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Configure TLS/SSL in Postgres
KubeDB provides support for TLS/SSL encryption with SSLMode (allow, prefer, require, verify-ca, verify-full) for Postgres. This tutorial will show you how to use KubeDB to deploy a Postgres database with TLS/SSL configuration.
Before You Begin
At first, you need to have a Kubernetes cluster, and the kubectl command-line tool must be configured to communicate with your cluster. If you do not already have a cluster, you can create one by using kind.
Install
cert-mangerv1.4.0 or later to your cluster to manage your SSL/TLS certificates.Install
KubeDBcommunity and enterprise operator in your cluster following the steps here.To keep things isolated, this tutorial uses a separate namespace called
demothroughout this tutorial.$ kubectl create ns demo namespace/demo created
Note: YAML files used in this tutorial are stored in docs/guides/postgres/tls/configure/yamls folder in GitHub repository kubedb/docs.
Deploy Postgres database with TLS/SSL configuration
As pre-requisite, at first, we are going to create an Issuer/ClusterIssuer. This Issuer/ClusterIssuer is used to create certificates. Then we are going to deploy a Postgres with TLS/SSL configuration.
Create Issuer/ClusterIssuer
Now, we are going to create an example Issuer that will be used throughout the duration of this tutorial. Alternatively, you can follow this cert-manager tutorial to create your own Issuer. By following the below steps, we are going to create our desired issuer,
- Start off by generating our ca-certificates using openssl,
openssl req -x509 -nodes -days 365 -newkey rsa:2048 -keyout ./ca.key -out ./ca.crt -subj "/CN=postgres/O=kubedb"
- create a secret using the certificate files we have just generated,
$ kubectl create secret tls postgres-ca --cert=ca.crt --key=ca.key --namespace=demo
secret/postgres-ca created
Now, we are going to create an Issuer using the postgres-ca secret that contains the ca-certificate we have just created. Below is the YAML of the Issuer cr that we are going to create,
apiVersion: cert-manager.io/v1
kind: Issuer
metadata:
name: postgres-ca-issuer
namespace: demo
spec:
ca:
secretName: postgres-ca
Let’s create the Issuer cr we have shown above,
kubectl apply -f https://github.com/kubedb/docs/raw/v2023.01.31/docs/guides/postgres/tls/configure/yamls/issuer.yaml
issuer.cert-manager.io/postgres-ca-issuer created
Deploy Postgres cluster with TLS/SSL configuration
Here, our issuer postgres-ca-issuer is ready to deploy a Postgres Cluster with TLS/SSL configuration. Below is the YAML for Postgres Cluster that we are going to create,
apiVersion: kubedb.com/v1alpha2
kind: Postgres
metadata:
name: demo-pg
namespace: demo
spec:
version: "13.2"
replicas: 3
standbyMode: Hot
sslMode: verify-full
storageType: Durable
tls:
issuerRef:
apiGroup: cert-manager.io
name: postgres-ca-issuer
kind: Issuer
certificates:
- alias: server
subject:
organizations:
- kubedb:server
dnsNames:
- localhost
ipAddresses:
- "127.0.0.1"
storage:
storageClassName: "standard"
accessModes:
- ReadWriteOnce
resources:
requests:
storage: 1Gi
terminationPolicy: WipeOut
Here,
spec.sslModespecifies the SSL/TLS client connection to the server is required.spec.tls.issuerRefrefers to thepostgres-ca-issuerissuer.spec.tls.certificatesgives you a lot of options to configure so that the certificate will be renewed and kept up to date. You can found more details from here
Deploy Postgres Cluster:
Let’s create the Postgres cr we have shown above,
$ kubectl apply -f https://github.com/kubedb/docs/raw/v2023.01.31/docs/guides/postgres/tls/configure/yamls/tls-postgres.yaml
postgres.kubedb.com/pg created
Wait for the database to be ready:
Now, watch Postgres is going to Running state and also watch StatefulSet and its pod is created and going to Running state,
$ watch kubectl get postgres -n demo pg
Every 2.0s: kubectl get postgres --all-namespaces ac-emon: Fri Dec 3 15:14:11 2021
NAMESPACE NAME VERSION STATUS AGE
demo pg 13.2 Ready 62s
$ watch -n 3 kubectl get sts -n demo pg
Every 2.0s: kubectl get sts -n demo pg ac-emon: Fri Dec 3 15:15:41 2021
NAME READY AGE
pg 3/3 2m30s
$ watch -n 3 kubectl get pod -n demo -l app.kubernetes.io/name=postgreses.kubedb.com,app.kubernetes.io/instance=pg
Every 3.0s: kubectl get pod -n demo -l app.kubernetes.io/name=postg... ac-emon: Fri Dec 3 15:17:10 2021
NAME READY STATUS RESTARTS AGE
pg-0 2/2 Running 0 3m59s
pg-1 2/2 Running 0 3m54s
pg-2 2/2 Running 0 3m49s
Verify tls-secrets created successfully:
If everything goes well, you can see that our tls-secrets will be created which contains server, client, exporter certificate. Server tls-secret will be used for server configuration and client tls-secret will be used for a secure connection.
