Fix stirling_wrapper_bpftrace_bpf_test when stimulus is missing (pixi…

…e-io#929)

Summary: This test was failing on qemu because nothing else was running.
This adds soms stimulus to the test.
It also refactors the test to terminate as soon as input is seen.

Relevant Issues: pixie-io#709

Type of change: /kind test-infra

Test Plan: run test locally.

Signed-off-by: Zain Asgar <zasgar@pixielabs.ai>

src/stirling/e2e_tests/stirling_wrapper_bpftrace_bpf_test.sh

@@ -28,22 +28,47 @@ source src/stirling/scripts/test_utils.sh
 stirling_wrapper=$1
 trace_script=$2
 
+###############################################################################
+# Workload for test: This test needs binaries running in the background for
+# stirling_wrapper to capture.
+###############################################################################
+workload() {
+    for _ in {1..120}; do
+	sleep 1
+    done
+}
+
+workload &
+workload_pid=$!
+
 ###############################################################################
 # Main test: Run stirling_wrapper.
 ###############################################################################
 
 echo "Running stirling_wrapper"
-flags="--timeout_secs=60 --trace=$trace_script"
-# shellcheck disable=SC2086
-out=$(run_prompt_sudo "$stirling_wrapper" $flags 2>&1)
+flags=("--timeout_secs=60" "--trace=$trace_script")
+
+stirling_wrapper_log=$(mktemp --suffix=".log")
+stirling_wrapper_pid_file=$(mktemp --suffix=".pid")
+already_killed=0
+("$stirling_wrapper" "${flags[@]}" & echo $! > "${stirling_wrapper_pid_file}") 2>&1 | tee "${stirling_wrapper_log}" |\
+    while read -r line; do
+	echo "${line}"
+	# Once we see any exec_snoop records we can stop stirling_wrapper to exit early.
+	record_count=$(echo "${line}" | grep -c -e "^\[exec_snoop_table\]" || true)
+	if [[ "${record_count}" -gt "0" && "${already_killed}" -eq "0" ]]; then
+	    already_killed=1
+	    stirling_wrapper_pid=$(cat "${stirling_wrapper_pid_file}")
+	    kill "${stirling_wrapper_pid}" > /dev/null 2>&1 || true
+	fi
+    done
 
 ###############################################################################
 # Check output for errors/warnings.
 ###############################################################################
 
 check_dynamic_trace_deployment() {
   out=$1
-  echo "$out"
 
   # Look for GLOG errors or warnings, which start with E or W respectively.
   err_count=$(echo "$out" | grep -c -e ^E -e ^W || true)
@@ -71,4 +96,7 @@ check_dynamic_trace_deployment() {
   return 0
 }
 
-check_dynamic_trace_deployment "$out"
+# We can stop the workload generator now that stirling_wrapper has quit.
+kill "${workload_pid}" > /dev/null 2>&1 || true
+
+check_dynamic_trace_deployment "$(cat "${stirling_wrapper_log}")"