Convert kpm manifest.yaml to jsonnet to better manifest.yaml

1_original_manifest.yaml

---
package:
  name: kubespray/etcd
  author: Antoine Legrand
  version: 1.0.0
  description: etcd
  license: MIT

variables:
  cluster_token: etcd-cluster-1
  cluster_state: 'new'
  data_volumes:
    - name: varetcd
      emptyDir:
        medium: ""
  service: svc.cluster.local
  initial_cluster: etcd-1=http://etcd-1.{{namespace}}.{{service}}:2380,etcd-2=http://etcd-2.{{namespace}}.{{service}}:2380,etcd-3=http://etcd-3.{{namespace}}.{{service}}:2380


resources:
  - file: etcd-member-dp.yaml
    name: etcd
    type: deployment
    sharded: yes

  - file: etcd-member-svc.yaml
    name: etcd
    type: svc
    sharded: yes

  - file: etcd-svc.yaml
    name: etcd
    type: svc


shards:
  - name: 1
  - name: 2
  - name: 3

deploy:
  - name: $self

2_intermediate_manifest.jsonnet

function(
data_volumes=[{'emptyDir': {'medium': ''}, 'name': 'varetcd'}],
cluster_token="etcd-cluster-1",
initial_cluster="etcd-1=http://etcd-1.{{namespace}}.{{service}}:2380,etcd-2=http://etcd-2.{{namespace}}.{{service}}:2380,etcd-3=http://etcd-3.{{namespace}}.{{service}}:2380",
cluster_state="new",
service="svc.cluster.local",
)


{
 package: {'author': 'Antoine Legrand', 'version': '1.0.0', 'description': 'etcd', 'license': 'MIT', 'name': 'kubespray/etcd'},

 variables: {'data_volumes': [{'emptyDir': {'medium': ''}, 'name': 'varetcd'}], 'cluster_token': 'etcd-cluster-1', 'initial_cluster': 'etcd-1=http://etcd-1.{{namespace}}.{{service}}:2380,etcd-2=http://etcd-2.{{namespace}}.{{service}}:2380,etcd-3=http://etcd-3.{{namespace}}.{{service}}:2380', 'cluster_state': 'new', 'service': 'svc.cluster.local'},

 shards: [{'name': 1}, {'name': 2}, {'name': 3}],


 resources: [] 
 + [ {"type": "deployment", "sharded": true, "name": "etcd", "file": "etcd-member-dp.yaml"} + shard + {name: "etcd-%s" % shard.name}
  for shard in $.shards
  ]
 + [ {"type": "svc", "sharded": true, "name": "etcd", "file": "etcd-member-svc.yaml"} + shard + {name: "etcd-%s" % shard.name}
  for shard in $.shards
  ]
 + [ {"type": "svc", "name": "etcd", "file": "etcd-svc.yaml"} ],


 deploy: [{'name': '$self'}]

}

3_final_manifest.yaml

---
deploy:
- {name: $self}
package: {author: Antoine Legrand, description: etcd, license: MIT, name: kubespray/etcd,
  version: 1.0.0}
resources:
- {file: etcd-member-dp.yaml, name: etcd-1, sharded: true, type: deployment}
- {file: etcd-member-dp.yaml, name: etcd-2, sharded: true, type: deployment}
- {file: etcd-member-dp.yaml, name: etcd-3, sharded: true, type: deployment}
- {file: etcd-member-svc.yaml, name: etcd-1, sharded: true, type: svc}
- {file: etcd-member-svc.yaml, name: etcd-2, sharded: true, type: svc}
- {file: etcd-member-svc.yaml, name: etcd-3, sharded: true, type: svc}
- {file: etcd-svc.yaml, name: etcd, type: svc}
shards:
- {name: 1}
- {name: 2}
- {name: 3}
variables:
  cluster_state: new
  cluster_token: etcd-cluster-1
  data_volumes:
  - emptyDir: {medium: ''}
    name: varetcd
  initial_cluster: etcd-1=http://etcd-1.{{namespace}}.{{service}}:2380,etcd-2=http://etcd-2.{{namespace}}.{{service}}:2380,etcd-3=http://etcd-3.{{namespace}}.{{service}}:2380
  service: svc.cluster.local

kpm_jsonnet.py

#!/usr/bin/env python
import argparse
import kpm.kub
import json
import _jsonnet
import yaml
import jinja2

TEMPLATE = """
function(
{% for key,value in manifest.variables.iteritems() -%}
{% if value is string  -%}
{{key}}="{{value}}",
{% else -%}
{{key}}={{value}},
{% endif -%}
{%- endfor -%}
)


{
 package: {{manifest.package}},

 variables: {{manifest.variables}},

 shards: {{manifest.shards}},

{% if manifest.resources|length > 0 %}
 resources: [] {% for item in manifest.resources %}
 + [ {{item|json}} {% if 'sharded' in item -%} + shard + {name: "{{item.name}}-%s" % shard.name}
  for shard in $.shards
  {% endif -%}
 ]
{%- endfor %},

{% endif %}
 deploy: {{manifest.deploy}}

}
"""

def do_json(value, **kwargs):
    """
    Serializes an object as JSON. Optionally given keyword arguments
    are passed to json.dumps(), ensure_ascii however defaults to False.
    """
    import json
    kwargs.setdefault('ensure_ascii', False)
    return json.dumps(value, **kwargs)


filters = {"json": do_json}


def render(template, package="rabbitmq/rabbitmq"):
    jinja_env = jinja2.Environment()
    jinja_env.filters.update(filters)
    template = jinja_env.from_string(template)
    k = kpm.kub.Kub(package)
    v = {"manifest": k.manifest}
    jsonnet_str = template.render(v)
    print jsonnet_str
    json_str = _jsonnet.evaluate_snippet("snippet", jsonnet_str)
    print json_str
    yaml_str = yaml.safe_dump(json.loads(json_str))
    return yaml_str


if __name__ == "__main__":
 # usage: ./kpm_jsonnet.py -p kubespray/etcd
 #        ./kpm_jsonnet.py -p rabbitmq/rabbitmq     
    parser = argparse.ArgumentParser()
    parser.add_argument("-p", "--package", default="rabbitmq/rabbitmq")
    args = parser.parse_args()
    print render(TEMPLATE, args.package)