Set up repo structure and implement base role

- Document architecture decisions in README (Ansible + Docker Compose + Traefik)
- Scaffold Ansible layout: inventory, site.yml, group_vars, 9 service roles
- Implement base role: package install, deploy user, SSH hardening,
  UFW firewall (22/80/443), fail2ban, unattended-upgrades
- Add reinstall runbook in docs/runbook.md
- Add ansible/requirements.yml for community.general and ansible.posix

README.md

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+Info:
+--
+Server:
+	Strato STRATO VPS Linux VC4-8
+	Order Number: 9478462 
+
+	Customer Number: 73171334
+	Customer Login: https://www.strato.de/apps/CustomerService
+
+	Cores: 4 Cores
+	RAM: 8 GB RAM
+	Storage: 240 HDD
+
+	IPv4: 217.154.207.148
+	IPv6: 2a01:239:35b:c400::1
+
+	OS: Ubuntu 24.04 LTS
+
+DNS Names:
+	cloud.ladkau.de
+	gitea.ladkau.de
+	nextcloud.ladkau.de
+	sso.ladkau.de
+	mail.ladkau.de
+	cr.ladkau.de
+	k8s.ladkau.de
+
+Purpose:
+--
+This repository tracks the complete server configuration so the server can be
+fully reinstalled from scratch using only this repo. Every configuration change
+must be committed here. The git history serves as the change log.
+
+Architecture:
+--
+Provisioning: Ansible
+	Ansible playbooks configure the OS and deploy all services. Roles are
+	idempotent — re-running them brings the server back to the desired state
+	without side effects. The master playbook is ansible/site.yml.
+
+Service runtime: Docker Compose
+	Each service runs as a Docker Compose stack. Compose files live inside
+	their respective Ansible roles (roles/<service>/files/docker-compose.yml).
+	This keeps service definition and deployment config together.
+
+Reverse proxy / TLS: Traefik
+	Traefik is the single entry point for all HTTP/HTTPS traffic. It runs as
+	a Docker Compose service and routes to other containers via Docker labels.
+	TLS certificates are issued automatically via Let's Encrypt (ACME).
+
+Repo layout:
+--
+	ansible/
+		inventory.ini        # host address and connection vars
+		site.yml             # master playbook — runs all roles in order
+		group_vars/all.yml   # shared variables (domains, image versions, ...)
+		roles/
+			base/            # OS hardening, non-root user, SSH, ufw firewall
+			docker/          # Docker Engine + Compose plugin install
+			traefik/         # reverse proxy, TLS termination
+			gitea/           # self-hosted Git
+			nextcloud/       # file storage and collaboration
+			sso/             # Single Sign-On
+			mail/            # mail server
+			registry/        # container registry (cr.ladkau.de)
+			k8s/             # k3s Kubernetes node
+	docs/
+		runbook.md           # step-by-step reinstall instructions
+	keys/
+		*.pub                # public SSH keys (private keys are gitignored)
+
+SSH keys:
+--
+	root_cloud_ladkau_de      — root access (initial setup only)
+	notroot_cloud_ladkau_de   — non-root deploy user (used by Ansible)

ansible/group_vars/all.yml

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+---
+# Domains
+domain_base: ladkau.de
+domain_cloud:      "cloud.{{ domain_base }}"
+domain_gitea:      "gitea.{{ domain_base }}"
+domain_nextcloud:  "nextcloud.{{ domain_base }}"
+domain_sso:        "sso.{{ domain_base }}"
+domain_mail:       "mail.{{ domain_base }}"
+domain_registry:   "cr.{{ domain_base }}"
+domain_k8s:        "k8s.{{ domain_base }}"
+
+# Let's Encrypt
+acme_email: matthias.ladkau@gmail.com
+
+# Non-root deploy user created by the base role
+deploy_user: deploy
+
+# System timezone
+timezone: Europe/Berlin
+
+# Docker network shared by all services and Traefik
+traefik_network: traefik_public

ansible/inventory.ini

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+[cloud]
+cloud.ladkau.de ansible_user=deploy ansible_ssh_private_key_file=../keys/notroot_cloud_ladkau_de

