mash-playbook/docs/services/system.md
2023-12-09 18:58:15 +02:00

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# System-related configuration
This Ansible playbook can install and configure various system-related things for you.
All the sections below relate to the host OS instead of the managed containers.
### swap
To enable [swap](https://en.wikipedia.org/wiki/Memory_paging) management (also read more in the [Swap](https://wiki.archlinux.org/title/Swap) article in the [Arch Linux Wiki](https://wiki.archlinux.org/)), add the following configuration to your `vars.yml` file and re-run the [installation](../installing.md) process:
```yaml
########################################################################
# #
# system #
# #
########################################################################
system_swap_enabled: true
########################################################################
# #
# /system #
# #
########################################################################
```
A swap file will be created in `/var/swap` (configured using the `system_swap_path` variable) and enabled in your `/etc/fstab` file.
By default, the swap file will have `1GB` size, but you can set the `system_swap_size` variable in megabytes, example (4gb):
```yaml
system_swap_size: 4096
```
**Warning**: changing `system_swap_size` subsequently will not recreate the SWAP file with the new size. You will need to disable swap, re-run the playbook (to make it clean up), then enable it again with the new size.
### ssh
> **Warning**: advanced functionality! While the default config with a few adjustments was battle tested on hundreds of servers,
> you should use it with caution and verify everything before you apply the changes!
To enable [ssh server](https://www.openssh.com/) config and authorized/unauthorized keys management, add the following configuration to your `vars.yml` file and re-run the [installation](../installing.md) process:
```yaml
########################################################################
# #
# system #
# #
########################################################################
system_security_ssh_enabled: true
system_security_ssh_port: 22
system_security_ssh_authorizedkeys_host: [] # list of authorized public keys
system_security_ssh_unauthorizedkeys_host: [] # list of unauthorized/revoked public keys
########################################################################
# #
# /system #
# #
########################################################################
```
The [default configuration](https://gitlab.com/etke.cc/roles/ssh/-/blob/main/defaults/main.yml) is good enough as-is, but we strongly suggest you to **verify everything before applying any changes!**, otherwise you may lock yourself out of the server.
With this configuration, the default `/etc/ssh/sshd_config` file on your server will be replaced by a new one, managed by the [ssh role](https://gitlab.com/etke.cc/roles/ssh) (see its [templates/etc/ssh/sshd_config.j2](https://gitlab.com/etke.cc/roles/ssh/-/blob/main/templates/etc/ssh/sshd_config.j2) file).
There are various configuration options - check the defaults and adjust them to your needs.
### cleanup
Playbook may perform some housekeeping automatically, cleaning up unused docker resources, logs, even kernels (debian-only) and packages (debian-only). Here is how to enable different housekeeping tasks that will run on `setup-all`, `setup-cleanup`, `install-cleanup`:
```yaml
########################################################################
# #
# system #
# #
########################################################################
# runs `docker system prune -a -f --volumes` to remove unused images and containers
system_cleanup_docker: true
# configures a systemd unit (and timer) that runs `journalctl --vacuum-time=7d` daily, you can control schedules using system_cleanup_logs_* vars
system_cleanup_logs: true
# list of arbitrary absolute paths to remove on each invocation
system_cleanup_paths: []
# The following options are Debian only, will have no effect on any other distro family
# runs safe-upgrade, apt autoclean, aptautoremove, etc.
system_cleanup_apt: true
# WARNING: very dangerous! Purges old linux kernels, and their modules
system_cleanup_kernels: false
########################################################################
# #
# /system #
# #
########################################################################
```
### fail2ban
To enable [fail2ban](https://fail2ban.org/wiki/index.php/Main_Page) installation, management and integration with SSHd, add the following configuration to your `vars.yml` file and re-run the [installation](../installing.md) process:
```yaml
########################################################################
# #
# system #
# #
########################################################################
system_security_fail2ban_enabled: true
system_security_fail2ban_sshd_port: 22
# If you enabled playbook-managed ssh as described above,
# you can replace the line above with the following:
# system_security_fail2ban_sshd_port: "{{ system_security_ssh_port }}"
########################################################################
# #
# /system #
# #
########################################################################
```