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refactor: `FmtLabels` impls use exhaustive bindings (#3988) 

this is based on #3987.

in #3987 (_see https://github.com/linkerd/linkerd2/issues/13821_) we discovered that some of the types that implement [`FmtLabels`](085be9978d/linkerd/metrics/src/fmt.rs (L5)) could collide when used in registry keys; i.e., they might emit identical label sets, but distinct `Hash` values.

#3987 solves two bugs. this pull request proposes a follow-on change, introducing _exhaustive_ bindings to implementations of `FmtLabels`, to prevent this category of bug from reoccurring again in the future.

this change means that the introduction of an additional field to any of these label structures, e.g. `OutboundEndpointLabels` or `HTTPLocalRateLimitLabels`, will cause a compilation error unless said new field is handled in the corresponding `FmtLabels` implementation.

### 🔖 a note

in writing this pull request, i noticed one label that i believe is unintentionally being elided. i've refrained from changing behavior in this pull request. i do note it though, as an example of this syntax identifying the category of bug i hope to hedge against here.

---

* fix: do not key transport metrics registry on `ClientTls`

Signed-off-by: katelyn martin <kate@buoyant.io>

* fix: do not key transport metrics registry on `ServerTls`

Signed-off-by: katelyn martin <kate@buoyant.io>

* refactor(transport-metrics): exhaustive `Eos: FmtLabels`

Signed-off-by: katelyn martin <kate@buoyant.io>

* refactor(app/core): exhaustive `ServerLabels: FmtLabels`

Signed-off-by: katelyn martin <kate@buoyant.io>

* refactor(app/core): exhaustive `TlsAccept: FmtLabels`

Signed-off-by: katelyn martin <kate@buoyant.io>

* refactor(app/core): exhaustive `TargetAddr: FmtLabels`

Signed-off-by: katelyn martin <kate@buoyant.io>

* refactor(metrics): exhaustive `Label: FmtLabels`

Signed-off-by: katelyn martin <kate@buoyant.io>

* refactor(http/metrics): exhaustive `Status: FmtLabels`

Signed-off-by: katelyn martin <kate@buoyant.io>

* refactor(app/core): exhaustive `ControlLabels: FmtLabels`

Signed-off-by: katelyn martin <kate@buoyant.io>

* refactor(app/core): exhaustive `ProfileRouteLabels: FmtLabels`

Signed-off-by: katelyn martin <kate@buoyant.io>

* refactor(app/core): exhaustive `InboundEndpointLabels: FmtLabels`

Signed-off-by: katelyn martin <kate@buoyant.io>

* refactor(app/core): exhaustive `ServerLabel: FmtLabels`

Signed-off-by: katelyn martin <kate@buoyant.io>

* refactor(app/core): exhaustive `ServerAuthzLabels: FmtLabels`

Signed-off-by: katelyn martin <kate@buoyant.io>

* refactor(app/core): exhaustive `RouteLabels: FmtLabels`

Signed-off-by: katelyn martin <kate@buoyant.io>

* refactor(app/core): exhaustive `RouteAuthzLabels: FmtLabels`

Signed-off-by: katelyn martin <kate@buoyant.io>

* refactor(app/core): exhaustive `OutboundEndpointLabels: FmtLabels`

Signed-off-by: katelyn martin <kate@buoyant.io>

* refactor(app/core): exhaustive `Authority: FmtLabels`

Signed-off-by: katelyn martin <kate@buoyant.io>

* refactor(app/core): exhaustive `StackLabels: FmtLabels`

Signed-off-by: katelyn martin <kate@buoyant.io>

* refactor(app/inbound): exhaustive `HTTPLocalRateLimitLabels: FmtLabels`

Signed-off-by: katelyn martin <kate@buoyant.io>

* refactor(app/inbound): exhaustive `Key<L>: FmtLabels`

Signed-off-by: katelyn martin <kate@buoyant.io>

* nit(metrics): remove redundant banner comment

these impl blocks are all `FmtLabels`, following another series of the
same, above. we don't need another one of these comments.

Signed-off-by: katelyn martin <kate@buoyant.io>

* nit(metrics): exhaustive `AndThen: FmtMetrics`

Signed-off-by: katelyn martin <kate@buoyant.io>

* nit(app/core): note unused label

see #3262 (618838ec7), which introduced this label.

to preserve behavior, this label remains unused.

