feat(cold-start): add check for cold start check

mikaelvesavuori · Nov 10, 2022 · f09ef8d · f09ef8d
1 parent 8758113
commit f09ef8d
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Showing 6 changed files with 47 additions and 20 deletions.
diff --git a/README.md b/README.md
@@ -266,23 +266,24 @@ The dynamic metadata fields are picked up automatically if you pass them in duri
 
 If these values are not available, they will be dropped at the time of log output. In effect, this means you won't have to deal with them (being empty or otherwise) if you use MikroLog in another type of context.
 
-| Field                | Type   | Description                                               |
-| -------------------- | ------ | --------------------------------------------------------- |
-| `accountId`          | string | The AWS account ID that the system is running in.         |
-| `correlationId`      | string | Correlation ID for this function call.                    |
-| `functionMemorySize` | string | Memory size of the current function.                      |
-| `functionName`       | string | The name of the function.                                 |
-| `functionVersion`    | string | The version of the function.                              |
-| `id`                 | string | ID of the log.                                            |
-| `region`             | string | The region of the responding function/system.             |
-| `resource`           | string | The resource (channel, URL path...) that is responding.   |
-| `runtime`            | string | What runtime is used?                                     |
-| `stage`              | string | What AWS stage are we in?                                 |
-| `timestamp`          | string | Timestamp of this message in ISO 8601 (RFC 3339) format.  |
-| `timestampEpoch`     | string | Timestamp of this message in Unix epoch.                  |
-| `timestampRequest`   | string | Request time in Unix epoch of the incoming request.       |
-| `user`               | string | The user in this log context.                             |
-| `viewerCountry`      | string | Which country did AWS CloudFront infer the user to be in? |
+| Field                | Type    | Description                                               |
+| -------------------- | ------- | --------------------------------------------------------- |
+| `accountId`          | string  | The AWS account ID that the system is running in.         |
+| `correlationId`      | string  | Correlation ID for this function call.                    |
+| `functionMemorySize` | string  | Memory size of the current function.                      |
+| `functionName`       | string  | The name of the function.                                 |
+| `functionVersion`    | string  | The version of the function.                              |
+| `id`                 | string  | ID of the log.                                            |
+| `isColdStart`        | boolean | Is this a Lambda cold start?                              |
+| `region`             | string  | The region of the responding function/system.             |
+| `resource`           | string  | The resource (channel, URL path...) that is responding.   |
+| `runtime`            | string  | What runtime is used?                                     |
+| `stage`              | string  | What AWS stage are we in?                                 |
+| `timestamp`          | string  | Timestamp of this message in ISO 8601 (RFC 3339) format.  |
+| `timestampEpoch`     | string  | Timestamp of this message in Unix epoch.                  |
+| `timestampRequest`   | string  | Request time in Unix epoch of the incoming request.       |
+| `user`               | string  | The user in this log context.                             |
+| `viewerCountry`      | string  | Which country did AWS CloudFront infer the user to be in? |
 
 ## Redacting keys or masking values
 

diff --git a/package-lock.json b/package-lock.json
diff --git a/package.json b/package.json
@@ -1,7 +1,7 @@
 {
   "name": "mikrolog",
   "description": "The JSON logger you always wanted for Lambda.",
-  "version": "2.1.4",
+  "version": "2.1.5",
   "author": "Mikael Vesavuori",
   "license": "MIT",
   "main": "./lib/index.js",

diff --git a/src/entities/MikroLog.ts b/src/entities/MikroLog.ts
@@ -54,6 +54,7 @@ export class MikroLog {
   private static correlationId: string;
   private static debugSamplingLevel: number;
   private static isDebugLogSampled: boolean;
+  private coldStart = true;
 
   private constructor() {
     MikroLog.metadataConfig = {};
@@ -103,6 +104,18 @@ export class MikroLog {
     MikroLog.context = Object.assign(MikroLog.context, input.context || {});
   }
 
