Use your custom data source
After you've created a data source, you can use it to query data from that source to visualize it and to set alarms. If you used the template to create your custom data source connector or you added the tag listed in Step 3: Attach a resource tag to the Lambda function, you can follow the steps in Creating a graph of metrics from another data source to query it.
You can also use the metric math function LAMBDA to query it, as explained in the following
section.
For information about creating alarms on metrics from your data source, see Create an alarm based on a connected data source.
How to pass arguments to your Lambda function
The recommended way for you to pass arguments to your custom data source is to use the query builder in the CloudWatch console when you query the data source.
You can also use your Lambda function to retrieve data from your data source
by using the new LAMBDA expression in CloudWatch metric math.
LAMBDA("LambdaFunctionName" [, optional-arg]*)
optional-arg is up to 20 strings, numbers, or Booleans. For example,
param, 3.14, or true.
Note
Multi-line strings are not supported by the CloudWatch data source connectors. Every line feed is replaced with a space when the query is executed, or when you create an alarm or a dashboard widget with the query. In some cases, this might make your query not valid.
When you use the LAMBDA metric math function, you can provide the function
name ("MyFunction"). If your resource policy allows, you can also use a specific version of the function
("MyFunction:22"), or a Lambda function alias
("MyFunction:MyAlias"). You can't use *
The following are some examples of calling the LAMBDA function.
LAMBDA("AmazonOpenSearchDataSource", "MyDomain", "some-query")
LAMBDA("MyCustomDataSource", true, "fuzzy", 99.9)
The LAMBDA metric math function returns a list of time series that can be returned
to the requester or combined with other metric math functions. The following is an example of combining
LAMBDA with other metric math functions.
FILL(LAMBDA("AmazonOpenSearchDataSource", "MyDomain", "some-query"), 0)