Editing PostgreSQL image content for style and consistency

[tpoitras]

Edited PostgreSQL image content from the following PRs:

#240
#247

As per Trello Card https://trello.com/c/GZ0BoR0X

[tpoitras]

Ping @mnagy for Tech Review. Also: Please provide default values for "PostgreSQL Settings" environment variables (see the table I've created). Trying to make this consistent with docs I'm doing for other images.

[mnagy]

Maybe we could use the example without passing the password on a command line and instead enter it in the prompt? Since using the command line is generally considered insecure, we probably shouldn't give a bad example.

[tpoitras]

That's a great point. We definitely don't want to recommend our users to do something that isn't secure.

[mnagy]

@tpoitras Technically, all looks ok, thought I've made some comments. You can find the defaults in the postgresql repository's README.md. It's 100 connections and "32M" for shared buffers.

[mnagy]

Oh, and one more thing, that should maybe apply to all images. In order to build docker images, one needs to have docker working. Should we mention that? Possibly with the minimal required version I imagine, though I don't know off the top of my head which one that would be.

[tpoitras]

Updated as per tech review from Martin.

ping @mnagy -- please verify this looks good, specifically can you please make sure I got the syntax correct for the testing command, now that password is removed? I assumed that the colon should be removed as well.

Also, I think the overview at the start of the topic already covers the need for Docker.

[mnagy]

@tpoitras I apologize, but I just realized that this might not work, because the psql command will prompt for the password and I'm not sure if redirecting the "SELECT 1;' statement won't get caught by the password prompt. Still, this is easily fixed, we just need to use -c or --command.

psql -c "SELECT 1;" postgresql://_<user>_@127.0.0.1:5432/_<database>_

or

psql --command "SELECT 1;" postgresql://_<user>_@127.0.0.1:5432/_<database>_

As per http://www.postgresql.org/docs/9.2/static/app-psql.html

[tpoitras]

@mnagy -- thanks for that. Replaced with the 1st of your 2 suggested commands. Look good?

[mnagy]

LGTM

[tpoitras]

this is ready to be merged now @CowboysFan @adellape

[adellape]

Thanks, @tpoitras. LGTM as well, merging.