e2j2

e2j2 [|PyPi| |Build Status| |Coverage Status|]

.. contents:: Table of contents:

What is e2j2?

E2J2 (environment to jinja2 variables) is a command line tool which will render text and configuration files bases on jinja2 templates. Template variables can be defined by using plain or tagged environment variables.

With tags within the environment variable you can specify different sources, sources include hashicorp consul, hashicorp vault, dns lookups and json.

E2J2 can be used within docker containers, or for other simple configuration templating tasks. Within a docker container you can simply add the j2 extention to a configuration file, or to multiple files within one or more folder structures and then run e2j2 as part of your docker entrypoint script.

Command line switches and config file

Most flags can be set on either the command line or in a json formatted config file. The following flags / configuration keys are supported:

=========================== ==================== ======================================= ======= ============================================================================== Switch Type Config key Type Description =========================== ==================== ======================================= ======= ============================================================================== -h, --help Show help text and exit -v, --version Show version number -e, --ext, --extension string extension string Jinja2 file extention (default: .j2) -f, --filelist comma separated list filelist array List of jinja2 templates -s, --searchlist comma separated list searchlist array List of directories to search for templates (default: current directory) -N, --noop skip writing template to disk -r, --recursive recursive boolean Traverse recursively through the search list --no-color, --nocolor no_color boolean Disable ANSI color -2, --twopass twopass boolean Enable two pass rendering -n, --nested-tags nested_tags boolean Enable support for nested tags -m, --marker-set string marker_set string Select marker set (default: '{{') -A, --autodetect-marker-set autodetect_marker_set boolean Autodetect marker set, fallback to defined marker set --block-start string block_start string Block marker start (default from marker set) --block-end string block_end string Block marker start (default: from marker set) --variable-start string block_start string Variable marker start (default: from marker set) --variable-end string variable_end string Variable marker end (default: from marker set) --comment-start string comment_start string Comment marker start (default: from marker set) --comment-end string comment_end string Comment marker start (default: from marker set) -w, --env-whitelist comma separated list env_whitelist array List of envars to include -b, --env-blacklist comma separated list env_blacklist array List of envars to exclude -P, --copy-file_permissions copy_file_permissions boolean Copy file permissions and ownership from template to rendered file -S, --stacktrace stacktrace boolean Include stacktrace in error file --stderr boolean Print to stderr instead of to error file -c, --config string Config file path --watchlist comma separated list watchlist array Watch listed envvars for changes and render template(s) on change -R, --run string run array Run command after rendering templates (command arg1, ..) --splay int splay integer Random delay between 1 and X seconds between watchlist polls --initial-run render templates before starting watch =========================== ==================== ======================================= ======= ==============================================================================

Jinja2 filter support

By default only the jinja2 builtin filters <https://jinja.palletsprojects.com/en/2.10.x/templates/#list-of-builtin-filters>_ are supported this can be extended by installing the jinja2-ansible-filters <https://pypi.org/project/jinja2-ansible-filters/>_ module.

Example

lets assume we want to render the following server block in nginx, if we place the server configuration in a nginx include directory for example /etc/nginx/conf.d

.. code:: bash

server { server_name {{ NGINX.server_name }}; listen 80; listen [::]:80; error_page 500 502 503 504 /50x.html;

 location / {
   index {{ NGINX.index_page }};
   root {{ NGINX.web_root }};
 }

 location ~ \.php$ {
   fastcgi_index index.php;
   fastcgi_param SCRIPT_FILENAME  $document_root$fastcgi_script_name;
   fastcgi_pass unix:{{ NGINX.fpm_socket }};
   fastcgi_split_path_info ^(.+\.php)(/.+)$;
   include {{ NGINX.fcgi_params }};
   root {{ NGINX.web_root }};
   try_files $uri =404;
 }

}

if you then set the NGINX environment variable, running e2j2 will render the jinja2 template and place it in the same folder:

