db0b16b615
Add a ready plugin that allows plugin to signal when they are ready.
Once a plugin is ready it is not queried again.
This uses same mechanism as the health plugin: each plugin needs to
implement an interface.
Implement readines for the *erratic* plugin to aid in testing.
Add README.md and tests moduled after the health plugin; which will be
relegated to just providing process health. In similar vein to health
this is a process wide setting.
With this Corefile:
~~~
. {
erratic
whoami
ready
}
bla {
erratic
whoami
}
~~~
ready will lead to:
~~~ sh
% curl localhost:8181/ready
% dig @localhost -p 1053 mx example.org
% curl localhost:8181/ready
OK%
~~~
Meanwhile CoreDNS logs:
~~~
.:1053
bla.:1053
2019-02-26T20:59:07.137Z [INFO] CoreDNS-1.3.1
2019-02-26T20:59:07.137Z [INFO] linux/amd64, go1.11.4,
CoreDNS-1.3.1
linux/amd64, go1.11.4,
2019-02-26T20:59:11.415Z [INFO] plugin/ready: Still waiting on: "erratic"
2019-02-26T20:59:13.510Z [INFO] plugin/ready: Still waiting on: "erratic"
~~~
*ready* can be used in multiple server blocks and will do the right
thing; query all those plugins from all server blocks for readiness.
This does a similar thing to the prometheus plugin.
Signed-off-by: Miek Gieben <miek@miek.nl>
81 lines
2 KiB
Go
81 lines
2 KiB
Go
package ready
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import (
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"context"
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"fmt"
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"net/http"
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"sync"
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"testing"
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"github.com/coredns/coredns/plugin/erratic"
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clog "github.com/coredns/coredns/plugin/pkg/log"
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"github.com/coredns/coredns/plugin/test"
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"github.com/miekg/dns"
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)
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func init() { clog.Discard() }
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func TestReady(t *testing.T) {
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rd := &ready{Addr: ":0"}
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e := &erratic.Erratic{}
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plugins.Append(e, "erratic")
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wg := sync.WaitGroup{}
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wg.Add(1)
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go func() {
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if err := rd.onStartup(); err != nil {
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t.Fatalf("Unable to startup the readiness server: %v", err)
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}
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wg.Done()
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}()
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wg.Wait()
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defer rd.onFinalShutdown()
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address := fmt.Sprintf("http://%s/ready", rd.ln.Addr().String())
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wg.Add(1)
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go func() {
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response, err := http.Get(address)
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if err != nil {
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t.Fatalf("Unable to query %s: %v", address, err)
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}
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if response.StatusCode != 503 {
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t.Errorf("Invalid status code: expecting %d, got %d", 503, response.StatusCode)
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}
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response.Body.Close()
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wg.Done()
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}()
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wg.Wait()
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// make it ready by giving erratic 3 queries.
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m := new(dns.Msg)
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m.SetQuestion("example.org.", dns.TypeA)
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e.ServeDNS(context.TODO(), &test.ResponseWriter{}, m)
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e.ServeDNS(context.TODO(), &test.ResponseWriter{}, m)
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e.ServeDNS(context.TODO(), &test.ResponseWriter{}, m)
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response, err := http.Get(address)
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if err != nil {
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t.Fatalf("Unable to query %s: %v", address, err)
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}
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if response.StatusCode != 200 {
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t.Errorf("Invalid status code: expecting %d, got %d", 200, response.StatusCode)
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}
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response.Body.Close()
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// make erratic not-ready by giving it more queries, this should not change the process readiness
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e.ServeDNS(context.TODO(), &test.ResponseWriter{}, m)
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e.ServeDNS(context.TODO(), &test.ResponseWriter{}, m)
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e.ServeDNS(context.TODO(), &test.ResponseWriter{}, m)
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response, err = http.Get(address)
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if err != nil {
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t.Fatalf("Unable to query %s: %v", address, err)
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}
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if response.StatusCode != 200 {
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t.Errorf("Invalid status code: expecting %d, got %d", 200, response.StatusCode)
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}
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response.Body.Close()
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}
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