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Config Encoder Filters

This is an Ansible role used to deliver the Config Encoder Filters as a dependency of another Ansible role.

https://travis-ci.org/jtyr/ansible-config_encoder_filters.svg?branch=master

Table of Contents

Motivation

Ansible Galaxy contains a lot of useful roles. Some of them exist in many variations which differ only by their parameterization. The parameterization is often used mainly in templates which generate the configuration file. A good example such issues are roles for Nginx of which you can find almost 200 in the Ansible Galaxy.

Nginx is possible to configure in infinite number of ways and therefore is almost impossible to create an Ansible template file which would capture all possible variations of the configuration. Even if a suitable roles is found, users often want to customize even more. This is where people normally clone the role and add parameters they are missing. Some people try to get the change back into the original role by creating a pull request (PR) but sometimes such change is not accepted by the maintainer of the original role and the user ends up maintaining his/her own clone forever.

This is why the Config Encoder filters were developed to facilitate the creation of Ansible roles with universal configuration. The structure of the configuration file is described as a YAML data structure stored in a variable. The variable together with he Config Encoder filter is then used in the template file which is used to generate the final configuration file. This approach allows to shift the paradigm of thinking about configuration files as templates to thinking about them as data structures. The data structure can be dynamically generated which allows to create truly universal configuration.

Example

Imagine the following INI file:

[section1]
option11=value11
option12=value12

Such configuration file can be described as a YAML data structure:

myapp_config:
  section1:
    option11: value11
    option12: value12

The variable is then used together with the encode_ini Config Encoder filter in the template file myapp.cfg.j2 like this:

{{ myapp_config | encode_ini }}

And finally, the template file is used in a task like this:

- name: Create config file
  template:
    src: myapp.cfg.j2
    dest: /etc/myapp/myapp.cfg

When the task is executed, it creates exactly the same file as the original INI file.

So we can describe the configuration as a data structure which is then converted into the final configuration file format with the Config Encoder filter.

In order to change the above configuration, we would have to overwrite the myapp_config which is not very practical. Therefore we break the monolithic variable into a set of variables which will allow us to change any part of the configuration without the need to overwrite the whole data structure:

myapp_config_section1_option11: value11
myapp_config_section1_option12: value12

myapp_config_section1__default:
  option11: "{{ myapp_config_section1_option11 }}"
  option12: "{{ myapp_config_section1_option12 }}"

myapp_config_section1__custom: {}

myapp_config_default:
  section1: "{{
    myapp_config_section1__default | combine(
    myapp_config_section1__custom) }}"

myapp_config__custom: {}

myapp_config: "{{
  myapp_config__default | combine(
  myapp_config__custom) }}"

Like this, if we want to change the value of the option11, we only override the variable myapp_config_section1_option11:

myapp_config_section1_option11: My new value

If we want to add a new option into the section1, we add it into the variable myapp_config_section1__custom which is then merged with the default list of options:

myapp_config_section1__custom:
  section13: value13

And if we want to add a new section, we add it into the variable myapp_config__custom which is then merged with the default list of sections:

myapp_config__custom:
  section2:
    option21: value21

The above is showing an example for INI configuration files only but the same principle is possible to use for all the supported Config Encoders listed bellow.

Usage

Config Encoder filters can be used in any Ansible role by adding the config_encoder_filters role into the list of dependencies in the meta/main.yml file:

dependencies:
  - config_encoder_filters

The usage directy from a Playbook requires to add the config_encoder_filters into the list of roles:

- name: My test Play
  hosts: all
  roles:
    - config_encoder_filters
  tasks:
    - name: Create config file
      template:
        src: my.conf.j2
        dest: /tmp/my.conf

Installation

The role can be downloaded either via Ansible Galaxy command:

$ ansible-galaxy install jtyr.config_encoder_filters,master,config_encoder_filters

or via Ansible Gallaxy requirements file:

$ cat ./requirements.yaml
---

- src: https://github.com/jtyr/ansible-config_encoder_filters.git
  name: config_encoder_filters
$ ansible-galaxy -r ./requirements.yaml

or via Git:

