Docker

Notes on running containers with Docker Engine, Docker Compose and Podman, plus self-hosted apps such as Pi-hole and RustDesk.

RedHat - Install Docker Engine on RHEL 9

Last verified: October 2026 for RHEL 9 against Docker's Install Docker Engine on RHEL guide, Linux post-installation steps, and packet-filtering / firewalld notes (see Sources).

This installs Docker Engine Community (Docker CE) from Docker's official RHEL repository: the dockerd daemon, the docker CLI, containerd, Buildx, and the Compose v2 plugin. It is not Docker Desktop, and it is not Red Hat's Podman stack.

Red Hat ships Podman as the supported engine on RHEL 9. Use this page when you specifically need Docker Engine. If you want Podman instead, use the Podman page in the Docker book.

Prerequisites

Rocky Linux and AlmaLinux are RHEL rebuilds. Docker's documented repo for this procedure is download.docker.com/linux/rhel. Docker does not list Rocky/Alma as tested platforms on the RHEL install page.

1) Conflicts with Podman

Docker's packages conflict with the distribution's unofficial Docker packages and with Podman / runc. The uninstall step below is what Docker documents. Do not run it on a host that must keep Podman. Pick one engine per host.

sudo dnf remove docker \
  docker-client \
  docker-client-latest \
  docker-common \
  docker-latest \
  docker-latest-logrotate \
  docker-logrotate \
  docker-engine \
  podman \
  runc

dnf may report that none of those packages are installed. Images, containers, volumes and networks under /var/lib/docker/ are not removed by this command.

2) Add Docker's RHEL repository

sudo dnf -y install dnf-plugins-core
sudo dnf config-manager --add-repo https://download.docker.com/linux/rhel/docker-ce.repo

Confirm the repo is present:

dnf repolist docker-ce-stable

3) Install Docker Engine

Latest packages:

sudo dnf install docker-ce docker-ce-cli containerd.io docker-buildx-plugin docker-compose-plugin

If DNF asks you to accept the GPG key, check the fingerprint matches Docker's published key before you accept:

060A 61C5 1B55 8A7F 742B 77AA C52F EB6B 621E 9F35

This installs Docker but does not start it. It creates a docker group and does not add any users to that group.

To pin a version, list what the repo currently has, then install the fully qualified NEVRA (name + epoch/version from the second column):

dnf list docker-ce --showduplicates | sort -r
sudo dnf install docker-ce-<VERSION_STRING> docker-ce-cli-<VERSION_STRING> containerd.io docker-buildx-plugin docker-compose-plugin

Example NEVRA from Docker's docs at verification time: docker-ce-3:29.8.2-1.el9. The list on your host will change as Docker publishes updates.

4) Start and enable the service

sudo systemctl enable --now docker
sudo systemctl enable containerd.service
sudo systemctl status docker --no-pager

If you do not want Docker at boot, use sudo systemctl start docker instead of enable --now.

5) Verify

sudo docker version
sudo docker compose version
sudo docker run --rm hello-world

hello-world pulls a test image, runs a container, prints a confirmation message, and exits. Use sudo until you add a user to the docker group.

6) Configure Docker's default address pools

The address pools control which subnets Docker hands out to new bridge networks. Each network gets a /24, so Docker does not run out of address space. Create or edit the daemon config:

sudo vi /etc/docker/daemon.json

Add:

{
  "default-address-pools": [
    {
      "base": "172.17.0.0/12",
      "size": 24
    },
    {
      "base": "192.168.0.0/16",
      "size": 24
    },
    {
      "base": "10.100.0.0/16",
      "size": 24
    }
  ]
}

If /etc/docker/daemon.json already exists, merge the default-address-pools key into it instead of overwriting the file. Pick pools that do not overlap your LAN or VPN ranges.

Restart Docker and check that a new network gets a /24 from the pools:

sudo systemctl restart docker
sudo docker network create testnet && sudo docker network inspect testnet | grep Subnet && sudo docker network rm testnet

The Subnet line should show a /24 from one of the pools. sudo docker info also lists them under Default Address Pools.

7) Optional: run docker without sudo

The docker group is root-equivalent. Anyone in that group can control the daemon and, from there, the host. Do not add accounts you would not give root. For stronger isolation, use rootless mode (see Sources) or keep using sudo docker.

sudo usermod -aG docker YOUR_USER

Log out and back in (or reboot a VM) so the group is applied. Then:

docker run --rm hello-world

If you used sudo docker earlier and see a permission error on ~/.docker/config.json:

sudo chown "YOUR_USER":"YOUR_USER" /home/YOUR_USER/.docker -R
sudo chmod g+rwx "$HOME/.docker" -R

8) firewalld and SELinux (leave them on)

Keep SELinux enforcing. Do not set it to permissive for this install.