All tls-secret are created by KubeDB enterprise operator. Default tls-secret name formed as {postgres-object-name}-{cert-alias}-cert.
Let’s check if the tls-secrets have been created properly,
$ kubectl get secrets -n demo | grep pg
pg-auth kubernetes.io/basic-auth 2 4m41s
pg-client-cert kubernetes.io/tls 3 4m40s
pg-metrics-exporter-cert kubernetes.io/tls 3 4m40s
pg-server-cert kubernetes.io/tls 3 4m41s
pg-token-xvk9p kubernetes.io/service-account-token 3 4m41s
Verify Postgres Cluster configured with TLS/SSL:
Now, we are going to connect to the database to verify that Postgres server has configured with TLS/SSL encryption.
Let’s exec into the pod to verify TLS/SSL configuration,
$ kubectl exec -it -n demo pg-0 -- bash
bash-5.1$ ls /tls/certs
client exporter server
bash-5.1$ ls /tls/certs/server
ca.crt server.crt server.key
bash-5.1$ psql
psql (13.2)
Type "help" for help.
postgres=# SELECT * FROM pg_stat_ssl;
pid | ssl | version | cipher | bits | compression | client_dn | client_serial | issuer_dn
------+-----+---------+------------------------+------+-------------+-----------+---------------+-----------
129 | t | TLSv1.3 | TLS_AES_256_GCM_SHA384 | 256 | f | | |
130 | t | TLSv1.3 | TLS_AES_256_GCM_SHA384 | 256 | f | | |
2175 | f | | | | | | |
(3 rows)
postgres=# exit
bash-5.1$ cat /var/pv/data/postgresql.conf | grep ssl
ssl =on
ssl_cert_file ='/tls/certs/server/server.crt'
ssl_key_file ='/tls/certs/server/server.key'
ssl_ca_file ='/tls/certs/server/ca.crt'
primary_conninfo = 'application_name=pg-0 host=pg user=postgres password=0WpDlAbHsrNs-7hp sslmode=verify-full sslrootcert=/tls/certs/client/ca.crt'
#ssl = off
#ssl_ca_file = ''
#ssl_cert_file = 'server.crt'
#ssl_crl_file = ''
#ssl_key_file = 'server.key'
#ssl_ciphers = 'HIGH:MEDIUM:+3DES:!aNULL' # allowed SSL ciphers
#ssl_prefer_server_ciphers = on
#ssl_ecdh_curve = 'prime256v1'
#ssl_min_protocol_version = 'TLSv1.2'
#ssl_max_protocol_version = ''
#ssl_dh_params_file = ''
#ssl_passphrase_command = ''
#ssl_passphrase_command_supports_reload = off
The above output shows that the Postgres server is configured with TLS/SSL configuration and in /var/pv/data/postgresql.conf you can see that ssl= on. You can also see that the .crt and .key files are stored in the /tls/certs/ directory for client and server.
Verify secure connection for SSL required user:
Now, you can create an SSL required user that will be used to connect to the database with a secure connection.
Let’s connect to the database server with a secure connection,
# creating SSL required user
$ kubectl exec -it -n demo pg-0 -- bash
bash-5.1$ psql -d "user=postgres password=$POSTGRES_PASSWORD host=pg port=5432 connect_timeout=15 dbname=postgres sslmode=verify-full sslrootcert=/tls/certs/client/ca.crt"
psql (13.2)
SSL connection (protocol: TLSv1.3, cipher: TLS_AES_256_GCM_SHA384, bits: 256, compression: off)
Type "help" for help.
postgres=# exit
bash-5.1$ psql -d "user=postgres password=$POSTGRES_PASSWORD host=pg port=5432 connect_timeout=15 dbname=postgres sslmode=verify-full"
psql: error: root certificate file "/var/lib/postgresql/.postgresql/root.crt" does not exist
Either provide the file or change sslmode to disable server certificate verification.
From the above output, you can see that only using ca certificate we can access the database securely, otherwise, it ask for the ca verification. Our client certificate is stored in ls /tls/certs/client directory.
Cleaning up
To clean up the Kubernetes resources created by this tutorial, run:
kubectl delete pg -n demo pg
kubectl delete ns demo
Next Steps
- Detail concepts of Postgres object.