6. Quick Start

6.1. Activate the MFSERV environment

One of the first thing, you have to do is to load the “MFSERV environment” in your shell session. There are several ways to do that: check the related documentation.

In this tutorial, follow this way, i.e. log in as the mfserv user.

6.2. Create your first plugin

This step will teach you how to create, run, release and deploy a simple MFSERV plugin with a MFSERV template.

We are going to create a plugin with the default template implementing a simple WSGI hello-world web applications (type python3_sync) . We will called it foo_default.

If it’s the first time you log in as mfserv, you have to set a password before (passwd mfserv or sudo passwd mfserv).

6.2.1. Create the plugin

First, list the available templates, see plugin templates.

Use the default template template to create the plugin : run the following command:

bootstrap_plugin.py create --template=default foo_default

or you can omit the --template parameter, in this case the the default template template will be used:

bootstrap_plugin.py create foo_default

Once you have entered this command, you will be asked to fill in some fields to configure and customize your plugin: for now, press [ENTER] to set the default value, you will be able to modify your plugin configuration anytime later.

The /home/mfserv directory now contains a foo_default sub-directory with files:

config.ini: configuration file of the plugin
 Makefile: directives to build the plugin
 main/__init__.py: package initialization file (may be empty, but file must exist so that the package to be found)
 main/wsgi.py: python entry point of the application

You may check the config.ini file of the plugin, especially :

  • the [app_main] section:

    • type: type of the plugin (ideally, this setting may not be changed)

      [app_main]
type=python3_sync

    • timeout:

      [app_main]
type=python3_sync
# timeout (in seconds) for one request
# (if null or <=0, the MFSERV_NGINX_TIMEOUT is used)
timeout=0

    • main_arg: the entry point of the application,e.g. main.wsgi:application means the entry point is the application function defined in the wsgi.py script of the main python package.

      # main arg (module.submodule:application_function)
# (for example, with regular mfserv plugin, if you set here a value like "
# "main.application:app", then "app" must be a WSGI function available in
# "application.py" file in "main" directory (this directory must have a
# "__init__.py" file to be considered as a module)
main_arg = main.wsgi:application

    • debug: check also Interactive debugger section

      # if you set debug=1, then you will get an interactive debugger
# when you got an exception in your code
# (max age will also be automatically set to 0 and mflog minimal level will be
#  set to DEBUG)
# DON'T USE IT ON PRODUCTION!!!
debug=0

    • resource limits: see Resource limits

  • the [extra_daemon_xxx] section: see Extra daemon.

Tip

Every time you change the plugin configuration, this configuration will be always automatically reloaded.

Let’s now install (as dev build) the plugin by entering the command (from the foo_default plugin directory):

make develop

Check the plugin is installed:

plugins.list

You should show the plugin is installed as dev build, i.e. dev_link

Output:

┌Installed plugins (2)─────────────────┬──────────┬────────────────────────────────────────┐
│ Name          │ Version              │ Release  │ Home                                   │
├───────────────┼──────────────────────┼──────────┼────────────────────────────────────────┤
│ welcome       │ master.ci295.ea4af67 │ 1        │ /home/mfserv/var/plugins/welcome       │
│ foo_default   │ dev_link             │ dev_link │ /home/mfserv/var/plugins/foo_default   │
└───────────────┴──────────────────────┴──────────┴────────────────────────────────────────┘

Now we will see how to add specific configuration to our application. Let’s assume we want to add a configurable link to our main page. We will add this parameter in the config/config.ini file of the MFSERV module (read more about this purpose).

Edit the config/config.ini file and add the following line at the end:

[plugin_foo_default]
my_url=https://medium.com/metwork-framework

Edit and change the main/wsgi.py script as follows:

import os

from mflog import get_logger

logger = get_logger("myapp")

def application(environ, start_response):
    my_url = os.environ.get("MFSERV_PLUGIN_FOO_DEFAULT_MY_URL", "")

    status = '200 OK'
    output = '<h1>Hello World!</h1>'
    if my_url != "":
        output = '{}</br></br><a href="{}">Visit Metwork Framework blog</a>'.format(output, my_url)
    logger.info("this is a test message")
    response_headers = [('Content-Type', 'text/html; charset=utf-8'),
                        ('Content-Length', str(len(output)))]
    start_response(status, response_headers)
    return [output.encode('utf-8')]

Build the plugin:

make develop

Restart MFSERV in order to reload the new configuration (~/config/config.ini MFSERV configuration file)

mfserv.stop;mfserv.start

See also

How to configure mfserv metwork module ?.
Custom plugin configuration

6.2.2. Run the plugin

From a web browser, enter the url of your application: http://localhost:18868/foo_default or http://{remote_host}:18868/foo_default. A ‘Hello World!.’ HTML page with a link to my_url should be displayed.

