Why am I getting the error "WARNING server login failed..." when using PGBouncer on Heroku Postgres

Issue

When trying to connect to Heroku Postgres with a custom PGBouncer installation, all connections fail with an error like

WARNING server login failed: FATAL password authentication failed for user "..."

Note that this does not apply when using the Heroku PGBouncer buildpack.

Resolution

• Use the Heroku PGBouncer buildpack
• Use the Postgres md5-hidden password format when configuring your PGBouncer installation
• Check if you're using PGBouncer 1.8 or higher: This pull request, whose fix was included in 1.8, works around the issue by increasing the password buffer size and use a version that includes the fix.

Any of the above should work around the issue