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balancer: introduce env flag for case-sensitive registry #8837

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Merged
Pranjali-2501 merged 2 commits into from
Jan 26, 2026
+25 −15
Merged

balancer: introduce env flag for case-sensitive registry #8837

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e812241
use case-sensitive balancer registries
Pranjali-2501 Jan 14, 2026
750ae1e
resolve comments
Pranjali-2501 Jan 19, 2026
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32 changes: 17 additions & 15 deletions balancer/balancer.go
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Original file line number Diff line number Diff line change
Expand Up @@ -33,6 +33,7 @@ import (
estats "google.golang.org/grpc/experimental/stats"
"google.golang.org/grpc/grpclog"
"google.golang.org/grpc/internal"
"google.golang.org/grpc/internal/envconfig"
"google.golang.org/grpc/metadata"
"google.golang.org/grpc/resolver"
"google.golang.org/grpc/serviceconfig"
Expand All @@ -46,21 +47,21 @@ var (
)

// Register registers the balancer builder to the balancer map. b.Name
// (lowercased) will be used as the name registered with this builder. If the
// Builder implements ConfigParser, ParseConfig will be called when new service
// will be used as the name registered with this builder. If the Builder
// implements ConfigParser, ParseConfig will be called when new service
// configs are received by the resolver, and the result will be provided to the
// Balancer in UpdateClientConnState.
//
// NOTE: this function must only be called during initialization time (i.e. in
// an init() function), and is not thread-safe. If multiple Balancers are
// registered with the same name, the one registered last will take effect.
func Register(b Builder) {
name := strings.ToLower(b.Name())
if name != b.Name() {
// TODO: Skip the use of strings.ToLower() to index the map after v1.59
// is released to switch to case sensitive balancer registry. Also,
// remove this warning and update the docstrings for Register and Get.
logger.Warningf("Balancer registered with name %q. grpc-go will be switching to case sensitive balancer registries soon", b.Name())
name := b.Name()
if !envconfig.CaseSensitiveBalancerRegistries {
name = strings.ToLower(name)
if name != b.Name() {
logger.Warningf("Balancer registered with name %q. grpc-go will be switching to case sensitive balancer registries soon. After 2 releases, we will enable the env var by default.", b.Name())
}
}
m[name] = b
}
Expand All @@ -78,16 +79,17 @@ func init() {
}

// Get returns the resolver builder registered with the given name.
// Note that the compare is done in a case-insensitive fashion.
// Note that the compare is done in a case-sensitive fashion.
// If no builder is register with the name, nil will be returned.
func Get(name string) Builder {
if strings.ToLower(name) != name {
// TODO: Skip the use of strings.ToLower() to index the map after v1.59
// is released to switch to case sensitive balancer registry. Also,
// remove this warning and update the docstrings for Register and Get.
logger.Warningf("Balancer retrieved for name %q. grpc-go will be switching to case sensitive balancer registries soon", name)
if !envconfig.CaseSensitiveBalancerRegistries {
lowerName := strings.ToLower(name)
if lowerName != name {
logger.Warningf("Balancer retrieved for name %q. grpc-go will be switching to case sensitive balancer registries soon. After 2 releases, we will enable the env var by default.", name)
}
name = lowerName
}
if b, ok := m[strings.ToLower(name)]; ok {
if b, ok := m[name]; ok {
return b
}
return nil
Expand Down
8 changes: 8 additions & 0 deletions internal/envconfig/envconfig.go
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Original file line number Diff line number Diff line change
Expand Up @@ -78,6 +78,14 @@ var (
// - The DNS resolver is being used.
EnableDefaultPortForProxyTarget = boolFromEnv("GRPC_EXPERIMENTAL_ENABLE_DEFAULT_PORT_FOR_PROXY_TARGET", true)

// CaseSensitiveBalancerRegistries is set if the balancer registry should be
// case-sensitive. This is disabled by default, but can be enabled by setting
// the env variable "GRPC_GO_EXPERIMENTAL_CASE_SENSITIVE_BALANCER_REGISTRIES"
// to "true".
//
// TODO: After 2 releases, we will enable the env var by default.
CaseSensitiveBalancerRegistries = boolFromEnv("GRPC_GO_EXPERIMENTAL_CASE_SENSITIVE_BALANCER_REGISTRIES", false)

// XDSAuthorityRewrite indicates whether xDS authority rewriting is enabled.
// This feature is defined in gRFC A81 and is enabled by setting the
// environment variable GRPC_EXPERIMENTAL_XDS_AUTHORITY_REWRITE to "true".
Expand Down