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reworded the overlay section

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Christian Goll
2023-02-16 08:59:31 +01:00
parent cb06dc8ba0
commit 466d141cf4
1 changed files with 36 additions and 13 deletions
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49
userdocs/contents/overlays.rst
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@@ -11,23 +11,14 @@ Warewulf solves this with overlays and uses overlays in different ways through t
* Before boot, these overlays are called **system overlay** or **wwinit overlay**
* After boot into the running system which are the **runtime overlay** or **generic overlay**.
For both types preconfigured overlays are installed. Also for both types several overlays combined as list in the node/profile configuration. For conflicting files, the file of last defined one will be used.
The default profile of warewulf has this two profiles enabled.
Overlays are compiled for each compute node individually and should not contain static files.
Defined Overlays
================
Host Overlay
------------
In the host overlay the configuration files used for the configuration of the provision service are stored. In opposite the other overlays, it *must* have the name `host` and is stored under `/usr/share/warewulf/overlays/host/`. Existing file on the host are copied to backup file with `wwbackup` suffix at the first run. Subsequent builds of the host overlay won't overwrite the `wwbackup` file.
Following services get configuration files via templates
* ssh for which are keys created with the scrips `ssh_setup.sh` and `ssh_setup.csh`
* hosts entries are created by manipulating `/etc/hosts` with the template `hosts.ww`
* nfs kernel server receives its exports from the template `exports.ww`
* the dhcpd service is configured with `dhcpd.conf.ww`
System or wwinit overlay
------------------------
@@ -44,12 +35,41 @@ Before the `systemd` init is called, the overlay loops through the scripts in `/
* selinux
Runtime Overlay or generic Overlay
==================================
----------------------------------
The runtime overlay is updated by the `wwclient` service on a regular base (every minute per default). In the standard configuration it includes updates for `/etc/passwd`, `/etc/group` and `/etc/hosts`. Additionally the `authorized_keys` file of the root user is updated.
It recommended to use this overlay for dynamic configuration files like `slurm.conf`.
Once the system is provisioned and booted, the ``wwclient`` program (which is provisioned as part of the ``wwinit`` system overlay) will continuously update the node with updates in the runtime overlay.
Host Overlay
------------
In the host overlay the configuration files used for the configuration of the provision service are stored. In opposite the other overlays, it *must* have the name `host` and is stored under `/usr/share/warewulf/overlays/host/`. Existing file on the host are copied to backup file with `wwbackup` suffix at the first run. Subsequent builds of the host overlay won't overwrite the `wwbackup` file.
Following services get configuration files via templates
* ssh for which are keys created with the scrips `ssh_setup.sh` and `ssh_setup.csh`
* hosts entries are created by manipulating `/etc/hosts` with the template `hosts.ww`
* nfs kernel server receives its exports from the template `exports.ww`
* the dhcpd service is configured with `dhcpd.conf.ww`
Combining Overlay
=================
For changes in the overlays its recommended no to change them, but add the changed files to a new overlay and combine them in the configuration. This is possible as the configuration fields for the **wwinit** and **runtime** overlays are lists and can contain several overlays.
As an example for this, we will overwrite the `/etc/issue` file from the **Wwinit** overlay.
For this we will create a new overlay called welcome and import the file `/etc/issue` from the host to it. This profile is then combined with the existing **wwinit** overlay.
..code-block:: bash
$ wwctl overlay create welcome
$ wwctl overlay mkdir welcome /etc
$ wwctl overlay import welcome /etc/issue
$ wwctl profile set default --wwinit=wwinit,welcome
? Are you sure you want to modify 1 profile(s)? [y/N] y
$ wwctl profile list default -a |grep welcome
default SystemOverlay wwinit,welcome
Templates
=========
@@ -67,6 +87,9 @@ Using Overlays
Warewulf includes a command group for manipulating overlays (``wwctl overlay``). With this you can add, edit, remove, change ownership, permissions, etc.
..note::
There is now possibility to delete files with an overlay!
Build
-----