Accessing ssl .pem files inside docker container

I need to access a folder on my host machine which contains lets-encrypt files at

/docker-volumes/etc/letsencrypt/live/mydomain.com

on my one of the containers. I have mapped volume in compose file.

compose.yml

version: "3"
services:
  mongo:
    container_name: mongo
    image: mongo
    ports:
      - "27017:27017"
    volumes:
      - "./data:/data/db"
  api:
    container_name: my-api
    restart: always
    build:
      context: ./my_backend
       dockerfile: dockerfile
    ports:
      - "4002:443"
    volumes:
      - /docker-volumes/etc/letsencrypt/live/mydomain.com:/app/certs
    links:
      - mongo

dockerfile at my_backend

FROM node:10.16.3

WORKDIR /app

RUN mkdir certs

RUN mkdir public

RUN mkdir public/uploads

RUN mkdir public/videos

RUN mkdir public/reports

COPY ./package*.json ./

RUN npm install

COPY . .

CMD ["npm", "start"]

There are three files which i need to access from /app/certs in my server.js file.

server.js

const fs = require("fs");
const https = require("https");
const credentials = {};
const path = require("path");

if (process.env.NODE_ENV === "production") {
  const privateKey = fs.readFileSync(
    path.join(__dirname, "certs/privkey.pem"),
    "utf8"
  );
  const certificate = fs.readFileSync(
    path.join(__dirname, "certs/cert.pem"),
    "utf8"
  );
  const ca = fs.readFileSync(path.join(__dirname, "certs/fullchain.pem"), "utf8");

  credentials["key"] = privateKey;
  credentials["cert"] = certificate;
  credentials["ca"] = ca;
}
...other logic and server.listen on port 443

When I fire docker-compose up, it always gives me this

{"error":{"errno":-2,"syscall":"open","code":"ENOENT","path":"/app/certs/privkey.pem"}ENOENT: no such file or directory other two as well.

I am stuck, can any one help. I am new to docker.