From d4a7d89f564234e44012a763cc28c5a3991bd98e Mon Sep 17 00:00:00 2001 From: Alban Lecocq Date: Mon, 5 Dec 2022 19:28:12 +0100 Subject: reverseproxy: Improve hostByHashing distribution (#5229) * If upstreams are all using same host but with different ports ie: foobar:4001 foobar:4002 foobar:4003 ... Because fnv-1a has not a good enough avalanche effect Then the hostByHashing result is not well balanced over all upstreams As last byte FNV input tend to affect few bits, the idea is to change the concatenation order between the key and the upstream strings So the upstream last byte have more impact on hash diffusion --- .../caddyhttp/reverseproxy/selectionpolicies.go | 2 +- .../reverseproxy/selectionpolicies_test.go | 44 +++++++++++----------- 2 files changed, 23 insertions(+), 23 deletions(-) (limited to 'modules/caddyhttp/reverseproxy') diff --git a/modules/caddyhttp/reverseproxy/selectionpolicies.go b/modules/caddyhttp/reverseproxy/selectionpolicies.go index 2de830c..0b7f50c 100644 --- a/modules/caddyhttp/reverseproxy/selectionpolicies.go +++ b/modules/caddyhttp/reverseproxy/selectionpolicies.go @@ -528,7 +528,7 @@ func hostByHashing(pool []*Upstream, s string) *Upstream { if !up.Available() { continue } - h := hash(s + up.String()) // important to hash key and server together + h := hash(up.String() + s) // important to hash key and server together if h > highestHash { highestHash = h upstream = up diff --git a/modules/caddyhttp/reverseproxy/selectionpolicies_test.go b/modules/caddyhttp/reverseproxy/selectionpolicies_test.go index aa001e4..546a60d 100644 --- a/modules/caddyhttp/reverseproxy/selectionpolicies_test.go +++ b/modules/caddyhttp/reverseproxy/selectionpolicies_test.go @@ -95,18 +95,18 @@ func TestIPHashPolicy(t *testing.T) { // We should be able to predict where every request is routed. req.RemoteAddr = "172.0.0.1:80" h := ipHash.Select(pool, req, nil) - if h != pool[0] { - t.Error("Expected ip hash policy host to be the first host.") + if h != pool[1] { + t.Error("Expected ip hash policy host to be the second host.") } req.RemoteAddr = "172.0.0.2:80" h = ipHash.Select(pool, req, nil) - if h != pool[0] { - t.Error("Expected ip hash policy host to be the first host.") + if h != pool[1] { + t.Error("Expected ip hash policy host to be the second host.") } req.RemoteAddr = "172.0.0.3:80" h = ipHash.Select(pool, req, nil) - if h != pool[2] { - t.Error("Expected ip hash policy host to be the third host.") + if h != pool[1] { + t.Error("Expected ip hash policy host to be the second host.") } req.RemoteAddr = "172.0.0.4:80" h = ipHash.Select(pool, req, nil) @@ -117,18 +117,18 @@ func TestIPHashPolicy(t *testing.T) { // we should get the same results without a port req.RemoteAddr = "172.0.0.1" h = ipHash.Select(pool, req, nil) - if h != pool[0] { - t.Error("Expected ip hash policy host to be the first host.") + if h != pool[1] { + t.Error("Expected ip hash policy host to be the second host.") } req.RemoteAddr = "172.0.0.2" h = ipHash.Select(pool, req, nil) - if h != pool[0] { - t.Error("Expected ip hash policy host to be the first host.") + if h != pool[1] { + t.Error("Expected ip hash policy host to be the second host.") } req.RemoteAddr = "172.0.0.3" h = ipHash.Select(pool, req, nil) - if h != pool[2] { - t.Error("Expected ip hash policy host to be the third host.") + if h != pool[1] { + t.Error("Expected ip hash policy host to be the second host.") } req.RemoteAddr = "172.0.0.4" h = ipHash.Select(pool, req, nil) @@ -141,8 +141,8 @@ func TestIPHashPolicy(t *testing.T) { req.RemoteAddr = "172.0.0.4" pool[1].setHealthy(false) h = ipHash.Select(pool, req, nil) - if h != pool[2] { - t.Error("Expected ip hash policy host to be the third host.") + if h != pool[0] { + t.Error("Expected ip hash policy host to be the first host.") } req.RemoteAddr = "172.0.0.2" @@ -172,8 +172,8 @@ func TestIPHashPolicy(t *testing.T) { } req.RemoteAddr = "172.0.0.1:80" h = ipHash.Select(pool, req, nil) - if h != pool[1] { - t.Error("Expected ip hash policy host to be the second host.") + if h != pool[0] { + t.Error("Expected ip hash policy host to be the first host.") } req.RemoteAddr = "172.0.0.2:80" h = ipHash.Select(pool, req, nil) @@ -182,8 +182,8 @@ func TestIPHashPolicy(t *testing.T) { } req.RemoteAddr = "172.0.0.3:80" h = ipHash.Select(pool, req, nil) - if h != pool[1] { - t.Error("Expected ip hash policy host to be the second host.") + if h != pool[0] { + t.Error("Expected ip hash policy host to be the first host.") } req.RemoteAddr = "172.0.0.4:80" h = ipHash.Select(pool, req, nil) @@ -252,8 +252,8 @@ func TestURIHashPolicy(t *testing.T) { request := httptest.NewRequest(http.MethodGet, "/test", nil) h := uriPolicy.Select(pool, request, nil) - if h != pool[2] { - t.Error("Expected uri policy host to be the third host.") + if h != pool[1] { + t.Error("Expected uri policy host to be the second host.") } pool[2].setHealthy(false) @@ -264,8 +264,8 @@ func TestURIHashPolicy(t *testing.T) { request = httptest.NewRequest(http.MethodGet, "/test_2", nil) h = uriPolicy.Select(pool, request, nil) - if h != pool[1] { - t.Error("Expected uri policy host to be the second host.") + if h != pool[0] { + t.Error("Expected uri policy host to be the first host.") } // We should be able to resize the host pool and still be able to predict -- cgit v1.2.3