Nginx Configuration

Dokku uses nginx as its server for routing requests to specific applications. By default, access and error logs are written for each app to /var/log/nginx/${APP}-access.log and /var/log/nginx/${APP}-error.log respectively

nginx:access-logs <app> [-t]             # Show the nginx access logs for an application (-t follows)
nginx:build-config <app>                 # (Re)builds nginx config for given app
nginx:error-logs <app> [-t]              # Show the nginx error logs for an application (-t follows)
nginx:report [<app>] [<flag>]            # Displays a nginx report for one or more apps
nginx:set <app> <property> (<value>)     # Set or clear an nginx property for an app
nginx:show-config <app>                  # Display app nginx config
nginx:validate-config [<app>] [--clean]  # Validates and optionally cleans up invalid nginx configurations

Binding to specific addresses

New

Introduced in 0.19.2

By default, nginx will listen to all interfaces ([::] for IPv6, 0.0.0.0 for IPv4) when proxying requests to applications. This may be changed using the bind-address-ipv4 and bind-address-ipv6 properties. This is useful in cases where the proxying should be internal to a network or if there are multiple network interfaces that should respond with different content.

dokku nginx:set node-js-app bind-address-ipv4 127.0.0.1
dokku nginx:set node-js-app bind-address-ipv6 ::1

This may be reverted by setting an empty bind address.

dokku nginx:set node-js-app bind-address-ipv4
dokku nginx:set node-js-app bind-address-ipv6

Warning

Validation is not performed on either value.

Users with apps that contain a custom nginx.conf.sigil file will need to modify the files to respect the new NGINX_BIND_ADDRESS_IPV4 and NGINX_BIND_ADDRESS_IPV6 variables.

HSTS Header

New

Introduced in 0.20.0

If SSL certificates are present, HSTS will be automatically enabled. It can be toggled via nginx:set:

dokku nginx:set node-js-app hsts true
dokku nginx:set node-js-app hsts false

The following options are also available via the nginx:set command:

hsts (type: boolean, default: true): Enables or disables HSTS for your application.
hsts-include-subdomains (type: boolean, default: true): Tells the browser that the HSTS policy also applies to all subdomains of the current domain.
hsts-max-age (type: integer, default: 15724800): Time in seconds to cache HSTS configuration.
hsts-preload (type: boolean, default: false): Tells most major web browsers to include the domain in their HSTS preload lists.

Beware that if you enable the header and a subsequent deploy of your application results in an HTTP deploy (for whatever reason), the way the header works means that a browser will not attempt to request the HTTP version of your site if the HTTPS version fails until the max-age is reached.

Checking access logs

You may check nginx access logs via the nginx:access-logs command. This assumes that app access logs are being stored in /var/log/nginx/$APP-access.log, as is the default in the generated nginx.conf.

dokku nginx:access-logs node-js-app

You may also follow the logs by specifying the -t flag.

dokku nginx:access-logs node-js-app -t

Checking error logs

You may check nginx error logs via the nginx:access-logs command. This assumes that app error logs are being stored in /var/log/nginx/$APP-error.log, as is the default in the generated nginx.conf.

dokku nginx:error-logs node-js-app

You may also follow the logs by specifying the -t flag.

dokku nginx:error-logs node-js-app -t

Changing log path

New

Introduced in 0.20.1

The path to where log files are stored can be changed by calling the nginx:set command with the following options:

access-log-path (type: string, default: ${NGINX_LOG_ROOT}/${APP}-access.log): Log path for nginx access logs
error-log-path (type: string, default: ${NGINX_LOG_ROOT}/${APP}-error.log): Log path for nginx error logs

The defaults should not be changed without verifying that the paths will be writeable by nginx. However, this setting is useful for enabling or disabling logging by setting the values to off.

dokku nginx:set node-js-app access-log-path off
dokku nginx:set node-js-app error-log-path off

The default value may be set by passing an empty value for the option:

dokku nginx:set node-js-app access-log-path
dokku nginx:set node-js-app error-log-path

In all cases, the nginx config must be regenerated after setting the above values.

Regenerating nginx config

In certain cases, your app nginx configs may drift from the correct config for your app. You may regenerate the config at any point via the nginx:build-config command. This may fail if there are no current web listeners for your app.

dokku nginx:build-config node-js-app

Showing the nginx config

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

dokku nginx:show-config node-js-app

Validating nginx configs

It may be desired to validate an nginx config outside of the deployment process. To do so, run the nginx:validate-config command. With no arguments, this will validate all app nginx configs, one at a time. A minimal wrapper nginx config is generated for each app's nginx config, upon which nginx -t will be run.

dokku nginx:validate-config

As app nginx configs are actually executed within a shared context, it is possible for an individual config to be invalid when being validated standalone but also be valid within the global server context. As such, the exit code for the nginx:validate-config command is the exit code of nginx -t against the server's real nginx config.

