -buildmode=plugin 2>/dev/null >/dev/null
cd $main && GO111MODULE=off go run main.go
# GOMOD + vendoring
echo -n "GOMOD+vendoring:"
cd $p1 && GO111MODULE=on go build -buildmode=plugin -mod=vendor -n 2>&1 |
grep '#' | grep gopkg.in/yaml
cd $p1 && GO111MODULE=on go build -buildmode=plugin -mod=vendor 2>/dev/null
>/dev/null
cd $p2 && GO111MODULE=on go build -buildmode=plugin -mod=vendor 2>/dev/null
>/dev/null
cd $main && GO111MODULE=off go run main.go
output:
go: finding gopkg.in/yaml.v2 v2.2.1
go: finding gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405
go: downloading gopkg.in/yaml.v2 v2.2.1
go: finding gopkg.in/yaml.v2 v2.2.0
go: downloading gopkg.in/yaml.v2 v2.2.0
GOPATH+vendoring:# plugin/p1/vendor/gopkg.in/yaml.v2
Init yaml (p1)
p1: Type: yaml.Encoder
Init yaml (p2)
p2: Type: yaml.Encoder
GOMOD+vendoring:# gopkg.in/yaml.v2
Init yaml (p1)
p1: Type: yaml.Encoder
panic: plugin.Open("../p2/p2"): plugin was built with a different version
of package gopkg.in/yaml.v2
goroutine 1 [running]:
main.main()
/home/oszika/go/src/plugin/main/main.go:10 +0x97
exit status 2
Thank you,
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