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fix(koa): ignore generator-based Koa middleware #1119

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Aug 22, 2022
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fix(koa): ignore generator-based Koa middleware #1119

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4 changes: 3 additions & 1 deletion plugins/node/opentelemetry-instrumentation-koa/README.md
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Original file line number Diff line number Diff line change
Expand Up @@ -38,7 +38,9 @@ registerInstrumentations({
});
```

See [`examples`](https://github.com/open-telemetry/opentelemetry-js-contrib/tree/main/plugins/node/opentelemetry-instrumentation-koa/examples) for a short example using both Koa and @koa/router
See [`examples`](https://github.com/open-telemetry/opentelemetry-js-contrib/tree/main/plugins/node/opentelemetry-instrumentation-koa/examples) for a short example using both Koa and @koa/router.

Note that generator-based middleware are deprecated and won't be instrumented.

### Koa Instrumentation Options

Expand Down
10 changes: 10 additions & 0 deletions plugins/node/opentelemetry-instrumentation-koa/src/instrumentation.ts
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Expand Up @@ -147,7 +147,17 @@ export class KoaInstrumentation extends InstrumentationBase<typeof koa> {
isLayerIgnored(layerType, this.getConfig())
)
return middlewareLayer;

if (
middlewareLayer.constructor.name === 'GeneratorFunction' ||
middlewareLayer.constructor.name === 'AsyncGeneratorFunction'
) {
api.diag.debug('ignoring generator-based Koa middleware layer');
return middlewareLayer;
}
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Can you please add a unit-test for this?


middlewareLayer[kLayerPatched] = true;

api.diag.debug('patching Koa middleware layer');
return async (context: KoaContext, next: koa.Next) => {
const parent = api.trace.getSpan(api.context.active());
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142 changes: 106 additions & 36 deletions plugins/node/opentelemetry-instrumentation-koa/test/koa.test.ts
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Expand Up @@ -92,34 +92,44 @@ describe('Koa Instrumentation', () => {
server.close();
});

const simpleResponse: koa.Middleware = async (ctx, next) => {
ctx.body = 'test';
await next();
};

const customMiddleware: koa.Middleware = async (ctx, next) => {
for (let i = 0; i < 1000000; i++) {
continue;
}
await next();
};

const spanCreateMiddleware: koa.Middleware = async (ctx, next) => {
const span = tracer.startSpan('foo');
span.end();
await next();
};

const asyncMiddleware: koa.Middleware = async (ctx, next) => {
const start = Date.now();
await next();
const ms = Date.now() - start;
ctx.body = `${ctx.method} ${ctx.url} - ${ms}ms`;
};

const failingMiddleware: koa.Middleware = async (_ctx, _next) => {
throw new Error('I failed!');
};
const simpleResponse: () => koa.Middleware = () =>
async function simpleResponse(ctx, next) {
ctx.body = 'test';
await next();
};

const customMiddleware: () => koa.Middleware = () =>
async function customMiddleware(ctx, next) {
for (let i = 0; i < 1000000; i++) {
continue;
}
await next();
};

const spanCreateMiddleware: () => koa.Middleware = () =>
async function spanCreateMiddleware(ctx, next) {
const span = tracer.startSpan('foo');
span.end();
await next();
};

const asyncMiddleware: () => koa.Middleware = () =>
async function asyncMiddleware(ctx, next) {
const start = Date.now();
await next();
const ms = Date.now() - start;
ctx.body = `${ctx.method} ${ctx.url} - ${ms}ms`;
};

const failingMiddleware: () => koa.Middleware = () =>
async function failingMiddleware(_ctx, _next) {
throw new Error('I failed!');
};

const generatorMiddleware: () => koa.Middleware = () =>
