Suggesting to avoid systemd service units in a docker image.

Instead use cronttab script with @boot directive/selector.

In addition dbus is centrally managed by kernel and not allowed at container level. If Docker service is up then you probably have dbus active and running.

You can add capabilities to the root user running in the container. Read more here.

As last resort try to disable SELinux in your docker image.

Amazon Linux v 2.0 does support systemd and comes installed by default:

cat /etc/os-release
NAME="Amazon Linux"
VERSION="2.0 (2017.12)"
ID="amzn"
ID_LIKE="centos rhel fedora"
VERSION_ID="2.0"
PRETTY_NAME="Amazon Linux 2.0 (2017.12) LTS Release Candidate"
ANSI_COLOR="0;33"
CPE_NAME="cpe:2.3:o:amazon:amazon_linux:2.0"
HOME_URL="https://amazonlinux.com/"

rpm -qa | grep -i systemd
systemd-libs-219-42.amzn2.4.x86_64
systemd-219-42.amzn2.4.x86_64
systemd-sysv-219-42.amzn2.4.x86_64`

Using Amazon Linux 2 I tried to replicate the issue. Obviously, I don't have all the dependencies to run your exact docker-compose.yml, thus I used the docker-compose.yml from here for my verification. The file setups wordpress with mysql .

Steps I took were following (executed as ec2-user in home folder):

1. Install docker

sudo yum update -y  
sudo yum install -y docker
sudo systemctl enable docker
sudo systemctl start docker

2. Install docker-compose

sudo curl -L https://github.com/docker/compose/releases/latest/download/docker-compose-$(uname -s)-$(uname -m) -o /usr/bin/docker-compose

sudo chmod +x /usr/bin/docker-compose

3. Create docker-compose.yml

mkdir myapp 

Create file ./myapp/docker-compose.yml:

version: '3.3'

services:
   db:
     image: mysql:5.7
     volumes:
       - db_data:/var/lib/mysql
     restart: always
     environment:
       MYSQL_ROOT_PASSWORD: somewordpress
       MYSQL_DATABASE: wordpress
       MYSQL_USER: wordpress
       MYSQL_PASSWORD: wordpress

   wordpress:
     depends_on:
       - db
     image: wordpress:latest
     ports:
       - "8000:80"
     restart: always
     environment:
       WORDPRESS_DB_HOST: db:3306
       WORDPRESS_DB_USER: wordpress
       WORDPRESS_DB_PASSWORD: wordpress
       WORDPRESS_DB_NAME: wordpress
volumes:
    db_data: {}

4. Create docker_boot.service

The file is different then yours, as there were few potential issues in your file:

• not using absolute paths
• ec2-user may have no permissions to run docker

Create file ./myapp/docker_boot.service:

[Unit]
Description=docker boot
After=docker.service

[Service]
Type=oneshot
RemainAfterExit=yes
WorkingDirectory=/home/ec2-user/myapp
ExecStart=/usr/bin/docker-compose -f /home/ec2-user/myapp/docker-compose.yml up -d --remove-orphans

[Install]
WantedBy=multi-user.target

5. Copy docker_boot.service to systemd

sudo cp -v ./myapp/docker_boot.service /etc/systemd/system

6. Enable and start docker_boot.service

sudo systemctl enable docker_boot.service
sudo systemctl start docker_boot.service

Note: First start may take some time, as it will pull all docker images required. Alternatively start docker-compose manually first to avoid this.

7. Check status of the docker_boot.service

sudo systemctl status docker_boot.service

8. Check if the wordpress is up

curl -L localhost:8000

9. Reboot

Check if the docker_boot.service is running after instance reboot by logging in into the instance and using sudo systemctl status docker_boot.service and/or curl -L localhost:8000.