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"""Prepare a DaemonSet manifest to pre-pull a list of given images."""
from pathlib import Path
import os
import sys
import json
import yaml
import kubernetes
PROJECT_PATH = Path(__file__).resolve().parents[1]
def configure_kube_api(namespace):
"""Configure Kubernetes Python API."""
kube_config = kubernetes.config.load_incluster_config()
with kubernetes.client.ApiClient(kube_config) as api_client:
kube_apps_api = kubernetes.client.AppsV1Api(api_client)
kube_core_api = kubernetes.client.CoreV1Api()
return kube_apps_api, kube_core_api
def build_manifest():
# Extract list of images to pre-pull from charts
images_to_prepull = []
charts = [f.name for f in os.scandir(PROJECT_PATH / "charts")
if f.is_dir() and f.name != "library-chart"]
for chart in charts:
schema_path = PROJECT_PATH / "charts" / chart / "values.schema.json"
with open(schema_path, "r") as file_in:
chart_schema = json.load(file_in)
images = chart_schema["properties"]["service"]["properties"]["image"]["properties"]["version"]["listEnum"]
images_to_prepull.extend(images)
# Fill template with one init container per image to pre-pull
with open(PROJECT_PATH / "utils" / "prepull_template.yaml", "r") as file_in:
manifest = yaml.safe_load(file_in)
for image in images_to_prepull:
init_container = {
"name": image.split("/")[1].replace(":", "-").replace(".", "-"),
"image": image,
"command": ['bash', '-c', 'echo image pulled.'],
"imagePullPolicy": "Always",
"resources": {"limits": {"cpu": "100m", "memory": "100Mi"}}
}
manifest["spec"]["template"]["spec"]["initContainers"].append(init_container)
return manifest
def prepull_deployment(namespace):
kube_apps_api, kube_core_api = configure_kube_api(namespace=namespace)
manifest = build_manifest()
manifest["kind"] = "Deployment"
kube_apps_api.create_namespaced_deployment(namespace=namespace,
body=manifest)
# Wait for the Deployment to be in Running state and remove it
w = kubernetes.watch.Watch()
for event in w.stream(kube_core_api.list_namespaced_pod,
namespace=namespace,
label_selector="name=prepull"
):
pod_state = event['object'].status.phase
if pod_state == "Running":
w.stop()
kube_apps_api.delete_namespaced_deployment(namespace=NAMESPACE,
name="prepull")
break
def prepull_daemon(namespace):
kube_apps_api, kube_core_api = configure_kube_api(namespace=namespace)
manifest = build_manifest()
manifest["kind"] = "DaemonSet"
kube_apps_api.create_namespaced_daemon_set(namespace=namespace,
body=manifest)
# Wait for all daemons to be in Running state and remove the DaemonSet
w = kubernetes.watch.Watch()
for event in w.stream(kube_apps_api.list_namespaced_daemon_set,
namespace=namespace,
label_selector="name=prepull"):
n_daemons_ready = event['object'].status.number_ready
if n_daemons_ready == 11:
w.stop()
kube_apps_api.delete_namespaced_daemon_set(namespace=NAMESPACE,
name="prepull")
break
if __name__ == "__main__":
NAMESPACE = sys.argv[1]
# 1st step : create a Deployment to pull the images in the global registry cache once
prepull_deployment(namespace=NAMESPACE)
# 2nd step : create a DaemonSet to pull the images in each worker's local cache
prepull_daemon(namespace=NAMESPACE)