.. code:: bash

~> export NGINX='json: { "server_name": "www.myweb.com", "index_page": "index.php", "web_root": "/usr/local/www/myweb", "fcgi_params": "/usr/local/etc/nginx/myweb-fcgi-params", "fpm_socket": "/var/run/php-fpm/myweb.socket" }' ~> e2j2

In: . rendering: nginx_vhost_config.conf.j2=>done => writing: nginx_vhost_config.conf=>done

~> cat nginx_vhost_config.conf server { server_name www.myweb.com; listen 80; listen [::]:80; error_page 500 502 503 504 /50x.html;

 location / {
   index index.php;
   root /usr/local/www/myweb;
 }

 location ~ \.php$ {
   fastcgi_index index.php;
   fastcgi_param SCRIPT_FILENAME  $document_root$fastcgi_script_name;
   fastcgi_pass unix:/var/run/php-fpm/myweb.socket;
   fastcgi_split_path_info ^(.+\.php)(/.+)$;
   include /usr/local/etc/nginx/myweb-fcgi-params;
   root /usr/local/www/roundcube;
   try_files $uri =404;
 }

}

Environment variable examples

Plain environment variable

Example:

setting:

::

   MYENVVAR='plain environment variable'

will render envvar-example.j2 to:

::

   This is a plain environment variable

Tag file
~~~~~~~~

Example:

setting:

::

   MYFILEVAR=file:./file-example.txt

will render file-example.j2 to:

::

   This is a file example

Tag json
~~~~~~~~

Example:

setting:

::

   MYJSONVAR='json:{"key": "json-example"}'

will render json-example.j2 to:

::

   This is a json-example

Tag jsonfile
~~~~~~~~~~~~

Example:

setting:

::

   MYJSONFILEVAR='jsonfile:jsonfile-example.json'

will render jsonfile-example.j2 to:

::

   This is a jsonfile example with subkey

Tag base64
~~~~~~~~~~

Example:

Setting:

::

   export MYBASE64VAR='base64:YmFzZTY0IGV4YW1wbGU='

will render base64-example.j2 to:

::

   This is a base64 example

Tag consul
~~~~~~~~~~

Configuration:

You can configure the consul tag by setting the CONSUL_CONFIG
environment variable. The following config items are supported:

============ =============================== =====================
Item         Explanation                     Default
============ =============================== =====================
url          consul url                      http://127.0.0.1:8500
scheme       consul url scheme http or https scheme from url
host         consul host                     hostname from url
port         consul http(s) port             port from url
token        consul token                    none
============ =============================== =====================

Global config example:

::

   read -d '' CONSUL_CONFIG << EOF
   {
      "url": "https://consul.foobar.tld",
      "token": "abcdef01-0123-abcd-1234-0123456789ab"
   }
   EOF

The ACL token can be configured by either the above configuration or by setting the CONSUL_TOKEN variable.

As an alternative for the global configuration it is also possible to configure / adjust the global configuration for each consul tag, by simply include the configuration when using the consul tag.

CONSUL_TOKEN and config key token can either contain the actual token or point to a file containing the token, use the **file:** tag to point to a file.

Tag config examples:

::

    export MYCONSULVAR='consul:config={"url": "https://consul2.foobar.tld", "token": "012345678-0123-abcd-1234-0123456789ab"}:consulvar"

::

    export MYCONSULVAR='consul:config={"url": "https://consul2.foobar.tld", "token": "file:/path/to/token"}:consulvar"

Consul example:

Setting:

key: consulvar in consul to value: consul example

and

::

   export MYCONSULVAR='consul:consulvar'

will render consul-example.j2 to:

::

   This is a consul example

Tag list
~~~~~~~~

Example:

Setting:

::

   export MYLIST='list:"first","second","third","fourth"'

will render list-example.j2 to:

::

   "first"
   "second"
   "third"
   "fourth"

