Updating a deployment

After you have a deployment, you can update it as your app evolves. You can use Deployment Manager to update a deployment by:

Adding or removing resources to the deployment
Updating some properties of existing resources in your deployment

Deployment Manager uses the underlying APIs of Google Cloud services to manage resources in your deployment. Deployment Manager can update existing resources if there is an update or patch method in the corresponding API.

Deploy the original configuration

In this step, deploy the configuration that you will update later. Navigate to the folder in the GitHub repository, and deploy the configuration:

cd deploymentmanager-samples/examples/v2/step_by_step_guide/step8_metadata_and_startup_scripts/python

gcloud deployment-manager deployments create deployment-to-update --config config-with-many-templates.yaml

The configuration deploys two virtual machines (VMs) that run a startup script. The VM template is:

# Copyright 2016 Google Inc. All rights reserved.
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
#     http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.

"""Creates the virtual machine with environment variables and startup script."""


COMPUTE_URL_BASE = 'https://www.googleapis.com/compute/v1/'


def GenerateConfig(context):
  """Creates the virtual machine."""

  resources = [{
      'name': context.env['name'],
      'type': 'compute.v1.instance',
      'properties': {
          'zone': context.properties['zone'],
          'machineType': ''.join([COMPUTE_URL_BASE, 'projects/',
                                  context.env['project'], '/zones/',
                                  context.properties['zone'], '/machineTypes/',
                                  context.properties['machineType']]),
          'disks': [{
              'deviceName': 'boot',
              'type': 'PERSISTENT',
              'boot': True,
              'autoDelete': True,
              'initializeParams': {
                  'sourceImage': ''.join([COMPUTE_URL_BASE, 'projects/',
                                          'debian-cloud/global/',
                                          'images/family/debian-11'])
              }
          }],
          'networkInterfaces': [{
              'network': '$(ref.' + context.properties['network']
                         + '.selfLink)',
              'accessConfigs': [{
                  'name': 'External NAT',
                  'type': 'ONE_TO_ONE_NAT'
              }]
          }],
          'metadata': {
              'items': [{
                  'key': 'startup-script',
                  'value': ''.join(['#!/bin/bash\n',
                                    'python -m SimpleHTTPServer 80'])
              }]
          }
      }
  }]
  return {'resources': resources}

Open the updated template

Now, open the updated template:

cd deploymentmanager-samples/examples/v2/step_by_step_guide/step9_update_a_deployment/python

nano vm-template.py

In the updated template, in the metadata section, the VM's startup script has been changed:

# Copyright 2016 Google Inc. All rights reserved.
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
#     http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.

"""Creates the virtual machine with environment variables and startup script."""


COMPUTE_URL_BASE = 'https://www.googleapis.com/compute/v1/'


def GenerateConfig(context):
  """Creates the virtual machine."""

  resources = [{
      'name': context.env['name'],
      'type': 'compute.v1.instance',
      'properties': {
          'zone': context.properties['zone'],
          'machineType': ''.join([COMPUTE_URL_BASE, 'projects/',
                                  context.env['project'], '/zones/',
                                  context.properties['zone'], '/machineTypes/',
                                  context.properties['machineType']]),
          'disks': [{
              'deviceName': 'boot',
              'type': 'PERSISTENT',
              'boot': True,
              'autoDelete': True,
              'initializeParams': {
                  'sourceImage': ''.join([COMPUTE_URL_BASE, 'projects/',
                                          'debian-cloud/global/',
                                          'images/family/debian-11'])
              }
          }],
          'networkInterfaces': [{
              'network': '$(ref.' + context.properties['network']
                         + '.selfLink)',
              'accessConfigs': [{
                  'name': 'External NAT',
                  'type': 'ONE_TO_ONE_NAT'
              }]
          }],
          'metadata': {
              'items': [{
                  'key': 'startup-script',
                  'value': ''.join(['#!/bin/bash\n',
                                    'INSTANCE=$(curl http://metadata.google.',
                                    'internal/computeMetadata/v1/instance/',
                                    'hostname -H "Metadata-Flavor: Google")\n',
                                    'echo "<html><header><title>Hello from ',
                                    'Deployment Manager!</title></header>',
                                    '<body><h2>Hello from $INSTANCE</h2><p>',
                                    'Deployment Manager bids you good day!</p>',
                                    '</body></html>" > index.html\n',
                                    'python -m SimpleHTTPServer 80\n'])
              }]
          }
      }
  }]
  return {'resources': resources}

You will use this updated template to change the deployment you created.

Preview the update

To preview the updated deployment, run the update command with a --preview flag:

gcloud deployment-manager deployments update deployment-to-update --config config-with-many-templates.yaml --preview

Commit the update

To commit the update, run:

gcloud deployment-manager deployments update deployment-to-update

Verify the update

To check if the update worked, you must first restart the instances to use the new startup script. Restart the-first-vm:

gcloud compute instances reset the-first-vm

The instance might take some time to start back up. Wait a couple minutes before confirming the change.

Confirm the new startup script

Get the external IP of the-first-vm:

gcloud compute instances describe the-first-vm | grep "natIP"

Copy the value.
Open a browser and paste the IP address into the address bar to visit your instance.

The page should now show a welcome message that says "Deployment Manager bids you good day!"

You can also repeat these steps with the-second-vm and see a slightly different message.

Delete your deployment

As with previous steps, we recommend that you delete the deployment to avoid charges. Run the following command to delete the deployment:

gcloud deployment-manager deployments delete deployment-to-update

What's next

Here are some areas to explore as you use Deployment Manager more:

Exploring helper scripts