After running Keycloak in containers, we noticed that the System Encoding is set to ANSI_X3.4-1968 - however, if I were to run it locally using the source code and not a container, I see UTF-8.

The way I understand this can come about is it is derived from the system locale (on RHEL based systems there's a script that is often sourced - /etc/profile.d/lang.sh ) and the ANSI_X3.4-1968 value can happen when there isn't a locale set (default).

I am curious as to what impacts this could have

• Are there possibly edge cases or errors that could come up?
• Since the ANSI_X3.4-1968 charset is basically ASCII, that could mean there are potentially issues for localization?
• Is it possible that this value is ignored and doesn't matter based on how Keycloak works?
• If I update my container to actually set UTF-8, would one expect problems due to the switch?
• Is there some instruction I am missing that we should be setting the file.encoding Java system property manually?

EDIT: 2022-04-20

Looking closer, it appears this was actually handled in the "legacy" Keycloak image (Wildfly distribution) - https://github.com/keycloak/keycloak-containers/blob/main/server/Dockerfile#L12

Running the legacy image I was able to confirm that UTF-8 is reflected on the Server Info page.

docker run -p 8080:8080 -e KEYCLOAK_USER=admin -e KEYCLOAK_PASSWORD=admin -it quay.io/keycloak/keycloak:17.0.1-legacy

User Locale 	us_EN
System Encoding 	UTF-8

I do not see any of the similar fixes applied in the quarkus image build:
https://github.com/keycloak/keycloak/blob/main/quarkus/container/Dockerfile

And running that image I could confirm the ANSI_X3.4-1968 value is set.

docker run -p 8080:8080 -e KEYCLOAK_ADMIN=admin -e KEYCLOAK_ADMIN_PASSWORD=admin quay.io/keycloak/keycloak:17.0.1 start-dev

User Locale 	us_EN
System Encoding 	ANSI_X3.4-1968

And while not purely a Keycloak concern, it seems that RHSSO image is in similar shape, where the locale value is using the default - https://github.com/jboss-container-images/redhat-sso-7-openshift-image/blob/sso75-dev/image.yaml

docker run -p 8080:8080 -e SSO_ADMIN_USERNAME="admin" -e SSO_ADMIN_PASSWORD="admin" -it registry.redhat.io/rh-sso-7/sso75-openshift-rhel8

User Locale 	us_EN
System Encoding 	ANSI_X3.4-1968