How to load LDAP docker container data on startup

(Solved!)
To clear the solution:
Like answered by BMW ldap container has 2 volumes, which was removed when mounted to empty folder in mounting section of ansible role docker module.
So I first run a non-mounted ldap container and backup it's volumes as suggested by BMW. Then kill and remove it and run a whole new container on backed up data. Then for user data configuration I run another ldap container(from same image) which only has to register users' data from a config file.

Final Ansible role code:

- name: run temporary ldap container  docker:    image: muzili/ldap    name: temporary-ldap    hostname: temporary-ldap    state: restarted    ports: 389:389    env:      SLAPD_PASSWORD: ******      SLAPD_DOMAIN: dev.domain.com- name: ldap data copy container  docker:    image: ubuntu    name: backup_agent    state: started    volumes:    - /backup    volumes_from:    - temporary-ldap    command: tar cvf /backup/backup.tar  /var/lib/ldap  /etc/ldap- name: copy compressed data from backup_agent  command: /usr/bin/docker cp backup_agent:/backup/backup.tar "{{base_dir}}/ldap/import"- name: extract ldap configuration data  unarchive:    copy: "no"    src: "{{base_dir}}/ldap/import/backup.tar"    dest: "{{base_dir}}/ldap"- name: kill temporary ldap container  docker:    image: muzili/ldap    name: temporary-ldap    state: absent- name: run main ldap container  docker:    image: muzili/ldap    name: ldap-server    hostname: ldap-server    state: running    ports: 389:389    env:      SLAPD_PASSWORD: ******      SLAPD_DOMAIN: dev.domain.com    volumes:    - "{{base_dir}}/ldap/etc/ldap:/etc/ldap"    - "{{base_dir}}/ldap/var/lib/ldap:/var/lib/ldap"- name: wait for container to start  wait_for:    port: 389    delay: 5- name: copy ldap data configuration file  copy:    src: conf/    dest: "{{base_dir}}/ldap/import/conf"- name: run ldap-importer container  docker:    image: muzili/ldap    name: ldap-importer    hostname: ldap-importer    state: started    volumes:    - "{{base_dir}}/ldap/import/conf:/etc/ldap/conf"    command: "ldapadd -h ldap-server -c -x -D \"cn=admin,dc=dev,dc=domain,dc=com\" -w ****** -f /etc/ldap/conf/data.ldif"    links:    - "ldap-server"

you can start another container to backup the folders first.

Suppose the ldap container named ldap, it has two volumes: /var/lib/ldap & /etc/ldap, with below command, you can backup them easily.

docker run --volumes-from ldap -v $(pwd):/backup ubuntu tar cvf /backup/backup.tar  /var/lib/ldap  /etc/ldap

If you need input some config when run a new container, think to update Dockerfile with ONBUILD command, such as:

ONBUILD cp . /etc/ldapONBUILD COMMAND you'd like to run

With above code, your image can be stay as same (no re-build required), but when you start up the container, it will input the setting to /etc/ldap when start the container, and get some commands run after that.

Refer:

Managing data in containers

Dockerfile reference