Note

Because your application is named main you don’t need to specify the application name in the url. http://localhost:18868/foo_default and http://localhost:18868/foo_default/main do the same.

You can check the plugin log files. Log files are stored in the ${HOME}/log directory:

  • app_foo_default_main_workern.stdout (n depends on the numbers of workers defined in the config.ini file of you plugin (see MFSERV log section):

2019-07-02T16:22:16.730181Z [INFO] (myapp#26959) this is a test message {request_id=1bee1c4ce15ee370e98fb64285f9bfa6}

You will notice the request_id is automatically logged: see Disable request ID to be appeared in the logs

  • app_foo_default_main_workern.stdout: empty

You mays also check the nginx_access.log file ((Nginx information messages, in JSON format) and nginx_error.log (Nginx general error messages).

6.2.3. Release the plugin

We will now release the foo_default plugin (considering it as a stable version). Releasing a plugin makes it production-ready, ready to be deployed.

To do this, go to the foo_default plugin directory and enter the command:

make release

This will create a .plugin file that will be used to deploy the plugin, e.g. foo_default-[version]-1.metwork.mfserv.plugin where [version] is the value of the version parameter of the move_image config.ini you enter when you create the plugin (default value is ${MFMODULE_VERSION}). You may change it:

# Version of the plugin (X.Y.Z)
# If the value is [MFMODULE_VERSION],
# the current module version is used
version=1.0.0

6.2.4. Deploy the plugin

Let’s now deploy the foo_default plugin on a production environment.

Prerequisites:

  • Metwork have to be installed on this environment (at least MFSERV and its dependencies MFEXT).

  • You be logged in as mfserv user

In order to deploy the plugin on a production environment, put down the foo_default-[version]-1.metwork.mfserv.plugin in a directory on this target environment, e.g. /home/mfserv/released_plugins

Note

for this tutorial, if your production environment is the same as your development environment, you have to uninstall the foo_default plugin which is already installed (by the make develop command). To uninstall the plugin, enter:

plugins.uninstall foo_default

Then, check the foo_default plugin is no longer installed, enter:

plugins.list

You should not show the foo_default plugin

Output:

┌Installed plugins (1)─────────────────┬──────────┬────────────────────────────────────────┐
│ Name          │ Version              │ Release  │ Home                                   │
├───────────────┼──────────────────────┼──────────┼────────────────────────────────────────┤
│ welcome       │ master.ci295.ea4af67 │ 1        │ /home/mfserv/var/plugins/welcome       │
└───────────────┴──────────────────────┴──────────┴────────────────────────────────────────┘

Let’s now install the plugin on the production environment, enter:

plugins.install /home/mfserv/released_plugins/foo_default-1.0.0-1.metwork.mfserv.plugin

Then, check the foo_default plugin is installed, enter:

plugins.list

Output:

┌Installed plugins (2)─────────────────┬──────────┬────────────────────────────────────────┐
│ Name          │ Version              │ Release  │ Home                                   │
├───────────────┼──────────────────────┼──────────┼────────────────────────────────────────┤
│ welcome       │ master.ci295.ea4af67 │ 1        │ /home/mfserv/var/plugins/welcome       │
│ foo_default   │ 1.0.0                │ 1        │ /home/mfserv/var/plugins/foo_default   │
└───────────────┴──────────────────────┴──────────┴────────────────────────────────────────┘

In practice, the plugins are installed in the ${HOME}/var/plugins directory.

Tip

Another way to install the MFSERV foo_default plugin in a production environment is to put down the .plugin file into /etc/metwork.config.d/mfserv/external_plugins directory. Then to install the plugin, you just restart the MFSERV service by entering service metwork restart mfdata command (as root user). Check Release and Deploy a plugin.