# Configuration

The configuration documentation is intended for Linux Adminsistrators, that need to configure groups of systems at once.
For example:
* Groups of Servers
* Groups of Consoles

## Ansible Inventories

### Inventory Examples

Easy, simple and understandable examples are available under <a href="https://git.psi.ch/linux/engineering/ansible/inventories/psi-rhel-8-rc1-examples/tree/master" target="_blank">PSI RHEL-8 RC1 Examples</a>

### List of Ansible Inventories

The `RHEL-8 PSI Defaults` inventory houses the PSI wide defaults such as timeserver settings or access for support group members. The `AIT`, `CPT`, `GFA` and `HPCE` inventories are housing the division specific configuration.

* <a href="https://git.psi.ch/linux/engineering/ansible/inventories/rhel-8-psi-defaults" target="_blank">RHEL-8 PSI Defaults</a>
* <a href="https://git.psi.ch/linux/engineering/ansible/inventories/ait" target="_blank">AIT</a>
* <a href="https://git.psi.ch/linux/engineering/ansible/inventories/cpt" target="_blank">CPT</a>
* <a href="https://git.psi.ch/linux/engineering/ansible/inventories/gfa" target="_blank">GFA</a>
* <a href="https://git.psi.ch/linux/engineering/ansible/inventories/hpce" target="_blank">HPCE</a>

{{% alert text="You need to have permissions to access inventories.<br/>Please contact AIT Helpdesk." %}}

## Ansible Roles Configuration

### System Information and Responsibilty
Maintained by spreitzer_s

The system `/etc/motd` can be changed by settings as

```yaml
psi_motd_ou: CPT
psi_motd_contact: Gilles Martin    <gilles.martin@psi.ch>    / +41 56 310 36 90
```

or

```yaml
psi_motd_ou: AIT
psi_motd_contact_list: true
psi_motd_contact:
  - Alvise Dorigo    <alvise.dorigo@psi.ch>    / +41 56 310 55 67
  - Leonardo Sala    <leonardo.sala@psi.ch>    / +41 56 310 33 69
```

additional information can be provided as well

```yaml
psi_motd_ou: AIT
psi_motd_contact_list: true
psi_motd_contact:
  - Alvise Dorigo    <alvise.dorigo@psi.ch>    / +41 56 310 55 67
  - Leonardo Sala    <leonardo.sala@psi.ch>    / +41 56 310 33 69
psi_motd_additional: |
  Please be careful with this system.
  It is very sensitive.
```


---
### Network Configuration
Maintained by caubet_m

#### Configuring bonding re-using existing IP and interface

First, one needs to remove the **"System eth0"** created  during the installation which is the active interface. Then, one can create the bonding with a master interface (i.e. `bond0`) and the slave interface with a new name (i.e. `eth0` and, when using NetworkManager, it will generate a new `connection.id`). We ensure that the *state is up* and we *allow network restart* to apply changes on the fly, and we *persistent* changes.

**Note:** Is important to have it persistent and state *up* and `network_allow_restart` for applying **online** changes affecting to a connected interface, otherwise the network service (or machine) needs to be rebooted.

```yaml
- hosts: all,rhel-8-dev-7a95e9bb.psi.ch
  vars:
    network_allow_restart: yes
    network_connections:
      - name: "System eth0"
        persistent_state: absent
        state: down
      - name: bond0
        type: bond
        interface_name: bond0
        bond:
          mode: 'active-backup'
          miimon: 100
        persistent_state: present
        ip:
          address: "{{ ansible_default_ipv4.address }}/24"
          dns:
            - 129.129.190.11
            - 129.129.230.11
          dns_search:
            - psi.ch
          gateway4: '{{ ansible_default_ipv4.gateway }}'
        state: up
      - name: eth0
        type: ethernet
        interface_name: eth0
        persistent_state: present
        mac: "{{ ansible_default_ipv4.macaddress }}"
        master: bond0
        slave_type: bond
        state: up
  roles:
    - linux-system-roles.network
```

#### DHCP interfaces

Adding a new interface `eth1` with *dhcp* protocol for getting the IP address:

```yaml
- hosts: all,rhel-8-dev-7a95e9bb.psi.ch
  vars:
    network_allow_restart: yes
    network_connections:
      - name: eth1
        type: ethernet
        interface_name: eth1
        persistent_state: present
        mac: "0A:0B:0C:0D:0E:0F"
        ip:
          dhcp4: yes
        state: up
```

#### Using ethtool for changing interface settings

One can change network specific settings on an interface with ethtool. In example, we wante to disable `scatter-gather`:

```shell
[root@rhel-8-dev-7a95e9bb ~]# ethtool -k eth0 | grep scatter-gather
scatter-gather: on
	tx-scatter-gather: on
	tx-scatter-gather-fraglist: off [fixed]
```

