We are using apigee private cloud. What is the best way to monitor API transactions(Error rate, quota limit and proxy health) and send alert notification when something is wrong with API transactions? As far as I know apigee has a free tool, test.apigee.com to help user to monitor such things, but looks like it is for cloud user only?
For a customer, we wrote an application called Critical Infrastructure Monitor, which is basically a node.js application that would ping various Apigee URLs, back-end target, forward & reverse proxies and several other pieces of the customer's infrastructure to check their health and take the necessary action if things go wrong. This can be hosted on a third-party server separate from the Apigee infrastructure.