Two pass rendering
~~~~~~~~~~~~~~~~~~

Starting from version 0.1.12 e2j2 supports embedding jinja2 macros in
environment variables.

Example:

Setting the following two environment variables:

::

    export WORDPRESS='json:{"database": {"name": "mydb", "user": "mydb_user", "password": "{{ DBSECRET }}", "host": "localhost"}}'
    export DBSECRET='file:./twopass-secret'

will render (by running: ``e2j2 -f twopass-example.j2 -2``) to:

::

   // ** MySQL settings - You can get this info from your web host ** //
   /** The name of the database for WordPress */
   define( 'DB_NAME', 'mydb' );

   /** MySQL database username */
   define( 'DB_USER', 'mydb_user' );

   /** MySQL database password */
   define( 'DB_PASSWORD', 'Db$ecr3t' );

   /** MySQL hostname */
   define( 'DB_HOST', 'localhost' );

In version 0.5.0 support was introduced for nested tag variables, so the above listed example can be simplified.
The DBSECRET variable is no longer needed, if the WORDPRESS variable is changed to:

::

    export WORDPRESS='json:{"database": {"name": "mydb", "user": "mydb_user", "password": "file:./twopass-secret", "host": "localhost"}}'

If needed you can escape e2j2 tags by using the escape tag

Tag vault
~~~~~~~~~

Configuration:

You can configure the vault tag by setting the VAULT_CONFIG
environment variable. The following config items are supported:

============ ============================== =====================
Item         Explanation                    Default
============ ============================== =====================
url          vault url                      http://127.0.0.1:8200
scheme       vault url scheme http or https scheme from url
host         vault host                     hostname from url
port         vault http(s) port             port from url
backend      vault secret backend           raw
token        vault token                    none
============ ============================== =====================

the following backends are supported:

======= =========================================
backend Description
======= =========================================
raw     use plain GET request to secret store API
kv1     key/value version 1
kv2     key/value version 2
======= =========================================

Global config example:

::

   read -d '' VAULT_CONFIG << EOF
    {
      "url": "https://vault.foobar.tld:8200",
      "token": "s.xxxxxxxxxxxxxxxxxxxxxxx",
      "backend: "kv2"
    }
   EOF

The Authentication token can be configured by either the above configuration or by setting the VAULT_TOKEN variable.

As an alternative for the global configuration it is also possible to configure / adjust the global configuration for each vault tag, by simply include the configuration when using the vault tag.

VAULT_TOKEN and config key token can either contain the actual token or point to a file containing the token, use the **file:** tag to point to a file.

Tag config example:

::

    export MYVAULTVAR='vault:config={"backend": "kv2", "token": "s.xxxxxxxxx"}:kv/my-secret"

::

    export MYVAULTVAR='vault:config={"backend": "kv2", "token": "file:/path/to/token"}:kv/my-secret"

Vault example:

Setting:

::

   vault kv put secret/my-secret secret=topsecret
   export MYVAULTVAR='vault:secret/my-secret'

will render vault-kv1-example.j2 (by running: ``e2j2 -f vault-example.j2``) to:

::

   ** topsecret **
   This is a vault example

Tag dns
~~~~~~~~~

Configuration:

You can configure the dns tag by setting the DNS_CONFIG
environment variable. The following config items are supported:

============ ============================== =====================
Item         Explanation                    Default
============ ============================== =====================
nameservers  overwrite nameservers          use system resolvers
port         overwrite dns port             53
type         record type (A, AAAA or SRV)   A
============ ============================== =====================

the supported record types will return a dict with the following keys:

======= ===============================
Type    Keys
======= ===============================
A       address
AAAA    address
SRV     target, port, weight, priority
======= ===============================

DNS example:

Assuming a consul node running on localhost with the default dns port 8600.

Setting the DNS_CONFIG variable:
::

   read -d '' DNS_CONFIG << EOF
    {
      "nameservers": ['127.0.0.1'],
      "port": 8600,
      "type": "SRV"
    }
   EOF

Setting:

::

   export MYDNSVAR='dns:consul.service.consul'

will render dns-example.j2 (by running: ``e2j2 -f dns-example.j2``) to:

::

    My consul node:
    node1.node.dc1.consul. listening on port 8300


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