We can modify with *ethtool* the interface to change this setting as follows:

```yaml
- hosts: all,rhel-8-dev-7a95e9bb.psi.ch
  vars:
    network_allow_restart: yes
    network_connections:
      - name: eth0
        type: ethernet
        interface_name: eth0
        persistent_state: present
        mac: "{{ ansible_default_ipv4.macaddress }}"
        ip:
          dhcp4: yes
        state: up
        ethtool:
          features:
            tx_scatter_gather: no
```

As a result, we disable `scatter-gather`.

```shell
[root@rhel-8-dev-7a95e9bb ~]# ethtool -k eth0 | grep scatter-gather
scatter-gather: off
	tx-scatter-gather: off
	tx-scatter-gather-fraglist: off [fixed]
```

---
### Icinga client (NRPE) and SNMP

#### NRPE

For enabling the Nagios client together with NRPE, is necesary to have EPEL in the system (either enabled or disabled). Also, one needs to enable `psi_icinga_client_configure_nrpe`. In case that EPEL is not available in the system, one can enable the installation of the repository from the module itself (by enabling `psi_icinga_client_configure_epel`, which takes it from the official EPEL repositories.

Important parameters are:
* `psi_icinga_client_nrpe_allowed_hosts` (`String`) where one should specify a comma separated list of allowed hosts. Usually, this will be centrally updated from the default variables inventory, however, when a new Nagios worker or server is setup, might be useful to update this setting until this is centrally changed.
* `psi_icinga_client_nrpe_dont_blame` (`Boolean`) , this option determines whether or not the NRPE daemon will allow clients to specify arguments to commands that are executed. Since this option is a security risk, is disabled by default. However, there are many cases where this is needed, so this is the reason why is provided (under administrator's responsability).
* `psi_icinga_client_nrpe_allow_bash_command_substitution` (`Boolean`) , which determines whether or not the NRPE daemon will allow clients to specify arguments that contain bash command substitutions of the form $(...). Since this is also a security risk, is default by default.
* Icinga checks, which have three different variables. The reason for that is that Ansible is not capable to merge down variables, and this is the way to workaround it. Each settins is a `Hash` where:
   * Item name is the file name that will be placed in `include_dir` (usually `/etc/nrpe.d/`).
   * For each item:
      * one or more `commands` can be specified, and will be placed in the same file
      * all commands specified in that file, might need sudo or not. One can enable `sudo` for that file, which will place the proper sudoers rules in the default sudoers location (usually `/etc/sudoers.d/`).  
   * The 3 variables are:
      * `psi_icinga_client_nagios_include_dir_checks` (`Hash`)
      * `psi_icinga_client_nagios_include_dir_checks_common` (`Hash`)
      * `psi_icinga_client_nagios_include_dir_checks_extra` (`Hash`)

An example for setting Icinga alarms is the following:

```yaml
# Allow different Icinga hosts (PSI workers)
psi_icinga_client_nrpe_allowed_hosts: "emonma00.psi.ch,vemonma00.psi.ch,wmonag00.psi.ch,emonag00.psi.ch,eadmin00.psi.ch,wadmin00.psi.ch,monaggfa.psi.ch,monaggfa2.psi.ch,monagxbl.psi.ch,wmonagcpt.psi.ch,vwmonagcpt.psi.ch,monagmisc.psi.ch,wmonagnet.psi.ch,vwmonagnet.psi.ch,monagsfel.psi.ch"

# Allow arguments: NRPE Don't Blame
psi_icinga_client_nrpe_dont_blame: True

# Allow arguments: Bash Command Substitution
psi_icinga_client_nrpe_allow_bash_command_substitution: True

# Define NRPE checks with and withou "sudo"
psi_icinga_client_nagios_include_dir_checks:
  system_checks:
    commands:
      - command: "check_disk"
        path: "{{ psi_icinga_client_nagios_plugins_dir }}/check_disk"
        arguments: "$ARG1$"
      - command: "check_load"
        path: "{{ psi_icinga_client_nagios_plugins_dir }}/check_load"
        arguments: "$ARG1$"psi_icinga_client_nagios_include_dir_checks_common

psi_icinga_client_nagios_include_dir_checks_common: {}

psi_icinga_client_nagios_include_dir_checks_extra:
  gpfs_checks:
    sudo: True
    commands:
      - command: "check_gpfs_health"
        path: "{{ psi_icinga_client_nagios_plugins_dir }}/check_gpfs_health"
        arguments: "--unhealth --ignore-tips"
```

#### SNMP

For enabling SNMP, one needs to enable `psi_icinga_client_configure_snmp`. Once enabled, default settings should be ok for most of the use cases. However, is important to update at least:
* `psi_icinga_client_snmpd_syscontact` (which defaults to *servicesdesk@psi.ch*)
* `psi_icinga_client_snmpd_rocommunity`, which by default contains only the *PSI public network* (129.129.0.0/16) and *localhost*. Hence, one needs to specify extra networks if necessary.

