Cloud Foundry中的数据库实例是什么？

Question

After running below command,

     $ cf create-service-key mysql-db-service MY-KEY

There is a file created with name MY-KEY (shown below) that has key name (database instance) with value service-instance-db

{
  "hostname": "w-ns27y31.q-g1444.bosh",
  "jdbcUrl": "jdbc:mysql://w-ns27y31.q-g1444.bosh:3306/service_instance_db?user=ccd64a5aa128fffffffffff26d80&password=eddddddd50g&useSSL=false",
  "name": "service_instance_db",
  "password": "el99ffffffffff",
  "port": 3306,
  "uri": "mysql://ccd64a5aa1284dadab01271693d26d80:el9905261y23b50g@w-ns27y31.q-g1444.bosh:3306/service_instance_db?reconnect=true",
  "username": "ccd64ddddddddd271693d26d80"
}

If I create a more than one service key file, then hostname & name remains same in each service key file, but username and password changes

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In database world, we create database instance with syntax: create DATABASE statement

And an application runs on that database instance say instance1

For another new different application, we create another database instance say instance2

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1) Is value service-instance-db for key name a database instance? In service key file MY-KEY

2) if yes, then we create a separate service key file on mysql-db-service app for each new db application on cloud foundry, but I see same database instance name service-instance-db in service key file. How do I understand this?

Answer 1

1) Is value some-service-db for key name a database instance? In service key file MY-KEY

It honestly depends on the service broker how this is handled. Generally, running cf create-service will create an instance of the service and running cf bind-service or cf create-service-key will create a set of credentials you can use to access the service.

It depends on the broker though as to what exactly happens. Running cf create-service can result in anything from a partition in a shared multi-tenant service to a set of dedicated VMs running a cluster of your service.

2) if yes, then we create a separate service key file on mysql-db-service app for each new db application on cloud foundry, but I see same database instance name some-service-db in service key file. How do I understand this?

In most cases, the service key is just a new, likely unique, set of credentials for accessing the service instance. You need to look at the docs for your service broker to see exactly how this is handled though.

Hope that helps!