Keep firewalld enabled. When Docker's iptables integration is on (the default), Docker creates a firewalld zone named docker with target ACCEPT, puts bridge interfaces such as docker0 in that zone, and adds a docker-forwarding policy from ANY zone to the docker zone. You do not need to disable firewalld for published ports on the Docker host.

sudo getenforce
sudo systemctl is-active firewalld
sudo firewall-cmd --get-active-zones

Do not open the Docker socket on TCP (2375/2376) unless you have a TLS plan. This page leaves the daemon on the default Unix socket only.

9) Upgrade

With the repo in place, upgrade the same packages:

sudo dnf upgrade docker-ce docker-ce-cli containerd.io docker-buildx-plugin docker-compose-plugin
sudo systemctl restart docker

10) Uninstall

sudo dnf remove docker-ce docker-ce-cli containerd.io docker-buildx-plugin docker-compose-plugin docker-ce-rootless-extras

That does not delete images, containers, volumes or custom config. Only if you intend to wipe local Docker data:

sudo rm -rf /var/lib/docker
sudo rm -rf /var/lib/containerd

Remove any files you edited under /etc/docker/ yourself.

The get.docker.com convenience script is not recommended on production RHEL hosts. Use the repository steps above.

Sources

PiHole - Synology Configuration

This is to create a MAC vlan on you synology to bridge interfaces

You will need to create the following folders from the main docker folder.

mkdir -p /volume1/docker/pihole
mkdir -p /volume1/docker/pihole/pihole
mkdir -p /volume1/docker/pihole/dnsmasq.d

My testing vlan uses 192.168.10.0/24

sudo docker network create -d macvlan -o parent=eth3 --subnet=192.168.10.0/24 --gateway=192.168.10.1 --ip-range=192.168.10.44/32 ph_network

YAML Configurations

services:
  pihole:
    image: pihole/pihole:latest
    container_name: pihole
    hostname: pihole
    security_opt:
      - no-new-privileges=false
    networks:
      - ph_network
      - ph_bridge
    environment:
      PIHOLE_GID: 100
      PIHOLE_UID: 1024
      DNSMASQ_USER: root
      TZ: 'America/Montreal'
      FTLCONF_webserver_api_password: '[Your_Password_Here]'
      #FTLCONF_webserver_port: 8080
      FTLCONF_dns_listeningMode: all
    volumes:
      - /volume1/docker/pihole/pihole:/etc/pihole
      - /volume1/docker/pihole/dnsmasq.d:/etc/dnsmasq.d
      - /etc/localtime:/etc/localtime:ro
    cap_add:
      - NET_ADMIN
      - SYS_TIME
      - SYS_NICE
    restart: on-failure:5
networks:
    ph_bridge:
      driver: bridge
      ipam:
        config:
          - subnet: 192.168.100.0/24
            gateway: 192.168.100.1
            ip_range: 192.168.100.2/32
    ph_network:
      name: ph_network
      external: true

Accessing the pi-hole remotely

https://192.168.10.44/admin


If you are 7.1 DSM you will need to use this command

docker-compose -f /volume1/docker/pihole/compose.yaml up -d

Note: Pi-hole v6 sets the listening mode with FTLCONF_dns_listeningMode; the v5 DNSMASQ_LISTENING variable is not used.

Last verified: October 2026

Sources:

.gitignore - .gitIgnore File for Docker Compose Files

Use Case TrueNAS shared SMB with a folder dedicated to yaml files.

image.png

This is it to be used if you have a SMB drive and point Visual Code or Code Server to all of your docker folders.

The .gitignore file setup

# Ignore everything by default
*

# Allow directories to be traversed
!*/

# Include YAML files
!*.yaml
!*.yml
!.env
!env.*

# Include .gitignore and .gitattributes files
!.gitignore
!.gitattributes

RustDesk - pfSense and and HAProxy

You can configure self-hosted RustDesk (hbbs ID/rendezvous server + hbbr relay server) behind your pfSense + HAProxy Docker setup using hostname.domain.com as the external ID server address. However, there are important caveats due to how RustDesk works.

Important Limitations with HAProxy for RustDesk

RustDesk uses a custom protocol (not HTTP/HTTPS) with:

HAProxy (even in TCP mode) is not ideal for the core RustDesk traffic:

If you must route everything through HAProxy Docker, it's possible for the TCP ports only (see advanced section at the end), but UDP will still need a direct forward and performance/reliability will suffer.

