Connecting to Hasura Postgres database from microservices

To connect to any PostgreSQL instance, we need the hostname, port, username and password. You can find out hostnames (URLs) for all the microservices running in the cluster by executing the following command:

$ hasura microservice list
• Getting microservices...
• Custom microservices:
NAME      STATUS    INTERNAL-URL      EXTERNAL-URL
my-app    Running   my-app.default    http://my-app.gram29.hasura-app.io

• Hasura microservices:
NAME            STATUS    INTERNAL-URL           EXTERNAL-URL
auth            Running   auth.hasura            http://auth.gram29.hasura-app.io
data            Running   data.hasura            http://data.gram29.hasura-app.io
filestore       Running   filestore.hasura       http://filestore.gram29.hasura-app.io
gateway         Running   gateway.hasura
le-agent        Running   le-agent.hasura
notify          Running   notify.hasura          http://notify.gram29.hasura-app.io
platform-sync   Running   platform-sync.hasura
postgres        Running   postgres.hasura
session-redis   Running   session-redis.hasura
sshd            Running   sshd.hasura

As we can see from the list, the Postgres microservice is available at “Internal URL” (hostname) postgres.hasura. The internal URL should be used while accessing any microservice from inside the cluster. Since our microservice is going to be deployed on the cluster, we should use the internal URL. The port is 5432.

Username and password can be accessed through Hasura Secrets.

$ hasura secrets list
auth.facebook.client_secret---|
auth.admin.password-----------|xxxxxxxxxxxxxxxxxxxxxxxx
notify.sparkpost.key----------|
auth.secretKey----------------|xxxxxxxxxxxxxxxxxxxxxxxx
postgres.password-------------|xxxxxxxxxxxxxxxxxxxxxxxx
postgres.user-----------------|xxxxx
auth.linkedin.client_secret---|
notify.twilio.authtoken-------|
auth.msg91.key----------------|
auth.sparkpost.key------------|
auth.google.client_secret-----|
ssh.authorizedKeys------------|
auth.github.client_secret-----|
auth.recaptcha.secret---------|
notify.twilio.accountsid------|
notify.msg91.key--------------|

While you can add hostname, port, username, password to your code, it is not recommended to do so. Especially username, password etc. should not be added as it is to your code, since they are going to be committed into a git repository.

The standard practice is to access these parameters as environment variables and Hasura provides a convenient method to do so. Let’s look at the steps to add these environment variables.

(The following section assumes that you have a Hasura cluster and project ready, with at least one microservice [say <my-app>])

  1. Edit the k8s.yaml file inside the microservices/<my-app> directory and add the highlighted code:

    apiVersion: v1
items:
- apiVersion: extensions/v1beta1
kind: Deployment
metadata:
  creationTimestamp: null
  labels:
    app: my-app
    hasuraService: custom
  name: my-app
  namespace: '{{ cluster.metadata.namespaces.user }}'
spec:
  replicas: 1
  strategy: {}
  template:
    metadata:
      creationTimestamp: null
      labels:
        app: my-app
    spec:
      containers:
      - image: hasura/hello-world:latest
        env:
        - name: POSTGRES_HOSTNAME
          value: postgres.{{ cluster.metadata.namespaces.hasura }}
        - name: POSTGRES_PORT
          value: "5432"
        - name: POSTGRES_USERNAME
          valueFrom:
            secretKeyRef:
              name: hasura-secrets
              key: postgres.user
        - name: POSTGRES_PASSWORD
          valueFrom:
            secretKeyRef:
              name: hasura-secrets
              key: postgres.password
        imagePullPolicy: IfNotPresent
        name: my-app
        ports:
        - containerPort: 8080
          protocol: TCP
        resources: {}
      securityContext: {}
      terminationGracePeriodSeconds: 0
status: {}
- apiVersion: v1
kind: Service
metadata:
  creationTimestamp: null
  labels:
    app: my-app
    hasuraService: custom
  name: my-app
  namespace: '{{ cluster.metadata.namespaces.user }}'
spec:
  ports:
  - port: 80
    protocol: TCP
    targetPort: 8080
  selector:
    app: my-app
  type: ClusterIP
status:
  loadBalancer: {}
kind: List
metadata: {}

  2. Commit and push your code:

    $ git add microservices/<my-app>/k8s.yaml
$ git commit -m "add postgres credentials"
$ git push hasura master

  3. Hasura will make the following environment variables available for the microservice to use:

    • POSTGRES_HOSTNAME
    • POSTGRES_PORT
    • POSTGRES_USERNAME
    • POSTGRES_PASSWORD

    Depending on your application code, you can make use of these environment variables to connect to Hasura PostgreSQL database.

    Note

    The name of the database available through Hasura API Console and Hasura data API is hasuradb

    An example with Python and psycopg2:

    import os
import psycopg2


conn = psycopg2.connect(
    database='hasuradb',
    user=os.environ['POSTGRES_USERNAME'],
    password=os.environ['POSTGRES_PASSWORD'],
    host=os.environ['POSTGRES_HOSTNAME'],
    port=os.environ['POSTGRES_PORT']
)
« previous | next »
Want to contribute or report missing content? Check out the github repo for docs.
Powered by Sphinx. Copyright © 2019 Hasura.