185 lines
5.6 KiB
Text
185 lines
5.6 KiB
Text
cdist-tutorial(7)
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=================
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Nico Schottelius <nico-cdist--@--schottelius.org>
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NAME
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----
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cdist-tutorial - a guided introduction into cdist
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INTRODUCTION
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------------
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This tutorial is aimed at people learning cdist and shows
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typical approaches as well as gives an easy start into
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the world of configuration management.
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This tutorial assumes you are configuring **localhost**, because
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it is always available. Just replace **localhost** with your target
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host for real life usage.
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QUICK START - GET YOUR HANDS DIRTY NOW
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--------------------------------------
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For those who just want to configure a system with the
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cdist configuration management and do not need (or want)
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to understand everything.
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Cdist uses **ssh** for communication and transportation
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and usually logs into the **target host** as the
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**root** user. So you need to configure the **ssh server**
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of the target host to allow root logins: Edit
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the file **/etc/ssh/sshd_config** and add one of the following
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lines:
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--------------------------------------------------------------------------------
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# Allow login only via public key
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PermitRootLogin without-password
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# Allow login via password and public key
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PermitRootLogin yes
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--------------------------------------------------------------------------------
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As cdist uses ssh intensively, it is recommended to setup authentication
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with public keys:
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--------------------------------------------------------------------------------
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# Generate pubkey pair as a normal user
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ssh-keygen
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# Copy pubkey over to target host
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ssh-copy-id root@localhost
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--------------------------------------------------------------------------------
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Have a look at ssh-agent(1) and ssh-add(1) on how to cache the password for
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your public key. Usually it looks like this:
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--------------------------------------------------------------------------------
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# Start agent and export variables
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eval `ssh-agent`
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# Add keys (requires password for every identity file)
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ssh-add
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--------------------------------------------------------------------------------
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At this point you should be able to ***ssh root@localhost*** without
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re-entering the password. If something failed until here, ensure that
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all steps went successfully and you have read and understood the
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documentation.
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As soon as you are able to login without passwort to the target host,
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we can use cdist to configure it. You can copy and paste the following
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code into your shell to get started and configure localhost:
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# Get cdist
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git clone git://git.schottelius.org/cdist
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# Create manifest (maps configuration to host(s)
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cd cdist
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echo '__file /etc/cdist-configured' > conf/manifest/init
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# Configure localhost in verbose mode
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./bin/cdist config -v localhost
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# Find out that cdist created /etc/cdist-configured
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ls -l /etc/cdist-configured
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--------------------------------------------------------------------------------
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That's it, you've successfully used cdist to configure your first host!
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Continue reading the next sections, to understand what you did and how
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to create a more sophisticated configuration.
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The file 'conf/manifest/init' is usually the entry point for cdist,
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to find out what to configure on which host. All manifests are
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essentially shell scripts. Every manifest can use the types known to
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cdist, which are usually underline prefixed (__).
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DEFINE STATE IN THE INITIAL MANIFEST
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------------------------------------
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The **initial manifest** is the entry point for cdist to find out, which
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**objects** to configure on the selected host. Objects are instances of
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**types**, like in object orientated programming. An object is represented
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by the type + slash + object name: ***__file/etc/cdist-configured*** is an
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object of the type ***__file*** with the name ***etc/cdist-configured***.
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Cdist searches for the initial manifest at **conf/manifest/init** and
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executes it as a shell script using **/bin/sh -e**.
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Within this initial manifest, you define, which objects should be
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created on which host. To distinguish between hosts, you can use the
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environment variable **__target_host**. Let's have a look at a simple
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example:
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__file /etc/cdist-configured
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case "$__target_host" in
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localhost)
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__directory /home/services/kvm-vm --parents yes
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;;
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esac
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This manifest says: Independent of the host, always create the (empty) file
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***/etc/cdist-configured***, but create the directory ***/home/services/kvm-vm***,
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including all parent directories, only on the host ***localhost***.
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As you can see, there is no magic involved, the manifest is simple shell code that
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utilises cdist types.
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PARTS BELOW HERE ARE TO-BE-DONE
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MORE ABOUT TYPES AND OBJECTS
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----------------------------
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All available types in cdist can be called like normal executables.
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USING SOME BASIC TYPES
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----------------------
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what is a type, how to use it,
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CREATING YOUR FIRST OWN TYPE
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----------------------------
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<with object id? or signleton here already>
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USE A TYPE TO BUNDLE FUNCTIONALITY
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----------------------------------
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USING EXPLORERS
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---------------
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global, type explorer
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DEBUGGING YOUR TYPES
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--------------------
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__debug::
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If this variable is setup, cdist runs in debug mode.
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You can use this information, to only output stuff in debug
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mode as well.
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Available for: initial manifest, type manifest, gencode, code
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BRANCHES IN HERE?
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------------
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TUNING CDIST
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------------
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- speedup processing with ControlMaster option of
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ssh
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SEE ALSO
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--------
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cdist(1), cdist-type(7), cdist-stages(7)
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