9d87b953a0
This fix is an enhancement of external plugin enabling.
Previously, it was already able to build a customerized
coredns with plugins enabled selectively, without changing
coredns source code. However, all default plugins are
actually bundled because of the import rule:
```
"github.com/coredns/coredns/coremain"
```
The issue is best described with the following:
```
root@localhost:/go/src/github.com/coredns/coredns/sample# cat sample.go
package main
import (
_ "github.com/coredns/forward"
"github.com/coredns/coredns/coremain"
"github.com/coredns/coredns/core/dnsserver"
)
var directives = []string{
"forward",
"startup",
"shutdown",
}
func init() {
dnsserver.Directives = directives
}
func main() {
coremain.Run()
}
root@localhost:/go/src/github.com/coredns/coredns/sample#
root@localhost:/go/src/github.com/coredns/coredns/sample# go build -v sample.go
root@localhost:/go/src/github.com/coredns/coredns/sample# ./sample -plugins
root@localhost:/go/src/github.com/coredns/coredns/sample# ./sample -plugins
Server types:
dns
Caddyfile loaders:
flag
default
Other plugins:
dns.auto
dns.autopath
dns.bind
dns.cache
dns.chaos
dns.debug
dns.dnssec
dns.dnstap
dns.erratic
dns.errors
dns.etcd
dns.federation
dns.file
dns.forward
dns.health
dns.hosts
dns.kubernetes
dns.loadbalance
dns.log
dns.nsid
dns.pprof
dns.prometheus
dns.proxy
dns.reverse
dns.rewrite
dns.root
dns.route53
dns.secondary
dns.template
....
```
This fix moves zplugins.go to a different package/directory so that
it is possible to "only import plugins as needed".
The following is the new output after this fix:
```
root@localhost:/go/src/github.com/coredns/coredns/sample# ./sample -plugins
Server types:
dns
Caddyfile loaders:
flag
default
Other plugins:
dns.forward
dns.prometheus
shutdown
startup
root@localhost:/go/src/github.com/coredns/coredns/sample#
```
Signed-off-by: Yong Tang <yong.tang.github@outlook.com>
115 lines
2.4 KiB
Go
115 lines
2.4 KiB
Go
//+build ignore
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package main
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import (
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"bufio"
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"go/format"
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"io/ioutil"
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"log"
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"os"
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"strings"
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)
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func main() {
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mi := make(map[string]string, 0)
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md := []string{}
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file, err := os.Open(pluginFile)
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if err != nil {
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log.Fatalf("Failed to open %s: %q", pluginFile, err)
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}
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defer file.Close()
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scanner := bufio.NewScanner(file)
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for scanner.Scan() {
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line := scanner.Text()
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if strings.HasPrefix(line, "#") {
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continue
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}
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items := strings.Split(line, ":")
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if len(items) != 2 {
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// ignore empty lines
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continue
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}
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name, repo := items[0], items[1]
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if _, ok := mi[name]; ok {
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log.Fatalf("Duplicate entry %q", name)
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}
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md = append(md, name)
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mi[name] = pluginPath + repo // Default, unless overridden by 3rd arg
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if _, err := os.Stat(pluginFSPath + repo); err != nil { // External package has been given
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mi[name] = repo
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}
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}
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genImports("core/plugin/zplugin.go", "plugin", mi)
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genDirectives("core/dnsserver/zdirectives.go", "dnsserver", md)
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}
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func genImports(file, pack string, mi map[string]string) {
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outs := header + "package " + pack + "\n\n" + "import ("
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if len(mi) > 0 {
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outs += "\n"
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}
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outs += "// Include all plugins.\n"
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for _, v := range mi {
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outs += `_ "` + v + `"` + "\n"
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}
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outs += ")\n"
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if err := formatAndWrite(file, outs); err != nil {
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log.Fatalf("Failed to format and write: %q", err)
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}
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}
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func genDirectives(file, pack string, md []string) {
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outs := header + "package " + pack + "\n\n"
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outs += `
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// Directives are registered in the order they should be
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// executed.
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//
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// Ordering is VERY important. Every plugin will
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// feel the effects of all other plugin below
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// (after) them during a request, but they must not
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// care what plugin above them are doing.
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var Directives = []string{
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`
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for i := range md {
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outs += `"` + md[i] + `",` + "\n"
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}
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outs += "}\n"
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if err := formatAndWrite(file, outs); err != nil {
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log.Fatalf("Failed to format and write: %q", err)
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}
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}
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func formatAndWrite(file string, data string) error {
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res, err := format.Source([]byte(data))
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if err != nil {
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return err
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}
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if err = ioutil.WriteFile(file, res, 0644); err != nil {
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return err
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}
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return nil
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}
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const (
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pluginPath = "github.com/coredns/coredns/plugin/"
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pluginFile = "plugin.cfg"
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pluginFSPath = "plugin/" // Where the plugins are located on the file system
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header = "// generated by directives_generate.go; DO NOT EDIT\n\n"
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)
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