Step-by-Step Recommended Setup (Direct pfSense NAT + Domain)

  1. Set up DNS

    • Create an A record (and AAAA if IPv6) for hostname.domain.com pointing to your pfSense WAN public IP.
    • No special subdomains or paths needed.

  2. Run RustDesk Server in Docker (on your internal host/VM/LXC behind pfSense) You can also choose to use the official Docker Compose (download oss.yml from RustDesk or use this standard one):

    services:
  hbbs: # ID / signaling server
    container_name: hbbs
    image: rustdesk/rustdesk-server:latest
    command: hbbs -r {REMOTE HOSTNAME}:21117
    logging:
      driver: json-file
      options:
        max-file: ${DOCKERLOGGING_MAXFILE:-10}
        max-size: ${DOCKERLOGGING_MAXSIZE:-200k}
    ports:
      - "21115:21115"
      - "21116:21116"
      - "21116:21116/udp"
      - "21118:21118"
    volumes:
      - ${DOCKERFOLDER}/rustdesk/data:/root
    depends_on:
      - hbbr
    restart: unless-stopped
  hbbr: # Relay server
    container_name: hbbr
    image: rustdesk/rustdesk-server:latest
    command: hbbr
    logging:
      driver: json-file
      options:
        max-file: ${DOCKERLOGGING_MAXFILE:-10}
        max-size: ${DOCKERLOGGING_MAXSIZE:-200k}
    ports:
      - "21117:21117"
      - "21119:21119"
    volumes:
      - ${DOCKERFOLDER}/rustdesk/data:/root
    restart: unless-stopped
    • Run with docker compose up -d.
    • The ./data folder will contain your encryption key pair (id_ed25519.pub).
    • Check logs: docker logs hbbs → look for the public key (you’ll need this in clients).

  3. pfSense Configuration (Port Forwards + Firewall Rules) Go to Firewall → NAT → Port Forward and create these rules (all source = WAN, destination = your RustDesk Docker host’s internal IP):

    Protocol Destination Port Forward to IP Forward to Port Notes
    TCP 21115 RustDesk Docker IP 21115 hbbs signaling
    TCP 21116 RustDesk Docker IP 21116 hbbs
    UDP 21116 RustDesk Docker IP 21116 Critical for hole punching
    TCP 21117 RustDesk Docker IP 21117 hbbr relay
    • Set Source port range to any (RustDesk clients use random source ports).
    • Auto-create the associated firewall rules (or manually create matching WAN rules under Firewall → Rules → WAN allowing the same ports).

    Optional but recommended:

    • Enable System → Advanced → Firewall & NAT → NAT Reflection (Pure NAT mode) if you want LAN clients to reach the server via the public domain.

  4. Client Configuration On every RustDesk client (Windows/macOS/Linux/Android/iOS):

    • Go to Settings → ID/Relay Server
    • ID Server: hostname.domain.com (or hostname.domain.com:21115 if you changed the port)
    • Relay Server: leave blank (hbbs will tell clients to use hostname.domain.com:21117)
    • Key: paste the public key from your ./data/id_ed25519.pub file

  5. Test

    • From outside your network, connect using an ID from one of your machines.
    • Check connection type in the session (should be "Direct" most of the time; falls back to "Relay" if needed).
    • Monitor logs: docker logs hbbs and docker logs hbbr.

Advanced: Forcing Everything Through HAProxy Docker (Not Recommended)

If you really want HAProxy as the single entry point:

For the RustDesk Web Client only (if you use it), you can proxy the WebSocket ports (21118/21119) through HAProxy in HTTP mode with proper Upgrade headers — similar to the official Nginx example in the RustDesk docs.

This direct pfSense NAT + domain setup is what works reliably for almost everyone running RustDesk behind pfSense. Let me know if you hit any specific error logs or need the exact Docker Compose / HAProxy snippets adjusted for your environment!

PODMAN - Install Podman on Linux Redhat

Production-Ready Step-by-Step Guide Rootless Podman + Quadlet on Red Hat Enterprise Linux 10

This guide is designed for a production environment as assums a fresh install of Redhat. It uses the modern Quadlet method (recommended) and follows Red Hat best practices for RHEL 10.

