CloudWatch JSON queries

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CloudWatch Metrics Insight JSON Queries are JSON arrays that consist of a non-empty list of JSON items, where each item in the array consists of a separate query.

Each Metrics Insight JSON Query must include:

• A unique id.

• An expression (which could be an SQL query or an operation on the auxiliary queries: refer to the examples below).

• Other parameters, such as a period.

Here’s an example of a Metrics Insight JSON Query:

objectives:
  - countMetrics:
      good:
        cloudWatch:
          json: |
            [
                {
                    "Id": "e1",
                    "Expression": "SELECT AVG(CPUUtilization)FROM \"AWS/EC2\"",
                    "Period": 60
                }
            ]
          region: us-east-1
      incremental: false
      total:
        cloudWatch:
          json: |
            [
                {
                    "Id": "e2",
                    "Expression": "SELECT MAX(CPUUtilization)FROM \"AWS/EC2\"",
                    "Period": 60
                }
            ]
          region: us-east-1

Combining multiple queries

JSON queries are a powerful tool that entitles users to combine multiple time series, or even combine the results of the component queries.

The JSON query outlined in the below example consists of:

• An auxiliary query "Id": "m1" that queries for a one time series.

• An auxiliary query "Id": "m2" that queries for a different time series.

On top of that, the main query "Id": "e1" combines the results of the m1 and m2 queries. In the following example, the results of the query m1 are a numerator, while the results of the query m2 are a denominator, which is defined in the following query expression:

"Expression": "m1 / m2"

This means that number of correct HTTP requests from the query m1 (HTTPCode_Target_2XX_Count)are divided by the number of total requests in the m2 query (RequestCount). As a result, using such a query, we give input to our e1 indicator as a ratio of good to total HTTP requests:

    rawMetric:
      cloudWatch:
        json: |-
          [
              {
                  "Id": "e1",
                  "Expression": "m1 / m2",
                  "Period": 60
              },
              {
                  "Id": "m1",
                  "MetricStat": {
                      "Metric": {
                          "Namespace": "AWS/ApplicationELB",
                          "MetricName": "HTTPCode_Target_2XX_Count",
                          "Dimensions": [
                              {
                                  "Name": "LoadBalancer",
                                  "Value": "app/main-default-appingress-350b/904311bedb964754"
                              }
                          ]
                      },
                      "Period": 60,
                      "Stat": "SampleCount"
                  },
                  "ReturnData": false
              },
              {
                  "Id": "m2",
                  "MetricStat": {
                      "Metric": {
                          "Namespace": "AWS/ApplicationELB",
                          "MetricName": "RequestCount",
                          "Dimensions": [
                              {
                                  "Name": "LoadBalancer",
                                  "Value": "app/main-default-appingress-350b/904311bedb964754"
                              }
                          ]
                      },
                      "Period": 60,
                      "Stat": "SampleCount"
                  },
                  "ReturnData": false
              }
          ]
        region: eu-central-1

The only condition is for a single query in the array to have the ReturnData value set to true. true is the default value for the main query. See the section below for more details.

Query validation in the UI

The UI console where you paste your JSON query has several validation rules:

• The value of Period must be 60.

• The ReturnData must be true for at least one query in the array.

• The syntax of JSON query must be correct.

If these conditions are not met, the UI will return the following errors:

Video 1: Query Validation in the UI