$ git clone https://github.com/jtyr/ansible-config_encoder_filters.git config_encoder_filters

Supported encoders

The following is the list of supported Config Encoder filters. Each filter requires special data structure as its input. Each filter also has a set of parameters which can modify the behaviour of the filter.

encode_apache

This filter helps to create configuration in the format used by Apache web server. The expected data structure is the following:

my_apache_vhost:
  content:
    - sections:
      - name: VirtualHost
        param: "*:80"
        content:
          - options:
            - DocumentRoot: /www/example1
            - ServerName: www.example.com
            - ErrorLog: /var/log/httpd/www.example.com-error_log
            - CustomLog:
              - /var/log/httpd/www.example.com-access_log
              - common
            - "#": Other directives here ...

The variable starts with content which can contain list of sections or options. sections then contain list of individual sections which has the name, param and content parameter. The content can again contain a list of sections` or options.

The above variable can be used in the template file like this:

{{ my_apache_vhost | encode_apache }}

The output of such template would be:

<VirtualHost *:80>
  DocumentRoot /www/example1
  ServerName www.example.com
  ErrorLog /var/log/httpd/www.example.com-error_log
  CustomLog /var/log/httpd/www.example.com-access_log common
  # "Other directives here ..."
</VirtualHost>

The filter can have the following parameters:

  • convert_bools=false

    Indicates whether Boolean values presented as a string should be converted to a real Boolean value. For example var1: 'True' would be represented as a string but by using the convert_bools=true it will be converted into Boolean like it would be defined like var1: true.

  • convert_nums=false

    Indicates whether number presented as a string should be converted to number. For example var1: '123' would be represented as a string but by using the convert_nums=true it will be converted it to a number like it would be defined like var1: 123. It's also possible to use the YAML type casting to convert string to number (e.g. !!int "1234", !!float "3.14").

  • indent=" "

    Defines the indentation unit.

  • level=0

    Indicates the initial level of the indentation. Value 0 starts indenting from the beginning of the line. Setting the value to higher than 0 indents the content by indent * level.

  • quote_all_nums=false

    Number values are not quoted by default. This parameter will force to quote all numbers.

  • quote_all_strings=false

    String values are quoted only if they contain a space. This parameter will force to quote all strings regardless if the they contain the space or not.

encode_erlang

This filter helps to create configuration in the Erlang format. The expected data structure is the following:

my_rabbitmq_config:
  - rabbit:
    - tcp_listeners:
      - '"127.0.0.1"': 5672
    - ssl_listeners:
      - 5671
    - ssl_options:
      - cacertfile: /path/to/testca/cacert.pem
      - certfile: /path/to/server/cert.pem
      - keyfile: /path/to/server/key.pem
      - verify: :verify_peer
      - fail_if_no_peer_cert: true
    - cluster_nodes:
        ::
          -
            - :"'rabbit@node1'"
            - :"'rabbit@node2'"
          - :disc

The variable consists of a lists of dictionaries. The value of the key-value pair can be another list or simple value like a string or a number. Erlang tuples can be enforced by prepending the value with the special character specified in the atom_value_indicator. Order in tuple can be achieved by using special construction as shown for the cluste_nodes tuple from the above example. The indicator starting this special construction can be set with the parameter ordered_tuple_indicator.

The above variable can be used in the template file like this:

{{ my_rabbitmq_config | encode_erlang }}

The output of such template would be:

[
  {rabbit, [
      {tcp_listeners, [
          {"127.0.0.1", 5672}
      ]},
      {ssl_listeners, [
        5671
      ]},
      {ssl_options, [
          {cacertfile, "/path/to/testca/cacert.pem"},
          {certfile, "/path/to/server/cert.pem"},
          {keyfile, "/path/to/server/key.pem"},
          {verify, verify_peer},
          {fail_if_no_peer_cert, true}
      ]},
      {cluster_nodes,
        {[
          'rabbit@node1',
          'rabbit@node2'
        ], disc}}
  ]}
].