+  /**
+   * @description Is this a Lambda cold start?
+   */
+  public isColdStart(): boolean {
+    if (this.coldStart) {
+      this.coldStart = false;
+      return true;
+    }
+
+    return false;
+  }
+
   /**
    * @description Set correlation ID manually, for example for use in cross-boundary calls.
    *
@@ -217,6 +230,7 @@ export class MikroLog {
    */
   private loadEnrichedEnvironment() {
     return {
+      isColdStart: this.isColdStart(),
       timestampRequest: produceTimestampRequest(MikroLog.event),
       accountId: produceAccountId(MikroLog.event),
       region: produceRegion(MikroLog.context),

diff --git a/tests/MikroLog.test.ts b/tests/MikroLog.test.ts
@@ -29,6 +29,7 @@ test.serial(
       message: 'Hello World',
       error: false,
       httpStatusCode: 200,
+      isColdStart: true,
       level: 'INFO',
       id: '1256767f-c875-4d82-813d-bc260bd0ba07',
       timestamp: '2022-07-25T08:52:21.121Z',
@@ -76,6 +77,7 @@ test.serial('It should return (print out) a structured log when given a string m
     message: 'Hello World',
     error: false,
     httpStatusCode: 200,
+    isColdStart: true,
     level: 'INFO',
     id: '1256767f-c875-4d82-813d-bc260bd0ba07',
     timestamp: '2022-07-25T08:52:21.121Z',
@@ -125,6 +127,7 @@ test.serial(
       message: 'Hello World',
       error: false,
       httpStatusCode: 200,
+      isColdStart: true,
       level: 'INFO',
       id: '1256767f-c875-4d82-813d-bc260bd0ba07',
       timestamp: '2022-07-25T08:52:21.121Z',
@@ -175,6 +178,7 @@ test.serial(
       message: 'Hello World',
       error: false,
       httpStatusCode: 200,
+      isColdStart: true,
       level: 'DEBUG',
       id: '1256767f-c875-4d82-813d-bc260bd0ba07',
       timestamp: '2022-07-25T08:52:21.121Z',
@@ -225,6 +229,7 @@ test.serial(
       message: 'Hello World',
       error: false,
       httpStatusCode: 200,
+      isColdStart: true,
       level: 'WARN',
       id: '1256767f-c875-4d82-813d-bc260bd0ba07',
       timestamp: '2022-07-25T08:52:21.121Z',
@@ -275,6 +280,7 @@ test.serial(
       message: 'Hello World',
       error: true,
       httpStatusCode: 400,
+      isColdStart: true,
       level: 'ERROR',
       id: '1256767f-c875-4d82-813d-bc260bd0ba07',
       timestamp: '2022-07-25T08:52:21.121Z',
@@ -456,6 +462,7 @@ test.serial('It should redact keys when given a "redactedKeys" list', (t) => {
     message: 'Hello World',
     error: true,
     httpStatusCode: 400,
+    isColdStart: true,
     level: 'ERROR',
     id: '1256767f-c875-4d82-813d-bc260bd0ba07',
     timestamp: '2022-07-25T08:52:21.121Z',
@@ -499,6 +506,7 @@ test.serial('It should mask values when given a "maskedValues" list', (t) => {
     error: true,
     hostPlatform: 'aws',
     httpStatusCode: 400,
+    isColdStart: true,
     level: 'ERROR',
     message: 'Hello World',
     owner: 'MyCompany',
@@ -551,6 +559,7 @@ test.serial('It should accept a custom metadata configuration', (t) => {
     },
     error: false,
     httpStatusCode: 200,
+    isColdStart: true,
     level: 'INFO',
     message: 'Hello World'
   };
@@ -590,6 +599,7 @@ test.serial('It should retain falsy but defined values in logs', (t) => {
   const expected: any = {
     error: false,
     httpStatusCode: 200,
+    isColdStart: true,
     falsyTest1: false,
     falsyTest2: 0,
     level: 'INFO',
@@ -627,6 +637,7 @@ test.serial('It should be able to merge enrichment even if input is essentially
   const expected: any = {
     error: false,
     httpStatusCode: 200,
+    isColdStart: true,
     level: 'INFO',
     message: 'Hello World'
   };

diff --git a/tests/metadataUtils.test.ts b/tests/metadataUtils.test.ts
@@ -241,6 +241,7 @@ test.serial('It should emit a full log and filter out any empty fields', (t) =>
     functionName: 'somestack-FunctionName',
     functionVersion: '$LATEST',
     httpStatusCode: 200,
+    isColdStart: true,
     level: 'INFO',
     message: 'something',
     region: 'eu-north-1',