newrelic-lambda subscriptions install does not consider destination arn of existing subscription filter

[rittneje]

Description

When attempting to migrate from your old ingest Lambda function (see #267), we needed to update all existing CloudWach log group subscriptions. To do this, we ran newrelic-lambda subscriptions install --function newrelic-lambda subscriptions install.

However, this command had no effect at all. Upon reviewing the source code, we found a flaw in its logic.

newrelic-lambda-cli/newrelic_lambda_cli/subscriptions.py

Lines 132 to 142 in 6b5d8d4

	click.echo(
	"Found log subscription for '%s', verifying configuration" % function_name
	)
	newrelic_filter = newrelic_filters[0]
	if newrelic_filter["filterPattern"] != input.filter_pattern:
	return _remove_subscription_filter(
	input.session, function_name, newrelic_filter["filterName"]
	) and _create_subscription_filter(
	input.session, function_name, destination_arn, input.filter_pattern
	)
	return True

As you can see, if a NewRelicLogStreaming subscription filter already exists, it will only re-create it if the filter pattern changes. In our case, only the destination arn was changing, and thus the CLI incorrectly did not fix any of them.

As a workaround, we ran the command twice, once with a dummy --filter-pattern parameter and once without, in order to get it to properly re-create the subscription filter.

Steps to Reproduce

See above.

Expected Behavior

The newrelic-lambda subscriptions install must re-create the subscription filter if either the filter pattern or destination arn are wrong.

Relevant Logs / Console output

n/a

Your Environment

n/a

Additional context

[Newrelic-Boomi]

https://new-relic.atlassian.net/browse/NR-484220