Passage du conteneur autonome à des conteneurs web et données séparés

[5minpause]

Ceci est une configuration avancée. Ne suivez pas ces instructions à moins d’être expérimenté en administration de serveurs Linux et Docker. Vous devez également prêter une attention particulière aux commits sur discourse_docker pour vous assurer de remarquer s’il y a une mise à jour de version pour postgres ou redis.

Conversion de votre configuration actuelle

J’ai réussi à migrer vers deux conteneurs. Si quelqu’un d’autre a besoin d’instructions, voici comment cela a fonctionné pour moi.
Le processus comprend la sauvegarde, la configuration de conteneurs web et de données séparés, et la restauration des données.

1. Sauvegardez votre instance Discourse et téléchargez la sauvegarde. Vous pouvez suivre le guide simple ou la sauvegarde et restauration manuelles ultérieures.

2. Arrêtez le conteneur autonome actuel
   ./launcher stop app

3. Copiez web_only.yml et data.yml depuis samples/ vers containers/, renommez-les comme vous le souhaitez, par exemple web_rocks.yml et data2.yml.

4. Si vous les renommez, veuillez prêter attention aux entrées volumes: dans data.yml et web_only.yml
   Si vous avez renommé web_only.yml en web_rocks.yml, vous devez modifier l’entrée dans Web_rocks.yml comme suit :

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

Faites une modification similaire dans data.yml également.

Configuration du conteneur de données

Commencez avec data.yml et définissez un mot de passe pour la base de données. Ensuite :

• accédez au dossier racine du conteneur /var/discourse
• exécutez ./launcher bootstrap data2 (data2 ou quel que soit le nouveau nom que vous lui avez donné)
• exécutez ./launcher start data2 (en utilisant à nouveau le nouveau nom)
• si tout se passe bien, vous pouvez vous connecter au conteneur via : ./launcher enter data2 (en utilisant à nouveau le nouveau nom)
• Quittez le conteneur avec exit.

Configuration du conteneur web

Modifions web_only.yml.

Premièrement, changez le modèle et exposez les ports comme le fait votre app.yml.

Deuxièmement, assurez-vous de lier au bon conteneur de données. Si vous avez renommé data.yml en ‘something_else’, mettez-le pour ‘name’.

# Utilisez la clé 'links' pour lier les conteneurs ensemble, c'est-à-dire utilisez le drapeau Docker --link.
links:
  - link:
      name: data
      alias: data

Bien que nous ne souhaitions plus exposer ssh ou tout autre port, vous devrez toujours exposer les ports 80 et 443 pour l’accès web. Cela dépend si vous avez un nginx en frontal et comment vous connectez le conteneur avec lui.

Quelque part là-dedans, vous trouverez ce bloc :

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

• Entrez le mot de passe que vous avez défini dans le conteneur de données.
• Entrez l’alias du conteneur de données que vous venez d’écrire. Pour DB_HOST et pour REDIS_HOST. Il doit correspondre au bloc links que nous avons mentionné.
• Vous n’avez probablement pas changé le DB_USERNAME.

Vous trouverez les valeurs pour DISCOURSE_DEVELOPER_EMAILS et DISCOURSE_HOSTNAME et bien d’autres. Vous avez déjà ces valeurs dans votre app.yml. Copiez-les à partir de là.

Dans la section des hooks, n’oubliez pas de définir tous les plugins supplémentaires que vous utilisez déjà dans app.yml

Maintenant, vous devriez être prêt à le bootstrap :
./launcher bootstrap web_only (encore une fois avec votre nouveau/propre nom)

Une fois bootstrappé, vous pouvez démarrer web_only (utilisez votre nouveau nom) :
./launcher start web_only

Une fois que Discourse est prêt, connectez-vous et restaurez votre site.

Après cela, tout a fonctionné à nouveau pour moi et mon installation discourse fonctionnait à nouveau, mais maintenant dans deux conteneurs séparés.

Comment mettre à jour lors de l’utilisation de conteneurs web et de données séparés

Si vous ne vous souciez pas des quelques minutes d’indisponibilité – ou lorsque les données doivent être mises à jour. Les changements à postgres et redis sont rares, et laisser le conteneur de données en cours d’exécution est ce qui permet de construire un nouveau conteneur web_only pendant que l’ancien fonctionne.

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

Cela fonctionne pour une mise à niveau mineure de Postgres et/ou une mise à niveau de redis.

Si vous vous souciez de chaque minute d’indisponibilité et que les données n’ont pas besoin d’être mises à jour (ce qui est le cas la plupart du temps) :

mise à jour uniquement de web_only :

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

Il suffit de reconstruire web_only et de sauter data sauf en cas de mise à jour de postgres ou de redis. Celles-ci se produisent de l’ordre d’une fois par an et vous verrez une annonce comme PostgreSQL 15 update lorsque cela se produit, bien que les mises à jour de redis et les mises à jour mineures de postgres ne soient pas annoncées de manière aussi évidente.

La reconstruction de data nécessite un temps d’arrêt (pour la même raison que la version à conteneur unique – vous ne pouvez pas mettre à jour postgres pendant qu’un autre processus accède aux mêmes fichiers de base de données. De plus, lorsque vous construisez un nouveau conteneur de données, vous devez détruire et démarrer le conteneur web_only car il tentera de se connecter à l’ancien conteneur.

Vous n’avez pas souvent besoin de reconstruire le conteneur de données (c’est pourquoi cette méthode permet d’économiser du temps d’arrêt). Vous devez faire attention à quand il y a une mise à jour dans postgres ou redis ; le frontal ne le saura pas ; c’est une configuration avancée qui nécessite plus d’attention qu’un conteneur unique.

Gestion d’une installation à deux conteneurs

@pfaffman créera un sujet à ce sujet un jour, mais en attendant, il y a ceci : 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!

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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.