An example for configuring SNMP:

```yaml
# Configure SNMP
psi_icinga_client_configure_snmp: True
psi_icinga_client_snmpd_dontLogTCPWrappersConnects: true
psi_icinga_client_snmpd_trapcommunity: psi
psi_icinga_client_snmpd_syslocation: PSI
psi_icinga_client_snmpd_syscontact: marc.caubet@psi.ch
psi_icinga_client_snmpd_sysservices: 76
psi_icinga_client_snmpd_rocommunity:
  - community: psi
    network: 172.21.0.0/16
    oid: .1.3.6.1
  - community: psi
    network: 129.129.0.0/16
    oid: .1.3.6.1
  - community: psi
    network: 192.168.1.0/24
    oid: .1.3.6.1
  - community: psi
    network: localhost
    oid: .1.3.6.1
```
---
### Storage Configuration
Maintained by dorigo_a

#### Configuring a partition
Define the following variable:
```yaml
psi_local_storage_physical_volume:
  - /dev/<device>
```
This just tells to Ansible which device (or partition) must be used for the creation/modification of a volume group.
Multiple instances can be used; for example:
```yaml
psi_local_storage_physical_volumes:
  - /dev/sdb1
  - /dev/sdb2
  ...
  - /dev/sdb5
```


`<device>` can be either a block device (`sda`, `sdb`, …) or a partition previously (and manually) created in a block device using `fdisk/parted` (`sda1`, `sdc3`,...).

#### Configuring a volume group
```yaml
psi_local_storage_physical_name: <vg_name>
```
`<vg_name>` is the name of a new volume group or the name of an existing volume group in which one wants to create/modify logical volumes.
If the volume group already exists the role will simply add to it the new physical volumes specified in the previous variable `psi_local_storage_physical_volumes`, or no action is taken if the volume group is already built on top of the same physical volumes.

#### Configuring a logical volume
```yaml
psi_local_storage_logical_volumes:
  - name: <lv_name>
    size: N # size in unit of GB
    fstype: ext4 # or xfs
    mount_point: <somepath>
    createfs: <boolean_value>
```
The above configuration will do two different things depending on existence of `<lv_name>`. Please note that `psi_local_storage_logical_volumes` is a list of dictionaries, meaning that one can create/modify multiple logical volumes:
##### `<lv_name>` doesn’t exist
A logical volume name is created inside the volume group specified above (`<vg_name>`). It’s size will be N GBytes. If `<boolean_value>` is true then a filesystem will be created in the device `/dev/<vg_name>/<lv_name>` of type `fstype` and mounted persistently on `<somepath>`.
##### `<lv_name>` already exists and a filesystem is already present in it
The logical volume name `<lv_name>` is expanded (together with the filesystem) to `N` GBytes (only if `N` is greater than the current size). Filesystem is always expanded to fill up the entire volume group.
##### `<lv_name>` already exists and a filesystem is not present in it
The logical volume name `<lv_name>` is expanded (together with the filesystem) to `N` GB (only if `N` is greater than the current size); if `<boolean_value>` is true (or `yes`) then a filesystem of type `fstype` is created and mounted persistently on `<some_path>`.

#### Use Case 1: extending an existing partition after system first installation
ASSUMPTION 1: you have just installed a new system with the following partition scheme LVM-based:
```
[vagrant@your_server ~]$ df -h
Filesystem                    Size  Used Avail Use% Mounted on
devtmpfs                      393M     0  393M   0% /dev
tmpfs                         410M     0  410M   0% /dev/shm
tmpfs                         410M  5.7M  404M   2% /run
tmpfs                         410M     0  410M   0% /sys/fs/cgroup
/dev/mapper/cl-root            50G  2.6G   48G   6% /
/dev/sda1                     976M  183M  726M  21% /boot
/dev/mapper/cl-home            27G  225M   27G   1% /home
tmpfs                          82M     0   82M   0% /run/user/1000
/dev/mapper/myvg_root-first  1014M   40M  975M   4% /mnt/first
/dev/mapper/myvg_root-second  976M  2.6M  907M   1% /mnt/second
/dev/mapper/myvg_root-third  1014M   40M  975M   4% /mnt/third
```
ASSUMPTION 2: the partition scheme was not created by you (or by the automatic Tower system) using a specific playbook. It is just there and you do not like the current size of `/mnt/first` and/or `/mnt/second` and/or `/mnt/third`.

ASSUMPTION 3: the volume group/physical devices supporting the logical volumes `myvg_root-[first,second,third]` do have some extra un-allocated space you can use to extend the parition mounted on `/mnt/[first,second,third]`.

