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Add README.md to guestbook example. Remove local replicatedservice.py and reference the replicatedservice.py directly from the replicatedservice example from github in templates
Ville Aikas
9 years ago
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08c8e10c2d
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# Guestbook Example
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Guestbook example shows how to bring up the
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[Guestbook Example](https://github.com/kubernetes/kubernetes/tree/master/examples/guestbook)
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from Kubernetes using Deployment Manager. It also shows you how to construct
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and reuse parameterized templates.
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## Getting started
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It is assumed that you have bootstrapped the Deployment Manager on your cluster
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by following the [README.md][https://github.com/kubernetes/deployment-manager/blob/master/README.md]
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for bootstrapping the cluster.
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## Deploying Guestbook
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To deploy the Guestbook example, you run the following command.
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```
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client --name guestbook --service=http://localhost:8001/api/v1/proxy/namespaces/default/services/manager-service:manager examples/guestbook/guestbook.yaml
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```
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### Replicated Service
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Typical pattern for deploying microservices in Kubernetes is to create both a
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Replication Controller and a Service. We have created a parameterizable type
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for that called [Replicated Service](https://github.com/kubernetes/deployment-manager/tree/master/examples/replicatedservice)
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that we use throughout this example.
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The Guestbook example consists of 2 services, a frontend and a Redis service.
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Frontend is a replicated service with 3 replicas and is created like so:
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```
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- name: frontend
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type: https://raw.githubusercontent.com/kubernetes/deployment-manager/master/examples/replicatedservice/replicatedservice.py
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properties:
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service_port: 80
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container_port: 80
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external_service: true
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replicas: 3
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image: gcr.io/google_containers/example-guestbook-php-redis:v3
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```
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Redis is a composite type and consists of two replicated services. A master with a single replica
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and the slaves with 2 replicas. It's construced as follows:
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```
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{% set REDIS_PORT = 6379 %}
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{% set WORKERS = properties['workers'] or 2 %}
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resources:
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- name: redis-master
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type: https://raw.githubusercontent.com/kubernetes/deployment-manager/master/examples/replicatedservice/replicatedservice.py
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properties:
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# This has to be overwritten since service names are hard coded in the code
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service_name: redis-master
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service_port: {{ REDIS_PORT }}
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target_port: {{ REDIS_PORT }}
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container_port: {{ REDIS_PORT }}
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replicas: 1
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container_name: master
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image: redis
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- name: redis-slave
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type: https://raw.githubusercontent.com/kubernetes/deployment-manager/master/examples/replicatedservice/replicatedservice.py
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properties:
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# This has to be overwritten since service names are hard coded in the code
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service_name: redis-slave
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service_port: {{ REDIS_PORT }}
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container_port: {{ REDIS_PORT }}
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replicas: {{ WORKERS }}
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container_name: worker
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image: kubernetes/redis-slave:v2
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# An example of how to specify env variables.
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env:
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- name: GET_HOSTS_FROM
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value: env
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- name: REDIS_MASTER_SERVICE_HOST
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value: redis-master
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```
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### Displaying types
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You can also (currently using curl, work in progress) see what types have been deployed to the cluster:
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```
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curl http://localhost:8001/api/v1/proxy/namespaces/default/services/manager-service:manager/types
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["Service","ReplicationController","redis.jinja","https://raw.githubusercontent.com/kubernetes/deployment-manager/master/examples/replicatedservice/replicatedservice.py"]
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```
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This shows that there are 2 native types that we have deployed (Service and ReplicationController) and
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2 composite types (redis.jinja and one imported from github (replicatedservice.py)).
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You can also see where the types are being used by getting details on the particular type:
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```
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curl 'http://localhost:8001/api/v1/proxy/namespaces/default/services/manager-service:manager/types/redis.jinja/instances'
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[{"name":"redis","type":"redis.jinja","deployment":"guestbook","manifest":"manifest-1446584669795839153","path":"$.resources[1]"}]
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```
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It lists which deployment and manifest as well as JSON path to the type.
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"""Defines a ReplicatedService type by creating both a Service and an RC.
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This module creates a typical abstraction for running a service in a
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Kubernetes cluster, namely a replication controller and a service packaged
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together into a single unit.
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"""
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import yaml
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SERVICE_TYPE_COLLECTION = 'Service'
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RC_TYPE_COLLECTION = 'ReplicationController'
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def GenerateConfig(context):
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"""Generates a Replication Controller and a matching Service.
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Args:
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context: Template context, which can contain the following properties:
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container_name - Name to use for container. If omitted, name is
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used.
