It isn't well documented and only tested on a SQL connection but it's just a set of wrappers around Racket's DB drivers, so you could try including that into your app.

Unfortunately I seem to have completely lost my test project but the connection should work as follows:

    (= dbconn (postgresql-connect user db password))

btw I caught a misspelled 'password' in postgresql-secure-connect:

  (mac postgresql-secure-connect (user db ssl-protocol (o passowrd nil))

  (= dbconn (postgresql-connect "root" "root" password))
  (table-exists? dbconn "items")

I got it to work! I believe akkartik was right. Using command (-c) did the trick, which I assume ensured disconnecting from the database.

  (system "psql -U root -d root -c 'SELECT * FROM items'")

  item_id | name | type | description | created | location ---------+--------+------+-------------------------------------+----------------------------+---------------------------------------------------- 1 | marble | tool | A small, translucent orange bauble. | 2022-02-23 17:59:45.480545 | 0101000020E610000012C2A38D239A5EC040683D7C99E44240 (1 row)

Is this on hubski.com? Have y'all been using postgres there for a long time? Or are you trying it for the first time?

Can you show what command you're running to check that you "can connect to the db from the Arc command line"? I wonder if the app is able to connect but not disconnecting for some reason. That would explain the "thread took too long" timeout message.

It's a new project. However, Hubski has been using postgres for a few years, but it's currently an amalgam of Arc and Racket. I didn't write the db code, and am trying to start fresh. The Hubski racket connection looks like:

  (define db-conn
  (virtual-connection
   (connection-pool
    (lambda () (postgresql-connect
           #:user db-user
           #:password db-pass
           #:database db-database
           #:server db-server
           )))))

  (define db-user     "user")
  (define db-pass     "password")
  (define db-database "hubski")
  (define db-server   "localhost")

Here's my test code that works in the command line, and the response. (I named my db "root" atm and will change that and the user once I get it working. I'm running the app as root.):

  arc> (tostring (pipe-to (system "psql -U root -d root") (prn "SELECT * FROM items WHERE name = 'marble';"))                                     )
  " item_id |  name  | type |             description             |          created           |                                                           
  location                      \n---------+--------+------+-------------------------------------+--                                     ------------ 
  --------------+----------------------------------------------------\n       1 | marble | tool | A small, translucent orange bauble. | 2022-02-23 
  17:59:45.480545 | 0101000020E610000012C2A38D239A5EC040683D7C99E44240\n(1 row)\n\n"
  arc>

I even tried to specify the host and port:

  (pipe-to (system "psql -U root -h 159.203.186.97 -p 5432 -d root") (prn "SELECT * FROM items WHERE name = 'marble';"))

  host    all             root            159.203.186.97:5432      trust

  root@Xyrth:/home/xapp# netstat -tulnp | grep 5432
  tcp        0      0 159.203.186.97:5432     0.0.0.0:*               LISTEN      124232/postgres

BTW, I am using the domain xyrth.com with a nginx reverse proxy. I just had the thought it may be my nginx configuration. It probably needs to listen explicity on 5432? Here's my current sites-enabled:

  server {
    listen 80;
    server_name xyrth.com;
    return 301 https://xyrth.com$request_uri;
  }

  server {
    	listen              443 ssl;
    	server_name         xyrth.com;
        ssl_certificate "/etc/letsencrypt/live/xyrth.com/fullchain.pem";
        ssl_certificate_key "/etc/letsencrypt/live/xyrth.com/privkey.pem";
        ssl_session_cache shared:SSL:5m;
        ssl_session_timeout  10m;

        proxy_redirect      off;
        proxy_set_header    X-Real-IP $remote_addr;
        proxy_set_header    X-Forwarded-For $proxy_add_x_forwarded_for;
        proxy_set_header    Host $http_host;

        location / {
                proxy_buffers 16 4k;
                proxy_buffer_size 2k;
                proxy_pass http://159.203.186.97:8080;
		proxy_set_header Host xyrth.com;
        }

        location ~* \.(png|jpg|tif|ico|ttf|woff|svg|eot|otf|mp3|ogg|wav)$ {
        root /home/xapp/static;
        expires max;
        }

        location ~ ^/(xyrth.css) {
                root /home/xapp/static;
                expires max;
        }

  }

Maybe it isn't disconnecting?

  (tostring (system "psql -V"))

  psql (PostgreSQL) 12.9 (Ubuntu 12.9-0ubuntu0.20.04.1)