Creating and Configuring Instances

You can create an configure Compute Engine instances running Container-Optimized OS by using the gcloud command-line tool.

Viewing available images

Container-Optimized OS images are available on Google Cloud Platform Console's list of images with the prefix cos. These are hosted under the cos-cloud project. You can also see all currently available releases on command line by running:

gcloud compute images list \
    --project cos-cloud \
    --no-standard-images

The output is similar to the following:

NAME                      PROJECT            FAMILY         STATUS
cos-beta-56-9000-66-0     cos-cloud          cos-beta       READY
cos-dev-57-9196-0-0       cos-cloud          cos-dev        READY
cos-stable-55-8872-76-0   cos-cloud          cos-stable     READY

Creating an instance with the gcloud command-line interface

You can use the gcloud compute instances create command with --image and --image-project flags to create a cos node image instance as follows:

gcloud compute instances create INSTANCE_NAME \
    --image cos-stable-55-8872-76-0 \
    --image-project cos-cloud \
    --zone us-east1-d \
    --machine-type n1-standard-1

In the above example, cos-beta-51-8172-26-0 is one of the available cos releases. It is recommended to use --preemptible flag for one-off experimental instances.

Connecting to an instance

You can SSH into your VM instance running the cos node image the same way you SSH into your other Google Compute Engine instances. For example:

gcloud compute ssh INSTANCE_NAME \
    --project PROJECT
    --zone ZONE

Creating an instance using the Google Cloud Platform Console

To run a Compute Engine instance with the Container-Optimized OS and a Docker container of your choice, follow these steps:

  1. Open the Compute Engine instance creation page on Google Cloud Platform Console.

    Create a new Compute Engine instance

  2. In the Containers section, check the box labeled Create VM instance running Docker containers.

  3. In the New Container dialog, enter the necessary information for the Container Image URL, Port, Target Port, and Protocol fields, then click Done.

    For example, the configuration for nginx container might look like:

    Nginx on COS with UI

  4. In the Firewall section, check the box labeled Allow HTTP traffic.

  5. Click Create.

This brings up a Container-Optimized OS instance ready with your Docker container up and running.

Configuring an instance

In some cases, you may want to do additional configuration when you bring up your Docker containers. You can use the cloud-init tool with Container-Optimized OS to apply configuration information that you supply as a cloud-config format.

Using cloud-init

The cos node image includes cloud-init as a way to configure your instance when it boots up. Cloud-init reads value by the key user-data from the instance metadata. There are multiple formats for that field that Cloud-init understands. Below is a sample value for the user-data in cloud-config format that creates a user account and adds a systemd service:

#cloud-config

users:
- name: cloudservice
  uid: 2000

write_files:
- path: /etc/systemd/system/cloudservice.service
  permissions: 0644
  owner: root
  content: |
    [Unit]
    Description=Start a simple docker container

    [Service]
    ExecStart=/usr/bin/docker run --rm -u 2000 --name=mycloudservice busybox:latest /bin/sleep 3600
    ExecStop=/usr/bin/docker stop mycloudservice
    ExecStopPost=/usr/bin/docker rm mycloudservice

runcmd:
- systemctl daemon-reload
- systemctl start cloudservice.service

When creating an instance use --metadata-from-file to set cloud-init metadata:

gcloud compute instances create INSTANCE_NAME \
    --image IMAGE_NAME \
    --metadata-from-file user-data=FILENAME

Other metadata flags

Metadata Key Description Default Behavior
cos-update-strategy Specifies update behavior. The only value accepted is: update_disabled. If not set all update from the current channel are automatically downloaded and installed.
cos-metrics-enabled Enables usage statistics and crash dump collection. Values could be:
true
false (default).
Disabled by default

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