Project: EDB (App Definition and Development / Database)
File: expose_pg_services.md

This section explains how to expose a PostgreSQL service externally, allowing access to your PostgreSQL database from outside your Kubernetes cluster using NGINX Ingress Controller. If you followed the , you should have by now a database that can be accessed inside the cluster via the `cluster-example-rw` (primary) and `cluster-example-r` (read-only) services in the `default` namespace. Both services use port `5432`. Let's assume that you want to make the primary instance accessible from external accesses on port `5432`. A typical use case, when moving to a Kubernetes infrastructure, is indeed the one represented by legacy applications that cannot be easily or sustainably "containerized". A sensible workaround is to allow those applications that most likely reside in a virtual machine or a physical server, to access a PostgreSQL database inside a Kubernetes cluster in the same network. !!! Warning Allowing access to a database from the public network could expose your database to potential attacks from malicious users. Ensure you secure your database before granting external access or that your Kubernetes cluster is only reachable from a private network. For this example, you will use , since it is maintained directly by the Kubernetes project and can be set up on every Kubernetes cluster. Many other controllers are available (see the for a comprehensive list). We assume that: the NGINX Ingress controller has been deployed and works correctly it is possible to create a service of type `LoadBalancer` in your cluster !!! Important Ingresses are only required to expose HTTP and HTTPS traffic. While the NGINX Ingress controller can, not all Ingress objects can expose arbitrary ports or protocols. The first step is to create a `tcp-services` `ConfigMap` whose data field contains info on the externally exposed port and the namespace, service and port to point to internally. ```yaml apiVersion: v1 kind: ConfigMap metadata: name: tcp-services namespace: ingress-nginx data: 5432: default/cluster-example-rw:5432 ``` Then, if you've installed NGINX Ingress Controller as suggested in their documentation, you should have an `ingress-nginx` service. You'll have to add the 5432 port to the `ingress-nginx` service to expose it. The ingress will redirect incoming connections on port 5432 to your database. ```yaml apiVersion: v1 kind: Service metadata: name: ingress-nginx namespace: ingress-nginx labels: app.kubernetes.io/name: ingress-nginx app.kubernetes.io/part-of: ingress-nginx spec: type: LoadBalancer ports: name: http port: 80 targetPort: 80 protocol: TCP name: https port: 443 targetPort: 443 protocol: TCP name: postgres port: 5432 targetPort: 5432 protocol: TCP selector: app.kubernetes.io/name: ingress-nginx app.kubernetes.io/part-of: ingress-nginx ``` You can use and apply it using `kubectl`. !!! Warning If you apply this file directly, you will overwrite any previous change in your `ConfigMap` and `Service` of the Ingress Now you will be able to reach the PostgreSQL Cluster from outside your Kubernetes cluster. !!! Important Make sure you configure `pg_hba` to allow connections from the Ingress. On Minikube you can setup the ingress controller running: ```sh minikube addons enable ingress ``` You can then patch the deployment to allow access on port 5432. Create a file called `patch.yaml` with the following content: ```yaml spec: template: spec: containers: name: controller ports: containerPort: 5432 hostPort: 5432 ``` and apply it to the `ingress-nginx-controller` deployment: ```sh kubectl patch deployment ingress-nginx-controller --patch "$(cat patch.yaml)" -n ingress-nginx ``` You can access the primary from your machine running: ```sh psql -h $(minikube ip) -p 5432 -U postgres ```