I need to process the ENV from k8s Statefulset in the container before it starts up. Dockerfile:

RUN echo CREDENTIALS: $CREDENTIALS
ARG user="${CREDENTIALS%/*}"
ARG password="${CREDENTIALS#*/}"
ENV USER $user
ENV PASSWORD $password

Statefulset environment:

          env:
            - name: CREDENTIALS
              valueFrom:
                secretKeyRef:
                  name: app-secret
                  key: CREDENTIALS

When I run with d run -dt -e CREDENTIALS="user/P@$$w0rd" myimage:latest, the PASSWORD is missing.

I need to process the ENV from k8s Statefulset in the container before it starts up. Dockerfile:

RUN echo CREDENTIALS: $CREDENTIALS
ARG user="${CREDENTIALS%/*}"
ARG password="${CREDENTIALS#*/}"
ENV USER $user
ENV PASSWORD $password

Statefulset environment:

          env:
            - name: CREDENTIALS
              valueFrom:
                secretKeyRef:
                  name: app-secret
                  key: CREDENTIALS

When I run with d run -dt -e CREDENTIALS="user/P@$$w0rd" myimage:latest, the PASSWORD is missing.

• kubernetes
• dockerfile
• environment-variables
• kubernetes-statefulset

• Refer to this stacklink which will be helpful to resolve your issue. If not I am happy to assist you further. – Imran Premnawaz Commented yesterday

1 Answer 1

You misunderstand how Dockerfile ARG and ENV work. These values are all baked into the container image at build time. You need to modify your container's entry point to split $CREDENTIALS into separate USER and PASSWORD variables, for example with a small script:

#!/bin/sh
export USER="${CREDENTIALS%/*}"
export PASSWORD="${CREDENTIALS#*/}"
exec /actual/command "$@"