Write the following playbook (named `extend.yml`) assuming that you want the new partitions respectively resized to 4, 6 and 2 GB:
```
---
- name: Extend partition
  hosts: your_server.psi.ch
  roles:
    - name: psi.local_storage
      psi_local_storage_resizefs:
              - path: '/mnt/second'
                size: 4
              - path: '/mnt/third'
                size: 6
              - path: '/mnt/first'
                size: 2
...
```
Execute it with usual `ansible-playbook` command:
```
[vagrant@control ~]$ ansible-playbook extend.yml

PLAY [Extend storage] ******************************************************************************************************************************

TASK [Gathering Facts] *****************************************************************************************************************************
[DEPRECATION WARNING]: Distribution centos 8.2.2004 on host your_server should use /usr/libexec/platform-python, but is using /usr/bin/python for
backward compatibility with prior Ansible releases. A future Ansible release will default to using the discovered platform python for this host.
See https://docs.ansible.com/ansible/2.9/reference_appendices/interpreter_discovery.html for more information. This feature will be removed in
version 2.12. Deprecation warnings can be disabled by setting deprecation_warnings=False in ansible.cfg.
ok: [your_server]

TASK [psi.local_storage : Check that user specified a fstype which is supported] *******************************************************************

TASK [psi.local_storage : Ensure lmv2 package is installed] ****************************************************************************************
skipping: [your_server]

TASK [psi.local_storage : Create VG '' on physical volume '[]'] ************************************************************************************
skipping: [your_server]

TASK [psi.local_storage : Create logical volume(s) on ''] ******************************************************************************************

TASK [psi.local_storage : Create not mounted filesystem(s)] ****************************************************************************************

TASK [psi.local_storage : Mount filesystem(s)] *****************************************************************************************************

TASK [psi.local_storage : Resize Filesystem] *******************************************************************************************************
changed: [your_server] => (item={'path': '/mnt/second', 'size': 4})
changed: [your_server] => (item={'path': '/mnt/third', 'size': 6})
changed: [your_server] => (item={'path': '/mnt/first', 'size': 2})

PLAY RECAP *****************************************************************************************************************************************
your_server                    : ok=2    changed=1    unreachable=0    failed=0    skipped=6    rescued=0    ignored=0
```
#### Use Case 2: extending an existing partition after system first installation using additional device

ASSUMPTION 1: you have just installed a new system with the following partition scheme LVM-based:
```
[vagrant@your_server ~]$ df -h
Filesystem                    Size  Used Avail Use% Mounted on
devtmpfs                      393M     0  393M   0% /dev
tmpfs                         410M     0  410M   0% /dev/shm
tmpfs                         410M  5.7M  404M   2% /run
tmpfs                         410M     0  410M   0% /sys/fs/cgroup
/dev/mapper/cl-root            50G  2.6G   48G   6% /
/dev/sda1                     976M  183M  726M  21% /boot
/dev/mapper/cl-home            27G  225M   27G   1% /home
tmpfs                          82M     0   82M   0% /run/user/1000
/dev/mapper/myvg_root-first  1014M   40M  975M   4% /mnt/first
/dev/mapper/myvg_root-second  976M  2.6M  907M   1% /mnt/second
/dev/mapper/myvg_root-third  1014M   40M  975M   4% /mnt/third
```
ASSUMPTION 2: the partition scheme was not created by you (or by the automatic Tower system) using a specific playbook. It is just there and you do not like the current Size of `/mnt/first`

ASSUMPTION 3: you have a new HDD/SSD attached to your node and identified by device `/dev/sdc`, and you want to use it to expand the volume groups, logical volumes in order to be free to freely enlarge your partitions.

This procedure requires a bit more know-how on linux and logical volume management, but the following explanation will try to guide you as much as possible.

##### Step1 - Get Volume Group and physical devices
Identify the volume group associated with the partition `/mnt/first` you want to expand, by executing this:
```
[root@your_server ~]# theVG=$(lvdisplay $(df -h /mnt/first|grep /mnt/first|awk '{print $1}')|grep "VG Name"|awk '{print $NF}')
```

Identify the physical volumes on which the `vggroup` is built on:
```
[root@your_server ~]# vgdisplay -v $theVG |grep "PV Name"|awk '{print $NF}'
/dev/sdb1
/dev/sdb2
/dev/sdb3
```
Take notes of these three physical devices and remember that you will have to add to this list your new device `/dev/sdd`.

##### Step2 - Get Logical volume name and filesystem type

Execute the following command to get the logical volume name:
```
[root@your_server ~]# theLV=$(lvdisplay $(df -h /mnt/first|grep /mnt/first|awk '{print $1}')|grep "LV Name"|awk '{print $NF}')
[root@your_server ~]# echo $theLV
first
```
Identify the filesystem type by executing this command:
```
[root@your_server ~]# theFS=$(mount|grep "/mnt/first"|awk '{print $5}')
[root@your_server ~]# echo $theFS
xfs
```
##### Step3 - Prepare the ansible playbook

Write the following playbook (named `extend.yml`) taking care to use the correct volume group name (`theVG`), logical volume name (`theLV`) and the filesystem type (`theFS`); of course also keep unchanged the mount point:
```
---
- name: Extend storage
  hosts: your_server
  roles:
    - name: psi.local_storage
      psi_local_storage_physical_volumes:
              - /dev/sdb1
              - /dev/sdb2
              - /dev/sdb3
              - /dev/sdc # it doesn't matter that you didn't do any partition inside sdc; LVM is able to cope with RAW devices as well
      psi_local_storage_physical_name: 'myvg_root'
      psi_local_storage_logical_volumes:
              - name: 'first'
                size: 3
                fstype: 'xfs'
                mount_point: '/mnt/first'
                createfs: true
...
```
Note that we have put in the playbook the three devices that we found above (output of `vgdisplay`: `/dev/sdb[1,2,3]`) plus the new one `/dev/sdd`.

