71 lines
1.9 KiB
Go
71 lines
1.9 KiB
Go
package roundrobin
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import (
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"net/http"
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"net/url"
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)
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// StickySession is a mixin for load balancers that implements layer 7 (http cookie) session affinity
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type StickySession struct {
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cookieName string
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options CookieOptions
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}
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// CookieOptions has all the options one would like to set on the affinity cookie
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type CookieOptions struct {
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HTTPOnly bool
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Secure bool
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}
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// NewStickySession creates a new StickySession
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func NewStickySession(cookieName string) *StickySession {
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return &StickySession{cookieName: cookieName}
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}
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// NewStickySessionWithOptions creates a new StickySession whilst allowing for options to
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// shape its affinity cookie such as "httpOnly" or "secure"
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func NewStickySessionWithOptions(cookieName string, options CookieOptions) *StickySession {
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return &StickySession{cookieName: cookieName, options: options}
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}
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// GetBackend returns the backend URL stored in the sticky cookie, iff the backend is still in the valid list of servers.
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func (s *StickySession) GetBackend(req *http.Request, servers []*url.URL) (*url.URL, bool, error) {
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cookie, err := req.Cookie(s.cookieName)
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switch err {
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case nil:
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case http.ErrNoCookie:
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return nil, false, nil
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default:
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return nil, false, err
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}
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serverURL, err := url.Parse(cookie.Value)
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if err != nil {
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return nil, false, err
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}
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if s.isBackendAlive(serverURL, servers) {
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return serverURL, true, nil
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}
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return nil, false, nil
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}
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// StickBackend creates and sets the cookie
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func (s *StickySession) StickBackend(backend *url.URL, w *http.ResponseWriter) {
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opt := s.options
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cookie := &http.Cookie{Name: s.cookieName, Value: backend.String(), Path: "/", HttpOnly: opt.HTTPOnly, Secure: opt.Secure}
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http.SetCookie(*w, cookie)
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}
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func (s *StickySession) isBackendAlive(needle *url.URL, haystack []*url.URL) bool {
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if len(haystack) == 0 {
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return false
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}
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for _, serverURL := range haystack {
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if sameURL(needle, serverURL) {
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return true
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}
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}
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return false
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}
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