How to make GCE instance stop when its deployed container finishes?

Question

I have a Docker container that performs a single large computation. This computation requires lots of memory and takes about 12 hours to run.

I can create a Google Compute Engine VM of the appropriate size and use the "Deploy a container image to this VM instance" option to run this job perfectly. However once the job is finished the container quits but the VM is still running (and charging).

How can I make the VM exit/stop/delete when the container exits?

When the VM is in its zombie mode only the stackdriver containers are left running:

$ docker ps
CONTAINER ID        IMAGE                                                                COMMAND                  CREATED             STATUS              PORTS               NAMES
bfa2feb03180        gcr.io/stackdriver-agents/stackdriver-logging-agent:0.2-1.5.33-1-1   "/entrypoint.sh /u..."   17 hours ago        Up 17 hours                             stackdriver-logging-agent
161439a487c2        gcr.io/stackdriver-agents/stackdriver-metadata-agent:0.2-0.0.17-2    "/bin/sh -c /opt/s..."   17 hours ago        Up 17 hours         8000/tcp            stackdriver-metadata-agent

I create the VM like this:

gcloud beta compute --project=abc instances create-with-container vm-name \
                    --zone=us-central1-c --machine-type=custom-1-65536-ext \
                    --network=default --network-tier=PREMIUM --metadata=google-logging-enabled=true \
                    --maintenance-policy=MIGRATE \
                    --service-account=xyz \
                    --scopes=https://www.googleapis.com/auth/cloud-platform \
                    --image=cos-stable-69-10895-71-0 --image-project=cos-cloud --boot-disk-size=10GB \
                    --boot-disk-type=pd-standard --boot-disk-device-name=vm-name \
                    --container-image=gcr.io/abc/my-image --container-restart-policy=on-failure \
                    --container-command=python3 \
                    --container-arg="a" --container-arg="b" --container-arg="c" \
                    --labels=container-vm=cos-stable-69-10895-71-0

Answer 1

When you create the VM, you'll need to give it write access to compute so you can delete the instance from within. You should also set container environment variables like gce_zone and gce_project_id at this time. You'll need them to delete the instance.

gcloud beta compute instances create-with-container {NAME} \
    --container-env=gce_zone={ZONE},gce_project_id={PROJECT_ID} \
    --service-account={SERVICE_ACCOUNT} \
    --scopes=https://www.googleapis.com/auth/compute,...
    ...

Then within the container, whenever YOU determine your task is finished:

1. request an api token (im using curl for simplicity and DEFAULT gce service account)

curl "http://metadata.google.internal/computeMetadata/v1/instance/service-accounts/default/token" -H "Metadata-Flavor: Google"

This will respond with json that looks like

{
  "access_token": "foobarbaz...",
  "expires_in": 1234,
  "token_type": "Bearer"
}

2. Take that access token and hit the instances.delete api endpoint (notice the environment variables)

curl -XDELETE -H 'Authorization: Bearer {TOKEN}' https://www.googleapis.com/compute/v1/projects/$gce_project_id/zones/$gce_zone/instances/$HOSTNAME

Answer 2

I wrote a self-contained Python function based on Vincent's answer.

def kill_vm():
    """
    If we are running inside a GCE VM, kill it.
    """
    # based on https://stackoverflow.com/q/52748332/321772
    import json
    import logging
    import requests

    # get the token
    r = json.loads(
        requests.get("http://metadata.google.internal/computeMetadata/v1/instance/service-accounts/default/token",
                     headers={"Metadata-Flavor": "Google"})
            .text)

    token = r["access_token"]

    # get instance metadata
    # based on https://cloud.google.com/compute/docs/storing-retrieving-metadata
    project_id = requests.get("http://metadata.google.internal/computeMetadata/v1/project/project-id",
                              headers={"Metadata-Flavor": "Google"}).text

    name = requests.get("http://metadata.google.internal/computeMetadata/v1/instance/name",
                        headers={"Metadata-Flavor": "Google"}).text

    zone_long = requests.get("http://metadata.google.internal/computeMetadata/v1/instance/zone",
                             headers={"Metadata-Flavor": "Google"}).text
    zone = zone_long.split("/")[-1]

    # shut ourselves down
    logging.info("Calling API to delete this VM, {zone}/{name}".format(zone=zone, name=name))

    requests.delete("https://www.googleapis.com/compute/v1/projects/{project_id}/zones/{zone}/instances/{name}"
                    .format(project_id=project_id, zone=zone, name=name),
                    headers={"Authorization": "Bearer {token}".format(token=token)})

A simple atexit hook gets me my desired behavior:

import atexit
atexit.register(kill_vm)