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Propagate opentelemetry tracing headers in requests to limitador #49

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merged 4 commits into from
Mar 25, 2024
Merged

Propagate opentelemetry tracing headers in requests to limitador #49

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c37de84
Propagate opentelemetry tracing headers in requests to limitador
adam-cattermole Mar 19, 2024
b219de4
Use contants for headers and explicitly lowercase
adam-cattermole Mar 21, 2024
b2358cc
Refactor implementation
adam-cattermole Mar 21, 2024
c0bb113
Remove unnecessary package
adam-cattermole Mar 25, 2024
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18 changes: 17 additions & 1 deletion src/filter/http_context.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -21,6 +21,7 @@ pub struct Filter {
pub context_id: u32,
pub config: Rc<FilterConfig>,
pub response_headers_to_add: Vec<(String, String)>,
pub tracing_headers: Vec<(String, String)>,
}

impl Filter {
Expand Down Expand Up @@ -51,11 +52,17 @@ impl Filter {

let rl_req_serialized = Message::write_to_bytes(&rl_req).unwrap(); // TODO(rahulanand16nov): Error Handling

let rl_tracing_headers = self
.tracing_headers
.iter()
.map(|(header, value)| (header.as_str(), value.as_bytes()))
.collect();

match self.dispatch_grpc_call(
rlp.service.as_str(),
RATELIMIT_SERVICE_NAME,
RATELIMIT_METHOD_NAME,
Vec::new(),
rl_tracing_headers,
Some(&rl_req_serialized),
Duration::from_secs(5),
) {
Expand Down Expand Up @@ -207,6 +214,15 @@ impl HttpContext for Filter {
fn on_http_request_headers(&mut self, _: usize, _: bool) -> Action {
info!("on_http_request_headers #{}", self.context_id);

let req_headers = self.get_http_request_headers();
for (header, value) in req_headers.iter() {
match header.as_str() {
"traceparent" | "tracestate" | "baggage" => {
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self.get_http_request_headers returns lowercase header names? in other words, if the header is TraceParent, is the value captured? According to https://w3c.github.io/trace-context/#traceparent-header

The header name is [ASCII case-insensitive](https://infra.spec.whatwg.org/#ascii-case-insensitive). That is, TRACEPARENT, TraceParent, and traceparent are considered the same header. The header name is a single word; it does not contain any delimiters such as a hyphen.

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@adam-cattermole adam-cattermole Mar 21, 2024 •
edited
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Yep from what I could tell no matter the provided format the headers were retrieved in lowercase - perhaps due to this https://www.envoyproxy.io/docs/envoy/latest/configuration/http/http_conn_man/header_casing

I could add a .to_lowercase() before the match for safety in case though (perhaps this preserve case formatter causes the headers to no longer be lowercase when received by wasm shim). Also considering moving the three header strings out to constants

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if it's only used there, no need for a constant.

self.tracing_headers.push((header.clone(), value.clone()))
}
_ => (),
}
}
match self
.config
.index
Expand Down
1 change: 1 addition & 0 deletions src/filter/root_context.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -22,6 +22,7 @@ impl RootContext for FilterRoot {
context_id,
config: Rc::clone(&self.config),
response_headers_to_add: Vec::default(),
tracing_headers: Vec::default(),
}))
}

Expand Down
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