App reference

See all of the options for controlling your apps and how they’re built and deployed on

For single-app projects, the configuration is all done in a file, usually located at the root of your app folder in your Git repository. Multi-app projects can be set up in various ways.

See a comprehensive example of a configuration in a file. For reference, see a log of changes to app configuration.

Top-level properties 

The following table presents all properties available at the top level of the YAML for the app. The column Set in instance? defines whether the given property can be overridden within a web or workers instance. To override any part of a property, you have to provide the entire property.

Name Type Required Set in instance? Description
name string Yes No A unique name for the app. Must be lowercase alphanumeric characters. Changing the name destroys data associated with the app.
type A type Yes No The base image to use with a specific app language. Format: runtime:version.
size A size Yes How much resources to devote to the app. Defaults to AUTO in production environments.
relationships A dictionary of relationships Yes Connections to other services and apps.
disk integer or null Yes The size of the disk space for the app in MB. Minimum value is 128. Defaults to null, meaning no disk is available. See note on available space
mounts A dictionary of mounts Yes Directories that are writable even after the app is built. If set as a local source, disk is required.
web A web instance N/A How the web application is served.
workers A worker instance N/A Alternate copies of the application to run as background processes.
timezone string No The timezone for crons to run. Format: a TZ database name. Defaults to UTC, which is the timezone used for all logs no matter the value here. See also app runtime timezones
access An access dictionary Yes Access control for roles accessing app environments.
variables A variables dictionary Yes Variables to control the environment.
firewall A firewall dictionary Yes Outbound firewall rules for the application.
build A build dictionary No What happens when the app is built.
dependencies A dependencies dictionary No What global dependencies to install before the build hook is run.
hooks A hooks dictionary No What commands run at different stages in the build and deploy process.
crons A cron dictionary No Scheduled tasks for the app.
source A source dictionary No Information on the app’s source code and operations that can be run on it.
runtime A runtime dictionary No Customizations to your PHP or Lisp runtime.
additional_hosts An additional hosts dictionary Yes Maps of hostnames to IP addresses.

Root directory 

Some of the properties you can define are relative to your app’s root directory. The root defaults to the location of your file. To specify another directory, for example for a multi-app project), use the source.root property.


The type defines the base container image used to run the application. Available languages and their supported versions:

Language runtime Supported version
C#/.Net Core dotnet 6.0, 3.1
Elixir elixir 1.13, 1.12, 1.11
Go golang 1.19, 1.18, 1.17, 1.16
Java java 18, 17, 14, 13, 12, 11, 8
Lisp lisp 2.1, 2.0, 1.5
Node.js nodejs 18, 16, 14
PHP php 8.1, 8.0
Python python 3.10, 3.9, 3.8, 3.7, 3.6, 3.5, 2.7
Ruby ruby 3.1, 3.0, 2.7, 2.6, 2.5, 2.4, 2.3

Example configuration 

These are used in the format runtime:version:
type: 'php:8.1'


Resources are distributed across all containers in a project from the total available from your plan size. So if you have more than just a single app, it doesn’t get all of the resources available.

By default, resource sizes (CPU and memory) are chosen automatically for an app based on the plan size and the number of other containers in the cluster. Most of the time, this automatic sizing is enough.

You can set sizing suggestions for production environments when you know a given container has specific needs. Such as a worker that doesn’t need much and can free up resources for other apps. To do so, set size to one of the following values:

  • S
  • M
  • L
  • XL
  • 2XL
  • 4XL

The total resources allocated across all apps and services can’t exceed what’s in your plan.

Sizes in development environments 

Containers in development environments don’t follow the size specification. Application containers are set based on the plan’s setting for Environments application size. The default is Standard , but you can increase it by editing your plan. (Service containers in development environments are always set to Standard size.)


To access another container within your project, you need to define a relationship to it.

Relationships Diagram

You can give each relationship any name you want. This name is used in the PLATFORM_RELATIONSHIPS environment variable, which gives you credentials for accessing the service.

The relationship is specified in the form service_name:endpoint_name. The service_name is the name of the service given in the services configuration or the name of another application in the same project specified as the name in that app’s configration.

The endpoint_name is the exposed functionality of the service to use. For most services, the endpoint is the same as the service type. For some services (such as MariaDB and Solr), you can define additional explicit endpoints for multiple databases and cores in the service’s configuration.

The following example shows a single MySQL service named mysqldb offering two databases, a Redis cache service named rediscache, and an Elasticsearch service named searchserver.
    database: 'mysqldb:db1'
    database2: 'mysqldb:db2'
    cache: 'rediscache:redis'
    search: 'searchserver:elasticsearch'

Available disk space 

The maximum total space available to all applications and services is set by the storage in your plan settings. When deploying your project, the sum of all disk keys defined in app and service configurations must be equal or less than the plan storage size.

So if your plan storage size is 5 GB, you can, for example, assign it in one of the following ways:

  • 2 GB to your application, 3 GB to your database
  • 1 GB to your application, 4 GB to your database
  • 1 GB to your application, 1 GB to your database, 3 GB to your Elasticsearch service

If you exceed the total space available, you receive an error on pushing your code. You need to either increase your plan’s storage or decrease the disk values you’ve assigned.

Downsize a disk 

You can decrease the size of an existing disk for an app. If you do so, be aware that:

  • Backups from before the downsize are incompatible and can no longer be used. You need to create new backups.
  • The downsize fails if there’s more data on the disk than the desired size.


