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OpenResty Proxy


Introduced in 0.31.0

Dokku can provide integration with the OpenResty proxy service by utilizing the Docker label-based integration implemented by openresty-docker-proxy.

openresty:report [<app>] [<flag>]            # Displays a openresty report for one or more apps
openresty:logs [--num num] [--tail]          # Display openresty log output
openresty:set <app> <property> (<value>)     # Set or clear an openresty property for an app
openresty:show-config <app>                  # Display openresty compose config
openresty:start                              # Starts the openresty server
openresty:stop                               # Stops the openresty server


Using the openresty plugin integration requires the docker-compose-plugin for Docker. See this document from the Docker documentation for more information on the installation process for the docker-compose-plugin.



As using multiple proxy plugins on a single Dokku installation can lead to issues routing requests to apps, doing so should be avoided. As the default proxy implementation is nginx, users are encouraged to stop the nginx service before switching to OpenResty.

The OpenResty plugin has specific rules for routing requests:

  • OpenResty integration is exposed via docker labels attached to containers. Changes in labels require either app deploys or rebuilds.
  • While OpenResty will respect labels associated with other containers, only web containers have OpenResty labels injected by the plugin.
  • Only http:80 and https:443 port mappings are supported at this time.
  • Requests are routed as soon as the container is running and passing healthchecks.

Switching to OpenResty

To use the OpenResty plugin, use the proxy:set command for the app in question:

dokku proxy:set node-js-app openresty

This will enable the docker label-based OpenResty integration. All future deploys will inject the correct labels for OpenResty to read and route requests to containers. Due to the docker label-based integration used by OpenResty, a single deploy or rebuild will be required before requests will route successfully.

dokku ps:rebuild node-js-app

Any changes to domains or port mappings will also require either a deploy or rebuild.

Starting OpenResty container

OpenResty can be started via the openresty:start command. This will start a OpenResty container via the docker compose up command.

dokku openresty:start

Stopping the OpenResty container

OpenResty may be stopped via the openresty:stop command.

dokku openresty:stop

The OpenResty container will be stopped and removed from the system. If the container is not running, this command will do nothing.

Showing the OpenResty compose config

For debugging purposes, it may be useful to show the OpenResty compose config. This can be achieved via the openresty:show-config command.

dokku openresty:show-config

Customizing the OpenResty container image

While the default OpenResty image is hardcoded, users may specify an alternative by setting the image property with the --global flag:

dokku openresty:set --global image dokku/openresty-docker-proxy:0.5.6

Checking the OpenResty container's logs

It may be necessary to check the OpenResty container's logs to ensure that OpenResty is operating as expected. This can be performed with the openresty:logs command.

dokku openresty:logs

This command also supports the following modifiers:

--num NUM        # the number of lines to display
--tail           # continually stream logs

You can use these modifiers as follows:

dokku openresty:logs --tail --num 10

The above command will show logs continually from the openresty container, with an initial history of 10 log lines

Customizing Openresty Settings for an app

OpenResty Properties

The OpenResty plugin supports all properties supported by the nginx:set command via openresty:set. At this time, please consult the nginx documentation for more information on what properties are available.

Please note that the oldest running container will be used for OpenResty configuration, and thus newer config may not apply until older app containers are retired during/after a deploy, depending on your zero-downtime settings.

Custom OpenResty Templates

At this time, the OpenResty plugin does not allow complete customization of the template used to manage an app's vhost. Apps will use a template provided by the OpenResty container to proxy requests. See the next section for documentation on how to configure portions of the template.

Injecting custom snippets into the OpenResty config

The OpenResty plugin allows users to specify templates in their repository for auto-injection into the OpenResty config. Please note that this configuration should be validated prior to deployment or may cause outages in your OpenResty proxy layer.

The following folders within an app repository may have *.conf files that will be automatically injected into the OpenResty config.

  • openresty/http-includes/: Injected in the server block serving http(s) requests for the app.
  • openresty/http-location-includes/: Injected in the location block that proxies to the app in the app's respective server block.

SSL Configuration

The OpenResty plugin only supports automatic ssl certificates from it's letsencrypt integration. Managed certificates provided by the certs plugin are ignored.

Enabling letsencrypt integration

By default, letsencrypt is disabled and https port mappings are ignored. To enable, set the letsencrypt-email property with the --global flag:

dokku openresty:set --global letsencrypt-email

After enabling, the OpenResty container will need to be restarted and apps will need to be rebuilt. All http requests will then be redirected to https.

Customizing the letsencrypt server

The letsencrypt integration is set to the production letsencrypt server by default. To change this, set the letsencrypt-server property with the --global flag:

dokku openresty:set --global letsencrypt-server

After enabling, the OpenResty container will need to be restarted and apps will need to be rebuilt to retrieve certificates from the new server.

Limiting letsencrypt to certain domains


Changing this value may cause OpenResty to fail to start if the value is not valid. Caution should be exercised when changing this value from the defaults.

In cases where your server's IP may have invalid domains pointing at it, limiting letsencrypt to certain allowed domains may be desirable to reduce spam requests on the Letsencrypt servers. The default is to allow all domains to have certificates retrieved, but this can be limited by specifying the allowed-letsencrypt-domains-func-base64 global property.

The default internal value for allowed-letsencrypt-domains-func-base64 is the base64 representation of return true, and is meant to be the body of a lua function that return a boolean value.

value="$(echo 'return true' | base64 -w 0)"
dokku openresty:set --global allowed-letsencrypt-domains-func-base64 $value

As this is a global value, once changed, OpenResty should be stopped and started again for the value to take effect:

dokku openresty:stop
dokku openresty:start

A more complex example would be to limit provisioning of certificates to domains in a specific list. The body of the lua function has access to a variable domain, and we can use it like so:

body='allowed_domains = {"", ""}

for index, value in ipairs(allowed_domains) do
  if value == domain then
    return true

return false
value="$(echo "$body" | base64 -w 0)"
dokku openresty:set --global allowed-letsencrypt-domains-func-base64 $value

To reset the value to the default, simply specify a blank value prior to restarting OpenResty:

dokku openresty:set --global allowed-letsencrypt-domains-func-base64

Displaying OpenResty reports for an app

You can get a report about the app's OpenResty config using the openresty:report command:

dokku openresty:report
=====> node-js-app openresty information
       Openresty image:                   dokku/openresty-docker-proxy:0.5.6
       Openresty letsencrypt email:
=====> python-app openresty information
       Openresty image:                   dokku/openresty-docker-proxy:0.5.6
       Openresty letsencrypt email:
=====> ruby-app openresty information
       Openresty image:                   dokku/openresty-docker-proxy:0.5.6
       Openresty letsencrypt email:

You can run the command for a specific app also.

dokku openresty:report node-js-app
=====> node-js-app openresty information
       Openresty image:                   dokku/openresty-docker-proxy:0.5.6
       Openresty letsencrypt email:

You can pass flags which will output only the value of the specific information you want. For example:

dokku openresty:report node-js-app --openresty-letsencrypt-email