ansible/requirements.yml

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+---
+collections:
+  - name: community.general   # ufw, timezone modules
+  - name: ansible.posix       # authorized_key module

ansible/roles/base/files/20auto-upgrades

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+APT::Periodic::Update-Package-Lists "1";
+APT::Periodic::Unattended-Upgrade "1";

ansible/roles/base/handlers/main.yml

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+---
+- name: Restart sshd
+  ansible.builtin.service:
+    name: ssh
+    state: restarted

ansible/roles/base/tasks/main.yml

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+---
+# --- Packages ---
+
+- name: Update apt cache
+  ansible.builtin.apt:
+    update_cache: true
+    cache_valid_time: 3600
+  tags: base
+
+- name: Upgrade all packages
+  ansible.builtin.apt:
+    upgrade: dist
+  tags: base
+
+- name: Install base packages
+  ansible.builtin.apt:
+    name:
+      - curl
+      - git
+      - vim
+      - htop
+      - ufw
+      - fail2ban
+      - unattended-upgrades
+      - apt-listchanges
+    state: present
+  tags: base
+
+# --- System ---
+
+- name: Set timezone
+  community.general.timezone:
+    name: "{{ timezone }}"
+  tags: base
+
+# --- Deploy user ---
+
+- name: Create deploy user
+  ansible.builtin.user:
+    name: "{{ deploy_user }}"
+    shell: /bin/bash
+    create_home: true
+    groups: sudo
+    append: true
+    state: present
+  tags: base
+
+- name: Add SSH authorized key for deploy user
+  ansible.posix.authorized_key:
+    user: "{{ deploy_user }}"
+    state: present
+    key: "{{ lookup('file', playbook_dir + '/../keys/notroot_cloud_ladkau_de.pub') }}"
+  tags: base
+
+- name: Allow deploy user passwordless sudo
+  ansible.builtin.copy:
+    dest: /etc/sudoers.d/{{ deploy_user }}
+    content: "{{ deploy_user }} ALL=(ALL) NOPASSWD:ALL\n"
+    mode: "0440"
+    validate: visudo -cf %s
+  tags: base
+
+# --- SSH hardening ---
+
+- name: Deploy hardened sshd_config
+  ansible.builtin.template:
+    src: sshd_config.j2
+    dest: /etc/ssh/sshd_config
+    owner: root
+    group: root
+    mode: "0600"
+    validate: sshd -t -f %s
+  notify: Restart sshd
+  tags: base
+
+# --- Firewall ---
+
+- name: Set UFW default incoming policy to deny
+  community.general.ufw:
+    direction: incoming
+    policy: deny
+  tags: base
+
+- name: Set UFW default outgoing policy to allow
+  community.general.ufw:
+    direction: outgoing
+    policy: allow
+  tags: base
+
+- name: Allow SSH (22/tcp)
+  community.general.ufw:
+    rule: allow
+    port: "22"
+    proto: tcp
+  tags: base
+
+- name: Allow HTTP (80/tcp)
+  community.general.ufw:
+    rule: allow
+    port: "80"
+    proto: tcp
+  tags: base
+
+- name: Allow HTTPS (443/tcp)
+  community.general.ufw:
+    rule: allow
+    port: "443"
+    proto: tcp
+  tags: base
+
+- name: Enable UFW
+  community.general.ufw:
+    state: enabled
+  tags: base
+
+# --- Automatic security updates ---
+
+- name: Enable unattended-upgrades
+  ansible.builtin.copy:
+    src: 20auto-upgrades
+    dest: /etc/apt/apt.conf.d/20auto-upgrades
+    owner: root
+    group: root
+    mode: "0644"
+  tags: base
+
+# --- Fail2ban ---
+
+- name: Enable and start fail2ban
+  ansible.builtin.service:
+    name: fail2ban
+    state: started
+    enabled: true
+  tags: base

