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xds: fix hash policy header to skip bin headers and use extra metadata #6609

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merged 2 commits into from
Sep 7, 2023
Merged

xds: fix hash policy header to skip bin headers and use extra metadata #6609

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xds: fix hash policy header to skip bin headers and use extra metadata
dfawley Sep 7, 2023
34c602b
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dfawley Sep 7, 2023
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21 changes: 16 additions & 5 deletions xds/internal/resolver/serviceconfig.go
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Original file line number Diff line number Diff line change
Expand Up @@ -31,6 +31,7 @@ import (
"google.golang.org/grpc/codes"
"google.golang.org/grpc/internal/envconfig"
"google.golang.org/grpc/internal/grpcrand"
"google.golang.org/grpc/internal/grpcutil"
iresolver "google.golang.org/grpc/internal/resolver"
"google.golang.org/grpc/internal/serviceconfig"
"google.golang.org/grpc/internal/wrr"
Expand Down Expand Up @@ -229,19 +230,29 @@ func retryConfigToPolicy(config *xdsresource.RetryConfig) *serviceconfig.RetryPo
func (cs *configSelector) generateHash(rpcInfo iresolver.RPCInfo, hashPolicies []*xdsresource.HashPolicy) uint64 {
var hash uint64
var generatedHash bool
var md, emd metadata.MD
var mdRead bool
for _, policy := range hashPolicies {
var policyHash uint64
var generatedPolicyHash bool
switch policy.HashPolicyType {
case xdsresource.HashPolicyTypeHeader:
md, ok := metadata.FromOutgoingContext(rpcInfo.Context)
if !ok {
if strings.HasSuffix(policy.HeaderName, "-bin") {
continue
}
values := md.Get(policy.HeaderName)
// If the header isn't present, no-op.
if !mdRead {
md, _ = metadata.FromOutgoingContext(rpcInfo.Context)
emd, _ = grpcutil.ExtraMetadata(rpcInfo.Context)
mdRead = true
}
values := emd.Get(policy.HeaderName)
if len(values) == 0 {
continue
// Extra metadata takes precedence over the user's metadata.
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values = md.Get(policy.HeaderName)
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So at this point in the RPC lifecycle, the only overwriting extra metadata is "content-type"? "However, we will support matching against the content-type header; if a gRPC implementation does not add that header until after xDS route selection is done, then xDS route selection will assume a hard-coded value of application/grpc."

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Yes, the "extra metadata" is "content-type"... I'm not sure I like how this all was done (originally for route matching), but it works at least.

if len(values) == 0 {
// If the header isn't present at all, this policy is a no-op.
continue
}
}
joinedValues := strings.Join(values, ",")
if policy.Regex != nil {
Expand Down
30 changes: 30 additions & 0 deletions xds/internal/resolver/serviceconfig_test.go
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Expand Up @@ -25,6 +25,7 @@ import (

xxhash "github.com/cespare/xxhash/v2"
"github.com/google/go-cmp/cmp"
"google.golang.org/grpc/internal/grpcutil"
iresolver "google.golang.org/grpc/internal/resolver"
"google.golang.org/grpc/metadata"
_ "google.golang.org/grpc/xds/internal/balancer/cdsbalancer" // To parse LB config
Expand Down Expand Up @@ -106,6 +107,35 @@ func (s) TestGenerateRequestHash(t *testing.T) {
Method: "/some-method",
},
},
// Tests that bin headers are skipped.
{
name: "skip-bin",
hashPolicies: []*xdsresource.HashPolicy{{
HashPolicyType: xdsresource.HashPolicyTypeHeader,
HeaderName: "something-bin",
}, {
HashPolicyType: xdsresource.HashPolicyTypeChannelID,
}},
requestHashWant: channelID,
rpcInfo: iresolver.RPCInfo{
Context: metadata.NewOutgoingContext(context.Background(), metadata.Pairs("something-bin", "xyz")),
},
},
// Tests that extra metadata is used first.
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{
name: "extra-metadata",
hashPolicies: []*xdsresource.HashPolicy{{
HashPolicyType: xdsresource.HashPolicyTypeHeader,
HeaderName: "content-type",
}},
requestHashWant: xxhash.Sum64String("grpc value"),
rpcInfo: iresolver.RPCInfo{
Context: grpcutil.WithExtraMetadata(
metadata.NewOutgoingContext(context.Background(), metadata.Pairs("content-type", "user value")),
metadata.Pairs("content-type", "grpc value"),
),
},
},
}
for _, test := range tests {
t.Run(test.name, func(t *testing.T) {
Expand Down