Keep getting error status on Kubernetes Cron Job with connection refused? - kubernetes

Question

I am trying to write a cron job which hits a rest endpoint of the application it is pulling image of.
Below is the sample code:
---
apiVersion: batch/v1beta1
kind: CronJob
metadata:
name: {{ .Chart.Name }}-cronjob
labels:
app: {{ .Release.Name }}
chart: {{ .Chart.Name }}-{{ .Chart.Version }}
release: {{ .Release.Name }}
spec:
concurrencyPolicy: Forbid
successfulJobsHistoryLimit: 2
failedJobsHistoryLimit: 2
startingDeadlineSeconds: 1800
jobTemplate:
spec:
template:
metadata:
name: {{ .Chart.Name }}-cronjob
labels:
app: {{ .Chart.Name }}
spec:
restartPolicy: OnFailure
containers:
- name: demo
image: "{{ .Values.image.repository }}:{{ .Values.image.tag }}"
command: ["/bin/sh", "-c", "curl http://localhost:8080/hello"]
readinessProbe:
httpGet:
path: "/healthcheck"
port: 8081
initialDelaySeconds: 300
periodSeconds: 60
timeoutSeconds: 30
failureThreshold: 3
livenessProbe:
httpGet:
path: "/healthcheck"
port: 8081
initialDelaySeconds: 300
periodSeconds: 60
timeoutSeconds: 30
failureThreshold: 3
resources:
requests:
cpu: 200m
memory: 2Gi
limits:
cpu: 1
memory: 6Gi
schedule: "*/5 * * * *"
But i keep running into *curl: (7) Failed to connect to localhost port 8080: Connection refused*.
I can see from the events that it creates the container and immediately throws: Back-off restarting failed container.
I already have pods running of demo app and it works fine, it is just when i am trying to point to this existing app and hit a rest endpoint i start running into connection refused errors.
Exact output when seeing the logs:
% Total % Received % Xferd Average Speed Time Time Time Current
Dload Upload Total Spent Left Speed
0 0 0 0 0 0 0 0 --:--:-- --:--:-- --:--:-- 0curl: (7) Failed to connect to localhost port 8080: Connection refused
Event Logs:
Container image "wayfair/demo:728ac13-as_test_cron_job" already present on machine
9m49s Normal Created pod/demo-cronjob-1619108100-ndrnx Created container demo
6m17s Warning BackOff pod/demo-cronjob-1619108100-ndrnx Back-off restarting failed container
5m38s Normal SuccessfulDelete job/demo-cronjob-1619108100 Deleted pod: demo-cronjob-1619108100-ndrnx
5m38s Warning BackoffLimitExceeded job/demo-cronjob-1619108100 Job has reached the specified backoff limit
Being new to K8, Any pointers are helpful!

Answer 1

You are trying to connect to localhost:8080 with your curl which doesn't make sense from what I understand of your CronJob definition.
From the docs (at https://kubernetes.io/docs/tasks/inject-data-application/define-command-argument-container/#define-a-command-and-arguments-when-you-create-a-pod )
The command and arguments that you define in the configuration file
override the default command and arguments provided by the container
image. If you define args, but do not define a command, the default
command is used with your new arguments.
Note: The command field corresponds to entrypoint in some container
runtimes. Refer to the Notes below.
If you define a command for the image, even if the image would start a rest application on port 8080 on localhost with its default entrypoint (or command, depends on the container type you are using), the command overrides the entrypoint and no application is start.
If you have the necessity of both starting the application and then performing other operations, like curls and so on, I suggest to use a .sh script or something like that, depending on what is the Job objective.