Layer NGINX-Config

This layer provides a lib for higher layers to access NGINX and setup configurations for the HTTP and Stream modules.

For more information see the documentation.

Writing NGINX HTTP / Stream config

How it works

The layer will create per juju application and per juju layer within the charm a separate directory where NGINX configuration will be written. The generated dirs will only be created for layers which actually create the NginxConfig object. Each layer-directory has two default subdirectories sites-available and streams-available where respectively the HTTP and stream config is written to. If needed you can create your own directorys within these.

/etc/nginx/
    ├── juju/
    │   ├── backups/
    │   └── nginx-0/         # Juju unit 
    │       └── nginx_tcp/   # Calling layer
    │           ├── sites-available/
    │           └── streams-available/
    │               └── amq-tcp
    ├── nginx.conf
    ├── sites-available/
    │   └── default
    ├── sites-enabled/
    ├── streams-enabled/
    │   └── amq-tcp -> /etc/nginx/juju/nginx-0/nginx_tcp/streams-available/amq-tcp
    ├── ...

Examples

Writing some config with the default directories

from charms.layer.nginx_config_helper import (
    NginxConfig, 
    NginxConfigError, 
    NginxModule,
)

@when('nginx-config.installed',
      'endpoint.tcp.update')
def tcp_update():
    # Generate the tcp config
    tcp_config = ...
    tcp_filename = ...
    # Create a NginxConfig instance

    try:
        nginxCfg = NginxConfig()
        
                # Remove symb links and delete old stream configs
        nginxCfg.delete_all_config(NginxModule.STREAM) \ 
                # Write the new config to the streams-available dir
                .write_config(NginxModule.STREAM, tcp_config, tcp_filename) \ 
                # Create symb links to streams-enabled
                .enable_all_config(NginxModule.STREAM) \ 
                # Run a NGINX validation check
                .validate_nginx() \ 
                # Reload the NGINX config for all workers
                .reload_nginx() 
    except NginxConfigError as e:
        status_set('blocked', e)
        log(e)
        return
    clear_flag('endpoint.tcp.update')

Using custom directories

In some cases it can be helpful if you could split the NGINX configuration in more than one directory. For example if we have a charm that is setting up tcp and udp proxies from multiple interfaces, we might want seperate directories for tcp and udp. Our streams-available dir would look like this:

/etc/nginx/
    ├── juju/
    │   └── nginx-0/     
    │       └── nginx_tcp/
    │           └── streams-available/
    |               ├── tcp/
    |               |   └── amq-tcp
    │               └── udp/

In this case we need to do the following steps:

• Manually create the desired directory structure.
• use delete_all_config() with the optional subdir argument pointing to the tcp or udp directory.
• use write_config() with the optional subdir argument pointing to the tcp or udp directory.
• use enable_all_config() with the optional subdir argument pointing to the tcp or udp directory.

You can access the generated dirs via the following NginxConfig attributes (example with dir structure above):

• NginxConfig.base_path: Path to the layer directory. Ex. /etc/nginx/juju/nginx-0/nginx_tcp
• NginxConfig.http_available_path: Path to the sites-available directory. Ex /etc/nginx/juju/nginx-0/nginx_tcp/sites-available
• NginxConfig.streams_available_path: Path to the sites-available directory. Ex /etc/nginx/juju/nginx-0/nginx_tcp/streams-available

Reading / modifying the nginx.conf file

You can access and modify the nginx.conf file via the NginxMainConfig class. You can use this class to add modules (only stream and http are currently supported) and add include key-values to these modules. Checking the config file is easy via the NginxMainConfig.config_as_dict() method. If you are only interested in checking the includes use NginxMainConfig.get_includes(NginxModule).