The filter can have the following parameters:

  • atom_value_indicator=":"

    The value of this parameter indicates the string which must be prepended to a string value to treat it as an atom value.

  • convert_bools=false

    Indicates whether Boolean values presented as a string should be converted to a real Boolean value. For example var1: 'True' would be represented as a string but by using the convert_bools=true it will be converted into Boolean like it would be defined like var1: true.

  • convert_nums=false

    Indicates whether number presented as a string should be converted to number. For example var1: '123' would be represented as a string but by using the convert_nums=true it will be converted it to a number like it would be defined like var1: 123. It's also possible to use the YAML type casting to convert string to number (e.g. !!int "1234", !!float "3.14").

  • indent=" "

    Defines the indentation unit.

  • level=0

    Indicates the initial level of the indentation. Value 0 starts indenting from the beginning of the line. Setting the value to higher than 0 indents the content by indent * level.

  • ordered_tuple_indicator=":"

    Indicator used to start the special construction with ordered tuple.

encode_haproxy

This filter helps to create configuration in the format used in Haproxy. The expected data structure is the following:

my_haproxy_config:
  - global:
    - daemon
    - maxconn 256
  - "# This is the default section"
  - defaults:
    - mode http
    - timeout:
        - connect 5000ms
        - client 50000ms
        - server 50000ms
  - frontend http-in:
    - "# This is the bind address/port"
    - bind *:80
    - default_backend servers
    - backend servers
    - server server1 127.0.0.1:8000 maxconn 32

The variable is a list which can contain a simple string value or a dictionary which indicates a section.

The above variable can be used in the template file like this:

{{ my_haproxy_config | encode_haproxy }}

The output of such template would be:

global
  daemon
  maxconn 256

# This is the default section
defaults
  mode http
  timeout connect 5000ms
  timeout client 50000ms
  timeout server 50000ms

frontend http-in
  # This is the bind address/port
  bind *:80
  default_backend servers
  backend servers
  server server1 127.0.0.1:8000 maxconn 32

The filter can have the following parameters:

  • indent=" "

    Defines the indentation unit.

encode_ini

This filter helps to create configuration in the INI format. The expected data structure is the following:

my_rsyncd_config:
  uid: nobody
  gid: nobody
  use chroot: no
  max connections: 4
  syslog facility: local5
  pid file: /run/rsyncd.pid
  ftp:
    path: /srv/ftp
    comment: ftp area

The variable consist of dictionaries which can be nested. If the value of the key-value pair on the first level is of a simple type (string, number, boolean), such pair is considered to be global and gets processed first. If the value of the key-value pair on the first level is another dictionary, the key is considered to be the name of the section and the inner dictionary as properties of the section.

The above variable can be used in the template file like this:

{{ my_rsyncd_config | encode_ini }}

The output of such template would be:

gid=nobody
max connections=4
pid file=/run/rsyncd.pid
syslog facility=local5
uid=nobody
use chroot=False

[ftp]
comment=ftp area
path=/srv/ftp

The special value !!!null can be used, to create a key without any value. This must be wrapped in quotes, to avoid being evaluated as a YAML tag.

Take the following data structure:

config:
  myconf:
    key: value
    keyWithoutValue: '!!!null'

This would become:

[myconf]
key=value
keyWithoutValue

The filter can have the following parameters:

  • comment="#"

    Sign used to comment out lines when section_is_comment=true.

  • delimiter="="

    Sign separating the property and the value. By default it's set to '=' but it can also be set for example to ' = '.

  • indent=""

    Indent the keys with the specified string. E.g. indent="\t".

  • quote=""

    Sets the quoting of the value. Use quote="'" or quote='"'.

  • section_is_comment=false

    If this parameter is set to true, the section value will be used as a comment for the following properties of the section.

