205 lines
5.5 KiB
Markdown
205 lines
5.5 KiB
Markdown
## TO DOC
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Before initial release, document:
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- how to add package backends
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- how to write a minimal host manifest
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- create library with all functions (and their parameters)
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- cdist_package
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- cdist_file
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- cdist_dir
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- only do necessary work
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- install packages only if not existent
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- copy file only if different
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- how to write a module
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- module function autoloading via *.sh
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- module "manifest"?
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- create functions in *.sh
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- name functions "modulename_function"
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module hellow
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function kitty
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=> hellow_kitty
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- you are advised (not forced) to put files
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to a subdirectory named "files"
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## Testing cdist
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cdist-build-explorer| ssh localhost
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set -e
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git clone git://git.schottelius.org/cdist
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cd cdist
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export PATH=$PATH:$(pwd -P)/bin
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cdist-build-explorer | ssh localhost
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## Architecture
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- User write shell scripts, which are run on the server
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- Shell scripts call cdist functions
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- cdist functions generate cconfig, which can be verified
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- if verified, generate "command file" to execute on the client
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- client only sees the commands
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- no special requirements on the client
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## next: cdist-deploy-to
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- sync conf/{lib/,modules,host/$name}
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## Introduction
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cdist configures your system. It is similar to
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[cfengine](http://www.cfengine.org/) and
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[puppet](http://www.puppetlabs.com/).
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It is inspired by both of those tools:
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* Try to redo the great power you get
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* But leave out the bugs you also got
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### Principles
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cdist is unix: It's designed to reuse existing tools
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and does not need high level scripting language interpreters.
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### Requirements
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* A posix like shell
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## How cdist works
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### Exploring your system
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cdist analyses the system to apply the configuration on and
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selects the right backends. You can use ***cdist-explore*** to
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the results of the explore functions.
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### Applying the configuration
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cdist looks for the configuration to apply on the local host
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and applies it using ***cdist-apply***.
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### Managing many hosts
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Whereas ***cdist-apply*** manages one host, ***cdist-deploy***
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applies the configuration on enabled hosts.
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## How to use cdist?
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0. Create a host specification (/etc/cdist/hosts/**hostname**)
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0. Add functionalilty to add
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0. Run ***cdist-apply***
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## What do I need [from puppet?]
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### Abstraction of package managers
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I don't want to care about apt, rpm, yum, pacman, etc. I just
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want to ensure, some package exists or does not exist.
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### Common tasks already done
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- [LIBRARY] All the helper types like
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- file
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- ssh_keys
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- package
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- service
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- user
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### PORTABILITY
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- [PORTABILITY] clients for every unix
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- mostly ruby + facter in puppet
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### Other
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- Modules: Nice to put stuff together
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- and reuse
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- [CONDITIONS] facter is cool
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- the DSL
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- with many bugs
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- templates
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- Client/Server approach is nice to have
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- Clients only get the part of the documentation, that's
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relevant to them
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- detect impossible/unsafe things:
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- creating a file twice
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- installing and removing a package
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- and report location of occurence
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- parse afterwards?
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--------------------------------------------------------------------------------
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what is puppet? [FOR ME]
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A configuration deployment assistant,
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a DSL that allows you define the objectives.
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A webserver with fileserver capabilities.
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A client based scheduled polling infrastructure.
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--------------------------------------------------------------------------------
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What do I miss from puppet?
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- speed
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- elegance
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- clean design
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- documentation
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- the "no surprise" factor
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- easy to use "data memory" (i.e. external ressources)
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- easy integration into installation process
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- copy identity to master
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- multi master setups
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- development configurations / tests
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- editing of configuration files
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- similar to cfengine
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- replace bug squasher with bug avoidance
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- qmail did not need one either
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- push infrastructure
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- real / meaningful error messages
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--------------------------------------------------------------------------------
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Simple stuff done by Unix[notm]
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- DSL: Shell!
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- gives if, else and EVEN elsif for free!
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- and case
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- and and and
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- and there's no os (solaris doesn't count) without a usable /bin/sh
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- cdist defines what you can use
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- you _can_ use os specific stuff
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- but it's ugly and you shoot into your own foot
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- "manifests" (use the same name here?) will be run/sourced
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- inheritance possible via sourcing
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- cdist-lib always preloaded
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- library == functions?
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- version control via git
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- file distribution via ssh
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- authentication via ssh
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- dumb clients, similar to manifest compile in puppet
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- clients just execute commands
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- dependencies via make?
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- how to ensure sigletons / conflicting definitions?
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file { "/a":
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ensure => present,
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file { "/a":
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ensure => absent,
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- matching on explored items, not only on host name?
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- match function in host? [optional]
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- file source:
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- relative to specification
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- or absolute
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--------------------------------------------------------------------------------
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Architecture
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--------------------------------------------------------------------------------
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Implementation
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"cdist-server"
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-> called by cron?
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-> no need to reimplement scheduling
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"cdist-explore" (facter replacement)
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-> running on the client
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