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Warm ingress Squid peer connections with standby=2 #5887

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Merged
jhrozek merged 1 commit into from
Jul 21, 2026
Merged

Warm ingress Squid peer connections with standby=2 #5887

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7 changes: 6 additions & 1 deletion pkg/container/docker/squid.go
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Original file line number Diff line number Diff line change
Expand Up @@ -398,11 +398,16 @@ func writeIngressProxyConfig(
) {
portNum := strconv.Itoa(upstreamPort)
squidPortNum := strconv.Itoa(squidPort)
// standby=2 keeps warm idle connections open to the upstream so the first
// request after a cold start (notably a long-lived GET SSE stream that a
// server-initiated request rides on) is forwarded without paying inline DNS
// + TCP connect latency. Without it, the cold first GET races behind a
// later POST that reuses a warmed path, reordering server->client streams.
sb.WriteString(
"\n# Reverse proxy setup for port " + portNum + "\n" +
"http_port 0.0.0.0:" + squidPortNum + " accel defaultsite=" + serverHostname + "\n" +
"cache_peer " + serverHostname + " parent " + portNum + " 0 no-query originserver name=origin_" +
portNum + " connect-timeout=5 connect-fail-limit=5\n")
portNum + " connect-timeout=5 connect-fail-limit=5 standby=2\n")

// Check if inbound network permissions are configured
if networkPermissions != nil && networkPermissions.Inbound != nil && len(networkPermissions.Inbound.AllowHost) > 0 {
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3 changes: 3 additions & 0 deletions pkg/container/docker/squid_test.go
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Expand Up @@ -205,6 +205,9 @@ func TestCreateTempIngressSquidConf_Basics(t *testing.T) {
assert.Contains(t, s, "\n# Reverse proxy setup for port 8080\n")
assert.Contains(t, s, "http_port 0.0.0.0:18080 accel defaultsite=svc-example")
assert.Contains(t, s, "cache_peer svc-example parent 8080 0 no-query originserver name=origin_8080")
// standby=2 pre-warms upstream connections so a cold first GET SSE stream is
// not reordered behind a later POST (fixes the sampling conformance flake).
assert.Contains(t, s, "connect-timeout=5 connect-fail-limit=5 standby=2")
assert.Contains(t, s, "acl site_8080 dstdomain svc-example")
assert.Contains(t, s, "http_access allow site_8080")
assert.True(t, strings.HasSuffix(strings.TrimSpace(s), "http_access deny all"))
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