Configuration guide

Warning

This is a "general concept" guide not specific to mfext module as this module does not offer any configuration.

1. Concepts

There are several concepts about configuration in MetWork framework.

1.1 Configuration name

This is a completely optional step/concept.

You can set a configuration name globally for one machine in /etc/metwork.config file.

This file contains a single line with this uppercase configuration name.

Warning

Please use only alphanumeric uppercase characters here

Note

The underscore character has a special inheritance meaning. You can use it but read this configuration guide before to understand its special meaning.

By default, its value is GENERIC.

This configuration name will be used to select special configuration values in all metwork modules and plugins. But you have to define them! If these special configuration values do not exist for the given "configuration name", standard configuration values are used. So if you set a silly value like ZEERT455FRO as configuration name, it will probably change anything unless you defined (before!) some custom configuration value for this silly configuration name.

So changing the configuration name with /etc/metwork.config file can be a fast and practical way to select a kind of configuration variant (for example: PROD_DATACENTER1, DEV_JOHN...). But this variant must exist in other configuration files (see below). Else, default values will be used.

Note

Even, if the default value in /etc/metwork.config is GENERIC, you won't find any configuration variant with this name in upstream configuration files. So default values are used.

Note

With a MetWork profile loaded, you will also the configuration name under the ${MFCONFIG} environment variable (read from the /etc/metwork.config file).

1.2 Overriding roles

The plugin developer (and/or the MetWork Framework developer) provide some configuration files with default values.

These default values can be overriden by a user (who works with metwork runtime users (like mfserv, mfdata...) and who will use ${MFMODULE_RUNTIME_HOME}/config/*.ini files to do that).

But these default values (or user overriden ones) can also be overriden by an admin (who works with root rights and who will use /etc/metwork.config.d/... directories to do that).

Note

Of course, you don't need each role in your organization! For example, you can choose not to configure anything at the user level or at the admin level.

1.3 Configuration groups and keys

The configuration use ini files. So you will find some configurations files with configuration groups or sections with a name in square brackets ([ and ]) and keys (every key has a name and a value delimited by an equals sign (=).

Example:

[nginx]
# This is comment
port=8080

workers=8

[log]
level=debug

In this example, we have two configuration groups: [nginx] and [log]. And we have two keys under [nginx] and one key under [log].

1.4 Configuration variants and inheritance

1.4.1 Basic behavior

Let's say you have the following configuration files:

[group1]
debug=0
debug[DEV]=1

If you don't do anything special, the debug value will be 0 (standard default value).

But, if you set DEV in /etc/metwork.config (configuration name), the debug value will be 1 because of the debug[DEV]=1 line/variant.

Now, if you set PROD in /etc/metwork.config (configuration name), as there is no debug[PROD] line/variant, the debug value will failback to standard value: 0 (in this example).

1.4.2 Inheritance behavior

Still with the same example:

[group1]
debug=0
debug[DEV]=1

What about if we use DEV_JOHN_MONDAY in /etc/metwork.config? As there is no debug[DEV_JOHN_MONDAY] line, one might think that the retained value would be the default one: 0.

In fact, the retrained value will be 1! Why? Because _ (underscore) has a special meaning in configuration names. This is a kind of inheritance mark.

So DEV_JOHN_MONDAY means as a configuration name:

use DEV_JOHN_MONDAY if there is a variant with this exact name
(else) use DEV_JOHN (first level of inheritance) if there is a variant with this name: DEV_JOHN
(else) use DEV (second level of inheritance) if there is a variant with this name: DEV
(else) use standard/default value

So with this example:

[group1]
debug=0
debug[DEV]=1
debug[DEV_JOHN]=2
debug[DEV_PETER]=3
debug[DEV_JOHN_MONDAY]=4
debug[DEV_JOHN_TUESDAY]=5
debug[QA]=6

We get this table:

