How to install specific application to docker container

Sometimes we need to add some application to pre-configured docker container. We can do this with “docker build” in a few easy steps.

Step 1. Create Dockerfile. In it add source docker container to add requsted application installation procedure. Sampe Dockerfile

FROM Caddy/Caddy:latest

# Install mtr
USER root
RUN yum update -y
RUN yum install -y mtr

Step 2. Build docker container from Dockerfile.

#docker build --tag caddy-with-mtr .

Step 3. Modify docker-compose.yml file. replace original image with new one, you build on previous step. Fragment of modified docker-compose.yml file

services:
  caddy:
    image: caddy-with-mtr:latest
    restart: unless-stopped

Step 4. And finally start fresh-build docker container.

/usr/local/sbin/docker-compose -f /opt/docker/docker-compose.yml up -d