X-Ref: #3262
Signed-off-by: katelyn martin <kate@buoyant.io>

---------

Signed-off-by: katelyn martin <kate@buoyant.io>
This commit is contained in:
katelyn martin 2025-07-03 11:56:14 -04:00 committed by GitHub
parent 288fc74800
commit 34b46ab6cd
No known key found for this signature in database
GPG Key ID: B5690EEEBB952194
7 changed files with 110 additions and 56 deletions
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102
linkerd/app/core/src/metrics.rs
View File

@ -250,8 +250,10 @@ impl svc::Param<ControlLabels> for control::ControlAddr {
impl FmtLabels for ControlLabels {
fn fmt_labels(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
write!(f, "addr=\"{}\",", self.addr)?;
TlsConnect::from(&self.server_id).fmt_labels(f)?;
let Self { addr, server_id } = self;
write!(f, "addr=\"{}\",", addr)?;
TlsConnect::from(server_id).fmt_labels(f)?;
Ok(())
}
@ -281,10 +283,16 @@ impl ProfileRouteLabels {
impl FmtLabels for ProfileRouteLabels {
fn fmt_labels(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
self.direction.fmt_labels(f)?;
write!(f, ",dst=\"{}\"", self.addr)?;
let Self {
direction,
addr,
labels,
} = self;
if let Some(labels) = self.labels.as_ref() {
direction.fmt_labels(f)?;
write!(f, ",dst=\"{}\"", addr)?;
if let Some(labels) = labels.as_ref() {
write!(f, ",{}", labels)?;
}
@ -317,16 +325,19 @@ impl FmtLabels for EndpointLabels {
impl FmtLabels for InboundEndpointLabels {
fn fmt_labels(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
if let Some(a) = self.authority.as_ref() {
let Self {
tls,
authority,
target_addr,
policy,
} = self;
if let Some(a) = authority.as_ref() {
Authority(a).fmt_labels(f)?;
write!(f, ",")?;
}
(
(TargetAddr(self.target_addr), TlsAccept::from(&self.tls)),
&self.policy,
)
.fmt_labels(f)?;
((TargetAddr(*target_addr), TlsAccept::from(tls)), policy).fmt_labels(f)?;
Ok(())
}
@ -334,13 +345,14 @@ impl FmtLabels for InboundEndpointLabels {
impl FmtLabels for ServerLabel {
fn fmt_labels(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
let Self(meta, port) = self;
write!(
f,
"srv_group=\"{}\",srv_kind=\"{}\",srv_name=\"{}\",srv_port=\"{}\"",
self.0.group(),
self.0.kind(),
self.0.name(),
self.1
meta.group(),
meta.kind(),
meta.name(),
port
)
}
}
@ -364,39 +376,45 @@ impl prom::EncodeLabelSetMut for ServerLabel {
impl FmtLabels for ServerAuthzLabels {
fn fmt_labels(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
self.server.fmt_labels(f)?;
let Self { server, authz } = self;
server.fmt_labels(f)?;
write!(
f,
",authz_group=\"{}\",authz_kind=\"{}\",authz_name=\"{}\"",
self.authz.group(),
self.authz.kind(),
self.authz.name()
authz.group(),
authz.kind(),
authz.name()
)
}
}
impl FmtLabels for RouteLabels {
fn fmt_labels(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
self.server.fmt_labels(f)?;
let Self { server, route } = self;
server.fmt_labels(f)?;
write!(
f,
",route_group=\"{}\",route_kind=\"{}\",route_name=\"{}\"",
self.route.group(),
self.route.kind(),
self.route.name(),
route.group(),
route.kind(),
route.name(),
)
}
}
impl FmtLabels for RouteAuthzLabels {
fn fmt_labels(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
self.route.fmt_labels(f)?;
let Self { route, authz } = self;
route.fmt_labels(f)?;
write!(
f,
",authz_group=\"{}\",authz_kind=\"{}\",authz_name=\"{}\"",
self.authz.group(),
self.authz.kind(),
self.authz.name(),
authz.group(),
authz.kind(),
authz.name(),
)
}
}
@ -409,16 +427,25 @@ impl svc::Param<OutboundZoneLocality> for OutboundEndpointLabels {
impl FmtLabels for OutboundEndpointLabels {
fn fmt_labels(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
if let Some(a) = self.authority.as_ref() {
let Self {
server_id,
authority,
labels,
// TODO(kate): this label is not currently emitted.
zone_locality: _,
target_addr,
} = self;
if let Some(a) = authority.as_ref() {
Authority(a).fmt_labels(f)?;
write!(f, ",")?;
}
let ta = TargetAddr(self.target_addr);
let tls = TlsConnect::from(&self.server_id);
let ta = TargetAddr(*target_addr);
let tls = TlsConnect::from(server_id);
(ta, tls).fmt_labels(f)?;
if let Some(labels) = self.labels.as_ref() {
if let Some(labels) = labels.as_ref() {
write!(f, ",{}", labels)?;
}
@ -443,7 +470,8 @@ impl FmtLabels for Direction {
impl FmtLabels for Authority<'_> {
fn fmt_labels(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
write!(f, "authority=\"{}\"", self.0)
let Self(authority) = self;
write!(f, "authority=\"{}\"", authority)
}
}
@ -498,7 +526,13 @@ impl StackLabels {
impl FmtLabels for StackLabels {
fn fmt_labels(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
self.direction.fmt_labels(f)?;
write!(f, ",protocol=\"{}\",name=\"{}\"", self.protocol, self.name)
let Self {
direction,
protocol,
name,
} = self;
direction.fmt_labels(f)?;
write!(f, ",protocol=\"{}\",name=\"{}\"", protocol, name)
}
}