  • ucase_prop=false

    Indicates whether the property should be made upper case.

encode_json

This filter helps to create configuration in the JSON format. The expected data structure is the following:

my_sensu_client_config:
  client:
    name: localhost
    address: 127.0.0.1
    subscriptions:
      - test

Because JSON is very similar to YAML, the variable consists of dictionaries of which value can be either an simple type (number, string, boolean), list or another dictionary. All can be nested in any number of levels.

The above variable can be used in the template file like this:

{{ my_sensu_client_config | encode_json }}

The output of such template would be:

{
  "client": {
    "address": "127.0.0.1",
    "name": "localhost",
    "subscriptions": [
      "test"
    ]
  }
}

The filter can have the following parameters:

  • convert_bools=false

    Indicates whether Boolean values presented as a string should be converted to a real Boolean value. For example var1: 'True' would be represented as a string but by using the convert_bools=true it will be converted into Boolean like it would be defined like var1: true.

  • convert_nums=false

    Indicates whether number presented as a string should be converted to number. For example var1: '123' would be represented as a string but by using the convert_nums=true it will be converted it to a number like it would be defined like var1: 123. It's also possible to use the YAML type casting to convert string to number (e.g. !!int "1234", !!float "3.14").

  • indent=" "

    Defines the indentation unit.

  • level=0

    Indicates the initial level of the indentation. Value 0 starts indenting from the beginning of the line. Setting the value to higher than 0 indents the content by indent * level.

encode_logstash

This filter helps to create configuration in the format used by Logstash. The expected data structure is the following:

my_logstash_config:
  - :input:
      - :file:
          path: /var/log/httpd/access_log
          start_position: beginning
  - :filter:
      - ':if [path] =~ "access"':
          - :mutate:
              replace:
                type: apache_access
          - :grok:
              match:
                message: "%{COMBINEDAPACHELOG}"
          - :date:
              match:
                - timestamp
                - dd/MMM/yyyy:HH:mm:ss Z
      - ':else if [path] =~ "error"':
          - :mutate:
              replace:
                type: "apache_error"
      - :else:
          - :mutate:
              replace:
                type: "random_logs"
  - :output:
      - :elasticsearch:
          hosts:
            - localhost:9200
      - :stdout:
          codec: rubydebug

The variable consists of a list of sections where each section is prefixed by a special character specified by the section_prefix (: by default). The value of the top level sections can be either another section or a dictionary. The value of the dictionary can be a simple value, list or another dictionary.

The above variable can be used in the template file like this:

{{ my_logstash_config | encode_logstash }}

The output of such template would be:

input {
  file {
    path => "/var/log/httpd/access_log"
    start_position => "beginning"
  }
}
filter {
  if [path] =~ "access" {
    mutate {
      replace => {
        "type" => "apache_access"
      }
    }
    grok {
      match => {
        "message" => "%{COMBINEDAPACHELOG}"
      }
    }
    date {
      match => [
        "timestamp",
        "dd/MMM/yyyy:HH:mm:ss Z"
      ]
    }
  }
  else if [path] =~ "error" {
    mutate {
      replace => {
        "type" => "apache_error"
      }
    }
  }
  else {
    mutate {
      replace => {
        "type" => "random_logs"
      }
    }
  }
}
output {
  elasticsearch {
    hosts => [
      "localhost:9200"
    ]
  }
  stdout {
    codec => "rubydebug"
  }
}

The filter can have the following parameters:

  • backslash_ignore_prefix='@@@'

    This parameter defines a sets of characters than can be prepended to a string to prevent backslahes from being escaped in the resulting configuration (e.g. "@@@sshd(?:\[%{POSINT:[system][auth][pid]}\])?:" will turn to "sshd(?:\[%{POSINT:[system][auth][pid]}\])?:" instead of to "sshd(?:\\[%{POSINT:[system][auth][pid]}\\])?:").

  • convert_bools=false

    Indicates whether Boolean values presented as a string should be converted to a real Boolean value. For example var1: 'True' would be represented as a string but by using the convert_bools=true it will be converted into Boolean like it would be defined like var1: true.