Also note that the original size of the `/mnt/first` filesystem was 1GB, now in the playbook we put 3 (implicit unit is GB).


Execute your playbook (suppose you called it as `extend.yml`):
```
[vagrant@control ~]$ ansible-playbook extend.yml

PLAY [Extend storage] **********************************************************************************************************************************************************************************************

TASK [Gathering Facts] *********************************************************************************************************************************************************************************************

TASK [psi.local_storage : Check that user specified a fstype which is supported] ***********************************************************************************************************************************
skipping: [your_server] => (item={'name': 'first', 'size': 3, 'fstype': 'xfs', 'mount_point': '/mnt/first', 'createfs': True})

TASK [psi.local_storage : Ensure lmv2 package is installed] ********************************************************************************************************************************************************
ok: [your_server]

TASK [psi.local_storage : Create VG 'myvg_root' on physical volume '['/dev/sdb1', '/dev/sdb2', '/dev/sdb3']'] ******************************************************************************************************
ok: [your_server]

TASK [psi.local_storage : Create logical volume(s) on 'myvg_root'] *************************************************************************************************************************************************
changed: [your_server] => (item={'name': 'first', 'size': 3, 'fstype': 'xfs', 'mount_point': '/mnt/first', 'createfs': True})

TASK [psi.local_storage : Create not mounted filesystem(s)] ********************************************************************************************************************************************************
ok: [your_server] => (item={'name': 'first', 'size': 3, 'fstype': 'xfs', 'mount_point': '/mnt/first', 'createfs': True})

TASK [psi.local_storage : Mount filesystem(s)] *********************************************************************************************************************************************************************
ok: [your_server] => (item={'name': 'first', 'size': 3, 'fstype': 'xfs', 'mount_point': '/mnt/first', 'createfs': True})

TASK [psi.local_storage : Resize XFS filesystem(s)] ****************************************************************************************************************************************************************
changed: [your_server] => (item={'name': 'first', 'size': 3, 'fstype': 'xfs', 'mount_point': '/mnt/first', 'createfs': True})

TASK [psi.local_storage : Resize EXT filesystem(s)] ****************************************************************************************************************************************************************
skipping: [your_server] => (item={'name': 'first', 'size': 3, 'fstype': 'xfs', 'mount_point': '/mnt/first', 'createfs': True})

PLAY RECAP *********************************************************************************************************************************************************************************************************
your_server                    : ok=7    changed=2    unreachable=0    failed=0    skipped=2    rescued=0    ignored=0   
```

And now check the size of `/mnt/first` on your your_server node:
```
[root@your_server ~]# df -h
Filesystem                    Size  Used Avail Use% Mounted on
devtmpfs                      393M     0  393M   0% /dev
tmpfs                         410M     0  410M   0% /dev/shm
tmpfs                         410M  5.7M  404M   2% /run
tmpfs                         410M     0  410M   0% /sys/fs/cgroup
/dev/mapper/cl-root            50G  2.6G   48G   6% /
/dev/sda1                     976M  183M  726M  21% /boot
/dev/mapper/cl-home            27G  225M   27G   1% /home
tmpfs                          82M     0   82M   0% /run/user/1000
/dev/mapper/myvg_root-first   3.0G   55M  3.0G   2% /mnt/first
/dev/mapper/myvg_root-second  976M  2.6M  907M   1% /mnt/second
/dev/mapper/myvg_root-third  1014M   40M  975M   4% /mnt/third

```

#### Mount mountpoints
Define the following dictionary:
```yaml
psi_mounts_mounts:
  - fstype: <ext4|xfs>
    mount_point: <somepath>
    device: /dev/<somedevice_or_lvm>
    options: <otps-to-be-put-in-fstab>
    state: mounted|unmounted|absent|present|remounted
  - fstype: <ext4|xfs>
    mount_point: <somepath2>
    device: /dev/<somedevice_or_lvm>
    options: <otps-to-be-put-in-fstab>
    state: mounted|unmounted|absent|present|remounted
  - [...]
```
and run this playbook.
Note that block devices `/dev/something` must already be there and filesystem must me created.
   * `mounted/unmounted` has a clear meaning
   * `absent/present` concern the presence or not of the mount directive in /etc/fstab to have the mount automatically done at every boot of the system
   * `remounted` means that you want to remount the partition because, for example, you changed some parameter or option.

---
### System Registration
Maintained by spreitzer_s

Basically your system should receive default values that are supplied globally, from the PSI Default Inventory in GitLab and AWX, to successfully register it with Satellite, so it will have access to software repositories automatically.

