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Running CoreOS Container Linux on Google Compute Engine

Before proceeding, you will need a GCE account (GCE free trial ) and install gcloud on your machine. In each command below, be sure to insert your project name in place of <project-id>.

After installation, log into your account with gcloud auth login and enter your project ID when prompted.

Container Linux Config

Container Linux allows you to configure machine parameters, configure networking, launch systemd units on startup, and more via Container Linux Configs. These configs are then transpiled into Ignition configs and given to booting machines. Head over to the docs to learn about the supported features.

You can provide a raw Ignition config to Container Linux via the Google Cloud console's metadata field user-data or via a flag using gcloud.

As an example, this config will configure and start etcd:

etcd:
  # All options get passed as command line flags to etcd.
  # Any information inside curly braces comes from the machine at boot time.

  # multi_region and multi_cloud deployments need to use {PUBLIC_IPV4}
  advertise_client_urls:       "http://{PRIVATE_IPV4}:2379"
  initial_advertise_peer_urls: "http://{PRIVATE_IPV4}:2380"
  # listen on both the official ports and the legacy ports
  # legacy ports can be omitted if your application doesn't depend on them
  listen_client_urls:          "http://0.0.0.0:2379"
  listen_peer_urls:            "http://{PRIVATE_IPV4}:2380"
  # generate a new token for each unique cluster from https://discovery.etcd.io/new?size=3
  # specify the initial size of your cluster with ?size=X
  discovery:                   "https://discovery.etcd.io/<token>"

Choosing a channel

Container Linux is designed to be updated automatically with different schedules per channel. You can disable this feature, although we don't recommend it. Read the release notes for specific features and bug fixes.

Create 3 instances from the image above using our Ignition from example.ign:

The Alpha channel closely tracks master and is released frequently. The newest versions of system libraries and utilities will be available for testing. The current version is Container Linux {{site.alpha-channel}}.

gcloud compute instances create core1 core2 core3 --image-project coreos-cloud --image-family coreos-alpha --zone us-central1-a --machine-type n1-standard-1 --metadata-from-file user-data=config.ign

The Beta channel consists of promoted Alpha releases. The current version is Container Linux {{site.beta-channel}}.

gcloud compute instances create core1 core2 core3 --image-project coreos-cloud --image-family coreos-beta --zone us-central1-a --machine-type n1-standard-1 --metadata-from-file user-data=config.ign

The Stable channel should be used by production clusters. Versions of Container Linux are battle-tested within the Beta and Alpha channels before being promoted. The current version is Container Linux {{site.stable-channel}}.

gcloud compute instances create core1 core2 core3 --image-project coreos-cloud --image-family coreos-stable --zone us-central1-a --machine-type n1-standard-1 --metadata-from-file user-data=config.ign

Additional storage

Additional disks attached to instances can be mounted with a .mount unit. Each disk can be accessed via /dev/disk/by-id/google-<disk-name>. Here's the Container Linux Config to format and mount a disk called database-backup:

storage:
  filesystems:
    - mount:
        device: /dev/disk/by-id/scsi-0Google_PersistentDisk_database-backup
        format: ext4

systemd:
  units:
    - name: media-backup.mount
      enable: true
      contents: |
        [Mount]
        What=/dev/disk/by-id/scsi-0Google_PersistentDisk_database-backup
        Where=/media/backup
        Type=ext4

        [Install]
        RequiredBy=local-fs.target

For more information about mounting storage, Google's own documentation is the best source. You can also read about mounting storage on Container Linux.

Adding more machines

To add more instances to the cluster, just launch more with the same Ignition config inside of the project.

SSH and users

Users are added to Container Linux on GCE by the user provided configuration (i.e. Ignition, cloudinit) and by either the GCE account manager or GCE OS Login. OS Login is used if it is enabled for the instance, otherwise the GCE account manager is used.

Using the GCE account manager

You can log in your Container Linux instances using:

gcloud compute ssh --zone us-central1-a core@<instance-name>

Users other than core, which are set up by the GCE account manager, may not be a member of required groups. If you have issues, try running commands such as journalctl with sudo.

Using OS Login

You can log in using your Google account on instances with OS Login enabled. OS Login needs to be enabled in the GCE console and on the instance. It is enabled by default on instances provisioned with Container Linux 1898.0.0 or later. Once enabled, you can log into your Container Linux instances using:

gcloud compute ssh --zone us-central1-a <instance-name>

This will use your GCE user to log in.

Disabling OS Login on newly provisioned nodes

You can disable the OS Login functionality by masking the oem-gce-enable-oslogin.service unit:

systemd:
  units:
    - name: oem-gce-enable-oslogin.service
      mask: true

When disabling OS Login functionality on the instance, it is also recommended to disable it in the GCE console.

Using CoreOS Container Linux

Now that you have a machine booted it is time to play around. Check out the Container Linux Quickstart guide or dig into more specific topics.