Docker - Copy file from host machine to image

During building of an image using Dockerfile, i wanted to copy a file from my host to the container. While i was trying to do this, i came across this error:

[rancher@host-a alpine/]$ pwd

[rancher@host-a alpine/]$ docker build -t my_image .
Sending build context to Docker daemon 3.072 kB
Step 1 : FROM
 ---> 4dd48e2236fe
Step 2 : ENV http_proxy '' https_proxy '' no_proxy 'localhost,'
 ---> Using cache
 ---> ef16b2c8ceea
Step 3 : RUN apk add --no-cache openssl && mkdir -p /etc/docker/certs.d/
 ---> Running in cf9126051357
(1/1) Installing openssl (1.0.2k-r0)
Executing busybox-1.24.2-r13.trigger
OK: 7 MiB in 14 packages
 ---> 8644044ac525
Removing intermediate container cf9126051357
Step 4 : COPY /etc/docker/certs.d/ /etc/docker/certs.d/
lstat etc/docker/certs.d/ no such file or directory