The nginx:validate-config command also takes an optional --clean flag. If specified, invalid nginx configs will be removed.

Warning

Invalid app nginx config's will be removed even if the config is valid in the global server context.

dokku nginx:validate-config --clean

The --clean flag may also be specified for a given app:

dokku nginx:validate-config node-js-app --clean

Customizing the nginx configuration

New

Introduced in 0.5.0

Dokku uses a templating library by the name of sigil to generate nginx configuration for each app. You may also provide a custom template for your application as follows:

Copy the following example template to a file named nginx.conf.sigil and either:
If using a buildpack application, you must check it into the root of your app repo.
ADD it to your dockerfile WORKDIR
if your dockerfile has no WORKDIR, ADD it to the /app folder

Info

When using a custom nginx.conf.sigil file, depending upon your application configuration, you may be exposing the file externally. As this file is extracted before the container is run, you can, safely delete it in a custom entrypoint.sh configured in a Dockerfile ENTRYPOINT.

Info

The default template is available here, and can be used as a guide for your own, custom nginx.conf.sigil file. Please refer to the appropriate template file version for your Dokku version.

Available template variables

{{ .APP }}                          Application name
{{ .APP_SSL_PATH }}                 Path to SSL certificate and key
{{ .DOKKU_ROOT }}                   Global Dokku root directory (ex: app dir would be `{{ .DOKKU_ROOT }}/{{ .APP }}`)
{{ .PROXY_PORT }}                   Non-SSL nginx listener port (same as `DOKKU_PROXY_PORT` config var)
{{ .PROXY_SSL_PORT }}               SSL nginx listener port (same as `DOKKU_PROXY_SSL_PORT` config var)
{{ .NOSSL_SERVER_NAME }}            List of non-SSL VHOSTS
{{ .PROXY_PORT_MAP }}               List of port mappings (same as `DOKKU_PROXY_PORT_MAP` config var)
{{ .PROXY_UPSTREAM_PORTS }}         List of configured upstream ports (derived from `DOKKU_PROXY_PORT_MAP` config var)
{{ .RAW_TCP_PORTS }}                List of exposed tcp ports as defined by Dockerfile `EXPOSE` directive (**Dockerfile apps only**)
{{ .SSL_INUSE }}                    Boolean set when an app is SSL-enabled
{{ .SSL_SERVER_NAME }}              List of SSL VHOSTS

Finally, each process type has it's network listeners - a list of IP:PORT pairs for the respective app containers - exposed via an .DOKKU_APP_${PROCESS_TYPE}_LISTENERS variable - the PROCESS_TYPE will be upper-cased with hyphens transformed into underscores. Users can use the new variables to expose non-web processes via the nginx proxy.

Note

Application config variables are available for use in custom templates. To do so, use the form of {{ var "FOO" }} to access a variable named FOO.

Customizing via configuration files included by the default templates

The default nginx.conf template will include everything from your apps nginx.conf.d/ subdirectory in the main server {} block (see above):

include {{ .DOKKU_ROOT }}/{{ .APP }}/nginx.conf.d/*.conf;

That means you can put additional configuration in separate files, for example to limit the uploaded body size to 50 megabytes, do

mkdir /home/dokku/node-js-app/nginx.conf.d/
echo 'client_max_body_size 50m;' > /home/dokku/node-js-app/nginx.conf.d/upload.conf
chown dokku:dokku /home/dokku/node-js-app/nginx.conf.d/upload.conf
service nginx reload

The example above uses additional configuration files directly on the Dokku host. Unlike the nginx.conf.sigil file, these additional files will not be copied over from your application repo, and thus need to be placed in the /home/dokku/node-js-app/nginx.conf.d/ directory manually.

For PHP Buildpack users, you will also need to provide a Procfile and an accompanying nginx.conf file to customize the nginx config within the container. The following are example contents for your Procfile

web: vendor/bin/heroku-php-nginx -C nginx.conf -i php.ini php/

Your nginx.conf file - not to be confused with Dokku's nginx.conf.sigil - would also need to be configured as shown in this example:

client_max_body_size 50m;
location / {
    index index.php;
    try_files $uri $uri/ /index.php$is_args$args;
}

Please adjust the Procfile and nginx.conf file as appropriate.

Custom Error Pages

By default, Dokku provides custom error pages for the following three categories of errors:

4xx: For all non-404 errors with a 4xx response code.
404: For "404 Not Found" errors.
5xx: For all 5xx error responses

These are provided as an alternative to the generic Nginx error page, are shared for all applications, and their contents are located on disk at /var/lib/dokku/data/nginx-vhosts/dokku-errors. To customize them for a specific app, create a custom nginx.conf.sigil as described above and change the paths to point elsewhere.