Hello!
I am setting up a phoenix app and want to deploy it on Azure app service.

I run the docker image locally, and can connect to the Azure postgres app.
When I use the same image for app deployment I get this error

2025-02-01T21:23:27.0698211Z 21:23:27.069 [error] Postgrex.Protocol (#PID<0.2973.0>) failed to connect: ** (DBConnection.ConnectionError) tcp connect (company-name-staging.postgres.database.azure.com:5432): non-existing domain - :nxdomain

config:

config :company-name, App.Repo,
    ssl: true,
    ssl_opts: [
      stacktrace: true,
      protocol: :tls,
      protocol_version: :"tlsv1.3",
      verify: :verify_peer,
      cacertfile: "/etc/ssl/certs/ca-certificates.crt",
      server_name_indication: String.to_charlist(pghostname),
      verify_fun:
        {&:ssl_verify_hostname.verify_fun/3,
          [check_hostname: String.to_charlist(pghostname)]}
    ],
    database: pgdatabase,
    username: pgusername,
    password: pgpassword,
    hostname: pghostname,
    pool_size: String.to_integer(System.get_env("POOL_SIZE") || "10")

bonus weirdness:
in my start up script I run
psql "host=<hostname>.database.azure.com port=5432 dbname=postgres user=admin password=$PGPASSWORD" -c "SELECT * FROM users;"
and I can connect to the db even from deployed app

the database’s authentication method is PostgreSQL user and password only