  • convert_nums=false

    Indicates whether number presented as a string should be converted to number. For example var1: '123' would be represented as a string but by using the convert_nums=true it will be converted it to a number like it would be defined like var1: 123. It's also possible to use the YAML type casting to convert string to number (e.g. !!int "1234", !!float "3.14").

  • indent=" "

    Defines the indentation unit.

  • level=0

    Indicates the initial level of the indentation. Value 0 starts indenting from the beginning of the line. Setting the value to higher than 0 indents the content by indent * level.

  • section_prefix=":"

    This parameter specifies which character will be used to identify the Logstash section.

encode_lua

This filter helps to create configuration in a Lua friendly format. The expected data structure is the following:

my_lua_config:
  fork: false
  external_addresses:
    - 1.2.3.4
    - 5.6.7.8
  admins:
    - [email protected]
  contact_info:
    abuse: [email protected]
    admin: [email protected]

Lua is a small scripting language, often embedded into C/C++ applications. This encoder does a best effort to match configuration files seen in the wild, while allowing the user to further customize how the final output is rendered.

The above variable can be used in the template file like this:

{{ my_lua_config | encode_lua }}

The output of such a template would be:

fork = false;
external_addresses = {
    "1.2.3.4";
    "5.6.7.8";
}
admins = {
    "[email protected]";
}
contact_info = {
    abuse = "[email protected]";
    admin = "[email protected]";
}

The filter can have the following parameters:

  • convert_bools=false

    Indicates whether Boolean values presented as a string should be converted to a real Boolean value. For example var1: 'True' would be represented as a string but by using the convert_bools=true it will be converted into Boolean like it would be defined like var1: true.

  • convert_nums=false

    Indicates whether number presented as a string should be converted to number. For example var1: '123' would be represented as a string but by using the convert_nums=true it will be converted it to a number like it would be defined like var1: 123. It's also possible to use the YAML type casting to convert string to number (e.g. !!int "1234", !!float "3.14").

  • sort_keys=false

    Indicates whether the keys should be sorted when the output is rendered, or left to python's implicit handling of dict ordering.

  • indent=" "

    Defines the indentation unit.

  • level=0

    Indicates the initial level of the indentation. Value 0 starts indenting from the beginning of the line. Setting the value to higher than 0 indents the content by indent * level.

encode_nginx

This filter helps to create configuration in the format used by Nginx web server. The expected data structure is the following:

my_nginx_vhost_config:
  - server:
    - listen 80
    - server_name $hostname
    - "location /":
      - root /srv/www/myapp
      - index index.html

As Nginx configuration is order sensitive, the all configuration is defined as a nested list. As it would be difficult to recognize how many elements each configuration definition has, the list item value is no further separated into key/value dictionary. Every line of the configuration is treated either as a key indicating another nested list or simply as a string.

The above variable can be used in the template file like this:

{{ my_nginx_vhost | encode_nginx }}

The output of such template would be:

server {
  listen 80;
  server_name $hostname;

  location / {
    root /srv/www/myapp;
    index index.html;
  }
}

The filter can have the following parameters:

  • block_semicolon=false

    Allows to add a semicolon to the end of each block.

  • indent=" "

    Defines the indentation unit.

  • level=0

    Indicates the initial level of the indentation. Value 0 starts indenting from the beginning of the line. Setting the value to higher than 0 indents the content by indent * level.

  • semicolon=';'

    Semicolon character. Set this to empty string to ignore all semicolons.