1. System Requirements (Production)

Resource Minimum Recommended (Production) Our Systems
CPU 2 cores 4+ cores 8 cores
RAM 4 GB 8–16 GB+ 32 GB
Disk 40 GB free 100 GB+ (SSD preferred) 350 GB
cgroup cgroup v2 cgroup v2 (required)
SELinux Enforcing Enforcing

Check cgroup version:

podman info --format '{{.Host.CgroupVersion}}'
Install Needed Tools:

Epel Release

subscription-manager repos --enable codeready-builder-for-rhel-10-$(arch)-rpms
dnf install https://dl.fedoraproject.org/pub/epel/epel-release-latest-10.noarch.rpm -y

After Epel installation rerun the upgrade to update if any are needed

dnf upgrade -y
Toolset
dnf install bind-utils bzip2 cups cifs-utils enscript ftp gdb ghostscript krb5-workstation ksh lftp lrzsz lsof libnsl lzop plocate mutt ncompress net-tools net-snmp net-snmp-utils net-tools nfs-utils nmap nvme-cli openldap-clients openssh-clients psmisc realmd rsync samba-client strace sysstat tcpdump telnet telnet-server tmux unix2dos vim vim-enhanced vsftpd wget xfsdump vsftpd htop mc rsyslog rsyslog-doc postfix dbus-daemon s-nail dovecot cyrus-sasl cyrus-sasl-lib cyrus-sasl-plain tree figlet toilet coreutils -y

2. Prepare the System

2.1 Register and Update RHEL 10

sudo dnf update -y
sudo reboot

2.2 Install Container Tools

sudo dnf install -y container-tools

Optional (Docker CLI compatibility):

sudo dnf install -y podman-docker

Verify:

podman --version
podman info

3. Create a Dedicated Service User (Best Practice)

For production, avoid running services under a regular interactive user.

# Create a system user for containers
sudo useradd -r -m -d /home/podman -s /bin/bash podman

# Set a strong password or disable password login
sudo passwd podman          # or lock the account later

Grant subordinate UIDs/GIDs (required for rootless):

sudo usermod --add-subuids 100000-165535 --add-subgids 100000-165535 podman

4. Enable Lingering (Critical for Production)

This allows the user services to run even when the user is not logged in.

sudo loginctl enable-linger podman

Verify:

loginctl show-user podman | grep Linger
# Linger=yes

5. Configure Rootless Environment

Switch to the service user:

# systemctl --user needs a real login session; sudo -u / su do not create one
sudo dnf install -y systemd-container
sudo machinectl shell podman@

Create required directories:

mkdir -p ~/.config/containers/systemd
mkdir -p ~/.config/containers
mkdir -p ~/.local/share/containers

Optional but Recommended: Storage Configuration

cat > ~/.config/containers/storage.conf << 'EOF'
[storage]
driver = "overlay"
# Rootless defaults: graphroot = $HOME/.local/share/containers/storage
# and runroot = $XDG_RUNTIME_DIR/containers. Set them here only to use other paths.
# Native overlay works rootless on current RHEL kernels; fuse-overlayfs is not needed.
EOF

Optional: Registries Configuration

cat > ~/.config/containers/registries.conf << 'EOF'
unqualified-search-registries = ["registry.access.redhat.com", "registry.redhat.io", "docker.io", "quay.io"]

[[registry]]
location = "docker.io"
insecure = false
EOF

6. Create Your First Production Quadlet

A) Example: Nginx reverse proxy / web service

cat > ~/.config/containers/systemd/nginx.container << 'EOF'
[Unit]
Description=Nginx Web Server (Production)
After=network-online.target
Wants=network-online.target

[Container]
Image=docker.io/library/nginx:alpine
ContainerName=nginx
PublishPort=8080:80
Volume=nginx-data.volume:/usr/share/nginx/html:Z
Volume=nginx-conf.volume:/etc/nginx/conf.d:Z
AutoUpdate=registry
Environment=TZ=America/New_York
PodmanArgs=--memory=512m --cpus=1.0 --memory-swap=512m

[Service]
Restart=always
TimeoutStartSec=300

[Install]
WantedBy=default.target
EOF

A) Create supporting volumes:

cat > ~/.config/containers/systemd/nginx-data.volume << 'EOF'
[Volume]
VolumeName=nginx-data
EOF

cat > ~/.config/containers/systemd/nginx-conf.volume << 'EOF'
[Volume]
VolumeName=nginx-conf
EOF
B) Another Example

cat > ~/.config/containers/systemd/myapp.container << 'EOF'
[Unit]
Description=My Application (Production)
After=network-online.target
Wants=network-online.target

