tcoopman
Delay the startup of an application while waiting for a dependency to be started
I have an application with an external dependency (let’s call it Dep). When my application (App) starts up, the first thing it does it that it also tries to make a connection to Dep.
But when I deploy or do integration tests, I start Dep and App at roughly the same time. Dep takes a while to start (5-20seconds).
My current workaround is to introduce sleep in the startup scripts, but this is quite error prone, so I would like to solve it in a clean way.
My initial tought was to try to make a connection, when that fails, sleep for 2 seconds and try again. If it succeeds, start up. But is that allowed in Application.start/2? Or can I delay the startup in the GenServer.init?
What would be the correct way to solve this? Thanks!
Marked As Solved
josevalim
Here is a good post on the topic: https://ferd.ca/it-s-about-the-guarantees.html
If you need your connections when the app boots, then you need to start and wait for them. But if you don’t, then in your init callback you can send a message to yourself and pick it up immediately.
def init(...) do
send(self(), :async_init)
{:ok, ...state...}
end
def handle_info(:async_init, state) do
# finish init
{:noreply, state}
end
Popular in Questions
Other popular topics
Latest on Elixir Forum
Sponsor Spotlight
Supporting innovation across the BEAM ecosystem.
Categories:
Sub Categories:
Forums
Our Sponsors
Build Elixir applications with speed and confidence.
Supporting innovation across the BEAM ecosystem.
We build reliable cloud platforms for business-critical systems.
Catch errors, track performance, monitor hosts and more.
Develop your skills with books, videos, and courses.
Producing high quality Elixir screencasts since 2017.
The deployment platform built for Elixir: PaaS ease, VPS control.
Courses that'll move you from confusion to "Aha, now I get it!"