问题
As I mention in this title, can I skip the step of install hadoop cluster for that cluster already exist and which in service?
回答1:
Ambari relies on 'Stack' definitions to describe what services the Hadoop cluster consists of. Hortonworks defined a custom Ambari stack, its called HDP.
You could define your own stack and use any services and respective versions that you wanted. See the ambari wiki for more information about defining stacks and services.
That being said, I don't think it's possible to use your pre-existing installation of Hadoop with Ambari. Ambari is used to provision and manage hadoop clusters. It keeps track of the state of each of its stacks services, and the states of each services components. Since your cluster is already provisioned it would be difficult (maybe impossible) to add it to an Ambari instance.
回答2:
One of the minimum requierments of installing Ambari is removing the pre-existing installations of tools mentioned here.It is not mentioned to remove any pre-existing hadoop installation.
来源：https://stackoverflow.com/questions/15892864/how-to-deploy-ambari-for-an-existing-hadoop-cluster