However the following settings can be made.

```yaml
psi_subscription_manager_activation_key: RHEL8-GFA
psi_subscription_manager_org: PSI
psi_subscription_manager_server: satint.psi.ch
psi_subscription_manager_force_register: 'False'
```

#### psi_subscription_manager_activation_key
The Satellite activation key to use. Usually something that starts with `RHEL8-`.

#### psi_subscription_manager_org
The Satellite Organization to use. Usually `PSI`.

#### psi_subscription_manager_server
The Satellite to register with. Usually `satint.psi.ch`.

#### psi_subscription_manager_force_register
Whether to or not run the subscription-management enforced. Usually `true` to ensure a system has software access.

---
### SELinux
Maintained by caubet_m

This documentation shows how to manage SELinux with the Ansible *selinux* role. More examples can be found in the  **['linux-system-roles' Official GitHUB Project Webpage](https://github.com/linux-system-roles/selinux)**

#### Enabling/Disabling SELinux

The defaults at PSI are:

```yaml
selinux_state: enforcing
selinux_policy: targeted
```
* Allowed values for **`selinux_state`** are `disabled`, `enforcing` and `permissive`.
* Allowed values for **`selinux_policy`** are `targeted`, and `mls`.

#### (Un)Setting SELinux booleans

Common examples for setting SELinux booleans are the following:
* Enabling the `use_nfs_home_dirs` Boolean to allow the usage of NFS based home directories, and make it persistent accross machine reboots.
* Enabling the `httpd_use_nfs` Boolean to allow *httpd* to access and share NFS volumes.

```yaml
selinux_booleans:
  - name: use_nfs_home_dirs
    state: on
    persistent: 'yes'
  - name: httpd_use_nfs
    state: on
```
 Enable the httpd_use_nfs Boolean to allow httpd to access and share NFS volumes (labeled with the nfs_t type):

#### Set SELinux file contexts

In this example, we set /tmp/test_dir directories with `user_home_dir_t` context.

```yaml
selinux_fcontexts:
  - target: '/tmp/test_dir(/.*)?'
    setype: user_home_dir_t
    ftype: d
    state: present
```

#### Set SELinux Ports

In the example below, we allow SSH to use TCP port 22100, in that way we can tell *sshd* to listen on a non-standard port 22100 instead of the standard port 22. For that, we would neeed to update also `/etc/ssh/sshd_config` by changing `Port 22`to `Port 22100`.

```yaml
selinux_ports:
  - ports: '22100'
    proto: tcp
    setype: ssh_port_t
```

* (Persistent file contextes, semanage fcontext, if you have time)

#### Set linux user to SELinux mapping

When `selinux_policy: mls`, one would need to update linux users to SELinux users mapping.

In the example, we remove `feichtinger` from `staff_u`, and we add a new user `caubet_m`, as well as a generic username `staff`, to be mapped to the SELinux user `staff_u` (`caubet_m`, has more security privileges than a generic `staff` user; this is defined with `serange`). On the other hand, we set that any other not mapped user (`__default__`), should be mapped to the SELinux user `user_u`. Any user mapped in that way, have very low security level (`s0`, which is the lowest).

```yaml
selinux_logins:
  - login: feichtinger
    seuser: staff_u
    state: absent
  - login: caubet_m
    seuser: staff_u
    serange: 's0-s15:c0.c1023'
  - login: staff
    seuser: staff_u
    serange: 's2:c100'
  - login: __default__
    seuser: user_u
    serange: 's0-s0:'

```

In example:

```bash
[root@hpc-rhel8devel01 home]# semanage login -l

__default__          user_u               s0-s0                *
caubet_m             staff_u              s0-s15:c0.c1023      *
root                 root                 s0-s15:c0.c1023      *
staff                staff_u              s2:c100              *
sysadm               staff_u              s0-s15:c0.c1023      *
system_u             system_u             s0-s15:c0.c1023      *
```

#### Restorecon

Run `restorecon` on filesystem trees for applying `selinux` policies:

```yaml
selinux_restore_dirs:
  - /var
  - /tmp
```

---
### Systemd Services
Maintained by caubet_m

This role creates by default **systemd** **service** *units*, however, is also possible to configure
other system *units* such like **slice**, **socket**, **timers*, **mount**, etc.