  • semicolon_ignore_postfix='!;'

    If the line ends with !; then don't add the final semicolon.

encode_pam

This filter helps to create configuration in the format user by Linux Pluggable Authentication Modules (PAM). The expected data structure is the following:

my_system_auth_config:
  aa:
    type: auth
    control: required
    path: pam_unix.so
    args:
      - try_first_pass
      - nullok
  bb:
    type: auth
    control: optional
    path: pam_permit.so
  cc:
    type: auth
    control: required
    path: pam_env.so
  dd:
    type: account
    control: required
    path: pam_unix.so
  ee:
    type: account
    control: optional
    path: pam_permit.so
  ff:
    type: account
    control: required
    path: pam_time.so
  gg:
    type: password
    control: required
    path: pam_unix.so
    args:
      - try_first_pass
      - nullok
      - sha512
      - shadow
  hh:
    type: password
    control: optional
    path: pam_permit.so
    args:
  ii:
    type: session
    control: required
    path: pam_limits.so
  jj:
    type: session
    control: required
    path: pam_unix.so
  kk:
    type: session
    control: optional
    path: pam_permit.so

The variable is a dictionary of which the key is a labels and the value is the PAM rule. The label is used to order the PAM rules. Using labels with even number of characters allows to insert another rule in between of any two rules.

The above variable can be used in the template file like this:

{{ my_system_auth_config | encode_pam }}

The output of such template would be:

auth  required  pam_unix.so  try_first_pass nullok
auth  optional  pam_permit.so
auth  required  pam_env.so

account  required  pam_unix.so
account  optional  pam_permit.so
account  required  pam_time.so

password  required  pam_unix.so  try_first_pass nullok sha512 shadow
password  optional  pam_permit.so

session  required  pam_limits.so
session  required  pam_unix.so
session  optional  pam_permit.so

The filter can have the following parameters:

  • print_label=false

    Print labels as a comment in the output.

  • separate_types=true

    Add a newline between the groups of types.

  • separator=" "

    Separator between the collection of tokens.

encode_toml

This filter helps to create configuration in the TOML format. The expected data structure is the following:

my_grafana_ldap_config:
  verbose_logging: false
  servers:
    - host: 127.0.0.1
      port: 389
      use_ssl: no
      start_tls: no
      ssl_skip_verify: no
      bind_dn: cn=admin,dc=grafana,dc=org
      bind_password: grafana
      search_filter: (cn=%s)
      search_base_dns:
        - dc=grafana,dc=org
    - attributes:
        name: givenName
        surname: sn
        username: cn
        member_of: memberOf
        email: email
    - group_mappings:
        - group_dn: cn=admins,dc=grafana,dc=org
          org_role: Admin
        - group_dn: cn=users,dc=grafana,dc=org
          org_role: Editor
        - group_dn: "*"
          org_role: Viewer

The variable is a dictionary of which value can be either a simple type (number, string, boolean), list or another dictionary. The dictionaries and lists can be nested.

The above variable can be used in the template file like this:

{{ my_grafana_ldap_config | encode_toml }}

The output of such template would be:

verbose_logging = false

[[servers]]
host = "127.0.0.1"
port = 389
use_ssl = false
start_tls = false
ssl_skip_verify = false
bind_dn = "cn=admin,dc=grafana,dc=org"
bind_password = 'grafana'
search_filter = "(cn=%s)"
search_base_dns = ["dc=grafana,dc=org"]

[servers.attributes]
name = "givenName"
surname = "sn"
username = "cn"
member_of = "memberOf"
email =  "email"

[[servers.group_mappings]]
group_dn = "cn=admins,dc=grafana,dc=org"
org_role = "Admin"

[[servers.group_mappings]]
group_dn = "cn=users,dc=grafana,dc=org"
org_role = "Editor"

[[servers.group_mappings]]
group_dn = "*"
org_role = "Viewer"

The filter can have the following parameters:

  • convert_bools=false

    Indicates whether Boolean values presented as a string should be converted to a real Boolean value. For example var1: 'True' would be represented as a string but by using the convert_bools=true it will be converted into Boolean like it would be defined like var1: true.

  • convert_nums=false

    Indicates whether number presented as a string should be converted to number. For example var1: '123' would be represented as a string but by using the convert_nums=true it will be converted it to a number like it would be defined like var1: 123. It's also possible to use the YAML type casting to convert string to number (e.g. !!int "1234", !!float "3.14").

