26d8680a11
* Support multiple k8s api servers specification and load balance among api servers This fix adds supports for multiple k8s api servers specification, load balance among api servers. When two or more api servers are specified in kubernetes block (endpoint ...), a proxy is created locally (with randomly generately port). The coredns will points to the generated proxy so that load balancing could be achieved. Signed-off-by: Yong Tang <yong.tang.github@outlook.com> * Setup initial healthcheck at the beginning Signed-off-by: Yong Tang <yong.tang.github@outlook.com> * Update README.md for kubernetes middleware and remove whitespaces. Signed-off-by: Yong Tang <yong.tang.github@outlook.com> * Use middleware/pkg/healthcheck in middleware/kubernetes for api proxy Signed-off-by: Yong Tang <yong.tang.github@outlook.com>
76 lines
1.7 KiB
Go
76 lines
1.7 KiB
Go
package kubernetes
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import (
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"fmt"
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"io"
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"log"
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"net"
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"net/http"
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"github.com/coredns/coredns/middleware/pkg/healthcheck"
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)
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type proxyHandler struct {
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healthcheck.HealthCheck
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}
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type apiProxy struct {
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http.Server
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listener net.Listener
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handler proxyHandler
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}
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func (p *proxyHandler) ServeHTTP(w http.ResponseWriter, r *http.Request) {
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upstream := p.Select()
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network := "tcp"
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if upstream.Network != "" {
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network = upstream.Network
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}
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address := upstream.Name
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d, err := net.Dial(network, address)
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if err != nil {
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log.Printf("[ERROR] Unable to establish connection to upstream %s://%s: %s", network, address, err)
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http.Error(w, fmt.Sprintf("Unable to establish connection to upstream %s://%s: %s", network, address, err), 500)
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return
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}
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hj, ok := w.(http.Hijacker)
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if !ok {
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log.Printf("[ERROR] Unable to establish connection: no hijacker")
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http.Error(w, "Unable to establish connection: no hijacker", 500)
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return
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}
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nc, _, err := hj.Hijack()
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if err != nil {
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log.Printf("[ERROR] Unable to hijack connection: %s", err)
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http.Error(w, fmt.Sprintf("Unable to hijack connection: %s", err), 500)
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return
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}
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defer nc.Close()
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defer d.Close()
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err = r.Write(d)
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if err != nil {
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log.Printf("[ERROR] Unable to copy connection to upstream %s://%s: %s", network, address, err)
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http.Error(w, fmt.Sprintf("Unable to copy connection to upstream %s://%s: %s", network, address, err), 500)
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return
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}
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errChan := make(chan error, 2)
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cp := func(dst io.Writer, src io.Reader) {
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_, err := io.Copy(dst, src)
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errChan <- err
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}
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go cp(d, nc)
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go cp(nc, d)
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<-errChan
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}
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func (p *apiProxy) Run() {
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p.handler.Start()
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p.Serve(p.listener)
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}
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func (p *apiProxy) Stop() {
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p.handler.Stop()
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p.Close()
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}
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