Configuration name	selected value for `debug` key	comment
`FOO`	`0`	standard value is used
`DEV`	`1`	exact variant
`DEV_JOHN_MONDAY`	`4`	exact variant
`DEV_JOHN_FRIDAY`	`2`	`DEV_JOHN` level of inheritance is used
`DEV_PETER`	`3`	exact variant
`DEV_KATE`	`1`	`DEV` level of inheritance is used
`DEV_SMITH_FOO_BAR_1`	`1`	`DEV` level of inheritance is used
`DEV_JOHN_QA`	`2`	`DEV_JOHN` level of inheritance is used
`FOO_QA`	`0`	the `QA` level can be used only if the configuration name begins with `QA`
`QA5`	`0`	the `QA5` variant does not exist and there is no inheritance because there is no `underscore`
`QA_5`	`6`	`QA` level of inheritance

1.5 Configuration files and environment variables

The value in the configuration file is read only by a custom profile script that will transform into an environment variable.

Only this environment variable will be used by the rest of the module.

To resume the previous example, the selected value for the key debug in [group1] group of the mfserv module configuration is put into MFSERV_GROUP1_DEBUG environment variable.

In a more general way, every configuration option is stored in an environment variable: {MFMODULE}_{SECTION}_{KEY}.

And this environment variable is set only during profile loading.

Warning

When you change the configuration file, it does not change existing environment variables so in some cases you will have to close and reopen your terminal to get new environment variable values.

Note

To get current environment variables values for the current module, you can use for example:

env |grep "^${MFMODULE}_"

Note

There is no configuration variants anymore in environment values as the "good" value has been selected before. So environment variables contain "already resolved" values and that's why all metwork applications read the configuration from environment variables and not directly from ini configuration files.

2. How to configure a MetWork module?

In this chapter, we don't talk about plugins. But only about MetWork modules: mfserv, mfdata...

Let's take mfadmin module as an example. When you install the mfadmin module, you get a default configuration file for the module. With standard packaging, the file is available in /opt/metwork-mfadmin/config/config.ini. In this file, for instance, you will find a default port value of 15605 for the [nginx] group.

This is default values provided by MetWork Framework developers. Let's name it: the upstream configuration file.

Failure

NEVER edit the upstream configuration file. There is no good reason to do that.

To override these default values, there are two ways: the user way or the admin way.

I'm lost! Which way should I use: user or admin?

If you are lost, use the user way first (easier but less powerful)

2.1 As a user

With mfadmin unix user, you will find a config/config.ini file in mfadmin home directory (probably /home/mfadmin).

This file is created (if necessary) when you first log in as mfadmin unix user. It's a copy of the upstream configuration file will all keys commented. As it overrides the upstream configuration file, if the key is commented, the upstream value is used. If you uncomment a key, this is the corresponding value in upstream is not used any more.

Note

Configuration groups [name_of_the_group] are not commented and it is normal! Never comment them!

So to keep our example, in this file, you will find a [nginx] group with a commented line # port=15605 in it.

If you want to change this port, first uncomment the line and set a new value to get (for example): port=8080.

you are using a <= 0.9 version?

If you are using a <= 0.9 version, you also need a [INCLUDE_config.ini] special line at the very beginning of your config.ini file.

2.2 As an admin

With root user, you can set a /etc/metwork.config.d/mfadmin/config.ini file with the groups/keys you want to override.

There is no commented lines by default. You have to create the file by yourself.

To override the port of [nginx] to 8081 you can use for example:

$ # as root user
$ cat >/etc/metwork.config.d/mfadmin/config.ini <<EOF
[nginx]
port=8081
EOF

Note

Admin values can't be overridden.

you are using a <= 0.9 version?

If you are using a <= 0.9 version, you also need a [INCLUDE_config.ini] special line at the very beginning of your config.ini file.

3. How to configure a MetWork plugin?

Most of configuration concepts explained here are also available for MetWork plugins.

Please refer ton the "Plugin Guide" for details and specific things.