135 lines
4.6 KiB
Markdown
135 lines
4.6 KiB
Markdown
[[!meta title="Sexy and cdist @ local.ch"]]
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## Introduction
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This article describes the real world setup of
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[[sexy|software/sexy]] and
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[[cdist|software/cdist]] at [local.ch](http://www.local.ch).
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Sexy and cdist are used to configure
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* dhcp servers
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* dns servers
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* KVM hosts
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at local.ch.
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As I am soon leaving local.ch, this blog post is written for
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those interested in sexy and cdist, as well as the other
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sysadmins at local.ch to remember how things are setup.
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The following picture will give you a general impression how things
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are setup.
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[[!img sexy-cdist-interaction-local.ch.png alt="How cdist and sexy act at local.ch"]]
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## Sexy installation
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As you may be aware, sexy is an inventory management utility. It manages
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**hosts** and **IPv4 networks** (IPv6 support planned - but currently not required).
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Sexy uses a [[cconfig|docs/cconfig]] database, which is stored at **~/.sexy**.
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At local.ch, almost all important configurations are backed up at
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[github](http://www.github.com). The sexy database is backed up there in a private
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repository named **sexy-database**.
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Sexy requires only Python 3 to be installed.
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### Sexy database
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[[!img sexy-database-overview.png alt="Overview of the sexy database"]]
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As you can see in the above image,
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the sexy database contains three databases:
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* host
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* mac
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* net-ipv4
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The **host** database contain all hosts, including mac addresses, host type (VM or hardware),
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network cards, etc.
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The **mac** database contains the prefix for generating new mac addresses (we are using 00:16:3e -
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guess which vendor it is!) and the used mac addresses. The mac database is essentially used
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for generating mac addresses for virtual machines.
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The **net-ipv4** database contains the configured **IPv4 networks**.
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Each IPv4 network contains
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* the network mask
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* last used address
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* list of free addresses
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* list of hosts
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Every hosts in an **IPv4 network** contains
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* an IPv4 address
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* a mac address
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### Sexy backends
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Sexy uses backends to interact with other systems. As can be seen
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below, both the **host** and **net-ipv4** backends write configuration
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files in cdist.
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[[!img sexy-backends-local.ch.png alt="Sexy backends @local.ch"]]
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Sexy outputs the VM to KVM host mapping into a cdist manifest stored in
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**cdist/manifest/kvm-hosts**. The cdist type **\_\_localch_kvm_vm** is
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being used to create VMs.
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Sexy also generates [BIND](https://www.isc.org/downloads/bind/) zone files
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as well as [DHCP](https://www.isc.org/downloads/DHCP/) configuration files.
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These files are stored within the cdist types
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**\_\_localch_bind** and **\_\_localch_dhcpd**.
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## cdist installation
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Similar to sexy, cdist requires only Python 3 to be installed, but only on the
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computer you use to configure the target hosts. The target hosts only require
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shell and ssh.
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cdist normally reads its configuration from **~/.cdist**. As the
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current installation is old-style, the custom configuration and cdist code
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is both stored at **~/localch/vcs/cdist**, which is also backed up
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as a private repository named **cdist** at github.
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cdist is currently being used directly from the sysadmin notebooks and thus
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requires to synchronise the repository before running.
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cdist is being utilised using scripts from the **sysadmin-logs** repository,
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which are stored in the **cdist** folder. They mainly wrap around
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**cdist config -vp <hostnames...>**.
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## Interaction with other systems
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### Sexy connection to cdist
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To be able to interact with cdist, the sexy backends do have some paths hardcoded.
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One of them being **~/localch/vcs/cdist**, which refers to the cdist installation.
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On **sexy host apply --all**, sexy will regenerate the
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cdist manifest **~/localch/vcs/cdist/conf/manifest/kvm-hosts**, which contains
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the configuration for all kvm hosts.
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### cdist with dhcp and dns servers
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To configure the dhcp servers, the script **sysadmin-logs/cdist/dhcp-servers** can
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be used, to configure the dns servers, the script
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**sysadmin-logs/cdist/dns-servers** can be used.
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If you want to change both systems at the same time, the
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script **sysadmin-logs/cdist/dhcp-dns-together**.
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All three scripts depend on sexy and the sexy database being installed, as they lookup
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the host names using sexy.
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### cdist creates virtual machines
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The KVM infrastructure is based on very simple assumptions: All files are contained
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on the host, machines are started from simple shell scripts. The shell scripts are
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maintained or created within cdist. Virtual machines are not started by default,
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because the installation process is triggered manually at PXE bootup.
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## Outlook
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In one of the next articles I'll cover the KVM VM infrastructure of local.ch.
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