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SSL Configuration


Introduced in 0.4.0

Dokku supports SSL/TLS certificate inspection and CSR/Self-signed certificate generation via the certs plugin. Note that whenever SSL/TLS support is enabled SPDY is also enabled.

certs:add <app> CRT KEY                  # Add an ssl endpoint to an app. Can also import from a tarball on stdin.
certs:generate <app> DOMAIN              # Generate a key and certificate signing request (and self-signed certificate)
certs:remove <app>                       # Remove an SSL Endpoint from an app.
certs:report [<app>] [<flag>]            # Displays an ssl report for one or more apps
certs:update <app> CRT KEY               # Update an SSL Endpoint on an app. Can also import from a tarball on stdin
# for 0.3.x
dokku nginx:import-ssl <app> < certs.tar


Adding an ssl certificate before deploying an application will result in port mappings being updated. This may cause issues for applications that use non-standard ports, as those may not be automatically detected. Please refer to the proxy documentation for information as to how to reconfigure the mappings.

Per-application certificate management

Dokku provides built-in support for managing SSL certificates on a per-application basis. SSL is managed via nginx outside of application containers, and as such can be updated on-the-fly without rebuilding containers. At this time, applications only support a single SSL certificate at a time. To support multiple domains for a single application, wildcard certificate usage is encouraged.

Certificate setting

The certs:add command can be used to push a tar containing a certificate .crt and .key file to a single application. The command should correctly handle cases where the .crt and .key are not named properly or are nested in a subdirectory of said tar file. You can import it as follows:

tar cvf cert-key.tar server.crt server.key
dokku certs:add node-js-app < cert-key.tar


If your .crt file came alongside a .ca-bundle, you'll want to concatenate those into a single .crt file before adding it to the .tar.

cat yourdomain_com.crt > server.crt

SSL and Multiple Domains

When an SSL certificate is associated to an application, the certificate will be associated with all domains currently associated with said application. Your certificate should be associated with all of those domains, otherwise accessing the application will result in SSL errors. If you wish to remove one of the domains from the application, refer to the domain configuration documentation.

Note that with the default nginx template, requests will be redirected to the https version of the domain. If this is not the desired state of request resolution, you may customize the nginx template in use. For more details, see the nginx documentation.

Certificate generation


Using this method will create a self-signed certificate, which is only recommended for development or staging use, not production environments.

The certs:generate command will walk you through the correct openssl commands to create a key, csr and a self-signed cert for a given app/domain. We automatically put the self-signed cert in place as well as add the specified domain to the application configuration.

If you decide to obtain a CA signed certificate, you can import that certificate using the aforementioned dokku certs:add command.

Certificate removal

The certs:remove command only works on app-specific certificates. It will rm the app-specific tls directory, rebuild the nginx configuration, and reload nginx.

Displaying certificate reports about an app


Introduced in 0.8.1

You can get a report about the apps ssl status using the certs:report command:

dokku certs:report
=====> node-js-sample
       Ssl dir:             /home/dokku/node-js-sample/tls
       Ssl enabled:         true
       Ssl hostnames:       *
       Ssl expires at:      Oct  5 23:59:59 2019 GMT
       Ssl issuer:          C=GB, ST=Greater Manchester, L=Salford, O=COMODO CA Limited, CN=COMODO RSA Domain Validation Secure Server CA
       Ssl starts at:       Oct  5 00:00:00 2016 GMT
       Ssl subject:         OU=Domain Control Validated; OU=PositiveSSL Wildcard; CN=*
       Ssl verified:        self signed.
=====> python-sample
       Ssl dir:             /home/dokku/python-sample/tls
       Ssl enabled:         false
       Ssl hostnames:
       Ssl expires at:
       Ssl issuer:
       Ssl starts at:
       Ssl subject:
       Ssl verified:

You can run the command for a specific app also.

dokku certs:report node-js-sample
=====> node-js-sample ssl information
       Ssl dir:             /home/dokku/node-js-sample/tls
       Ssl enabled:         true
       Ssl hostnames:       *
       Ssl expires at:      Oct  5 23:59:59 2019 GMT
       Ssl issuer:          C=GB, ST=Greater Manchester, L=Salford, O=COMODO CA Limited, CN=COMODO RSA Domain Validation Secure Server CA
       Ssl starts at:       Oct  5 00:00:00 2016 GMT
       Ssl subject:         OU=Domain Control Validated; OU=PositiveSSL Wildcard; CN=*
       Ssl verified:        self signed.

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

dokku certs:report node-js-sample --ssl-enabled

HSTS Header

The HSTS header is an HTTP header that can inform browsers that all requests to a given site should be made via HTTPS. Dokku does not, by default, enable this header. It is thus left up to you, the user, to enable it for your site.

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.

HTTP/2 support

Certain versions of nginx have bugs that prevent HTTP/2 from properly responding to all clients, thus causing applications to be unavailable. For HTTP/2 to be enabled in your applications' nginx configs, you need to have installed nginx 1.11.5 or higher. See issue 2435 for more details.

Running behind a load balancer

Your application has access to the HTTP headers X-Forwarded-Proto, X-Forwarded-Port and X-Forwarded-For. These headers indicate the protocol of the original request (HTTP or HTTPS), the port number, and the IP address of the client making the request, respectively. The default configuration is for Nginx to set these headers.

If your server runs behind an HTTP/S load balancer, then Nginx will see all requests as coming from the load balancer. If your load balancer sets the X-Forwarded- headers, you can tell Nginx to pass these headers from load balancer to your application by using the following nginx custom template

server {
  listen      [::]:{{ .NGINX_PORT }};
  listen      {{ .NGINX_PORT }};
  server_name {{ .NOSSL_SERVER_NAME }};
  access_log  /var/log/nginx/{{ .APP }}-access.log;
  error_log   /var/log/nginx/{{ .APP }}-error.log;

  location    / {
    proxy_pass  http://{{ .APP }};
    proxy_http_version 1.1;
    proxy_set_header Upgrade $http_upgrade;
    proxy_set_header Connection "upgrade";
    proxy_set_header Host $http_host;
    proxy_set_header X-Forwarded-Proto $http_x_forwarded_proto;
    proxy_set_header X-Forwarded-For $http_x_forwarded_for;
    proxy_set_header X-Forwarded-Port $http_x_forwarded_port;
    proxy_set_header X-Request-Start $msec;
  include {{ .DOKKU_ROOT }}/{{ .APP }}/nginx.conf.d/*.conf;

upstream {{ .APP }} {
{{ range .DOKKU_APP_LISTENERS | split " " }}
  server {{ . }};
{{ end }}

Only use this option if: 1. All requests are terminated at the load balancer, and forwarded to Nginx 2. The load balancer is configured to send the X-Forwarded- headers (this may be off by default)

If it's possible to make HTTP/S requests directly to Nginx, bypassing the load balancer, or if the load balancer is not configured to set these headers, then it becomes possible for a client to set these headers to arbitrary values.

This could result in security issue, for example, if your application looks at the value of the X-Forwarded-Proto to determine if the request was made over HTTPS.

SSL Port Exposure

When your app is served from port 80 then the /home/dokku/APP/nginx.conf file will automatically be updated to instruct nginx to respond to ssl on port 443 as a new cert is added. If your app uses a non-standard port (perhaps you have a dockerfile deploy exposing port 99999) you may need to manually expose an ssl port via dokku proxy:ports-add <APP> https:443:99999.