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SSL Configuration

New as of 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:info <app>                         # Show certificate information for an ssl endpoint.
certs:remove <app>                       # Remove an SSL Endpoint from an app.
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
# replace APP with the name of your application
dokku certs:add <app> < cert-key.tar

Note: 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 yourdomain_com.ca-bundle > 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

Note: 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 certficate, you can import that certificate using the aformentioned dokku certs:add command.

Certificate information

The certs:info command will simply inspect the install SSL cert and print out details. NOTE: The server-wide certificate will be inspect if installed and no app-specific certificate exists.

dokku certs:info node-js-app
-----> Fetching SSL Endpoint info for node-js-app...
-----> Certificate details:
=====> Common Name(s):
=====>    test.dokku.me
=====> Expires At: Aug 24 23:32:59 2016 GMT
=====> Issuer: C=US, ST=California, L=San Francisco, O=dokku.me, CN=test.dokku.me
=====> Starts At: Aug 25 23:32:59 2015 GMT
=====> Subject: C=US; ST=California; L=San Francisco; O=dokku.me; CN=test.dokku.me
=====> SSL certificate is self signed.

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.

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.

Running behind a load balancer

Your application has access to the HTTP headers X-Forwarded-Proto, X-Forwarded-For and X-Forwarded-Port. 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.

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