Setting up traefik with existing SSL

HI guys.

I'm pretty new with traefik and I've been reading articles since last year. I'm able to make it work but I'm having problem regarding adding an existing SSL to my apps. I'm running traefik 1.7 without any toml file for config because I'm still having problem on how to use the config toml.

My question is. It's because I already have multiple app that has ssl. How I'm gonna attach the the cert and key on each app?

Here's my traefik compose file.

version: '3.7'
services:
  traefik:
    image: traefik:1.7.13
    ports:
      - target: 80
        published: 80
        mode: host
      - target: 443
        published: 443
        mode: host
    command: >
      --api
      --docker
      --docker.swarmMode
      --docker.watch
      --defaultentrypoints=http,https
      --entrypoints='Name:http Address::80'
      --entrypoints='Name:https Address::443 TLS'
      --logLevel=INFO
      --accessLog
      --metrics
      --metrics.prometheus
    volumes:
      - /var/run/docker.sock:/var/run/docker.sock
    configs:
      - source: traefik_htpasswd
        target: /etc/htpasswd
    networks:
      - public
    deploy:
      mode: replicated
      replicas: 1
      placement:
        constraints:
          - node.role == manager
      update_config:
        parallelism: 1
        delay: 10s
      restart_policy:
        condition: on-failure
      labels:
        - "traefik.docker.network=public"
        - "traefik.port=8080"
        - "traefik.backend=traefik"
        - "traefik.enable=true"
        - "traefik.frontend.rule=PathPrefixStrip: /traefik"
        - "traefik.frontend.auth.basic.usersFile=/etc/htpasswd"
        - "traefik.frontend.entryPoints=http,https"

configs:
  traefik_htpasswd:
    file: ./htpasswd

networks:
  public:
    driver: overlay
    attachable: true
    name: public

Thanks guys.