OpenShift Access Mongodb Pod from another Pod - node.js

Question

I'm currentrly trying to deploy a mongodb pod on OpenShift and accessing this pod from another node.js application via mongoose. Now at first everything seems fine. I have created a route to the mongodb and when i open it in my browser I get
It looks like you are trying to access MongoDB over HTTP on the
native driver port.
So far so good. But when I try opening a connection to the database from another pod it refuses the connection. I'm using the username and password provided by OpenShift and connect to
mongodb://[username]:[password]#[host]:[port]/[dbname]
unfortunately without luck. It seems that the database is just accepting connections from the localhost. However I could not find out how to change that. Would be great if someone had an idea.
Heres the Deployment Config
apiVersion: v1
kind: DeploymentConfig
metadata:
annotations:
template.alpha.openshift.io/wait-for-ready: "true"
creationTimestamp: null
generation: 1
labels:
app: mongodb-persistent
template: mongodb-persistent-template
name: mongodb
spec:
replicas: 1
selector:
name: mongodb
strategy:
activeDeadlineSeconds: 21600
recreateParams:
timeoutSeconds: 600
resources: {}
type: Recreate
template:
metadata:
creationTimestamp: null
labels:
name: mongodb
spec:
containers:
- env:
- name: MONGODB_USER
valueFrom:
secretKeyRef:
key: database-user
name: mongodb
- name: MONGODB_PASSWORD
valueFrom:
secretKeyRef:
key: database-password
name: mongodb
- name: MONGODB_ADMIN_PASSWORD
valueFrom:
secretKeyRef:
key: database-admin-password
name: mongodb
- name: MONGODB_DATABASE
valueFrom:
secretKeyRef:
key: database-name
name: mongodb
image: registry.access.redhat.com/rhscl/mongodb-32-rhel7#sha256:82c79f0e54d5a23f96671373510159e4fac478e2aeef4181e61f25ac38c1ae1f
imagePullPolicy: IfNotPresent
livenessProbe:
failureThreshold: 3
initialDelaySeconds: 30
periodSeconds: 10
successThreshold: 1
tcpSocket:
port: 27017
timeoutSeconds: 1
name: mongodb
ports:
- containerPort: 27017
protocol: TCP
readinessProbe:
exec:
command:
- /bin/sh
- -i
- -c
- mongo 127.0.1:27017/$MONGODB_DATABASE -u $MONGODB_USER -p $MONGODB_PASSWORD
--eval="quit()"
failureThreshold: 3
initialDelaySeconds: 3
periodSeconds: 10
successThreshold: 1
timeoutSeconds: 1
resources:
limits:
memory: 512Mi
securityContext:
capabilities: {}
privileged: false
terminationMessagePath: /dev/termination-log
volumeMounts:
- mountPath: /var/lib/mongodb/data
name: mongodb-data
dnsPolicy: ClusterFirst
restartPolicy: Always
securityContext: {}
terminationGracePeriodSeconds: 30
volumes:
- name: mongodb-data
persistentVolumeClaim:
claimName: mongodb
test: false
triggers:
- imageChangeParams:
automatic: true
containerNames:
- mongodb
from:
kind: ImageStreamTag
name: mongodb:3.2
namespace: openshift
type: ImageChange
- type: ConfigChange
status:
availableReplicas: 0
latestVersion: 0
observedGeneration: 0
replicas: 0
unavailableReplicas: 0
updatedReplicas: 0
The Service Config
apiVersion: v1
kind: Service
metadata:
annotations:
template.openshift.io/expose-uri: mongodb://{.spec.clusterIP}:{.spec.ports[?(.name=="mongo")].port}
creationTimestamp: null
labels:
app: mongodb-persistent
template: mongodb-persistent-template
name: mongodb
spec:
ports:
- name: mongo
port: 27017
protocol: TCP
targetPort: 27017
selector:
name: mongodb
sessionAffinity: None
type: ClusterIP
status:
loadBalancer: {}
and the pod
apiVersion: v1
kind: Pod
metadata:
annotations:
kubernetes.io/created-by: |
{"kind":"SerializedReference","apiVersion":"v1","reference":{"kind":"ReplicationController","namespace":"some-name-space","name":"mongodb-3","uid":"xxxx-xxx-xxx-xxxxxx","apiVersion":"v1","resourceVersion":"244413593"}}
kubernetes.io/limit-ranger: 'LimitRanger plugin set: cpu request for container
mongodb'
openshift.io/deployment-config.latest-version: "3"
openshift.io/deployment-config.name: mongodb
openshift.io/deployment.name: mongodb-3
openshift.io/scc: nfs-scc
creationTimestamp: null
generateName: mongodb-3-
labels:
deployment: mongodb-3
deploymentconfig: mongodb
name: mongodb
ownerReferences:
- apiVersion: v1
controller: true
kind: ReplicationController
name: mongodb-3
uid: a694b832-5dd2-11e8-b2fc-40f2e91e2433
spec:
containers:
- env:
- name: MONGODB_USER
valueFrom:
secretKeyRef:
key: database-user
name: mongodb
- name: MONGODB_PASSWORD
valueFrom:
secretKeyRef:
key: database-password
name: mongodb
- name: MONGODB_ADMIN_PASSWORD
valueFrom:
secretKeyRef:
key: database-admin-password
name: mongodb
- name: MONGODB_DATABASE
valueFrom:
secretKeyRef:
key: database-name
name: mongodb
image: registry.access.redhat.com/rhscl/mongodb-32-rhel7#sha256:82c79f0e54d5a23f96671373510159e4fac478e2aeef4181e61f25ac38c1ae1f
imagePullPolicy: IfNotPresent
livenessProbe:
failureThreshold: 3
initialDelaySeconds: 30
periodSeconds: 10
successThreshold: 1
tcpSocket:
port: 27017
timeoutSeconds: 1
name: mongodb
ports:
- containerPort: 27017
protocol: TCP
readinessProbe:
exec:
command:
- /bin/sh
- -i
- -c
- mongo 127.0.1:27017/$MONGODB_DATABASE -u $MONGODB_USER -p $MONGODB_PASSWORD
--eval="quit()"
failureThreshold: 3
initialDelaySeconds: 3
periodSeconds: 10
successThreshold: 1
timeoutSeconds: 1
resources:
limits:
memory: 512Mi
requests:
cpu: 250m
memory: 512Mi
securityContext:
capabilities:
drop:
- KILL
- MKNOD
- SETGID
- SETUID
- SYS_CHROOT
privileged: false
runAsUser: 1049930000
seLinuxOptions:
level: s0:c223,c212
terminationMessagePath: /dev/termination-log
volumeMounts:
- mountPath: /var/lib/mongodb/data
name: mongodb-data
- mountPath: /var/run/secrets/kubernetes.io/serviceaccount
name: default-token-rfvr5
readOnly: true
dnsPolicy: ClusterFirst
imagePullSecrets:
- name: default-dockercfg-3mpps
nodeName: thenode.name.net
nodeSelector:
region: primary
restartPolicy: Always
securityContext:
fsGroup: 1049930000
seLinuxOptions:
level: s0:c223,c212
supplementalGroups:
- 5555
serviceAccount: default
serviceAccountName: default
terminationGracePeriodSeconds: 30
volumes:
- name: mongodb-data
persistentVolumeClaim:
claimName: mongodb
- name: default-token-rfvr5
secret:
defaultMode: 420
secretName: default-token-rfvr5
status:
phase: Pending