[Container]
Image=your-registry/your-app:latest
ContainerName=myapp
PublishPort=8080:8080
Volume=myapp-data.volume:/data:Z
AutoUpdate=registry
Environment=TZ=America/New_York
PodmanArgs=--memory=1g --cpus=1.5 --memory-swap=1g

[Service]
Restart=always
TimeoutStartSec=300

[Install]
WantedBy=default.target
EOF

B) Create supporting volume:

cat > ~/.config/containers/systemd/myapp-data.volume << 'EOF'
[Volume]
VolumeName=myapp-data
EOF

 

7. Activate the Service

A) Example for Nginx

# Reload systemd user units
systemctl --user daemon-reload

# Start and enable
systemctl --user enable --now nginx.service

# Check status
systemctl --user status nginx.service
podman ps

View logs:

journalctl --user -u nginx.service -f

B) Second Example


systemctl --user daemon-reload
systemctl --user enable --now myapp.service

# Verify
systemctl --user status myapp.service
podman ps

View logs:

journalctl --user -u myapp.service -f

 

8. Configure pfSense HAProxy

In pfSense HAProxy:

  1. Backend
    • Mode: http
    • Server: IP of your RHEL 10 host
    • Port: 8080 (or whatever you published)
    • Health check: recommended
  2. Frontend
    • Bind to WAN / desired interface
    • TLS offloading (recommended)
    • ACL based on Host header (e.g. hdr(host) -i app.yourdomain.com)
    • Use backend created above
  3. Firewall Rules
    • Allow traffic from HAProxy (or LAN) to the RHEL host on the published port(s) only.

Firewall example:

sudo firewall-cmd --permanent --add-port=8080/tcp
sudo firewall-cmd --reload

 

9. Production Hardening Checklist

Item Command / Action Status
SELinux Keep enforcing ☐
Linger enabled loginctl show-user podman ☐
Resource limits Set in Quadlet (--memory, --cpus) ☐
Auto-update AutoUpdate=registry in Quadlet ☐
Firewall Open only required ports ☐
Log rotation Configure journald or ship logs ☐
Image scanning Use an external image scanner (Podman has no built-in scan command) ☐
Backup volumes Backup ~/.local/share/containers ☐
Non-interactive user Disable password / use key-based access only ☐

Log management

journalctl --user or forward logs

Enable auto-update timer (as podman user):

systemctl --user enable --now podman-auto-update.timer

9. Useful Management Commands

A) Example for Nginx 
# List all user services
systemctl --user list-units --type=service

# Restart a service
systemctl --user restart nginx.service

# Stop a service
systemctl --user stop nginx.service

# View resource usage
podman stats

# Update all containers with AutoUpdate
podman auto-update
B) Another Example
# Service management
systemctl --user status myapp.service
systemctl --user restart myapp.service
systemctl --user stop myapp.service

# Container status & resources
podman ps
podman stats

# Logs
journalctl --user -u myapp.service -f

# Manual update
podman auto-update

 

10. Optional: Auto-Update Timer

Enable Podman’s auto-update timer (as the podman user):

Bash 
systemctl --user enable --now podman-auto-update.timer

Summary of Key Directories (Rootless)

Purpose Path
Quadlet files ~/.config/containers/systemd/
Container storage ~/.local/share/containers/storage/
User systemd units ~/.config/systemd/user/
Configuration ~/.config/containers/

Summary

Last verified: October 2026

Sources:

Docker - Linux Docker Compose Wrapper

Docker Compose Wrapper (dc)

A small wrapper around docker compose that automatically loads shared environment files for all stacks.

Why

Docker Compose only interpolates ${VARIABLES} from:

It does not use the env_file: directive for interpolation.
This wrapper always passes the shared files so every stack gets consistent variable substitution.

Shared Files

/mnt/volume1/docker/stacks/_shared/.env
/mnt/volume1/docker/stacks/_shared/.secret

Install

  1. Create the wrapper:
Bash 

sudo tee /usr/local/bin/dc > /dev/null << 'EOF'
#!/bin/bash
exec docker compose \
  --env-file /mnt/volume1/docker/stacks/_shared/.env \
  --env-file /mnt/volume1/docker/stacks/_shared/.secret \
  "$@"
EOF
  1. Make it executable:
Bash 

sudo chmod +x /usr/local/bin/dc
  1. Verify:
Bash 

which dc
dc version

Usage

Use dc exactly like docker compose.
All subcommands work.

Bash 

dc up -d
dc logs
dc logs -f
dc ps
dc restart <service>
dc down
dc config

Notes

Bash 

dc config

Updating

Edit the script if the shared file paths change:

Bash 

sudo nano /usr/local/bin/dc