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Add note for runtime host configuration for checks.

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Please see https://github.com/dokku/dokku/issues/2159 for motivation.

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Luke Murphy
2018-02-03 16:49:51 +01:00
parent fe1275d4e7
commit 2475b9e7ea
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docs/deployment/zero-downtime-deploys.md
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@@ -250,6 +250,22 @@ dokku checks:run node-js-app web.3
Invalid container id specified (APP.web.3)
```
## `CHECKS` and your Application
Some applications, for example, Django, make a point of mandating that the host
header of the incoming request is defined in the configuration. This is for
security purposes. This can result in errors when checks are being performed.
Dokku cannot make decisions here because it is the responsibility of the
application to configure this.
One potential solution is to dynamically configure your hosts at run-time. In
the case of Django, this might look like:
```
from socket import gethostname, gethostbyname
ALLOWED_HOSTS = [ gethostname(), gethostbyname(gethostname()), ]
```
## Example: Successful Rails Deployment
In this example, a Rails application is successfully deployed to dokku. The initial round of checks fails while the server is starting, but once it starts they succeed and the deployment is successful. `WAIT` is set to `10` because our application takes a while to boot up. `ATTEMPTS` is set to `6`, but the third attempt succeeds.