  • quote='"'

    Sets the quoting of the value. Use quote="'" or quote='"'.

encode_xml

This filter helps to create configuration in the XML format. The expected data structure is the following:

my_oddjob_config:
  - oddjobconfig:
    - service:
      - ^name: com.redhat.oddjob
      - object:
        - ^name: /com/redhat/oddjob
        - interface:
          - ^name: com.redhat.oddjob
          - method:
            - ^name: listall
            - allow:
              - ^min_uid: 0
              - ^max_uid: 0
          - method:
            - ^name: list
            - allow: ''
          - method:
            - ^name: quit
            - allow:
              - ^user: root
          - method:
            - ^name: reload
            - allow:
              - ^user: root
    - include:
      - ^ignore_missing: "yes"
      - /etc/oddjobd.conf.d/*.conf
    - include:
      - ^ignore_missing: "yes"
      - /etc/oddjobd-local.conf

The variable can be a list of dictionaries, lists or strings. This config encoder does not handle mixed content very well so the safest way how to include mixed content is to define it as a string and use the parameter escape_xml=false. This config encoder also produces no XML declaration. Any XML declaration or DOCTYPE must be a part of the template file.

The above variable can be used in the template file like this:

{{ my_oddjob_config | encode_xml }}

The output of such template would be:

<oddjobconfig>
  <service name="com.redhat.oddjob">
    <object name="/com/redhat/oddjob">
      <interface name="com.redhat.oddjob">
        <method name="listall">
          <allow min_uid="0" max_uid="0" />
        </method>
        <method name="list">
          <allow />
        </method>
        <method name="quit">
          <allow user="root" />
        </method>
        <method name="reload">
          <allow user="root" />
        </method>
      </interface>
    </object>
  </service>
  <include ignore_missing="yes">/etc/oddjobd.conf.d/*.conf</include>
  <include ignore_missing="yes">/etc/oddjobd-local.conf</include>
</oddjobconfig>

The filter can have the following parameters:

  • attribute_sign="^"

    XML attribute indicator.

  • indent=" "

    Defines the indentation unit.

  • level=0

    Indicates the initial level of the indentation. Value 0 starts indenting from the beginning of the line. Setting the value to higher than 0 indents the content by indent * level.

encode_yaml

This filter helps to create configuration in the YAML format. The expected data structure is the following:

my_mongodb_config:
  systemLog:
    destination: file
    logAppend: true
    path: /var/log/mongodb/mongod.log
  storage:
    dbPath: /var/lib/mongo
    journal:
      enabled: true
  processManagement:
    fork: true
    pidFilePath: /var/run/mongodb/mongod.pid
  net:
    port: 27017
    bindIp: 127.0.0.1

The variable is ordinary YAML. The only purpose of this encoder filter is to be able to convert YAML data structure into the string in a template file in unified way compatible with the other config encoders.

The above variable can be used in the template file like this:

{{ my_mongodb_config | encode_yaml }}

The output of such template would be:

net:
  bindIp: "127.0.0.1"
  port: 27017
processManagement:
  fork: true
  pidFilePath: "/var/run/mongodb/mongod.pid"
storage:
  dbPath: "/var/lib/mongo"
  journal:
    enabled: true
systemLog:
  destination: "file"
  logAppend: true
  path: "/var/log/mongodb/mongod.log"

The filter can have the following parameters:

  • block_prefix=';;;'

    Allows to maintain block signs in the output.

    aaa: |-
  ;;;|-
  bbb = ccc
  ddd = eee

  • convert_bools=false

    Indicates whether Boolean values presented as a string should be converted to a real Boolean value. For example var1: 'True' would be represented as a string but by using the convert_bools=true it will be converted into Boolean like it would be defined like var1: true.

  • convert_nums=false

    Indicates whether number presented as a string should be converted to number. For example var1: '123' would be represented as a string but by using the convert_nums=true it will be converted it to a number like it would be defined like var1: 123. It's also possible to use the YAML type casting to convert string to number (e.g. !!int "1234", !!float "3.14").

  • indent=" "

    Defines the indentation unit.

