Passaggio da container standalone a container web e dati separati

[5minpause]

Questa è una configurazione avanzata. Non seguirla a meno che tu non abbia esperienza con l’amministrazione di server Linux e Docker. Devi anche prestare molta attenzione ai commit su discourse_docker per assicurarti di notare se c’è un aumento di versione per postgres o redis.

Conversione della configurazione corrente

Sono riuscito a migrare a due container. Se qualcun altro ha bisogno di istruzioni, ecco come ha funzionato per me.
Il processo include backup, configurazione di container web e dati separati e ripristino dei dati.

1. Esegui il backup della tua istanza di discourse e scarica il backup. Puoi seguire la guida semplice o eseguire il backup e ripristinare manualmente più tardi.

2. Ferma il container standalone corrente
   ./launcher stop app

3. Copia web_only.yml e data.yml da samples/ a containers/ rinominali come preferisci, ad esempio web_rocks.yml e data2.yml.

4. Se li rinomini, presta attenzione alle voci volumes: in data.yml e web_only.yml
   Se hai rinominato web_only.yml in web_rocks.yml devi modificare la voce in Web_rocks.yml in questo modo:

volumes:
  - volume:
      host: /var/discourse/shared/web_rocks
      guest: /shared
  - volume:
      host: /var/discourse/shared/web_rocks/log/var-log
      guest: /var/log

Allo stesso modo, esegui modifiche simili anche in data.yml.

Configurazione del container dati

Inizia con data.yml e imposta una password per il database. Quindi:

• vai alla cartella root del container /var/discourse
• esegui ./launcher bootstrap data2 (data2 o qualsiasi nuovo nome tu gli abbia dato)
• esegui ./launcher start data2 (usando di nuovo il nuovo nome)
• se tutto procede senza problemi puoi connetterti al container tramite: ./launcher enter data2 (usando di nuovo il nuovo nome)
• Esci dal container con exit.

Configurazione del container web

Modifichiamo web_only.yml.

Innanzitutto, cambia il template ed esponi le porte come fa il tuo app.yml.

In secondo luogo, assicurati di collegarti al container dati corretto. Se hai rinominato data.yml in ‘something_else’ inseriscilo per ‘name’.

# Usa la chiave 'links' per collegare i container, ovvero usa il flag Docker --link.
links:
  - link:
      name: data
      alias: data

Anche se non vogliamo più esporre ssh o altre porte, dovrai comunque esporre le porte 80 e 443 per l’accesso web. Questo dipende dal fatto che tu abbia un nginx in esecuzione frontalmente e da come colleghi il container ad esso.

Da qualche parte troverai questo blocco:

  DISCOURSE_DB_USERNAME: discourse
  DISCOURSE_DB_PASSWORD: mypassword
  DISCOURSE_DB_HOST: data
  DISCOURSE_REDIS_HOST: data

• Inserisci la password che hai impostato all’interno del container dati.
• Inserisci l’alias del container dati che hai appena scritto. Per DB_HOST e per REDIS_HOST. Deve corrispondere al blocco links che abbiamo menzionato.
• Probabilmente non hai cambiato DB_USERNAME.

Troverai i valori per DISCOURSE_DEVELOPER_EMAILS e DISCOURSE_HOSTNAME e molti altri. Hai già questi valori nel tuo app.yml. Copiali da lì.

Nella sezione hooks ricorda di impostare eventuali plugin aggiuntivi che usi già in app.yml

Ora dovresti essere pronto per avviarlo:
./launcher bootstrap web_only (di nuovo con il tuo nuovo/proprio nome)

Una volta avviato, puoi avviare web_only (usa il tuo nuovo nome):
./launcher start web_only

Quando Discourse è pronto, accedi e ripristina il tuo sito.

Dopo questo, tutto ha funzionato di nuovo per me e la mia installazione di discourse è tornata operativa, ma ora in due container separati.

Come aggiornare quando si utilizzano container web e dati separati

Se non ti interessa il breve tempo di inattività – o quando i dati devono essere aggiornati. Le modifiche a postgres e redis sono infrequenti e lasciare in esecuzione il container dati è ciò che rende possibile costruire un nuovo container web_only mentre quello vecchio è in esecuzione.

./launcher stop web_only && ./launcher rebuild data && ./launcher rebuild web_only

Questo funziona per un aggiornamento minore di Postgres e/o un aggiornamento di redis.

Se ti interessa ogni minuto di inattività e i dati non devono essere aggiornati (il che accade la maggior parte delle volte):

aggiorna solo web_only:

./launcher bootstrap web_only && ./launcher destroy web_only && ./launcher start web_only

È sufficiente ricostruire web_only e saltare data tranne quando c’è un aggiornamento a postgres o redis. Questi avvengono nell’ordine di una volta all’anno e vedrai un annuncio come PostgreSQL 15 update quando accade, anche se gli aggiornamenti a redis e gli aggiornamenti minori di postgres non sono annunciati in modo così evidente.

La ricostruzione dei dati richiede tempi di inattività (per la stessa ragione per cui lo fa la versione a container singolo: non puoi aggiornare postgres mentre un altro processo sta accedendo agli stessi file di database. Inoltre, quando costruisci un nuovo container dati, devi distruggere e avviare il container web_only perché tenterà di connettersi al vecchio container).

Non hai spesso bisogno di ricostruire il container dati (motivo per cui questo metodo consente di risparmiare tempi di inattività). Devi prestare attenzione a quando c’è un aggiornamento in postgres o redis; il frontend non lo saprà; questa è una configurazione avanzata che richiede più attenzione rispetto a un singolo container.

Gestione di un’installazione a due container

@pfaffman creerà un argomento su questo un giorno, ma nel frattempo, c’è questo: Managing a Two-Container Installation - Documentation - Literate Computing Support

[downey (Michael Downey)]

This … didn’t work as expected.

(The instructions are a bit off but I followed the update at https://meta.discourse.org/t/faster-rebuilds/40341/4.)

Should the new 2-container installation present an empty/fresh site? I was assuming it would copy all of my settings & data from my app container, but it was brand new.

Edit: I did a restore from a backup made just before the process, and it seemed to restore everything. So probably this just needs to be made clear.

[fantasticfears (Erick Guan)]

I updated the guide. Hope it reflects your process.

[downey (Michael Downey)]

When someone like @sam puts out instructions to rebuild the “app” container for fixes like this one, is it safe to assume it’s generally going to be in the web_only container?

ImageMagick CVE-2016–3714

Fixed per: https://github.com/discourse/discourse_docker/commit/d47aa69bb72dea153b6901866bb66afe2cca6915 I will also rebuild the entire image next week when Image Magick do a new point release. To take advantage of the fix: cd /var/discourse ./launcher rebuild app

[sam (Sam Saffron)]

Yes, anything that mixes in the template I hacked get this.

[pmusaraj (Penar Musaraj)]

Sorry for the bump on this old conversation, but I had a related issue.

While doing server upgrades that included docker daemon upgrades, docker restarted, but when it did restart, it also restarted the standalone app container, which brought the site back to what it was pre-transitioning to separate containers. After panicking, I stopped the app container, and then started web_only again, and site is back to normal.

But how can I fix this permanently? I tried moving the app.yml file away from the containers folder, but the app docker container still restarts. Should I run ./launcher destroy app ?

P.S. I am mentioning this here, because I did successfully move from a standalone app container to separate data/web_only containers as described here.

[tophee (Christoph)]

Excuse my ignorance but could someone explain to me why this is not the default setup (or an optional setup) in the 30 min install guide?

I understand that using two containers minimizes the downtime during rebuilds and since nobody likes downtime, it seems like everyone would want two containers…

In other words: what’s the catch?

[jomaxro (Joshua Rosenfeld)]

@tophee

In other words: what’s the catch?

It’s more complicated to set up? More has to be done during setup? More potential points of failure? Harder to debug if you don’t understand Docker?

[pfaffman (Jay Pfaffman)]

@tophee

In other words: what’s the catch?

For people like you and me, there is none.

When the 30 minute install was conceived, it involved editing app.yml with a tool like nano (I’m an Emacs user and even I prefer vi to nano). Having people edit copy and edit two files and bootstrap and start both of them in the right order is on the order of 10 times more complicated. Now that ./discourse-setup is how most people configure Discourse, the setup part could be exactly the same for a two-container setup. I’ve looked in to doing just that & it wouldn’t be very hard.

But even still, with two containers, there would then be a bunch of problems with the data container wasn’t running and then no one would say which way their site was configured and that would be a lot more complicated to help out. Most of the time the web-based upgrade works just fine, and so unless you’re changing your plugin config, there’s not that much of a win for the two-container setup.

I think soon that I’ll start offering a two-container setup along side of my $99 install, but I’ve not gotten around to it.

[tophee (Christoph)]

@pfaffman

For people like you and me, there is none

So is everyone here just pretending that they’re running one container but privately they’re running two?

Well, I guess, maybe even for “people like you and me” it is more convenient with one container, given that you don’t change plugins so often.

On the other hand, on standard troubleshooting advice that keeps coming up is obviously “disable all apps and re-enable them onr by one” and unless you do that by just disabling them under settings, this will give you plenty of downtime with one container…

And when I see that people are talking about 10,000 visits per day, that is quite a few annoyed users, even for half an hour downtime.

Anyway, thanks for explaining. And, yes, you should offer the 2-container install, if only to make it better known

[pfaffman (Jay Pfaffman)]

@tophee

So is everyone here just pretending that they’re running one container but privately they’re running two?

No. Usually if someone posts a problem and they’re running multiple containers, they’ll mention that (probably because it’s a problem specifically with multiple containers), but mostly, if you know how to have multiple containers, it won’t make any difference that you do.

FWIW, it took me nearly 2 years to (bother to) figure it out. And six months of that time I was earning all of my income from Discourse consulting (not to say that the income I earned was a living all of that time).

I’d guess that the vast majority of people running Discourse have a single container. I’d guess that the vast majority of people* who earn some of their income from managing or hosting it* and/or would identify as a “system administrator” run two.

[net_deamon]

@tophee

In other words: what’s the catch?

It is not that hard too. You have app.yml file which contains both the properties of datasource and web related(which port discourse should run eg 9000, or the plugins config and the custom commands)

So you just divide the app.yml into data.yml and web.yml.
Data.yml will contain the datasources part from app.yml
While the web.yml will contain rest of config.

I usually use nginx webserver infront of discourse.
So I can rebuild another web contianer at say 9001, and reverse proxy to it from nginx.
Then I safely stop the previous web container running at 9000.
This swapping is done in few seconds… So there is no downtime.

[Berto]

Could use some help here:

@5minpause

Start with data.yml and set a password for the database. Then:

This is confusing. It states to do a step (set a password) but doesn’t state how to do that aforementioned step… and immediately says “then” do some other stuff. Are we missing instructions on setting this password here?

So I didn’t change any password because I don’t know how or what OP is talking about, but did run ./launcher boostrap data and got the following response:

[...bootstrap command running...]
Successfully bootstrapped, to startup use ./launcher start data

prompt$ ./launcher enter data
Error: No such container: data

Note that I didn’t rename anything, only copied the files. I simply have data.yml and web_only.yml in my /var/discourse/containers directory.

Thanks!

[5minpause]

I wrote this “guide” in May 2015. I do not use Discourse any more (stopped soon after). I do not know if any of these instructions still work or how things are done nowadays.

[Berto]

Thanks, people are still linking to it, going to just hire some help. Cheers!

[codinghorror (Jeff Atwood)]

Thanks for getting it started, we will take it from here!

[TheBestPessimist]

Is this still the good tutorial?

Or should follow

Configure Discourse to use a separate PostgreSQL server

Let’s say you’re using AWS RDS, or an existing PostgreSQL server managed elsewhere. It’s fairly straightforward to get Discourse to use such a setup, without needing to grant superuser privileges to anything that Discourse itself runs. Here’s how. Prerequisites Discourse requires PostgreSQL 13; if you try to run on a newer or older version, it might work, but we don’t guarantee it, and if something breaks in the future, you get to keep both pieces. We also require some extensions that are di…

or

Multisite configuration with Docker

While multisite is supported in the Discourse application, this is an advanced sysadmin setup. If you don’t know what you’re doing, do not set up multisite. The Discourse team is unable to provide multisite configuration support. If you wish to host multiple domains on a singled Docker setup, you’ll need a multisite configuration. Here are the basic building blocks for one. Understand hooks Multisite is a fairly advanced topic. Before attempting a multisite build, spend some time…

Right now both of those tutorials still leave me with questions :-/.

[Falco]

The 3 tutorials apply to 3 different situations, so pick the one that applies to what you want.

Running Discourse with a separate PostgreSQL server is for when you have an external PostgreSQL running somewhere else, like AWS RDS.

Multisite configuration with Docker is about running multiple Discourse instances inside the same container.

And this topic is about using different containers for data and web.

The three guides are for advanced users, and we recommend sticking to defaults for people who aren’t familiar with Discourse, containers and the whole sysadmin lingo.

[TheBestPessimist]

well, what i want is to be able to host 3 discourse forums on my own VM.

From that i understand that i need to

1. Separate the data and web containers (this also brings speedup when rebuilding the app)
2. Configure 2 other discourse instances (somehow?) for my 2 other forums.

So this is why i don’t know exactly how to approach this situation.

[fefrei (Felix Freiberger)]

@TheBestPessimist

Separate the data and web containers (this also brings speedup when rebuilding the app)

You may want to do that (mainly to reduce rebuild times), but this is not required, and doesn’t really have anything to do with running multiple sites.

To run three sites, you can either bootstrap them separately (which is rather easy, but triples resource requirements), or use these instructions for setting up multisite:

Multisite configuration with Docker

While multisite is supported in the Discourse application, this is an advanced sysadmin setup. If you don’t know what you’re doing, do not set up multisite. The Discourse team is unable to provide multisite configuration support. If you wish to host multiple domains on a singled Docker setup, you’ll need a multisite configuration. Here are the basic building blocks for one. Understand hooks Multisite is a fairly advanced topic. Before attempting a multisite build, spend some time…

I’m running a setup like this (i.e. multisite, but without separating data and web containers or any other fanciness), and this works fine, but setup is indeed a bit tricky.