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e2j2 is a commandline utility to render text/configuration files from jinja2 templates

Project description

e2j2

What is e2j2?

e2j2 (environment to jinja2 variables) is a commandline tool which will render jinja2 templates to textfiles. all environment variables can be used in the jinja2 templates, within the environment variables you can use special tags which give you the option to insert json, json file paths, base64 hashes, consul kv keys.

e2j2 is intended to be used within docker containers, you can simply add the j2 extention to a configuration file and then run e2j2 before you’re starting the actual executable.

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

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:

~> 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
scheme url scheme http or https http
host consul host localhost
port consul http(s) port 8500
token consul token none

Config example:

$ read -d '' CONSUL_CONFIG << EOF
> {
>   "scheme": "https",
>   "host": "consul.foobar.tld",
>   "port": 443,
>   "token": "abcdef01-0123-abcd-1234-0123456789ab"
> }
> EOF

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' );

Changelog

0.1.12 (2019-03-14)

Added

  • add support for two pass rendering

0.1.11 (2019-01-30)

Changed

  • Changed behavior of nested keys with the consul tag.

example: in consul we have an key key1/key2/123 envvar KEY=consul:key1/key2 => {{ KEY }} will now render to 123 and no longer to {“key2”: 123}

0.1.10 (2018-09-24)

Added

  • add file tag, this tag will place the content of the file into the variable

0.1.9 (2018-09-21)

Fixed

  • fix import issue on python 2.7

0.1.8 (2018-09-21)

Changed

  • handle hashrocket characters in json tag (as produced by hiera)

0.1.7 (2018-09-20)

Added

  • Add list tag which will parse a comma separated list

0.1.6 (2018-05-17)

Changed

  • Improved error messages
  • Handle json decode errors

0.1.5 (2018-05-11)

Added

  • add no-color option

0.1.4 (2017-08-21)

Added

  • add version option
  • add file list option

Fixed

  • Fix bug with empty consul key values

0.1.3 (2017-07-11)

Breaking change

  • the consul tags will now use default jinja2 objects, this breaks the previous behaviour of separation by underscores

Changed

  • remove dependency click, use argparse instead.

Fixed

  • make sure that bytes are casted to strings (for base64 and consul tags)

0.1.2 (2017-05-17)

Fixed

  • additional fix for install issue on python2 (added MANIFEST.in)

0.1.1 (2017-05-17)

Fixed

  • add README.rst and CHANGELOG.rst as package_data this fixes install issue with python 2.x

Removed

  • remove dependency colorama

Changed

  • move methods to separate helper files

0.1.0 (2017-05-16)

Added

  • add short options for extention (-e) searchlist (-s) and noop (-N)
  • add (MIT) license

Changed

  • e2j2 is now packaged as pip package
  • split script and module, script will be installed in /usr/bin or /usr/local/bin

0.0.2 (2017-05-16)

Added

  • Add recurse flag

Changed

  • Searchlist is no longer a required option e2j2 will use the current directory as default
  • Recursion is no longer on by default
  • Improve error handling, e2j2 will now report failures and render *.err files which will make debugging errors much easier

0.0.1 (2017-05-01)

Initial release

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