140 lines
4.5 KiB
ReStructuredText
140 lines
4.5 KiB
ReStructuredText
===============
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os-apply-config
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===============
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-----------------------------------------------
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Apply configuration from cloud metadata (JSON)
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-----------------------------------------------
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What does it do?
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================
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It turns metadata from one or more JSON files like this::
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{"keystone": {"database": {"host": "127.0.0.1", "user": "keystone", "password": "foobar"}}}
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into service config files like this::
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[sql]
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connection = mysql://keystone:foobar@127.0.0.1/keystone
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...other settings...
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Usage
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=====
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Just pass it the path to a directory tree of templates::
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sudo os-apply-config -t /home/me/my_templates
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By default it will read config files according to the contents of
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the file `/var/lib/os-collect-config/os_config_files.json`. In
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order to remain backward compatible it will also fall back to
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/var/run/os-collect-config/os_config_files.json, but the fallback
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path is deprecated and will be removed in a later release. The main
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path can be changed with the command line switch `--os-config-files`,
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or the environment variable `OS_CONFIG_FILES_PATH`. The list can
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also be overridden with the environment variable `OS_CONFIG_FILES`.
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If overriding with `OS_CONFIG_FILES`, the paths are expected to be colon,
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":", separated. Each json file referred to must have a mapping as their
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root structure. Keys in files mentioned later in the list will override
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keys in earlier files from this list. For example::
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OS_CONFIG_FILES=/tmp/ec2.json:/tmp/cfn.json os-apply-config
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This will read `ec2.json` and `cfn.json`, and if they have any
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overlapping keys, the value from `cfn.json` will be used. That will
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populate the tree for any templates found in the template path. See
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https://git.openstack.org/cgit/openstack/os-collect-config for a
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program that will automatically collect data and populate this list.
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You can also override `OS_CONFIG_FILES` with the `--metadata` command
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line option, specifying it multiple times instead of colon separating
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the list.
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`os-apply-config` will also always try to read metadata in the old
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legacy paths first to populate the tree. These paths can be changed
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with `--fallback-metadata`.
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Templates
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=========
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The template directory structure should mimic a root filesystem, and
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contain templates for only those files you want configured. For
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example::
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~/my_templates$ tree
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.
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└── etc
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├── keystone
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│ └── keystone.conf
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└── mysql
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└── mysql.conf
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An example tree can be found `here <http://git.openstack.org/cgit/openstack/tripleo-image-elements/tree/elements/keystone/os-apply-config>`_.
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If a template is executable it will be treated as an *executable
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template*. Otherwise, it will be treated as a *mustache template*.
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Mustache Templates
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------------------
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If you don't need any logic, just some string substitution, use a
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mustache template.
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Metadata settings are accessed with dot ('.') notation::
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[sql]
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connection = mysql://{{keystone.database.user}}:{{keystone.database.password}}@{{keystone.database.host}}/keystone
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Executable Templates
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--------------------
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Configuration requiring logic is expressed in executable templates.
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An executable template is a script which accepts configuration as a
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JSON string on standard in, and writes a config file to standard out.
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The script should exit non-zero if it encounters a problem, so that
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os-apply-config knows what's up.
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The output of the script will be written to the path corresponding to
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the executable template's path in the template tree::
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#!/usr/bin/env ruby
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require 'json'
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params = JSON.parse STDIN.read
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puts "connection = mysql://#{c['keystone']['database']['user']}:#{c['keystone']['database']['password']}@#{c['keystone']['database']['host']}/keystone"
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You could even embed mustache in a heredoc, and use that::
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#!/usr/bin/env ruby
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require 'json'
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require 'mustache'
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params = JSON.parse STDIN.read
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template = <<-eos
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[sql]
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connection = mysql://{{keystone.database.user}}:{{keystone.database.password}}@{{keystone.database.host}}/keystone
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[log]
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...
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eos
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# tweak params here...
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puts Mustache.render(template, params)
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Quick Start
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===========
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::
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# install it
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sudo pip install -U git+git://git.openstack.org/openstack/os-apply-config.git
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# grab example templates
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git clone git://git.openstack.org/openstack/tripleo-image-elements /tmp/config
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# run it
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os-apply-config -t /tmp/config/elements/nova/os-apply-config/ -m /tmp/config/elements/seed-stack-config/config.json -o /tmp/config_output
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