ansible/roles/base/templates/sshd_config.j2

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+# Managed by Ansible — do not edit manually
+Port 22
+Protocol 2
+
+# Authentication
+PermitRootLogin no
+PasswordAuthentication no
+ChallengeResponseAuthentication no
+PubkeyAuthentication yes
+AuthorizedKeysFile .ssh/authorized_keys
+
+# Only allow the deploy user over SSH
+AllowUsers {{ deploy_user }}
+
+# Misc hardening
+X11Forwarding no
+PrintMotd no
+MaxAuthTries 3
+LoginGraceTime 30
+
+UsePAM yes
+AcceptEnv LANG LC_*
+Subsystem sftp /usr/lib/openssh/sftp-server

ansible/roles/docker/tasks/main.yml

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+---
+# TODO: implement docker role

ansible/roles/gitea/tasks/main.yml

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+---
+# TODO: implement gitea role

ansible/roles/k8s/tasks/main.yml

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+---
+# TODO: implement k8s role

ansible/roles/mail/tasks/main.yml

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+---
+# TODO: implement mail role

ansible/roles/nextcloud/tasks/main.yml

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+---
+# TODO: implement nextcloud role

ansible/roles/registry/tasks/main.yml

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+---
+# TODO: implement registry role

ansible/roles/sso/tasks/main.yml

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+---
+# TODO: implement sso role

ansible/roles/traefik/tasks/main.yml

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+---
+# TODO: implement traefik role

ansible/site.yml

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+---
+- name: Full server provisioning
+  hosts: cloud
+  become: true
+  roles:
+    - base
+    - docker
+    - traefik
+    - gitea
+    - nextcloud
+    - sso
+    - mail
+    - registry
+    - k8s

docs/runbook.md

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+# Reinstall Runbook
+
+Follow these steps to provision a fresh server from scratch.
+
+## Prerequisites
+
+On your local machine:
+- Ansible installed (`pip install ansible`)
+- SSH access to the server as root using `keys/root_cloud_ladkau_de`
+
+## Steps
+
+### 1. Install Ansible collections
+
+From the repo root:
+
+```bash
+ansible-galaxy collection install -r ansible/requirements.yml
+```
+
+Required collections:
+- `community.general` — ufw, timezone modules
+- `ansible.posix` — authorized_key module
+
+### 2. Initial root login
+
+Connect as root and verify the server is reachable:
+
+```
+ssh -i keys/root_cloud_ladkau_de root@217.154.207.148
+```
+
+### 3. Create the deploy user (one-time, manual)
+
+On the server as root:
+
+```bash
+adduser deploy
+usermod -aG sudo deploy
+mkdir -p /home/deploy/.ssh
+cat >> /home/deploy/.ssh/authorized_keys <<'EOF'
+<paste contents of keys/notroot_cloud_ladkau_de.pub>
+EOF
+chown -R deploy:deploy /home/deploy/.ssh
+chmod 700 /home/deploy/.ssh
+chmod 600 /home/deploy/.ssh/authorized_keys
+```
+
+### 4. Run the Ansible master playbook
+
+From the repo root:
+
+```bash
+ansible-playbook -i ansible/inventory.ini ansible/site.yml
+```
+
+This runs all roles in order:
+1. `base`      — OS hardening, SSH config, ufw firewall
+2. `docker`    — Docker Engine + Compose plugin
+3. `traefik`   — reverse proxy, TLS via Let's Encrypt
+4. `gitea`     — self-hosted Git
+5. `nextcloud` — file storage
+6. `sso`       — Single Sign-On
+7. `mail`      — mail server
+8. `registry`  — container registry
+9. `k8s`       — k3s node
+
+### 5. DNS
+
+Ensure the following DNS A records point to `217.154.207.148` before running:
+
+- cloud.ladkau.de
+- gitea.ladkau.de
+- nextcloud.ladkau.de
+- sso.ladkau.de
+- mail.ladkau.de
+- cr.ladkau.de
+- k8s.ladkau.de
+
+Traefik will attempt ACME certificate issuance on first start; DNS must resolve first.
+
+## Re-running after changes
+
+The playbook is idempotent. To apply a single role only:
+
+```bash
+ansible-playbook -i ansible/inventory.ini ansible/site.yml --tags <role>
+```