[feature] Avoid unnecessary restart when postgresql.conf changes

[willthames]

Most postgresql.conf changes don't need a restart, just a reload. And a reload is much safer.

To avoid a restart except where essential, there are a few approaches.
One is documented at http://www.postgresql.org/message-id/80920AC4-56A3-4E4F-9AF2-7E7A8635F0D2@redzonesoftware.com

My thought was to have postgresql.conf only include postgresql_needs_restart.conf and postgresql_needs_reload.conf. postgresql_needs_restart.conf would include the parameters mentioned in the above email thread.

If postgresql.conf or postgresql_needs_restart.conf changes, the restart postgresql handler is fired as now. But if postgresql_needs_reload.conf changes, a new reload postgresql handler is fired.

I'm happy to implement this but thought I'd see what your thoughts were first on whether it's a sensible approach or if there's anything I've missed.

[Trikke76]

It will ask a bit of implementation but would indeed be a great addition to the rule imho.
I don't know what others are thinking about this but for me it looks awesome
next week i'm rather busy but after that i could probably help implementing this rule if you want some help on this.

Anyone else any toughts ? maybe on negative impacts it might have that i am missing ?

[ciphernaut]

meta/main.yml:
postgresql_need_full_postgresql_restart: False

---

tasks/configure.yml"

• name: foo
  register: something_fundamental
• set_fact: postgresql_need_full_postgresql_restart=True
  when: something_fundamental|changed

---

handlers/main/yml:

• name: restart postgresql
  shell: /bin/true #(needed for ansible v1.9)
  always_run: true
  notify: restart postgresql full
  notify: restart postgresql soft
• name: restart postgresql full
  service: name=postgresql{{join_char | default("-")}}{{postgresql_version}} state=restarted
  when: postgresql_need_full_postgresql_restart
• name: restart postgresql soft
  service: name=postgresql{{join_char | default("-")}}{{postgresql_version}} state=reloaded
  when: not postgresql_need_full_postgresql_restart

[willthames]

Trouble is working out something_fundamental. Some things in postgresql.conf need a restart, most just need a reload.

postgresql_need_full_postgresql_restart should presumably be in defaults/main.yml, not meta/main.yml

Also, notify takes a list (two notify keys would just mean one is ignored)

python -c 'import yaml; d = "test_dict:\n  notify: one\n  notify: two"; y = yaml.load(d); print y'
{'test_dict': {'notify': 'two'}}

I'm not convinced the logic is any easier - I'd just notify a full restart when something fundamental changed, and a reload otherwise.

[Trikke76]

hey 

Thx for all the contributions

I will try to test en merge in the coming weeks

On holiday now till end of next week ...

Patrik

-----Original message-----
From: Will Thames notifications@github.com
Sent: Friday 26th February 2016 7:25
To: Open-Future-Belgium/PostgreSQL PostgreSQL@noreply.github.com
Cc: Patrik Uytterhoeven patrik@open-future.be
Subject: Re: [PostgreSQL] [feature] Avoid unnecessary restart when postgresql.conf changes (#41)

Trouble is working out something_fundamental. Some things in postgresql.conf need a restart, most just need a reload.

postgresql_need_full_postgresql_restart should presumably be in defaults/main.yml, not meta/main.yml

Also, notify takes a list (two notify keys would just mean one is ignored)

python -c 'import yaml; d = "test_dict:\n notify: one\n notify: two"; y = yaml.load(d); print y'
{'test_dict': {'notify': 'two'}}

I'm not convinced the logic is any easier - I'd just notify a full restart when something fundamental changed, and a reload otherwise.

—
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