  • level=0

    Indicates the initial level of the indentation. Value 0 starts indenting from the beginning of the line. Setting the value to higher than 0 indents the content by indent * level.

  • quote='"'

    Sets the quoting of the value. Use quote="'" or quote='"'.

Utilities

The followng is a list of utilities that can be used in conjunction with the Config Encoder filters.

template_replace

This filter allows to use extra templating layer which gets processed during the template file processing. That can be useful if it's necessary to create repetitive but slightly different definitions inside the template file.

The extra templating layer is represented by a templating variable which contains specially decorated variables which get replaced by its real value at the time of template file processing. The template variable can be composed dynamically which provides extra flexibility that would otherwise have to be hardcoded in the template file.

The filter expects the template variable containing the specially decorated variables as its input. The filter has one parameter which is used to replaced the specially decorated variables in the template variable.

Let's have a look at an example of such usage:

# The variable used as the replacement in the template variable
my_clients:
  - host: myclient01
    jobdefs: Default
    password: Passw0rd1
    file_retention: 30 days
  - host: myclient02
    jobdefs: HomeOnly
    password: Passw0rd2
    file_retention: 90 days

# The actual template variable used in the template file
bacula_director_config_job_client:
  # First template variable containing the specially decorated variables
  - template:
      - Job:
        - Name = Job-{[{ item['jobdefs'] }]}-{[{ item['host'] }]}
        - Client = {[{ item['host'] }]}-fd
        - JobDefs = {[{ item['jobdefs'] }]}
    # Variable used to replace the specially decorated variables
    items: "{{ my_clients }}"
  # Second template and its items
  - template:
      - Client:
        - Name = {[{ item['host'] }]}-fd
        - Address = {[{ item['host'] }]}
        - FD Port = 9102
        - Catalog = Default
        - Password = {[{ item['password'] }]}
        - File Retention = {[{ item['file_retention'] }]}
        - Job Retention = 3 months
        - AutoPrune = yes
    items: "{{ my_clients }}"

The above variable can be used together with the template_replace filter in the template file (bacula-dir.conf.j2) like this:

{% for record in bacula_director_config_job_client %}
  {%- for item in record['items'] -%}
    {{ record['template'] | template_replace(item) | encode_nginx }}{{ "\n" }}
  {%- endfor -%}
{% endfor %}

The template file can be called from the playbook/role like this:

- name: Configure Bacula Director
  template:
    src: bacula-dir.conf.j2
    dest: /etc/bacula/bacula-dir.conf

And the result of such usage is the following:

Job {
  Name = Job-Default-myclient01;
  Client = myclient01-fd;
  JobDefs = Default;
}

Job {
  Name = Job-HomeOnly-myclient02;
  Client = myclient02-fd;
  JobDefs = HomeOnly;
}

Client {
  Name = myclient01-fd;
  Address = myclient01;
  FD Port = 9102;
  Catalog = Default;
  Password = Passw0rd1;
  File Retention = 30 days;
  Job Retention = 3 months;
  AutoPrune = yes;
}

Client {
  Name = myclient02-fd;
  Address = myclient02;
  FD Port = 9102;
  Catalog = Default;
  Password = Passw0rd2;
  File Retention = 90 days;
  Job Retention = 3 months;
  AutoPrune = yes;
}

Testing

All encoders have a set of unit tests automated through tox. Full test can be executed like this:

$ tox

Individual encoder can be tested like this:

$ tox -- python -m unittest tests.test_config_encoders.TestYaml

Individual tests can be executed like this:

$ tox -- python -m unittest tests.test_config_encoders.TestYaml.test_string

Tests are great source of advanced examples of how to use each of the encoders. Explore them in the directory tests/files. The content of the .in files must be assigned to a variable when using in Ansible. The output in the .out files might depend on additional parameters used in the tests/test_config_encoders.py file. Testing via Ansible can be executed like this:

$ ansible-playbook -i localhost, tests/test_config_encoders.yaml

License

GPLv3

Author

Jiri Tyr