Port Service (Harbor)

HTTP and HTTPS ports and routing are provided automatically for all web applications deployed to Helion Stackato (unless processes: web: is set to ~).

If your application requires additional TCP or UDP ports, use the Harbor service to allocate them.

Requesting a Port

Additional ports are provisioned like any other data service. To request a port with the stackato client:

$ stackato create-service harbor debug-port

To request a port from Harbor in the manifest.yml file, add it to a services: block. For example:

name: port-test
memory: 256
  my-port: harbor

This creates a TCP port tunnel which the application can access on the host and port specified in the $STACKATO_SERVICES environment variable.

The example above might create the following my-port object in $STACKATO_SERVICES:

  "my-port": {
    "hostname": "",
    "host": "",
    "port": 30134,
    "name": "cf7f868a-8b7b-4ac8-ab4d-9fd87efb7c09",
    "node_id": "harbor_node_1",
    "int_port": 4100,
    "ext_hostname": "ports.example.com",
    "ext_host": ""

This provides the following information:

  • hostname: The internal hostname (if configured) of the node providing the service (the Harbor node). If none is configured by the admin, this will show the internal IP address.
  • host: The internal IP address of the Harbor node.
  • port: The external port number exposed by the service. Connections from external clients and other internal applications (those not directly bound to the service) will connect with this port number.
  • name: The service instance ID (Helion Stackato internal refer).
  • node_id: The Harbor node ID (Helion Stackato internal).
  • int_port: The port on the application container which forwards to Harbor (see also Harbor Environment Variables). Applications bound to the service should connect to this port.

Access to the port from outside of the Helion Stackato VM or cluster may or may not be exposed, depending on how the Harbor service is configured by the Admin. If Harbor is set up to allow public port access, the following two settings will also be displayed:

  • ext_hostname: The public hostname (if configured) exposing the port.
  • ext_host: The public IP address exposing the port.


To remotely check the settings and credentials of any Helion Stackato service, run the stackato service command.

Harbor Environment Variables

If there is only one Harbor service, the STACKATO_HARBOR environment variable can be used to get the internal port number.

If there is more than one Harbor service, STACKATO_HARBOR is not available. Instead, a custom STACKATO_HARBOR_<SERVICE_NAME> environment variable will be created for each harbor service (service name upper-cased with hyphens replaced by underscores).

For example, if your manifest.yml file configures the following services:

  udp-port: harbor
  tcp-port: harbor

Two environment variables would be created: STACKATO_HARBOR_UDP_PORT and STACKATO_HARBOR_TCP_PORT.

This naming scheme can be used in conjunction with the STACKATO_APP_NAME_UPCASE environment variable. For example, in an app with the following harbor services defined:

  udp-${name}: harbor
  tcp-${name}: harbor

The Harbor port number for the UDP service could be accessed within the container with a construct such as:



To use declarations like these in a hooks: key, put them in a separate bash script. Brace expansion and grouping cannot be used directly in YAML files.

Setting the Port Protocols

Harbor supports both the TCP and UDP protocols. When you provision a service with Harbor it will create a TCP enabled port by default. If you want to have a UDP port provisioned instead, prefix your service name with udp. For example:

$ stackato create-service harbor udp-debug-port

If you have an application that requires both TCP and UDP, you can prefix your service name with either multi- or both-. For example:

$ stackato create-service harbor both-debug-port

Harbor will then create UDP and TCP proxies for your application, so applications like DNS can use both protocols on the same provisioned port.

Multiple Application Instances

Harbor recognizes when you have multiple instances of your app running, and will update the available app backends accordingly.

  • For TCP connections it will round-robin between your available backends on each new connection, in a similar fashion to the router component.
  • For UDP this is not the case, because it is a stateless protocol. For multiple UDP backends harbor will use a FIFO queue, that is the first app instance available becomes the primary backend, and any added later are queued.


The ZNC sample application allows you to deploy an IRC bouncer on Helion Stackato using the Harbor port service.

HTTPS via Harbor

SSL termination of HTTPS to applications hosted on Helion Stackato normally happens at the Router.

There is currently no mechanism for users to add SSL certs for their own applications to the Router, but you can expose an external HTTPS interface via the Harbor port service which uses your SSL certs.

To do this, upload the SSL certificates and keys along with your application, and expose your application server directly on the TCP port provided by Harbor.


When using this approach, the hostname or IP address of the app will be the one provided by the Harbor node and the client will connect using the Harbor-assigned port number, not port 443.

For example, an application running through the port service might have a URL such as https://harbor-node.stackato.com:35048/.

You can set up aliases to this URL using DNS, but the explicit port specification must always be added.

HTTPS Container Proxy

If you are using a framework such as Python or Perl which sets up uWSGI (or any other framework that provides its own intermediate web server) Harbor can provision an HTTPS server in the app container that forwards HTTPS requests to the framework's HTTP server. To do this, add the suffix https to the name of your Harbor service. For example:

name: harbor-test-app

  custom-cert-https: harbor

Put your server certificate and key (named harbor.crt and harbor.key respectively) in a directory called cert in the application's root directory. For example:

─── certs
    ─── harbor.crt
    ─── harbor.key
─── ...

Alternatively, use a standalone or buildpack setup which provisions its own intermediate web server instead.

Multiple SSL Certificates

If your application uses multiple SSL certificates, use the following naming scheme:

  • <harbor service name>.key
  • <harbor service name>.crt

For example:

─── certs
    ─── harbor-https-custom-1.crt
    ─── harbor-https-custom-2.key
─── ...

The proxy will look for these certs before reverting to harbor.crt and harbor.key.


Using Harbor in this way does not take advantage of any load balancing set up for regular web traffic through the Routers and Load Balancer.

If you have multiple instances of your app routing through a Harbor TCP port as above, connections will be distributed via round-robin.