ejabberd doesn't store roster persistently - xmpp

Question

I'm running ejabberd in Kubernetes using the following image: https://hub.docker.com/r/jprjr/ejabberd/
I've tried to test persistency by removing an account from Pidgin and adding it again. Pidgin does not load the previously added roster.
I tried Mnesia and Postgres. The Postgres database seems to be untouched by ejabberd but I don't get any erros in the logs either.
Any ideas, what could cause this behavior?
My configuration:
hosts: ["example.com"]
loglevel: 4
hide_sensitive_log_data: true
listen:
- port: 5222
module: ejabberd_c2s
access: c2s
shaper: c2s_shaper
zlib: true
starttls_required: true
starttls: true
certfile: "/etc/ejabberd/ejabberd.pem"
- port: 5269
module: ejabberd_s2s_in
shaper: s2s_shaper
max_stanza_size: 65536
s2s_use_starttls: true
s2s_certfile: "/etc/ejabberd/ejabberd.pem"
transport: tcp
auth_method: [ldap]
ldap_servers: ["ldap.example.com"]
ldap_port: 389
ldap_rootdn: "CN=ejabberd,OU=ServiceAccounts,DC=example,DC=com"
ldap_password: "*********"
ldap_base: "OU=User,DC=example,DC=com"
ldap_uids:
- "sAMAccountName": "%u"
ldap_filter: "(&(objectClass=user)(memberof=CN=ejabberdUsers,CN=Users,DC=example,DC=com))"
# tried with and w/o
# default_db: odbc
# sm_db_type: odbc
# odbc_type: pgsql
# odbc_server: "db.example.com"
# odbc_password: "********"
# odbc_port: 10051
shaper:
normal: 1000
fast: 50000
acl:
admin:
user:
"admin1": "example.com"
"admin2": "example.com"
access:
local:
local: allow
c2s:
blocked: deny
all: allow

Answer 1

ejabberd store roster persistently.
you need to enable mod_roster in ejabberd configuration file and database setting what you want for example
mod_roster:
db_type: odbc
it seems you are missing configuration for more detail of configuration check these links.
https://github.com/processone/ejabberd/blob/master/test/ejabberd_SUITE_data/ejabberd.yml
https://www.process-one.net/docs/ejabberd/guide_en.html