Configuring Rails application in Kubernates - ruby-on-rails

Question

I am configuring rails application in kubernates.I am using redis,sidekiq and Postgres DB.Below the yaml I am using.
apiVersion: extensions/v1beta1
kind: Deployment
metadata:
namespace: dev-app
name: test-deployment
spec:
replicas: 1
template:
metadata:
labels:
app: Dev-app
spec:
nodeSelector:
cloud.io/sec-zone-green: "true"
containers:
- name: dev-application
image: hub.docker.net/appautomation/dev.app.1.0:latest
command: ["/bin/sh"]
args: ["-c", "while true; do echo test; sleep 20;done"]
resources:
limits:
memory: 8Gi
cpu: 5
requests:
memory: 8Gi
cpu: 5
ports:
- containerPort: 3000
- name: dev-app-nginx
image: hub.docker.net/appautomation/dev.nginx.1.0:latest
resources:
limits:
memory: 4Gi
cpu: 4
requests:
memory: 4Gi
cpu: 4
ports:
- containerPort: 80
- name: dev-app-redis
image: hub.docker.net/appautomation/dev.redis.1.0:latest
resources:
limits:
memory: 4Gi
cpu: 4
requests:
memory: 4Gi
cpu: 4
ports:
- containerPort: 6379
In kubectl I am not seeing any error.But when I try to execute logs in pods I am getting below.I could see three containers build internally.I have executed my dev-application and tried rails s to check server is running or not.But I am getting "/usr/local/bundle/gems/redis-3.3.5/lib/redis/connection/ruby.rb:229:in `getaddrinfo': getaddrinfo: Name or service not known (SocketError." How to check my application linked with redis and nginx? My yaml configuration is correct? or I need to use depends on in my yaml file.
kubectl get pods
NAME READY STATUS RESTARTS AGE
dev-database-57b6ff5997-mgdhm 1/1 Running 0 11d
test-deployment-5f59864c8b-4t5b7 3/3 Running 0 8m44s
kubectl logs test-deployment-5f59864c8b-4t5b7
error: a container name must be specified for pod test-deployment-5f59864c8b-4t5b7, choose one of: [dev-application dev-app-nginx dev-app-redis]
Service yams file
apiVersion: v1
kind: Service
metadata:
namespace: Dev-app
name: test-deployment
spec:
selector:
app: Dev-app
ports:
- name: Dev-application
protocol: TCP
port: 3001
targetPort: 3000
- name: redis
port: 6379
targetPort: 6379

Answer 1

you are not running right way container. ideally POD running must be single application if require multiple container then and then use the multiple container inside the single POD or deployment.
you should be deploying single container in single POD or deployment instead of 3 in single.
for logs issue you check specific container logs using
kubectl logs test-deployment-5f59864c8b-4t5b7
error: a container name must be specified for pod test-deployment-5f59864c8b-4t5b7, choose one of: [dev-application dev-app-nginx dev-app-redis]
-c is used to check the specific container logs
kubectl logs test-deployment-5f59864c8b-4t5b7 -c <any one name dev-application dev-app-nginx dev-app-redis>
ideally distributed system structure goes like you run the standalone POD or deployment of the REDIS so all the services can use it here you are running your application redis if Redis crash your application will auto-restart (Kubernetes behavior).
If application crash Redis will auto-restart as Kubernetes auto-restart whole if any of container fails inside the POD.
I am getting "/usr/local/bundle/gems/redis-3.3.5/lib/redis/connection/ruby.rb:229:in `getaddrinfo': getaddrinfo: Name or service not known (SocketError.
if you are getting this error check you have set the proper host path into the application code. If all the Redis, Nginx and application running in single container you connect with any or service over the localhost. So Redis will be running at localhost 6379 for application
if you want to further debug you try using the exec command to go inside the pod and check the
kubectl exec -it test-deployment-5f59864c8b-4t5b7 -c dev-application -- /bin/bash
by this way, you will be inside the container and test out the connections to Redis using CLI.
Update :
Redis deployment.yaml
apiVersion: v1
kind: Service
metadata:
name: redis
spec:
type: ClusterIP
ports:
- port: 6379
name: redis
selector:
app: redis
---
apiVersion: apps/v1beta2
kind: StatefulSet
metadata:
name: redis
spec:
selector:
matchLabels:
app: redis
serviceName: redis
replicas: 1
template:
metadata:
labels:
app: redis
spec:
containers:
- name: redis
image: redislabs/rejson
args: ["--appendonly", "no", "--loadmodule"]
ports:
- containerPort: 6379
name: redis
volumeMounts:
- name: redis-volume
mountPath: /data
volumeClaimTemplates:
- metadata:
name: redis-volume
spec:
accessModes: [ "ReadWriteOnce" ]
resources:
requests:
storage: 1Gi