How to use external Postgres when deploy by Helm Chart?

Usage Questions
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1

When deploy Prefect Server into Kubernetes by Helm Chart, I can disable default Postgres by changing

to

postgresql:
  enabled: false

Next step, I am trying to point to a existing Postgres, however, I didn’t find any info in the Helm chart.

Any guide would be appreciate. Thanks! :smiley:

2

Hey Hongbo, the field postgresql.externalHostname is used to define the hostname for your external postgres database, then set postgresql to disabled and fill in all of the credential fields.

4

Thanks @George_Coyne !

For example, I have a database at http://postgres-service.hm-postgres.svc:5432.

I tried

helm install \
  prefect-server \
  prefect/prefect-server \
  --namespace=hm-prefect \
  --create-namespace \
  --values=my-values.yaml

my-values.yaml

server:
  publicApiUrl: https://xxx.com/api
postgresql:
  enabled: false
  auth:
    username: admin
    password: passw0rd
  externalHostname: postgres-service.hm-postgres.svc

I did set enabled: false, but Prefect Server helm chart still created a Postgres.

image
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Any idea? Thanks!

5

I believe you want:

postgresql:
    useSubChart: false

instead of enabled: false.

This isn’t clear in the current prefect-helm default values, could definitely do with an update. There’s a comment about it here though: server/values.yaml at master · PrefectHQ/server · GitHub

1 Like
6

Thanks @George_Coyne and @jwlarocque !

The helm values are quite confused, it turns out I actually only need set two values:

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Here is my final solution to use external Postgres host.

Assuming my Postgres host is postgres-service.hm-postgres.svc, port is 5432, username is admin, password is passw0rd.

First, I need create a secret, and this secret has to be in same namespace with Prefect Server.

kubectl create secret generic hm-prefect-postgres-secret \
  --namespace=hm-prefect \
  --from-literal="connection-string=postgresql+asyncpg://admin:passw0rd@postgres-service.hm-postgres.svc:5432/hm_prefect_db"

Then, I can deploy Prefect Server by:

helm install \
  prefect-server \
  prefect/prefect-server \
  --namespace=hm-prefect \
  --create-namespace \
  --values=my-values.yaml

my-values.yaml

server:
  publicApiUrl: https://prefect.example.com/api
postgresql:
  useSubChart: false
  auth:
    existingSecret: hm-prefect-postgres-secret

Hopefully it helps save people some time in future! :smiley: