Feature/support pgbouncer

[jsvisa]

• CHANGELOG.md updated
• README.md updated

[sparrc]

what does this add that the regular postgres plugin isn't able to provide?

[sparrc]

closing for lack of updates

[jsvisa]

@sparrc Sorry for the delay.

Yes, the postgres plugin can provide the detail.

For PgBouncer, all statistics are stored in one database, default as 'pgbouncer', and the backend databases' information are stored in it as regular records. See more from PgBouncer usage.

For telegraf/postgresql.go at master · influxdata/telegraf, the command not applied,

and for telegraf/postgresql_extensible.go at master · influxdata/telegraf, it always need version information

[sparrc]

For telegraf/postgresql.go at master · influxdata/telegraf, the command not applied,

what does that mean exactly? can you add "the command" to that plugin?

and for telegraf/postgresql_extensible.go at master · influxdata/telegraf, it always need version information

please also explain more, what do you mean that it always needs version information? why is pgbouncer not compatible with "version information"?

[jsvisa]

Sorry for my rudeness. First of all, pgbouncer/pgbouncer: PgBouncer development is a

Lightweight connection pooler for PostgreSQL.

Pgbouncer always store the stat info inside it's own datebase, not in PostgreSQL's side.
The stat of PostgreSQL not applied to pgbouncer.

And in postgresql_extensible.go, we need to fetch the PostgreSQL's version first, then execute the specified query string, but the version query

query = select substring(setting from 1 for 3) as version from pg_settings where name='server_version_num'

is not available in the special administration database pgbouncer , which only support below commands:

SHOW [HELP|CONFIG|DATABASES|FDS|POOLS|CLIENTS|SERVERS|SOCKETS|LISTS|VERSION]
SET key = arg
RELOAD
PAUSE
SUSPEND
RESUME
SHUTDOWN

So I think we need add the pgbouncer plugin along with postgresql and postgresql_extension.

[sparrc]

okay, fair enough, thanks for the clarification

[jsvisa]

May I reopen this PR?

[sparrc]

yes, sorry, I meant to do that with the last comment

[jsvisa]

@sparrc thanks, rebased

[sparrc]

Can you explain why you've used your own docker image for the tests? From googling there appears to be some others that are more common/popular. I ask because I've had contributors add docker images that have gone defunct.

[jsvisa]

Mine is based on alpine as base image, which is smaller(only 16MB), and seems the others use Ubuntu, which size almost is 98MB.