otel: add build tooling to include otel code

Adds the --otel flag to the configure command and the various build time
variables and checks that are needed in this flow.

It also includes the nxt_otel.c and nxt_otel.h files that are needed for
the rest of Unit to talk to the compiled static library that's generated
from the rust crate.

Signed-off-by: Ava Hahn <a.hahn@f5.com>
Co-authored-by: Gabor Javorszky <g.javorszky@f5.com>
Signed-off-by: Gabor Javorszky <g.javorszky@f5.com>

1 files changed, 72 insertions, 0 deletions

diff --git a/src/nxt_otel.h b/src/nxt_otel.h
new file mode 100644
index 00000000..f5a2de8b
--- /dev/null
+++ b/src/nxt_otel.h
@@ -0,0 +1,72 @@
+/*
+ * Copyright (C) F5, Inc.
+ */
+
+#ifndef _NXT_OTEL_H_INCLUDED_
+#define _NXT_OTEL_H_INCLUDED_
+
+#include <nxt_router.h>
+#include <nxt_string.h>
+
+
+#if (NXT_HAVE_OTEL)
+extern void nxt_otel_rs_send_trace(void *trace);
+extern void * nxt_otel_rs_get_or_create_trace(u_char *trace_id);
+extern void nxt_otel_rs_init(
+    void (*log_callback)(nxt_uint_t log_level, const char *log_string),
+    const nxt_str_t *endpoint, const nxt_str_t *protocol,
+    double sample_fraction, double batch_size);
+extern void nxt_otel_rs_copy_traceparent(u_char *buffer, void *span);
+extern void nxt_otel_rs_add_event_to_trace(void *trace, nxt_str_t *key,
+    nxt_str_t *val);
+extern uint8_t nxt_otel_rs_is_init(void);
+extern void nxt_otel_rs_uninit(void);
+#endif
+
+
+typedef enum nxt_otel_status_e   nxt_otel_status_t;
+typedef struct nxt_otel_state_s  nxt_otel_state_t;
+
+
+/*
+ * nxt_otel_status_t
+ * more efficient than a single handler state struct
+ */
+enum nxt_otel_status_e {
+    NXT_OTEL_UNINIT_STATE = 0,
+    NXT_OTEL_INIT_STATE,
+    NXT_OTEL_HEADER_STATE,
+    NXT_OTEL_BODY_STATE,
+    NXT_OTEL_COLLECT_STATE,
+    NXT_OTEL_ERROR_STATE,
+};
+
+
+/*
+ * nxt_otel_state_t
+ * cache of trace data needed per request and
+ * includes indicator as to current flow state
+ */
+struct nxt_otel_state_s {
+    u_char             *trace_id;
+    u_char             *version;
+    u_char             *parent_id;
+    u_char             *trace_flags;
+    void               *trace;
+    nxt_otel_status_t  status;
+    nxt_str_t          trace_state;
+};
+
+
+nxt_int_t nxt_otel_parse_traceparent(void *ctx, nxt_http_field_t *field,
+    uintptr_t data);
+nxt_int_t nxt_otel_parse_tracestate(void *ctx, nxt_http_field_t *field,
+    uintptr_t data);
+void nxt_otel_log_callback(nxt_uint_t log_level, const char *arg);
+
+
+void nxt_otel_test_and_call_state(nxt_task_t *task, nxt_http_request_t *r);
+void nxt_otel_request_error_path(nxt_task_t *task, nxt_http_request_t *r);
+
+
+#endif /* _NXT_OTEL_H_INCLUDED_ */