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namespace - Namespace to create the resources in. If omitted,
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'default' is used.
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service_name - Name to use for service. If omitted name-service is
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used.
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protocol - Protocol to use for the service
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service_port - Port to use for the service
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target_port - Target port for the service
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container_port - Container port to use
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replicas - Number of replicas to create in RC
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image - Docker image to use for replicas. Required.
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labels - labels to apply.
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env - Environmental variables to apply (list of maps). Format
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should be:
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[{'name': ENV_VAR_NAME, 'value':'ENV_VALUE'},
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{'name': ENV_VAR_NAME_2, 'value':'ENV_VALUE_2'}]
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external_service - If set to true, enable external Load Balancer
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Returns:
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A Container Manifest as a YAML string.
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"""
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# YAML config that we're going to create for both RC & Service
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config = {'resources': []}
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name = context.env['name']
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container_name = context.properties.get('container_name', name)
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namespace = context.properties.get('namespace', 'default')
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# Define things that the Service cares about
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service_name = context.properties.get('service_name', name + '-service')
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service_type = SERVICE_TYPE_COLLECTION
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# Define things that the Replication Controller (rc) cares about
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rc_name = name + '-rc'
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rc_type = RC_TYPE_COLLECTION
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service = {
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'name': service_name,
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'type': service_type,
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'properties': {
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'apiVersion': 'v1',
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'kind': 'Service',
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'namespace': namespace,
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'metadata': {
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'name': service_name,
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'labels': GenerateLabels(context, service_name),
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},
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'spec': {
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'ports': [GenerateServicePorts(context, container_name)],
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'selector': GenerateLabels(context, name)
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}
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}
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}
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set_up_external_lb = context.properties.get('external_service', None)
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if set_up_external_lb:
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service['properties']['spec']['type'] = 'LoadBalancer'
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config['resources'].append(service)
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rc = {
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'name': rc_name,
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'type': rc_type,
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'properties': {
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'apiVersion': 'v1',
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'kind': 'ReplicationController',
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'namespace': namespace,
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'metadata': {
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'name': rc_name,
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'labels': GenerateLabels(context, rc_name),
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},
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'spec': {
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'replicas': context.properties['replicas'],
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'selector': GenerateLabels(context, name),
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'template': {
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'metadata': {
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'labels': GenerateLabels(context, name),
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},
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'spec': {
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'containers': [
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{
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'env': GenerateEnv(context),
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'name': container_name,
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'image': context.properties['image'],
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'ports': [
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{
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'name': container_name,
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'containerPort': context.properties['container_port'],
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}
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]
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}
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]
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}
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}
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}
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}
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}
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config['resources'].append(rc)
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return yaml.dump(config)
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# Generates labels either from the context.properties['labels'] or generates
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# a default label 'name':name
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def GenerateLabels(context, name):
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"""Generates labels from context.properties['labels'] or creates default.
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We make a deep copy of the context.properties['labels'] section to avoid
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linking in the yaml document, which I believe reduces readability of the
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expanded template. If no labels are given, generate a default 'name':name.
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Args:
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context: Template context, which can contain the following properties:
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labels - Labels to generate
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Returns:
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A dict containing labels in a name:value format
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"""
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tmp_labels = context.properties.get('labels', None)
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ret_labels = {'name': name}
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if isinstance(tmp_labels, dict):
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for key, value in tmp_labels.iteritems():
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ret_labels[key] = value
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return ret_labels
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def GenerateServicePorts(context, name):
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"""Generates a ports section for a service.
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Args:
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context: Template context, which can contain the following properties:
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service_port - Port to use for the service
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target_port - Target port for the service
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protocol - Protocol to use.
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Returns:
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A dict containing a port definition
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"""
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service_port = context.properties.get('service_port', None)
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target_port = context.properties.get('target_port', None)
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protocol = context.properties.get('protocol')
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ports = {}
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if name:
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ports['name'] = name
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if service_port:
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ports['port'] = service_port
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if target_port:
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ports['targetPort'] = target_port
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if protocol:
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ports['protocol'] = protocol
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return ports
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def GenerateEnv(context):
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"""Generates environmental variables for a pod.
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Args:
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context: Template context, which can contain the following properties:
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env - Environment variables to set.
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Returns:
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A list containing env variables in dict format {name: 'name', value: 'value'}
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"""
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env = []
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tmp_env = context.properties.get('env', [])
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for entry in tmp_env:
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if isinstance(entry, dict):
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env.append({'name': entry.get('name'), 'value': entry.get('value')})
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return env
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