function* generatorMiddleware(next) {
yield next;
};

describe('Instrumenting @koa/router calls', () => {
it('should create a child span for middlewares', async () => {
Expand Down Expand Up @@ -331,9 +341,9 @@ describe('Koa Instrumentation', () => {
app.use((ctx, next) =>
context.with(trace.setSpan(context.active(), rootSpan), next)
);
app.use(customMiddleware);
app.use(simpleResponse);
app.use(spanCreateMiddleware);
app.use(customMiddleware());
app.use(simpleResponse());
app.use(spanCreateMiddleware());

await context.with(
trace.setSpan(context.active(), rootSpan),
Expand Down Expand Up @@ -384,8 +394,8 @@ describe('Koa Instrumentation', () => {
});

it('should not create span if there is no parent span', async () => {
app.use(customMiddleware);
app.use(simpleResponse);
app.use(customMiddleware());
app.use(simpleResponse());

const res = await httpRequest.get(`http://localhost:${port}`);
assert.strictEqual(memoryExporter.getFinishedSpans().length, 0);
Expand All @@ -397,7 +407,7 @@ describe('Koa Instrumentation', () => {
app.use((ctx, next) =>
context.with(trace.setSpan(context.active(), rootSpan), next)
);
app.use(asyncMiddleware);
app.use(asyncMiddleware());

await context.with(
trace.setSpan(context.active(), rootSpan),
Expand All @@ -423,12 +433,72 @@ describe('Koa Instrumentation', () => {
);
});

it('should not instrument generator middleware functions', async () => {
const rootSpan = tracer.startSpan('rootSpan');
app.use((_ctx, next) =>
context.with(trace.setSpan(context.active(), rootSpan), next)
);

app.use(generatorMiddleware());
app.use(simpleResponse());

await context.with(
trace.setSpan(context.active(), rootSpan),
async () => {
await httpRequest.get(`http://localhost:${port}`);
rootSpan.end();
assert.deepStrictEqual(memoryExporter.getFinishedSpans().length, 2);

const simpleResponseSpan = memoryExporter
.getFinishedSpans()
.find(span => span.name.includes('simpleResponse'));
assert.notStrictEqual(simpleResponseSpan, undefined);

const exportedRootSpan = memoryExporter
.getFinishedSpans()
.find(span => span.name === 'rootSpan');
assert.notStrictEqual(exportedRootSpan, undefined);
}
);
});

it('should not instrument the same middleware more than once', async () => {
const sameAsyncMiddleware = asyncMiddleware();

const rootSpan = tracer.startSpan('rootSpan');
app.use((_ctx, next) =>
context.with(trace.setSpan(context.active(), rootSpan), next)
);

app.use(sameAsyncMiddleware);
app.use(sameAsyncMiddleware);

await context.with(
trace.setSpan(context.active(), rootSpan),
async () => {
await httpRequest.get(`http://localhost:${port}`);
rootSpan.end();
assert.deepStrictEqual(memoryExporter.getFinishedSpans().length, 2);

const asyncMiddlewareSpan = memoryExporter
.getFinishedSpans()
.find(span => span.name.includes('asyncMiddleware'));
assert.notStrictEqual(asyncMiddlewareSpan, undefined);

const exportedRootSpan = memoryExporter
.getFinishedSpans()
.find(span => span.name === 'rootSpan');
assert.notStrictEqual(exportedRootSpan, undefined);
}
);
});

it('should propagate exceptions in the middleware while marking the span with an exception', async () => {
const rootSpan = tracer.startSpan('rootSpan');
app.use((_ctx, next) =>
context.with(trace.setSpan(context.active(), rootSpan), next)
);
app.use(failingMiddleware);
app.use(failingMiddleware());
const res = await httpRequest.get(`http://localhost:${port}`);
assert.deepStrictEqual(res, 'Internal Server Error');

Expand Down Expand Up @@ -573,7 +643,7 @@ describe('Koa Instrumentation', () => {
it('should not create new spans', async () => {
plugin.disable();
const rootSpan = tracer.startSpan('rootSpan');
app.use(customMiddleware);
app.use(customMiddleware());

await context.with(
trace.setSpan(context.active(), rootSpan),
Expand Down