k8s-restart-app

A simple application that allows to restart services running in K8s. The service that should be allowed to be restarted, must be defined in the configuration file.

UI

The application provides a simple UI to restart services. The UI is available at the root path of the application.

Configuration

The configuration of the application is mostly done through environment variables. The following environment variables are available:

Name	Type	Default	Description
LISTEN_ADDRESS	string	:8080	The address the application should listen on.
CONFIG_FILE_PATH	string	config.yaml	The path to the configuration file.
KUBE_CONFIG_PATH	string	``	The path to the kubeconfig file. If not specified, the application tries to use the in-cluster config.
WATCH_INTERVAL	int	10	The interval in seconds the application watches for pod, deployment or statefulset changes
FORCE_UNLOCK_SEC	int	300	The time in seconds a restart can take before the lock is force released.

In order to provide a list of services that should be allowed to be restarted, a configuration file must be provided. In that file, the services are defined as follows:

services:
  - kind: Deployment # The kind of the service (Deployment, StatefulSet)
    name: my-deployment # The name of the service
    namespace: my-namespace # The namespace the service is running in

In order for the application to actually be able to restart the services, the service account the application is running under, must have the necessary permissions. The following RBAC configuration can be used to grant the necessary permissions:

apiVersion: rbac.authorization.k8s.io/v1
kind: ClusterRole
metadata:
  name: restart-app
rules:
  - apiGroups: [""]
    resources: ["pods"]
    verbs: ["get", "list", "watch"]
  - apiGroups: ["apps"]
    resources: ["deployments", "statefulsets"]
    verbs: ["get", "list", "watch", "patch"]
---
apiVersion: rbac.authorization.k8s.io/v1
kind: ClusterRoleBinding
metadata:
  name: restart-app
roleRef:
  apiGroup: rbac.authorization.k8s.io
  kind: ClusterRole
  name: restart-app
subjects:
  - kind: ServiceAccount
    name: restart-app
    namespace: default
---
apiVersion: v1
kind: ServiceAccount
metadata:
  name: restart-app

API

The application provides a simple API to restart services. The following endpoints are available:

Endpoint	Method	Description
/	GET	Returns the HTML control page.
/metrics	GET	Returns the Prometheus metrics.
/api/v1/service	GET	Returns a list of services that can be restarted.
/api/v1/service/status	GET	Returns the status of the service with the given kind, namespace and name. As websocket stream.
/api/v1/service/{kind}/{namespace}/{name}/restart	POST	Restarts the service with the given kind, namespace and name.

Metrics

The application provides the Go runtime metrics as well as a number of custom metrics. The metrics are available at the /metrics endpoint. The following custom metrics are available:

Name	Type	Description
restart_app_connected_status_watchers	Gauge	The number of connected status watchers.
restart_app_restarts_total	Counter	The total number of restarts.
restart_app_restarts_failed_total	Counter	The total number of failed restarts.

All custom metrics are labeled with the kind, namespace and name of the service.