Users want Ambassador to normalize route weights to integers.

Describe the bug Configuration generation crash (config.py)

To Reproduce Create any app that you have, integrate with ambassador with following piece of yaml

---
apiVersion: v1
kind: Service
metadata:
  name: sample-application
  annotations:
    getambassador.io/config: |
      ---
      apiVersion: ambassador/v0
      kind:  Mapping
      name:  sample-application
      prefix: /sample-application/
      service: https://sample-application:80
      tls: upstream
spec:
  ports:
  - port: 80
    name: http
    protocol: TCP
    targetPort: 8080
  selector:
    app: sample-application
  type: ClusterIP
---
apiVersion: v1
kind: Service
metadata:
  name: sample-application-2
  annotations:
    getambassador.io/config: |
      ---
      apiVersion: ambassador/v0
      kind:  Mapping
      name:  sample-application-2
      prefix: /sample-application/
      service: https://sample-application-2:80
      tls: upstream
spec:
  ports:
  - port: 80
    name: http
    protocol: TCP
    targetPort: 8080
  selector:
    app: sample-application
  type: ClusterIP
---
apiVersion: v1
kind: Service
metadata:
  name: sample-application-3
  annotations:
    getambassador.io/config: |
      ---
      apiVersion: ambassador/v0
      kind:  Mapping
      name:  sample-application-3
      prefix: /sample-application/
      service: https://sample-application-3:80
      tls: upstream
spec:
  ports:
  - port: 80
    name: http
    protocol: TCP
    targetPort: 8080
  selector:
    app: sample-application
  type: ClusterIP
---

this will result in following error

[2018-09-17 15:06:54.898][1941][critical][main] source/server/config_validation/server.cc:48] error initializing configuration '/ambassador/ambassador-config-104-envoy.json': JSON at lines 1-1 does not conform to schema.
Invalid schema: #/definitions/weighted_clusters/properties/clusters/items/properties/weight
Schema violation: type
Offending document key: #/weighted_clusters/clusters/0/weight
2018-09-17 15:06:54 kubewatch 0.39.0 INFO: Invalid envoy config
2018-09-17 15:06:54 kubewatch 0.39.0 INFO: {

.... a lot of stuff here ...

2018-09-17 15:06:54 kubewatch 0.39.0 ERROR: could not restart Envoy
Traceback (most recent call last):
 File "/ambassador/kubewatch.py", line 126, in run
   self.restart()
 File "/ambassador/kubewatch.py", line 135, in restart
   config = self.generate_config(output)
 File "/ambassador/kubewatch.py", line 192, in generate_config
   raise ValueError("Unable to generate config")
ValueError: Unable to generate config

Expected behavior Ambassador is able to consume following piece of configuration

"clusters": [
      { "name": "cluster_https___sample_app_80_otls_upstream", "weight": 33.333333333333336 },
      { "name": "cluster_https___sample_app_80_otls_upstream", "weight": 33.333333333333336 },
      { "name": "cluster_https___sample_app_80_otls_upstream", "weight": 33.333333333333336 }   
]

Versions (please complete the following information):

• Ambassador: ambassador:0.39.0
• Kubernetes environment:
• Version:

Additional context Problem is probably with following piece of code

for cluster in configuration.get('clusters', []):
    maps_to_service = cluster_to_service_mapping.get(cluster['name'])
    if maps_to_service:
        service_weigth = 100.0 / len(cluster['urls'])
        for url in cluster['urls']:
            ambassador_services.append(SourcedDict(
                _from=cluster,
                type=maps_to_service,
                name=url,
                cluster=cluster['name'],
                _service_weight=service_weigth

ambassador generates floating variable

"weight": 33.333333333333336 

but requires integer in the schema : https://github.com/datawire/ambassador/blob/master/ambassador/schemas/v0/Mapping.schema#L70

In newest version, this causes crash, but not cause downtime, as far as I remember, when I first time saw this error, it caused ambassador downtime (so, is better), this is not a blocker 😃

[richarddli]

Thanks for testing!

[Nightapes]

We run into the same issue, when you add 3 times the same service without weight, the calculated weight is: 33.333333333. This will break envoy.

I tried to fix it: https://github.com/datawire/ambassador/compare/master...Nightapes:fix/weight?expand=1#diff-497e4afaf589877b6ff5f8325ef97798. But i have problems running the tests on my machine. Should i make a PR for that?