Mercure

More info: Mercure Website, Mercure is used in Mbin for real-time communication between the server and the clients.

Caddybundle

Download and install Mercure (we are using Caddyserver.com mirror to download Mercure):

sudo wget "https://caddyserver.com/api/download?os=linux&arch=amd64&p=github.com%2Fdunglas%2Fmercure%2Fcaddy&idempotency=69982897825265" -O /usr/local/bin/mercure

sudo chmod +x /usr/local/bin/mercure

Prepare folder structure with the correct permissions:

cd /var/www/mbin
mkdir -p metal/caddy
sudo chmod -R 775 metal/caddy
sudo chown -R mbin:www-data metal/caddy

Caddyfile Global Options

note

Caddyfiles: The one provided should work for most people, edit as needed via the previous link. Combination of mercure.conf and Caddyfile

Add new Caddyfile file:

nano metal/caddy/Caddyfile

The content of the Caddyfile:

{
        {$GLOBAL_OPTIONS}
        # No SSL needed
        auto_https off
        http_port {$HTTP_PORT}
        persist_config off

        log {
                # DEBUG, INFO, WARN, ERROR, PANIC, and FATAL
                level WARN
                output discard
                output file /var/www/mbin/var/log/mercure.log {
                        roll_size 50MiB
                        roll_keep 3
                }

                format filter {
                        wrap console
                        fields {
                                uri query {
                                        replace authorization REDACTED
                                }
                        }
                }
        }
}

{$SERVER_NAME:localhost}

{$EXTRA_DIRECTIVES}

route {
	mercure {
		# Transport to use (default to Bolt with max 1000 events)
		transport_url {$MERCURE_TRANSPORT_URL:bolt://mercure.db?size=1000}
		# Publisher JWT key
		publisher_jwt {env.MERCURE_PUBLISHER_JWT_KEY} {env.MERCURE_PUBLISHER_JWT_ALG}
		# Subscriber JWT key
		subscriber_jwt {env.MERCURE_SUBSCRIBER_JWT_KEY} {env.MERCURE_SUBSCRIBER_JWT_ALG}
    # Workaround for now
		anonymous
		# Extra directives
		{$MERCURE_EXTRA_DIRECTIVES}
	}

	respond /healthz 200
	respond "Not Found" 404
}

Ensure not random formatting errors in the Caddyfile

mercure fmt metal/caddy/Caddyfile --overwrite

Supervisor Job

We use supervisor for running the Mercure job:

sudo nano /etc/supervisor/conf.d/mercure.conf

With the following content:

[program:mercure]
command=/usr/local/bin/mercure run --config /var/www/mbin/metal/caddy/Caddyfile
process_name=%(program_name)s_%(process_num)s
numprocs=1
environment=MERCURE_PUBLISHER_JWT_KEY="{!SECRET!!KEY!-32_3-!}",MERCURE_SUBSCRIBER_JWT_KEY="{!SECRET!!KEY!-32_3-!}",SERVER_NAME=":3000",HTTP_PORT="3000"
directory=/var/www/mbin/metal/caddy
autostart=true
autorestart=true
startsecs=5
startretries=10
user=www-data
redirect_stderr=false
stdout_syslog=true

Afterwards let supervisor reread the configuration and update the processing groups:

sudo supervisorctl reread && sudo supervisorctl update && sudo supervisorctl start all