Full examples for the **systemd** Ansible role can be found in the **['0x0I' Official GitHUB Project Webpage](https://github.com/0x0I/ansible-role-systemd#role-variables)**. The example below, shows how to create different *systemd* units: *service*, *socket*, *mount*, *target* and *timer*

```yaml
unit_config:
  - name: "test-service"
    Unit:
      Description: "This is a test service unit which listens at port 1234"
      After: network-online.target
      Wants: network-online.target
      Requires: test-service.socket
    Service:
      User: 'kitchen'
      Group: 'kitchen'
      ExecStart: '/usr/bin/sleep infinity'
      ExecReload: '/bin/kill -s HUP $MAINPID'
    Install:
      WantedBy: 'multi-user.target'
  - name: "test-service"
    type: "socket"
    Unit:
      Description: "This is a test socket unit which specifies the test-service 'socket' unit type"
    Socket:
      ListenStream: '0.0.0.0:1234'
      Accept: 'true'
    Install:
      WantedBy: 'sockets.target'
  - name: "tmp-stdin"
    type: "mount"
    path: "/run/systemd/system"
    Unit:
      Description: "This is a test mount unit which overrides the default unit path"
    Mount:
      What: '/dev/stdin'
      Where: '/tmp/stdin'
    Install:
      WantedBy: 'mount.target'
  - name: "test-target"
    type: "target"
    path: "/etc/systemd/system"
    Unit:
      Description: This is an example unit Target
      Wants: test-service.service test-service.socket tmp-stdin.mount
      PartOf: test-service.service
   - name: dnf-makecache
     type: timer
     Unit:
      Description: "This is a test timer unit which refreshes dnf cache"
     Timer:
       OnBootSec: 10min
       OnUnitInactiveSec: 1h
       Unit: dnf-makecache.service
     Install:
       WantedBy: multi-user.target
```

---
### System Time/NTP
Maintained by caubet_m

This document describes how to configure the system 'time' on RHEL8 based systems. Current *defaults* should fit for most of the cases at PSI:
* The recommended service on RHEL8 systems for configuring *system time* is **`chrony`**
* PSI provides different NTP servers which should be accessible by most of the PSI subnets:
   * `pstime1.psi.ch`
   * `pstime2.psi.ch`
   * `pstime3.psi.ch`
* We usually apply custom settings in Chrony or logging and rapid clock measuring during boot time:
   * We setup `initstepslew` to `60` seconds. It is, if system's error is found to be 60 seconds or less, a slew will be used to correct it; if the error is above 60 seconds, a step will be used.
   * We log different metrics which would help to debug different timesync related problems: `measurements statistics tracking`

Example of default configuration at PSI, which should be adapted according to your needs:

```yaml
# linux-system-roles.timesync settings
timesync_chrony_custom_settings:
  - "# Allow chronyd to make a rapid measurement of the system and correct clock error at boot time"
  - "initstepslew 60 pstime1.psi.ch pstime2.psi.ch pstime3.psi.ch"
  - "# Select which information is logged."
  - "log measurements statistics tracking"
timesync_ntp_provider: chrony
timesync_ntp_servers:
  - hostname: pstime1.psi.ch
  - hostname: pstime2.psi.ch
  - hostname: pstime3.psi.ch
```

---
### User Management
Maintained by spreitzer_s

User management is divided in two parts:
* PSI Active Directory
* Local system

**Overall users and group and group memberships must be managed in Active Directory!** Please consult the PSI Service Catalog to request users, groups and group membership as well as their removal. http://css.psi.ch/psisp

*Use `*_common` for inventory group variables and `*_extra` for host variables.*

#### psi_aaa_allow_groups{_common,_extra}

List of groups that are allowed to login to a system.

```yaml
psi_aaa_allow_groups_extra:
  - unx-ait
  - unx-sls
```

#### psi_aaa_allow_users{_common,_extra}

List of users that are allowed to login to a system. *Prefer using groups over users!*

```yaml
psi_aaa_allow_users_extra:
  - kapeller
  - talamo_i
```

### Local User Management
{{% alert text="Do not use this method, prefer Active Directory for users" %}}

#### psi_aaa_local_sudo_rules{_common,_extra}

Manage local sudo roles by lists of (name, content and state). Be very cautios with the sudo rules, as one faulty rule will break sudo for the whole system.

```yaml
psi_aaa_local_sudo_rules_extra:
  - name: sspreitz-root-nopasswd
    content: "sspreitz ALL=(ALL) NOPASSWD: ALL\n"
  - name: group-wheel-root-nopasswd
    content: "%wheel ALL=(ALL) NOPASSWD: ALL\n"
  - name: linuxsupport-root-nopasswd
    content: |
      jill ALL=(ALL) NOPASSWD: ALL
      joe  ALL=(ALL) NOPASSWD: ALL
      jack ALL=(ALL) NOPASSWD: ALL
      tom  ALL=(ALL) NOPASSWD: ALL
  - name: sam-root-nopasswd
    state: absent
```

#### psi_aaa_local_groups{_common,_extra}

Manage local groups by a list of ansible group definitions. https://docs.ansible.com/ansible/latest/collections/ansible/builtin/group_module.html

```yaml
psi_aaa_local_groups_extra:
  - name: group1
    gid: 30000
  - name: group2
  - name: support
    system: yes
  - name: group3
    state: absent
```

#### psi_aaa_local_users{_common,_extra}

Manage local users by a list of ansible user definitions. https://docs.ansible.com/ansible/latest/collections/ansible/builtin/user_module.html

```yaml
psi_aaa_local_users_extra:
  - name: guest
  - name: joe
    uid: 1000
    group: group1
    groups:
      - wheel
      - staff
      - audio
    home: /home/joe
    shell: /bin/fish
    # mkpasswd -m sha512crypt joe
    password: '$6$Mrq9msM24W$boAK1IYwuG6ze1qgk.HpqMqvj/zRThT2fTrb80kJTAiMg1CNXjbEEMH7A8KwAeKQJZuF14KRrpOK5NXxYvqqn1'
  - name: jill
    state: absent
    remove: yes
```

