Liveness Probes

All probe fields are the same as readiness probes. The only difference is using the livenessProbe field instead of readinessProbe.

What are liveness probes?

Liveness probes determine whether a container is alive. If the probe fails, kubelet restarts the container. This is useful when a container is running but the application inside is no longer responding — for example, an API server that is stuck but whose process has not exited. A successful probe means the container is healthy. A failed probe triggers a container restart. Probe types:

HTTP

Sends an HTTP GET request to the container. A 2xx or 3xx response is healthy.

TCP

Opens a TCP socket to the container. A successful connection is healthy.

exec

Runs a command inside the container. An exit code of 0 is healthy.

Usage

HTTP
TCP
exec

liveness-probes.yaml

apiVersion: v1
kind: Pod
metadata:
  name: sample-pod
spec:
  containers:
    - name: web-app
      image: webapp
      livenessProbe:
        httpGet:
          path: /api/v1/health
          port: 8000
        initialDelaySeconds: 5 # wait before performing the 1st probe
        periodSeconds: 3       # how often to perform the probe
        failureThreshold: 5    # restart after this many consecutive failures (default 3)

liveness-probes.yaml

apiVersion: v1
kind: Pod
metadata:
  name: sample-pod
spec:
  containers:
    - name: web-app
      image: webapp
      livenessProbe:
        tcpSocket:
          port: 8080
        initialDelaySeconds: 5
        periodSeconds: 3
        failureThreshold: 5

kubelet attempts to open a socket to the container on port 8080. A successful connection means the container is healthy.

liveness-probes.yaml

apiVersion: v1
kind: Pod
metadata:
  name: sample-pod
spec:
  containers:
    - name: web-app
      image: webapp
      livenessProbe:
        exec:
          command:
            - cat
            - /app/healthy
        initialDelaySeconds: 5
        periodSeconds: 3
        failureThreshold: 5

The command returns exit code 0 on success. Any other exit code is treated as a failure.

Key probe fields

Field	Description
`initialDelaySeconds`	Seconds to wait after the container starts before the first probe
`periodSeconds`	How often the probe is performed
`failureThreshold`	Number of consecutive failures before the container is restarted (default: `3`)

Overview

Docker

Git

Kubernetes

Kubernetes Scheduling

Kubernetes Observability

Kubernetes Cluster Maintenance

Kubernetes Security

Linux

SSH

Ansible

Taskfile

Python OOP

Data Structures & Algorithms

12-Factor App

What are liveness probes?

HTTP

TCP

exec

Usage

Key probe fields

Build docs developers (and LLMs) love

Overview

Docker

Git

Kubernetes

Kubernetes Scheduling

Kubernetes Observability

Kubernetes Cluster Maintenance

Kubernetes Security

Linux

SSH

Ansible

Taskfile

Python OOP

Data Structures & Algorithms

12-Factor App

​What are liveness probes?

HTTP

TCP

exec

​Usage

​Key probe fields

Build docs developers (and LLMs) love

What are liveness probes?

Usage

Key probe fields