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In addition to the basic functions you should be familiar with, YAML allows for special tags. Upsun accepts certain custom tags to facilitate working with configuration files. These tags work with Upsun configuration files, but may not elsewhere.

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Include

Use the !include tag to embed external files within a given YAML file. The tag requires two properties:
PropertyTypePossible valuesDescription
typestringstring, binary, or yamlSee the descriptions of strings, binaries, and YAML. Defaults to yaml.
pathstringThe path to the file to include, relative to the application directory or source.root.
By default, path is relative to the current application’s directory (what you would define with source.root). It is possible to include files from a directory parent to the folder however.For example, for the following project structure:
.
├── .upsun/
|   └── .upsun/config.yaml
├── backend
│   ├── main.py
│   ├── requirements.txt
│   └── scripts
│       ├── ...
│       └── common_build.sh
└── frontend
    ├── README.md
    ├── package-lock.json
    ├── package.json
    ├── public
    ├── scripts
    │   └── clean.sh
    └── src
This configuration is valid:
.upsun/config.yaml
applications:
  frontend:
    source:
      root: frontend

    # ...

    hooks:
      build: !include
        type: string
        path: ../backend/scripts/common_build.sh

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string

Use string to include an external file inline in the YAML file as if entered as a multi-line string. For example, if you have a build hook like the following:
.upsun/config.yaml
applications:
  myapp:
    hooks:
      build: |
        set -e
        cp a.txt b.txt
You could create a file for the script:
build.sh
set -e
cp a.txt b.txt
And replace the hook with an include tag for an identical result:
.upsun/config.yaml
applications:
  myapp:
    hooks:
      build: !include
        type: string
        path: build.sh
This helps you break longer configuration like build scripts out into a separate file for easier maintenance. Even if path is relative to the current application’s directory, it is also possible to include a shell script from a directory parent to the folder however. For example, for the following project structure: 
.
├── .upsun/
|   └── config.yaml
├── backend
│   ├── main.py
│   ├── requirements.txt
│   └── scripts
│       ├── ...
│       └── common_build.sh
└── frontend
    ├── README.md
    ├── package-lock.json
    ├── package.json
    ├── public
    ├── scripts
    │   └── clean.sh
    └── src
This configuration is valid:
.upsun/config.yaml
applications:
  frontend:
    source:
      root: frontend
    # ...
    hooks:
      build: !include
        type: string
        path: ../backend/scripts/common_build.sh
Please note that Upsun will execute this ../backend/scripts/common_build.sh script using Dash.

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binary

Use binary to include an external binary file inline in the YAML file. The file is base64 encoded. For example, you could include a favicon.ico file in the same folder as your app configuration. Then you can include it as follows:
.upsun/config.yaml
some-property:
  favicon: !include
    type: binary
    path: favicon.ico

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yaml

Use yaml to include an external YAML file inline as if entered directly. Because yaml is the default, you can use it without specifying the type. For example, you could have your configuration for works defined in a worker.yaml file:
worker.yaml
commands:
  start: python queue-worker.py
variables:
  env:
    type: worker
Then the following three configurations are exactly equivalent:
.upsun/config.yaml
workers:
  queue1: !include "worker.yaml"
.upsun/config.yaml
workers:
  queue1: !include
    type: yaml
    path: 'worker.yaml'
.upsun/config.yaml
workers:
  queue1:
    commands:
      start: python queue-worker.py
    variables:
      env:
        type: worker
This can help simplify more complex files. For multiple application project, you can also include another .upsun/apps/my-app.yaml file in the main .upsun/config.yaml.
.upsun/apps/my-app.yaml
source:
  root: "/"
type: "nodejs:18"
web:
  commands:
    start: "node index.js"
  upstream:
    socket_family: tcp
  locations:
    "/":
      passthru: true
and including it:
.upsun/config.yaml
applications:
  myapp:
    !include ./apps/my-app.yaml

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Archive

Use the !archive tag for a reference to an entire directory specified relative to where the YAML file is. For example, you might want to define a configuration directory for your Solr service. You might do so as follows:
.upsun/config.yaml
mysearch:
  type: solr:8.0
  configuration:
      conf_dir: !archive "solr/conf"
The !archive tag means that the value for conf_dir isn’t the string solr/conf but the entire solr/conf directory. This directory is in the .upsun/ directory, since that’s where the .upsun/config.yaml file is. The solr/conf directory is then copied into the Upsun management system to use with the service.
Last modified on March 10, 2026