Add endpoint to RDS DBCluster connection details

[benagricola]

Description of your changes

Endpoint was not being copied into the connection details of the generated RDS DBCluster reconciler. This adds the endpoint field as it is trivially available in the status of the resource, and returns the FQDN (minus port) of the instance.

This does not set the port as well, as it is not exposed by the status. I suspect in most cases this is defaulted from the AWS side, and it doesn't look like late init is implemented for this reconciler yet (so we potentially have no value to populate).

Fixes #695

I have:

• Read and followed Crossplane's contribution process.
• Run make reviewable test to ensure this PR is ready for review.

How has this code been tested

Test suite passes but I don't think this particular method is directly targeted. Will be using the built image to test on a live cluster.

[hasheddan]

LGTM pending your test results :) Thanks!

[benagricola]

Tested using the following resource:

apiVersion: rds.aws.crossplane.io/v1alpha1
kind: DBCluster
metadata:
  name: example-dbcluster
spec:
  forProvider:
    region: us-east-1
    engineMode: serverless
    engine: aurora-mysql
    masterUsername: admin
    masterUserPasswordSecretRef:
      name: dbcluster-pwd
      namespace: crossplane-system
      key: password
    dbSubnetGroupName: example-dbsubnet-group
    vpcSecurityGroupIDs:
      - sg-<redacted>
    databaseName: exampledbcluster
  writeConnectionSecretToRef:
    name: mysqlserver-conn
    namespace: crossplane-system

Which after reconciliation, produced the following DBCluster:

apiVersion: rds.aws.crossplane.io/v1alpha1
kind: DBCluster
metadata:
annotations:
    crossplane.io/external-name: example-dbcluster
name: example-dbcluster
spec:
    deletionPolicy: Delete
    forProvider:
        databaseName: exampledbcluster
        dbSubnetGroupName: example-dbsubnet-group
        engine: aurora-mysql
        engineMode: serverless
        masterUserPasswordSecretRef:
        key: password
        name: dbcluster-pwd
        namespace: crossplane-system
        masterUsername: admin
        region: us-east-1
        vpcSecurityGroupIDs:
        - sg-<redacted>
    providerConfigRef:
        name: default
    writeConnectionSecretToRef:
        name: mysqlserver-conn
        namespace: crossplane-system
status:
    atProvider:
        activityStreamStatus: stopped
        allocatedStorage: 1
        capacity: 8
        clusterCreateTime: "2021-06-03T14:51:12Z"
        crossAccountClone: false
        dbClusterARN: arn:aws:rds:us-east-1:<redacted>:cluster:example-dbcluster
        dbClusterIdentifier: example-dbcluster
        dbClusterParameterGroup: default.aurora-mysql5.7
        dbClusterResourceID: cluster-<redacted>
        dbSubnetGroup: example-dbsubnet-group
        earliestRestorableTime: "2021-06-03T14:52:07Z"
        endpoint: example-dbcluster.cluster-<redacted>.us-east-1.rds.amazonaws.com
        hostedZoneID: <redacted>
        httpEndpointEnabled: false
        iamDatabaseAuthenticationEnabled: false
        latestRestorableTime: "2021-06-03T14:52:07Z"
        multiAZ: false
        scalingConfigurationInfo:
            autoPause: true
            maxCapacity: 16
            minCapacity: 2
            secondsUntilAutoPause: 300
            timeoutAction: RollbackCapacityChange
        status: available
        vpcSecurityGroups:
            - status: active
              vpcSecurityGroupID: sg-<redacted>

And the corresponding secret:

➜  crossplane-test-resources k get secret -n crossplane-system mysqlserver-conn -o jsonpath='{.data.endpoint}' | base64 -d
example-dbcluster.cluster-<redacted>.us-east-1.rds.amazonaws.com%