25
linkerd/app/core/src/transport/labels.rs
View File

@ -99,14 +99,17 @@ impl ServerLabels {
impl FmtLabels for ServerLabels {
fn fmt_labels(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
self.direction.fmt_labels(f)?;
let Self {
direction,
tls,
target_addr,
policy,
} = self;
direction.fmt_labels(f)?;
f.write_str(",peer=\"src\",")?;
(
(TargetAddr(self.target_addr), TlsAccept(&self.tls)),
self.policy.as_ref(),
)
.fmt_labels(f)?;
((TargetAddr(*target_addr), TlsAccept(tls)), policy.as_ref()).fmt_labels(f)?;
Ok(())
}
@ -122,7 +125,8 @@ impl<'t> From<&'t tls::ConditionalServerTlsLabels> for TlsAccept<'t> {
impl FmtLabels for TlsAccept<'_> {
fn fmt_labels(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
match self.0 {
let Self(tls) = self;
match tls {
Conditional::None(tls::NoServerTls::Disabled) => {
write!(f, "tls=\"disabled\"")
}
@ -170,12 +174,13 @@ impl FmtLabels for TlsConnect<'_> {
impl FmtLabels for TargetAddr {
fn fmt_labels(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
let Self(target_addr) = self;
write!(
f,
"target_addr=\"{}\",target_ip=\"{}\",target_port=\"{}\"",
self.0,
self.0.ip(),
self.0.port()
target_addr,
target_addr.ip(),
target_addr.port()
)
}
}

22
linkerd/app/inbound/src/metrics/authz.rs
View File

@ -251,18 +251,24 @@ impl FmtMetrics for TcpAuthzMetrics {
impl FmtLabels for HTTPLocalRateLimitLabels {
fn fmt_labels(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
self.server.fmt_labels(f)?;
if let Some(rl) = &self.rate_limit {
let Self {
server,
rate_limit,
scope,
} = self;
server.fmt_labels(f)?;
if let Some(rl) = rate_limit {
write!(
f,
",ratelimit_group=\"{}\",ratelimit_kind=\"{}\",ratelimit_name=\"{}\",ratelimit_scope=\"{}\"",
rl.group(),
rl.kind(),
rl.name(),
self.scope,
scope,
)
} else {
write!(f, ",ratelimit_scope=\"{}\"", self.scope)
write!(f, ",ratelimit_scope=\"{}\"", scope)
}
}
}
@ -281,7 +287,13 @@ impl<L> Key<L> {
impl<L: FmtLabels> FmtLabels for Key<L> {
fn fmt_labels(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
(self.target, (&self.labels, TlsAccept(&self.tls))).fmt_labels(f)
let Self {
target,
tls,
labels,
} = self;
(target, (labels, TlsAccept(tls))).fmt_labels(f)
}
}

3
linkerd/http/metrics/src/requests/report.rs
View File

@ -146,6 +146,7 @@ where
impl FmtLabels for Status {
fn fmt_labels(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
write!(f, "status_code=\"{}\"", self.0.as_u16())
let Self(status) = self;
write!(f, "status_code=\"{}\"", status.as_u16())
}
}

8
linkerd/metrics/src/fmt.rs
View File

@ -188,8 +188,6 @@ impl<A: FmtLabels, B: FmtLabels> FmtLabels for (Option<A>, B) {
}
}
// === impl FmtMetrics ===
impl<'a, A: FmtMetrics + 'a> FmtMetrics for &'a A {
#[inline]
fn fmt_metrics(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
@ -210,8 +208,10 @@ impl<M: FmtMetrics> FmtMetrics for Option<M> {
impl<A: FmtMetrics, B: FmtMetrics> FmtMetrics for AndThen<A, B> {
#[inline]
fn fmt_metrics(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
self.0.fmt_metrics(f)?;
self.1.fmt_metrics(f)?;
let Self(a, b) = self;
a.fmt_metrics(f)?;
b.fmt_metrics(f)?;
Ok(())
}

3
linkerd/metrics/src/histogram.rs
View File

@ -224,7 +224,8 @@ impl<V: Into<u64>, F: Factor> FmtMetric for Histogram<V, F> {
impl<K: fmt::Display, V: fmt::Display> FmtLabels for Label<K, V> {
fn fmt_labels(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
write!(f, "{}=\"{}\"", self.0, self.1)
let Self(k, v) = self;
write!(f, "{}=\"{}\"", k, v)
}
}

3
linkerd/transport-metrics/src/lib.rs
View File

@ -82,7 +82,8 @@ impl<K: Eq + Hash + FmtLabels> Registry<K> {
impl FmtLabels for Eos {
fn fmt_labels(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
match self.0 {
let Self(errno) = self;
match errno {
None => f.pad("errno=\"\""),
Some(errno) => write!(f, "errno=\"{}\"", errno),
}