How do I get the value of MONGODB_URI in a kubernetes deploy?-CodePudding

I have a working mongoDB deployment on minikube and I have managed to create a database , collection as well as a user (same as the user referenced in yaml) to do backups on that database.

In the yaml file for my backup cron job I need to specify a MONGODB_URI parameter and quite frankly I am at a loss as to the exact convention for getting this (where exactly do you get the value).

As a check I have done a kubectl exec -it <pod_name> so that I can check if I am going to put the correct URI beforehand. After running kubectl exec -it <pod_name> at the prompt that follows I tried the following :

mongosh mongodb://aaa:[email protected]:27017/plaformdb/?directConnection=true

Not working I get error :

Current Mongosh Log ID: 62938b50880f139dad4b19c4
Connecting to:          mongodb://mongodb-service.default.svc.cluster.local:27017/platformdb/?directConnection=true&appName=mongosh 1.4.2
MongoServerSelectionError: Server selection timed out after 30000 ms

mongosh mongodb://aaa:[email protected]:27017/platformdb?directConnection=true

Not working also I get error:

MongoNetworkError: getaddrinfo ENOTFOUND mongodb-service.svc.cluster.local

mongosh mongodb://aaa:abc123@mongodb-deployment-757ffdfdr5-thuiy.mongodb-service.default.svc.cluster.local:27017/platformdb

Not working I get an error :

Current Mongosh Log ID: 62938c93829ft678h88990
Connecting to:          mongodb://mongodb-deployment-757ccdd6y8-thhhh.mongodb-service.default.svc.cluster.local:27017/platformdb?directConnection=true&appName=mongosh 1.4.2
MongoNetworkError: getaddrinfo ENOTFOUND mongodb-deployment-757ffdd5f5-tpzll.mongodb-service.default.svc.cluster.local

This however is the recommended way according to the : On the 1st attempt I managed to login and run a show collections command but once I logout and try to connect I get Authentication Failed. The feature seems unstable at best.

CodePudding user response：

Given the structure of your Service, you'll need to use the hostname mongodb-service (or mongodb-service.<namesapce>.svc.cluster.local, if you like fully qualified names). The connection URI -- as far as I can tell from the documentation -- would be:

mongodb://<username>:<password>@mongodb-service/dbname?authSource=admin

You can also connect successfully like this:L

mongodb://<username>:<password>@mongodb-service/

Because:

If [the username and password are] specified, the client will attempt to authenticate the user to the authSource. If authSource is unspecified, the client will attempt to authenticate the user to the defaultauthdb. And if the defaultauthdb is unspecified, to the admin database.

I tested this using a slightly modified version of your Deployment (mostly, I dropped the volumeMounts, because I don't need persistent storage for testing, and I used envFrom because I find that easier in general).

I deployed this using kustomize (kubectl apply -k .) with the following kustomization.yaml:

apiVersion: kustomize.config.k8s.io/v1beta1
kind: Kustomization
namespace: mongo

commonLabels:
  app: mongodb

resources:
- deployment.yaml
- service.yaml

secretGenerator:
  - name: mongo-credentials
    envs:
      - mongo.env

This deployment.yaml:

apiVersion: apps/v1
kind: Deployment
metadata:
  name: mongodb-deployment
spec:
  replicas: 1
  template:
    spec:
      containers:
        - name: mongodb
          image: docker.io/mongo:latest
          imagePullPolicy: IfNotPresent
          ports:
            - containerPort: 27017
          envFrom:
            - secretRef:
                name: mongo-credentials

This service.yaml:

apiVersion: v1
kind: Service
metadata:
  name: mongodb-service
spec:
  ports:
    - protocol: TCP
      port: 27017
      targetPort: 27017

And this mongo.env:

MONGO_INITDB_ROOT_USERNAME=admin
MONGO_INITDB_ROOT_PASSWORD=secret

Once everything was up and running, I started a client pod:

kubectl run --image docker.io/mongo:latest mongoc -- sleep inf

And I was able to start a shell in that pod and connect to the database:

$ kubectl exec -it mongoc -- bash
Current Mongosh Log ID: 6293a4bc534ff40ec737c383
Connecting to:          mongodb://<credentials>@mongodb-service.mongo.svc.cluster.local/?directConnection=true&appName=mongosh 1.4.2
Using MongoDB:          5.0.8
Using Mongosh:          1.4.2
[...]
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