Answer 1

Ok that was a long search and finally I was able to solve it. My first mistake was, that routes are not suited to make a connection to a database as they only use the http-protocol.
Now there were 2 usecases left for me
You're working on your local machine and want to test code that you later upload to OpenShift
You deploy that code to OpenShift (has to be in the same project but is a different app than the database)
1. Local Machine
Since the route doesn't work port forwarding is used. I've read that before but didn't really understand what it meant (i thought the service itsself is forwading ports already).
When you are on your local machine you will do the following with the oc
oc port-forward <pod-name> <local-port>:<remote-port>
You'll get the info that the port is forwarded. Now the thing is, that in your app you will now connect to localhost (even on your local machine)
2. App running on OpenShift
After you will upload your code to OpenShift(In my case, just Add to project --> Node.js --> Add your repo), localhost will not be working any longer.
What took a while for me to understand is that as long as you are in the same project you will have a lot of information in your environment variables.
So just check the name of the service of your database (in my case mongodb) and you will find the host and port to use
Summary
Here's a little code example that works now, as well on the local machine as on OpenShift. I have already set up a persistand MongoDB on OpenShift called mongodb.
The code doesn't do much, but It will make a connection and tell you that it did, so you know it's working.
var mongoose = require('mongoose');
// Connect to Mongodb
var username = process.env.MONGO_DB_USERNAME || 'someUserName';
var password = process.env.MONGO_DB_PASSWORD || 'somePassword';
var host = process.env.MONGODB_SERVICE_HOST || '127.0.0.1';
var port = process.env.MONGODB_SERVICE_PORT || '27017';
var database = process.env.MONGO_DB_DATABASE || 'sampledb';
console.log('---DATABASE PARAMETERS---');
console.log('Host: ' + host);
console.log('Port: ' + port);
console.log('Username: ' + username);
console.log('Password: ' + password);
console.log('Database: ' + database);
var connectionString = 'mongodb://' + username + ':' + password +'#' + host + ':' + port + '/' + database;
console.log('---CONNECTING TO---');
console.log(connectionString);
mongoose.connect(connectionString);
mongoose.connection.once('open', (data) => {
console.log('Connection has been made');
console.log(data);
});