I have a two tier application. The frontend calls the webapi layer through simple http rest call http://mywebapi:5000/ My working docker compose code is below and the application works
version: '3'
services:
webfrontend:
image: webfrontend
build: ./nodeexpress-alibaba-ci-tutorial
ports:
- "3000:3000"
networks:
- my-shared-network
mywebapi:
image: mywebapi
build: ./dotnetcorewebapi-alibaba-ci-tutorial
ports:
- "5000:5000"
networks:
- my-shared-network
networks:
my-shared-network: {}
Now I'm trying to get this to work on kubernetes. I have created two deployments and two services-loadbalancer for webfrontend and clusterip for mywebapi
But, after deploying, I find that the data from mywebapi is not reaching the frontend. I can view the frontend on the browser through the load balancer public ip.
Mywebapi deployment yaml
apiVersion: apps/v1beta2
kind: Deployment
metadata:
annotations:
deployment.kubernetes.io/revision: '3'
creationTimestamp: '2019-09-28T13:31:32Z'
generation: 3
labels:
app: mywebapi
tier: backend
name: mywebapi
namespace: default
resourceVersion: '1047268388'
selfLink: /apis/apps/v1beta2/namespaces/default/deployments/mywebapi
uid: 493ab5e0-e1f4-11e9-9a64-d63fe9981162
spec:
progressDeadlineSeconds: 600
replicas: 2
revisionHistoryLimit: 10
selector:
matchLabels:
app: mywebapi
strategy:
rollingUpdate:
maxSurge: 25%
maxUnavailable: 25%
type: RollingUpdate
template:
metadata:
annotations:
aliyun.kubernetes.io/deploy-timestamp: '2019-09-28T14:36:01Z'
labels:
app: mywebapi
spec:
containers:
- image: >-
registry-intl-vpc.ap-southeast-1.aliyuncs.com/devopsci-t/mywebapi:1.0
imagePullPolicy: Always
name: mywebapi
resources: {}
terminationMessagePath: /dev/termination-log
terminationMessagePolicy: File
dnsPolicy: ClusterFirst
restartPolicy: Always
schedulerName: default-scheduler
securityContext: {}
terminationGracePeriodSeconds: 30
status:
availableReplicas: 2
conditions:
- lastTransitionTime: '2019-09-28T14:51:18Z'
lastUpdateTime: '2019-09-28T14:51:18Z'
message: Deployment has minimum availability.
reason: MinimumReplicasAvailable
status: 'True'
type: Available
- lastTransitionTime: '2019-09-28T14:49:55Z'
lastUpdateTime: '2019-09-28T14:51:19Z'
message: ReplicaSet "mywebapi-84cf98fb4f" has successfully progressed.
reason: NewReplicaSetAvailable
status: 'True'
type: Progressing
observedGeneration: 3
readyReplicas: 2
replicas: 2
updatedReplicas: 2
Mywebapi service yaml
apiVersion: v1
kind: Service
metadata:
creationTimestamp: '2019-09-28T13:31:33Z'
name: mywebapi-svc
namespace: default
resourceVersion: '1047557879'
selfLink: /api/v1/namespaces/default/services/mywebapi-svc
uid: 49e21207-e1f4-11e9-9a64-d63fe9981162
spec:
clusterIP: None
ports:
- name: mywebapiport
port: 5000
protocol: TCP
targetPort: 5000
selector:
app: mywebapi
sessionAffinity: None
type: ClusterIP
status:
loadBalancer: {}
I even tried updating the http rest call url to http://mywebapi-svc:5000/ but still does not work. In the webfrontend pod logs I find the below error
Got error: getaddrinfo ENOTFOUND mywebapi-svc mywebapi-svc:5000
Sincerely appreciate all help
Thanks
............................................................
Update..
Changed mywebapi-svc to disable headless. Current YAML is below. Problem still the same..
apiVersion: v1
kind: Service
metadata:
creationTimestamp: '2019-09-29T15:21:44Z'
name: mywebapi-svc
namespace: default
resourceVersion: '667545270'
selfLink: /api/v1/namespaces/default/services/mywebapi-svc
uid: d84503ee-e2cc-11e9-93ec-a65f0b53b1fa
spec:
clusterIP: 172.19.0.74
ports:
- name: mywebapiport
port: 5000
protocol: TCP
targetPort: 5000
selector:
app: mywebapi-default
sessionAffinity: None
type: ClusterIP
status:
loadBalancer: {}
It's because you're using headless service
I guess you don't need a headless service for this job. Because DNS server won't return a single IP address if there are more than one pod match by the label selector. Remove the spec.ClusterIP
field from your service.
apiVersion: v1
kind: Service
metadata:
name: mywebapi-svc
namespace: default
spec:
# clusterIP: None <-- remove
ports:
- name: mywebapiport
port: 5000
protocol: TCP
targetPort: 5000
selector:
app: mywebapi
type: ClusterIP
Now you can call at http://service-name.namespace-name.svc:port
endpoint from your front-end. It should work.
In case your webapi is stateful, then you should use statefulset
instead of deployment
.