fix(webapp): read Prisma initialization error codes from errorCode

PrismaClientInitializationError carries its code on errorCode, not code, so
connection failures such as P1001 were counted as unknown. Those are the
failures this counter most needs to name.

Author: ericallam

apps/webapp/app/utils/dbMetrics.server.test.ts

@@ -109,6 +109,26 @@ describe("dbMetrics", () => {
     expect(pointFor(all, "db.client.operation.duration", "create")).toBeDefined();
   });
 
+  it("reads errorCode for initialization errors, which do not carry code", async () => {
+    const failure = Object.assign(new Error("Can't reach database server"), {
+      errorCode: "P1001",
+    });
+
+    await expect(
+      recordOperation(
+        { datasource: "replica", client: "run-ops-new" },
+        "findFirst",
+        "TaskRun",
+        () => Promise.reject(failure)
+      )
+    ).rejects.toThrow("Can't reach database server");
+
+    const point = pointFor(await collect(), "db.client.operation.errors", "findFirst");
+
+    expect(point).toBeDefined();
+    expect(point!.attributes["db.error_code"]).toBe("P1001");
+  });
+
   it("labels a non-Prisma error as unknown rather than dropping the count", async () => {
     await expect(
       recordOperation({ datasource: "writer", client: "control-plane" }, "update", "TaskRun", () =>

apps/webapp/app/utils/dbMetrics.server.ts

@@ -62,11 +62,18 @@ function getInstruments(): Instruments {
  */
 const includeModel = process.env.DB_METRICS_INCLUDE_MODEL === "1";
 
+/**
+ * Prisma splits the error code across two property names: `PrismaClientKnownRequestError`
+ * carries `code`, while `PrismaClientInitializationError` carries `errorCode`. Both are
+ * worth labelling, and the initialization codes are the connection failures (P1001 and
+ * friends) this counter most needs to surface, so check `code` first and fall back.
+ */
 function errorCode(error: unknown): string {
-  if (typeof error === "object" && error !== null && "code" in error) {
-    const code = (error as { code: unknown }).code;
-    if (typeof code === "string") {
-      return code;
+  if (typeof error === "object" && error !== null) {
+    const candidate =
+      (error as { code?: unknown }).code ?? (error as { errorCode?: unknown }).errorCode;
+    if (typeof candidate === "string") {
+      return candidate;
     }
   }
   return "unknown";