Connecting to Postgres Via database_url and Unix Socket in Rails

Question

I've hunted around for this and just can't find a solution. Currently I have a database.yml connected to a local pgbouncer server on a Unix socket successfully. However, I'm transitioning to setting this to a database_url environment variable and cannot work out at all how to connect to a local Postgres server via a Unix socket. localhost obviously works OK. I was looking at a URL that looks like this as apparently you can use this with Postgres (http://www.postgresql.org/docs/9.2/interactive/libpq-connect.html): ``` export DATABASE_URL="postgresql://username@%Fvar%Frun%Fpostgresql%F.s.PGSQL.6432/dbname" ``` However, this will not get past the URI police: ``` rubies/ruby-2.1.5/lib/ruby/2.1.0/uri/common.rb:176:in `split': bad URI(is not URI?): postgresql://username@%Fvar%Frun%Fpostgresql%F.s.PGSQL.6432/dbname ``` Does anyone have any idea about the secret sauce needed for this? I've Googles endlessly and haven't found anything. It must be possible since the application currently connec…

Accepted Answer

31.1.1.2. Connection URIs

The general form for a connection URI is:

```
postgresql://[user[:password]@][netloc][:port][/dbname][?param1=value1&...]`
```

The URI scheme designator can be either postgresql:// or postgres://. Each of the URI parts is optional. The following examples illustrate valid URI syntax uses:

```
postgresql://
postgresql://localhost
postgresql://localhost:5433
postgresql://localhost/mydb 
postgresql://user@localhost
postgresql://user:secret@localhost
postgresql://other@localhost/otherdb?connect_timeout=10&application_name=myapp
```

Components of the hierarchical part of the URI can also be given as parameters. For example:

```
postgresql:///mydb?host=localhost&port=5433
```

Percent-encoding may be used to include symbols with special meaning in any of the URI parts.

Any connection parameters not corresponding to key words listed in Section 31.1.2 are ignored and a warning message about them is sent to stderr.

For improved compatibility with JDBC connection URIs, instances of parameter `ssl=true` are translated into `sslmode=require`.

The host part may be either host name or an IP address. To specify an IPv6 host address, enclose it in square brackets:

```
postgresql://[2001:db8::1234]/database
```

The host component is interpreted as described for the parameter host. In particular, a Unix-domain socket connection is chosen if the host part is either empty or starts with a slash, otherwise a TCP/IP connection is initiated. Note, however, that the slash is a reserved character in the hierarchical part of the URI. So, to specify a non-standard Unix-domain socket directory, either omit the host specification in the URI and specify the host as a parameter, or percent-encode the path in the host component of the URI:

```
postgresql:///dbname?host=/var/lib/postgresql

postgresql://%2Fvar%2Flib%2Fpostgresql/dbname
```

Connecting to Postgres Via database_url and Unix Socket in Rails

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