Ruby/PG - Cannot connect to PostgreSQL

Question

I've setup a new Linux Subsystem (Ubuntu) on Windows to run Ruby scripts, but the PG gem cannot connect to my PostgreSQL server. It seems like I can connect just fine using psql in the terminal (I think), but not using irb.

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Problem:

If I run the following in IRB (within the Linux subsystem shell):

require 'pg'
PG.connect(:dbname=>"postgres")

I get the following error:

PG::ConnectionBad: could not connect to server: No such file or directory
Is the server running locally and accepting connections on Unix domain socket "/var/run/postgresql/.s.PGSQL.5432"?

However, if I use psql to to select the version(), it returns that just fine:

psql -p 5432 -h localhost -U postgres
postgres=# select version();

Returns:

PostgreSQL 10.1 on x86_64-pc-mingw64, compiled by gcc.exe (Rev5, Built by MSYS2 project) 4.9.2, 64-bit (1 row)

I should mention that I installed Postgres in my Windows environment, and not within the Linux subsystem - however, due to limitations in the subsystem, this seems to be the only way to do it from what I've read online.

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I'm not sure if this belongs here or on Superuser or the unix/ubuntu SE, but my basic troubleshooting indicates that this is a problem with Ruby/pg gem, not the subsystem, so I'm posting my question here first.

Answer 1

The default connection is UNIX socket (a quasi-file, as you can see by the error message, /var/run/postgresql/.s.PGSQL.5432 ), not TCP socket (host:port). Pass your host/port explicitly to PG.connect .

PG.connect(dbname: "postgres", host: 'localhost', port: 5432)