Podman

Execute e gerencie contêineres sem um daemon usando o motor de contêineres sem root do Podman.

Quando Usar Esta Habilidade

Use esta habilidade quando:

• Executar contêineres sem privilégios de root
• Gerenciar contêineres em sistemas sem Docker
• Criar grupos de contêineres baseados em pods
• Usar systemd para gerenciamento de contêineres
• Trabalhar em ambientes com foco em segurança

Pré-requisitos

• Podman instalado (4.x+)
• Para sem root: namespaces de usuário habilitados
• Compreensão básica de conceitos de contêineres

Principais Diferenças do Docker

Comandos Básicos

Operações de Contêiner

# Run container (identical to Docker)
podman run -d --name webserver -p 8080:80 nginx

# List containers
podman ps -a

# Stop and remove
podman stop webserver
podman rm webserver

# Execute command
podman exec -it webserver /bin/sh

# View logs
podman logs -f webserver

Gerenciamento de Imagens

# Pull image
podman pull docker.io/library/nginx:latest

# List images
podman images

# Build image
podman build -t myapp:latest .

# Push to registry
podman push myapp:latest registry.example.com/myapp:latest

# Remove image
podman rmi nginx:latest

Contêineres Sem Root

Configuração

# Check user namespace support
cat /proc/sys/user/max_user_namespaces

# Enable if needed (as root)
echo "user.max_user_namespaces=28633" | sudo tee /etc/sysctl.d/userns.conf
sudo sysctl -p /etc/sysctl.d/userns.conf

# Configure subuid/subgid for user
sudo usermod --add-subuids 100000-165535 --add-subgids 100000-165535 $USER

# Verify
podman unshare cat /proc/self/uid_map

Executando Sem Root

# Run as regular user (no sudo)
podman run -d --name myapp -p 8080:80 nginx

# Check user namespace mapping
podman unshare id

# Verify non-root
podman top myapp user

Considerações de Porta

# Rootless cannot bind to ports < 1024 by default
# Use ports >= 1024
podman run -d -p 8080:80 nginx

# Or enable unprivileged ports (as root)
echo "net.ipv4.ip_unprivileged_port_start=80" | sudo tee /etc/sysctl.d/ports.conf
sudo sysctl -p /etc/sysctl.d/ports.conf

Pods

Criando Pods

# Create pod
podman pod create --name mypod -p 8080:80 -p 5432:5432

# Add containers to pod
podman run -d --pod mypod --name web nginx
podman run -d --pod mypod --name db postgres:15

# List pods
podman pod ps

# Containers share network namespace
podman exec web curl localhost:5432

Gerenciamento de Pods

# Start/stop pod (affects all containers)
podman pod start mypod
podman pod stop mypod

# Remove pod and containers
podman pod rm -f mypod

# View pod details
podman pod inspect mypod

# Generate Kubernetes YAML from pod
podman generate kube mypod > mypod.yaml

Integração com Systemd

Gerar Unidade Systemd

# Generate unit file for container
podman generate systemd --new --name myapp > ~/.config/systemd/user/container-myapp.service

# For pod
podman generate systemd --new --name mypod --files

# Reload systemd
systemctl --user daemon-reload

# Enable and start
systemctl --user enable --now container-myapp.service

Quadlet (Podman 4.4+)

# ~/.config/containers/systemd/webapp.container
[Container]
Image=docker.io/library/nginx:latest
PublishPort=8080:80
Volume=webapp-data:/usr/share/nginx/html

[Service]
Restart=always

[Install]
WantedBy=default.target

# Reload to generate service
systemctl --user daemon-reload

# Start the service
systemctl --user start webapp

Compatibilidade com Compose

Usando Podman Compose

# Install podman-compose
pip install podman-compose

# Run compose file
podman-compose up -d

# Or use Docker Compose with Podman socket
systemctl --user enable --now podman.socket
export DOCKER_HOST=unix:///run/user/$UID/podman/podman.sock
docker-compose up -d

Podman Kube Nativo

# Play Kubernetes YAML
podman kube play deployment.yaml

# Stop and remove
podman kube down deployment.yaml

Rede

Gerenciamento de Rede

# Criar rede
podman network create mynetwork

# Executar na rede
podman run -d --network mynetwork --name app myapp

# Conectar contêiner à rede
podman network connect mynetwork existing-container

# Listar redes
podman network ls


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