Containers not accessible via container name , running in single pod(multi-container)

[neetra]

Problem:
I have two applications say applicationA, applicationB.

Using Docker compose.yml:
version: '3.4'

services:
  applicationa:
    environment:
      - ASPNETCORE_ENVIRONMENT=Development  
     
    ports:
      - "7001:80"  
  applicationb:
    environment:
      - ASPNETCORE_ENVIRONMENT=Development      

In dockerfile of applicationa (Exposed port 80), applicationb(exposed port 5000)
Exposed port of applicationB is not mapped to external port thus it is not accessible directly
ApplicationA access applicationB via http://containername:containerexposedport i.e http://applicationb:5000

Using Minikube:
Deployment.yaml
apiVersion: apps/v1
kind: Deployment
metadata:
name: appaappb-deployment
labels:
app: appaappb
spec:
replicas: 1
selector:
matchLabels:
app: appaappb
template:
metadata:
labels:
app: appaappb
spec:
containers:
- name: appa
image: appa:latest
env:
- name: ASPNETCORE_ENVIRONMENT
value: "Development"
ports:
- containerPort: 80
imagePullPolicy: Never
containers:
- name: appb
image: appb:latest
env:
- name: ASPNETCORE_ENVIRONMENT
value: "Development"
ports:
- containerPort: 5000
imagePullPolicy: Never

Service (Map external port)

kubectl expose pod appaappb-deployment-8656cfcdff-wd4hv --name=appaappbservice --type="NodePort" --target-port 80 --port 80

Now as appA and appB are not in same docker network appA cannot access appB via container name and container internal port

So how to access appB in appA ?

information:

Minikube version:v1.9.2
Docker version: 19.0.3

[moshevayner]

Hey @neetra
If both containers are running in the same pod (as in the example you specified), that means that they share the same IP address. So if appA needs to interact with appB, you should just use local host (127.0.0.1 and the relevant port 5000).
Give that a try and let me know if that doesn’t work. Good luck!

[neetra]

@MoShitrit thanks for the response, but I am aware about this
I want to know if there is any way to access?

[moshevayner]

Hey @neetra
So backing up, I just want to make sure I understand the issue correctly.
By access- do you mean that you wish to access appB directly using a service, and not sure how to do that? If that's the case, then all you have to do is either add another port to your existing service (kubectl edit service appaappbservice) and under spec.ports just add another object for appB, like this for example:

  - name: appB
    port: 5000
    protocol: TCP
    targetPort: 5000

Or, you can also create an additional service by running the same expose command you specified earlier, only give it a different name and a different targetPort, like this: kubectl expose pod appaappb-deployment-8656cfcdff-wd4hv --name=appbservice --type="NodePort" --target-port 5000 --port 5000

Another thing to bare in mind- once the service is updated, you'll need to find the actual node port that k8s allocated to your service, since (unless you configured it differently) the default range is a higher-number port, between 30000-32767, so you'll need to run kubectl get svc appaappbservice and get the mapping between the ports (i.e. you'll see something like that:

$ kubectl get svc appaappbservice
NAME              TYPE       CLUSTER-IP      EXTERNAL-IP   PORT(S)          AGE
appaappbservice   NodePort   100.71.239.74   <none>        80:32588/TCP   610d

In the above example, you'll need to access your minikube instance using port 32588.

[moshevayner]

Hey, @neetra !
I was just curious if you had a chance to try that yet? Is everything good now?

[fejta-bot]

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[moshevayner]

/close

[k8s-ci-robot]

@MoShitrit: Closing this issue.

In response to this:

/close

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