#### psi_aaa_local_authorized_keys{_common,_extra}

Manage local ssh authorized keys by ansible ssh authorized keys definitions. https://docs.ansible.com/ansible/latest/collections/ansible/posix/authorized_key_module.html

```yaml
psi_aaa_local_authorized_keys_extra:
  - user: sspreitz
    key: 'ssh-rsa AAAAB3NzaC1yc2EAAAADAQABAAABAQC9gU640HBk4m0OA4b2ziTCnVP6QYhs2Zs/LJWTN85+vCudgZfiMip2MAAR0OlOVtB4JYXJh83Rihj0REA13ei3akAPzgG+B4Qlk3QYA2Bf2YDjRGqwgpmhVlTNgJy+l9lS9rn5kPheXTi1GOgGVKi4jd5f6TuYhMBmSl64oCtWnanIwXd/u6teStTd7V0HKgev+GbAvTJPFoxOHFSV51mMvFkkW0s0cPTwLvekAPsnjw4ztEoX8Ar72U+KOnt6YLOEuKB0bKZ4PKTEz7woltDcXKzN9g5HKSY+RgSk9APrOol+HVgs841/1KChri7xPao4J1OzU0Ap6wkG+GfqPVc/ sspreitz@redhat.com'
  - user: evil
    key: 'ssh-rsa AAAAB3NzaC1yc2EAAAADAQABAAABAQC9gU640HBk4m0OA4b2ziTCnVP6QYhs2Zs/LJWTN85+vCudgZfiMip2MAAR0OlOVtB4JYXJh83Rihj0REA13ei3akAPzgG+B4Qlk3QYA2Bf2YDjRGqwgpmhVlTNgJy+l9lS9rn5kPheXTi1GOgGVKi4jd5f6TuYhMBmSl64oCtWnanIwXd/u6teStTd7V0HKgev+GbAvTJPFoxOHFSV51mMvFkkW0s0cPTwLvekAPsnjw4ztEoX8Ar72U+KOnt6YLOEuKB0bKZ4PKTEz7woltDcXKzN9g5HKSY+RgSk9APrOol+HVgs841/1KChri7xPao4J1OzU0Ap6wkG+GfqPVc/ mrevil@example.com'
    state: absent
```

---
### Software Management
Maintained by klar_t

#### psi_packer_repo

A merged dictionary of yum repository definitions

#### psi_packer_inst

A merged list of rpm packages to be installed

#### psi_packer_rem

A merged list of rpm packages to be removed

#### psi_packer_update

`true` or `false` on whether to update all packages on each ansible run

#### Important

the `psi_packer_repo` and the `psi_packer_inst` variables are merged.
It is a wildcard merge, so any suffix can be used, but it is recommended to use the group- or hostname, so there is no accidental overlap.
The list of enabled and the list of disabled repos will be added to the repo file only. Otherwise a repo may e defined but will be ignored.
These 2 lists are also wildcard merged.

```yaml
- hosts: servers
  vars:
    psi_packer_update: true
    psi_packer_repo_group:
      myrepo:
        description: This is my repo
        baseurl: http://example.com/repos/myrepo/
        gpgcheck: yes
        gpgkey: file:///etc/pki/rpm-gpg/RPM-GPG-KEY-myrepo
    psi_packer_repo_host:
      myotherrepo:
        description: This is my other repo
        baseurl: http://example.com/repos/myotherrepo/
        gpgcheck: yes
        gpgkey: file:///etc/pki/rpm-gpg/RPM-GPG-KEY-myrepo
    psi_packer_enabled_repos_group:
      - myrepo
    psi_packer_disabled_repos_host:
      - myotherrepo
    psi_packer_inst_group:
      - httpd
      - mariadb
    psi_packer_inst_host:
      - mc
      - nano
    psi_packer_del_group:
      - matlab
      - office
    psi_packer_del_host:
      - kernel-devel
      - afs
  roles:
     - psi.packer
```
---
### AFS
Maintained by klar_t

Note: AFS and AFS homes are not enabled by default in RHEL-8.

PSI Linux Engineering does not support AFS and AFS homes. Contact Achim Gsell if you need AFS and AFS homes.

LVM partitioning and free space on the root VG are necessary to use this role. (The VG is selected based on where the root file system is located, the actual name does not matter)

#### psi_yfs_size

Default: `2147483648`

Cache LV size, strictly in bytes

#### psi_yfs_remove

Default: `false`

Set this to true and remove everything the role would have installed


#### Example Playbook

An example of how to use this role (with variables passed in as parameters).

```yaml
- hosts: servers
  roles:
     - psi.yfs
  psi_yfs_size: 2147483648
```
