96 lines
3.3 KiB
Go
96 lines
3.3 KiB
Go
package observability
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import (
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"context"
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"database/sql"
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"io"
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"net/http"
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"net/http/httptest"
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"strings"
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"testing"
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"time"
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_ "github.com/mattn/go-sqlite3"
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)
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func TestMetricsHandlerRendersPrometheusFamilies(t *testing.T) {
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metrics := NewMetrics()
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metrics.ObserveHTTPRequest(http.MethodGet, "/anime/:id", http.StatusOK, 125*time.Millisecond)
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metrics.ObserveJikanRequest("/anime/{id}", http.StatusTooManyRequests, 800*time.Millisecond, assertErr{})
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metrics.ObserveDBQuery("query", 25*time.Millisecond, nil)
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metrics.ObserveWorkerTick("episodes_availability", nil)
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metrics.ObserveCache("jikan", "hit")
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metrics.ObserveCache("episode_availability", "miss")
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req := httptest.NewRequestWithContext(context.Background(), http.MethodGet, "/metrics", nil)
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rec := httptest.NewRecorder()
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metrics.Handler().ServeHTTP(rec, req)
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body, err := io.ReadAll(rec.Result().Body)
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if err != nil {
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t.Fatalf("read body: %v", err)
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}
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text := string(body)
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assertContains(t, text, `mal_http_requests_total{method="GET",route="/anime/:id",status="200"} 1`)
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assertContains(t, text, `mal_http_request_duration_seconds_count{method="GET",route="/anime/:id",status="200"} 1`)
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assertContains(t, text, `mal_jikan_upstream_requests_total{endpoint="/anime/{id}",status="429"} 1`)
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assertContains(t, text, `mal_jikan_upstream_errors_total{endpoint="/anime/{id}",status="429"} 1`)
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assertContains(t, text, `mal_db_query_duration_seconds_count{operation="query",result="success"} 1`)
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assertContains(t, text, `mal_worker_ticks_total{result="success",worker="episodes_availability"} 1`)
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assertContains(t, text, `mal_cache_operations_total{cache="episode_availability",result="miss"} 1`)
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}
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func TestInstrumentDBRecordsQueryLatency(t *testing.T) {
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metrics := NewMetrics()
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sqlDB, err := sql.Open("sqlite3", ":memory:")
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if err != nil {
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t.Fatalf("open sqlite: %v", err)
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}
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defer func() {
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if err := sqlDB.Close(); err != nil {
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t.Errorf("close sqlite: %v", err)
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}
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}()
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instrumented := InstrumentDB(sqlDB, metrics)
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if _, err := instrumented.ExecContext(context.Background(), `CREATE TABLE item (id INTEGER PRIMARY KEY)`); err != nil {
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t.Fatalf("create table: %v", err)
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}
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if _, err := instrumented.QueryContext(context.Background(), `SELECT id FROM item`); err != nil {
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t.Fatalf("query table: %v", err)
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}
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if _, err := instrumented.QueryContext(context.Background(), `SELECT id FROM missing_table`); err == nil {
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t.Fatal("expected missing table query to fail")
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}
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samples := metrics.dbQueryLatency.snapshot()
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if len(samples) != 3 {
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t.Fatalf("db samples = %d, want 3", len(samples))
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}
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assertHistogramSample(t, samples, "exec", "success")
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assertHistogramSample(t, samples, "query", "success")
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assertHistogramSample(t, samples, "query", "error")
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}
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type assertErr struct{}
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func (assertErr) Error() string { return "boom" }
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func assertContains(t *testing.T, text string, want string) {
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t.Helper()
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if !strings.Contains(text, want) {
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t.Fatalf("missing metric line %q in:\n%s", want, text)
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}
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}
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func assertHistogramSample(t *testing.T, samples []histogramSample, operation string, result string) {
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t.Helper()
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for _, sample := range samples {
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if sample.labels["operation"] == operation && sample.labels["result"] == result && sample.count == 1 {
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return
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}
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}
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t.Fatalf("missing db histogram sample operation=%q result=%q in %#v", operation, result, samples)
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}
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