At work I run Elixir releases in Docker containers managed by Kubernetes, with two applications which are clusters of nodes. In my experience this setup works very well. Yes with containers you give up hot upgrades/downgrades, but I’m also of the opinion that unless you have a good reason to be doing hot upgrades, you don’t need the extra complexity, and Kubernetes makes blue/green and a/b style deployments easy to achieve. Without Kubernetes (or something like it), it’s probably much less interesting to use Docker.
bitwalker
Leader
freiden
Since you’re using Kubernetes I have an other question how do you manage the database connection when destroying and recreating a container?
In the project I’m working on it seems like the db connections are not correctly released when the container is destroyed and I didn’t find any resources on how to do a graceful shutdown of phoenix.
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bitwalker
Leader
@frieden I haven’t had this issue, but I’m running releases in my containers, and when they receive a kill signal, the node is shutdown with :init.stop(), which cleanly shuts down all applications then the node itself.
2
freiden
@bitwalker Did you had this command to your release or is it available through the generated release of exrm?
Do you have an example maybe?
Sorry if my question seems a little bit dumb but I’m new to this.
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imranismail
I’m went the Kubernetes way as well as @bitwalker suggested. Using the endpoints API to connect them together. https://github.com/bitwalker/swarm/blob/master/lib/swarm/cluster/kubernetes.ex
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dropfen
Found an easy to use flynn workflow.
http://nsomar.com/how-to-use-flynn-to-deploy-a-phenix-app/
It’s using heroku buildpacks.. which gives you the base to put your own logic into the build process..
I found it actually the most straightforward way to deploy an app.. so far.
And I really like the git control flow..
- commit your changes,
- merge it to master,
- git push flynn master.. and it will handle the rest for you.
As Bonus, it has some really nice dashboard, to check the logs and so on
3
jaimeiniesta
Flynn is really great, I’m also following that blog post to deploy a Phoenix application, but I get an error when trying to migrate the database (for a new app):
$ flynn run mix ecto.migrate
14:30:03.227 [error] Postgrex.Protocol (#PID<0.210.0>) failed to connect: ** (Postgrex.Error) ssl not available
** (DBConnection.ConnectionError) connection not available because of disconnection
(db_connection) lib/db_connection.ex:718: DBConnection.checkout/2
(db_connection) lib/db_connection.ex:619: DBConnection.run/3
(db_connection) lib/db_connection.ex:921: DBConnection.run_meter/3
(db_connection) lib/db_connection.ex:463: DBConnection.prepare_execute/4
(ecto) lib/ecto/adapters/postgres/connection.ex:82: Ecto.Adapters.Postgres.Connection.execute/4
(ecto) lib/ecto/adapters/sql.ex:228: Ecto.Adapters.SQL.sql_call/6
(ecto) lib/ecto/adapters/sql.ex:178: Ecto.Adapters.SQL.query!/5
(ecto) lib/ecto/adapters/postgres.ex:69: Ecto.Adapters.Postgres.execute_ddl/3
Have you deployed a Phoenix app with Postgres in Flynn?
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dropfen
Not yet, I’ll try to test in the next days, when I have some more time.
My first naive tries ended with the same error.
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jaimeiniesta
Found it, if you disable the SSL option for the repo in config/prod.exs, it works fine.
I guess it’s a safe option as both the app and the database live within the Flynn cluster.
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