I am new to containerization and am having some difficulties. I have an application that consists of a React frontend, a Python backend using FastAPI, and PostgreSQL databases using SQL Alchemy for object-relational mapping. I decided to put each component inside a Docker container so that I can deploy the application on Azure in the future (I know that some people may have strong opinions on deploying the frontend and database in containers, but I am doing so because it is required by the project's requirements).
After doing this, I started working with Minikube. However, I am having problems where all the containers that should be running inside pods have the status "CrashLoopBackOff". From what I can tell, this means that the images are being pulled from Docker Hub, containers are being started but then failing for some reason.
I tried running "kubectl logs" and nothing is returned. The "kubectl describe" command, in the Events section, returns: "Warning BackOff 30s (x140 over 30m) kubelet Back-off restarting failed container."
I have also tried to minimize the complexity by just trying to run the frontend component. Here are my Dockerfile and manifest file:
Dockerfile:
FROM node:18
WORKDIR /app
COPY package*.json ./
RUN npm install
COPY . .
EXPOSE 3000
CMD ["npm", "run", "dev"]
manifest file .yml:
apiVersion: apps/v1
kind: Deployment
metadata:
name: frontend
spec:
replicas: 1
selector:
matchLabels:
app: frontend
template:
metadata:
labels:
app: frontend
spec:
containers:
- name: frontend
image: xxxtest/my-first-repo:yyy-frontend
ports:
- containerPort: 3000
I do not have a service manifest yet, and I don't think it is related to this issue.
Can anyone provide any help or tips on how to troubleshoot this issue? I would really appreciate any guidance you can offer. Thank you in advance for your time and assistance!
Have a great day!
This CrashLoopBackOff is related to a container error. If you want to fix this error, you need to see the container log, these is my tips:
The best practice in K8s is to redirect the application logs to /dev/stdout or /dev/stderr is not recommended redirect to a file so that you can use the kubectl logs <POD NAME>.
Try to clear the cache of your local containers, download and run the same image, and tag you configured in your deployment file.
If you need any environment variable to run the container locally, you'll also need those env's in your deployment file.
Always use the flag imagePullPolicy: Always mainly if you are using the same image tag. EDIT: Because the default image pull policy is IfNotPresent, if you fixed the container image, the k8s will not pull a new image version.
Docs: