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ee398f0d7d
* lb: library for creation of load balancer * lb: library for creation of load balancer * Add balance subcommand to fn * make fnlb its own command * Update Changelogg * Add Makefile for fnlb
53 lines
1.3 KiB
Go
53 lines
1.3 KiB
Go
package lb
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import (
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"bytes"
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"context"
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"net/http"
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"net/http/httputil"
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"strconv"
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"sync"
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"sync/atomic"
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"github.com/golang/groupcache/consistenthash"
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)
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// ConsistentHashReverseProxy returns a new ReverseProxy that routes
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// URLs to the scheme, host, and base path provided in by a consistent hash
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// algorithm. If the target's path is "/base" and the incoming request was for
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// "/dir", the target request will be for /base/dir.
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// ConsistentHashReverseProxy does not rewrite the Host header.
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func ConsistentHashReverseProxy(ctx context.Context, nodes []string) *httputil.ReverseProxy {
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ch := consistenthash.New(len(nodes), nil)
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ch.Add(nodes...)
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bufPool := sync.Pool{
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New: func() interface{} {
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return new(bytes.Buffer)
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},
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}
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var i int64
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director := func(req *http.Request) {
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buf := bufPool.Get().(*bytes.Buffer)
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defer bufPool.Put(buf)
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buf.Reset()
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buf.WriteString(req.URL.Path)
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buf.WriteString("??")
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b := strconv.AppendInt(buf.Bytes(), atomic.AddInt64(&i, 1), 10)
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target := ch.Get(string(b))
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req.URL.Scheme = "http"
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req.URL.Host = target
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if _, ok := req.Header["User-Agent"]; !ok {
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// explicitly disable User-Agent so it's not set to default value
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req.Header.Set("User-Agent", "")
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}
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}
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return &httputil.ReverseProxy{
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Director: director,
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Transport: NewRoundTripper(ctx, nodes),
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}
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}
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