Add a password hash provider to handle SHA1 passwords inside Keycloak (e.g. migration from OpenLDAP).

./gradlew jar

cp build/libs/keycloak-sha1-1.0.0.jar docker/
docker-compose up -d

curl -L https://github.com/fassmus/keycloak-sha1/releases/download/1.0.0/keycloak-sha1-1.0.0.jar > KEYCLOAK_HOME/standalone/deployments/keycloak-sha1-1.0.0.jar

You need to restart Keycloak.

Go to Authentication / Password policy and add hashing algorithm policy with value sha1.

To test if installation works, create new user and set its credentials.