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docs: remove reference to django application and make it a warning

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This further clarifies the responsibility of the developer around managing checks in relation to their framework.
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Jose Diaz-Gonzalez
2018-02-13 02:38:57 -05:00
committed by GitHub
parent 2475b9e7ea
commit d8878fdfe2
1 changed files with 8 additions and 16 deletions
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docs/deployment/zero-downtime-deploys.md
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@@ -15,6 +15,14 @@ By default, Dokku will wait `10` seconds after starting each container before as
You may both create user-defined checks for web processes using a `CHECKS` file, as well as customize any and all parts of this experience using the checks plugin.
> Web checks are performed via `curl` on Dokku host. Some application code - such
> as the Django framework - checks for specific hostnames or header values, these
> checks will fail. To avoid this:
>
> - Remove such checks from your code: Modify your application to remove the hostname check completely
> - Allow checks from all hostnames: Modify your application to accept a dynamically provided hostname
> - Specify the domain within the check: See below for further documentation
## Configuring Check Settings using the `config` plugin
There are certain settings that can be configured via environment variables:
@@ -250,22 +258,6 @@ 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.