Mounts define directories that are writable after the build is complete. They aren’t available during the build.
        source: <SOURCE_LOCATION>
        source_path: <SOURCE_PATH_LOCATION>

The <DIRECTORY> is relative to the app’s root and represents the path in the app. If you already have a directory with that name, you get a warning that it isn’t accessible after the build. See how to troubleshoot the warning.

Name Type Required Description
source local or service Yes Specifies where the mount is. local sources are unique to the app (requires disk to be set for the app), while service sources can be shared among apps (requires service to be set here).
source_path string Yes The subdirectory within the mounted disk (the source) where the mount should point. If an empty string is passed, points to the entire directory.
service string The name of the network storage service.

Basic example:
        source: local
        source_path: uploads

The accessibility to the web of a mounted directory depends on the web.locations configuration. Files can be all public, all private, or with different rules for different paths and file types.

Note that mounted directories aren’t deleted when they’re removed from The files still exist on disk until manually removed.


Use the web key to configure the web server running in front of your app. Defaults may vary with a different image type.

Name Type Required Description
commands A web commands dictionary See note The command to launch your app.
upstream An upstream dictionary How the front server connects to your app.
locations A locations dictionary How the app container responds to incoming requests.

See some examples of how to configure what’s served.

Web commands 

Name Type Required Description
start string See note The command to launch your app. If it terminates, it’s restarted immediately.

        start: 'uwsgi --ini conf/server.ini'

This command runs every time your app is restarted, regardless of whether or not new code is deployed. So it can be useful for things like clearing ephemeral cache.
        start: 'redis-cli -h redis.internal flushall; sleep infinity'
        # For a Dedicated Gen 2 environment use:
        # start: 'redis-cli flushall ; sleep infinity'

Required command 

On all containers other than PHP, the value for start should be treated as required.

On PHP containers, it’s optional and defaults to starting PHP-FPM (/usr/sbin/php-fpm7.0 on PHP7 and /usr/sbin/php5-fpm on PHP5). It can also be set explicitly on a PHP container to run a dedicated process, such as React PHP or Amp.


Name Type Required Description
socket_family tcp or unix Whether your app listens on a Unix or TCP socket. Defaults to tcp.
protocol http or fastcgi Whether your app receives incoming requests over HTTP or FastCGI. Default varies based on image type.

For PHP, the defaults are configured for PHP-FPM and shouldn’t need adjustment. For all other containers, the default for protocol is http.

The following example is the default on non-PHP containers:
        socket_family: tcp
        protocol: http

Where to listen 

Where to listen depends on your setting for web.upstream.socket_family (defaults to tcp).

socket_family Where to listen
tcp The port specified by the PORT environment variable
unix The Unix socket file specified by the SOCKET environment variable

If your application isn’t listening at the same place that the runtime is sending requests, you see 502 Bad Gateway errors when you try to connect to your website.


Each key in the locations dictionary is a path on your site with a leading /. For, a / matches and /admin matches When multiple keys match an incoming request, the most-specific applies.

The following table presents possible properties for each location:

Name Type Default Description
root string The directory to serve static assets for this location relative to the app’s root directory. Must be an actual directory inside the root directory.
passthru boolean or string false Whether to forward disallowed and missing resources from this location to the app. A string is a path with a leading / to the controller, such as /index.php.
index Array of strings or null Files to consider when serving a request for a directory. When set, requires access to the files through the allow or rules keys.
expires string -1 How long static assets are cached. The default means no caching. Setting it to a value enables the Cache-Control and Expires headers. Times can be suffixed with ms = milliseconds, s = seconds, m = minutes, h = hours, d = days, w = weeks, M = months/30d, or y = years/365d.
allow boolean true Whether to allow serving files which don’t match a rule.
scripts boolean Whether to allow scripts to run. Doesn’t apply to paths specified in passthru. Meaningful only on PHP containers.
headers A headers dictionary Any additional headers to apply to static assets, mapping header names to values. Responses from the app aren’t affected.
request_buffering A request buffering dictionary See below Handling for chunked requests.
rules A rules dictionary Specific overrides for specific locations.


The rules dictionary can override most other keys according to a regular expression. The key of each item is a regular expression to match paths exactly. If an incoming request matches the rule, it’s handled by the properties under the rule, overriding any conflicting rules from the rest of the locations dictionary.

Each key can set all of the other possible locations properties.

In the following example, the allow key disallows requests for static files anywhere in the site. This is overridden by a rule that explicitly allows common image file formats.
            # Handle dynamic requests
            root: 'public'
            passthru: '/index.php'
            # Disallow static files
            allow: false
                # Allow common image files only.
                    allow: true

Request buffering 

Request buffering is enabled by default to handle chunked requests as most app servers don’t support them. The following table shows the keys in the request_buffering dictionary:

Name Type Required Default Description
enabled boolean Yes true Whether request buffering is enabled.
max_request_size string 250m The maximum size to allow in one request.

The default configuration would look like this:
            passthru: true
                enabled: true
                max_request_size: 250m


Workers are exact copies of the code and compilation output as a web instance after a build hook. They use the same container image.

Workers can’t accept public requests and so are suitable only for background tasks. If they exit, they’re automatically restarted.

The keys of the workers definition are the names of the workers. You can then define how each worker differs from the web instance using the top-level properties.

Each worker can differ from the web instance in all properties except for:

  • build and dependencies properties, which must be the same
  • crons as cron jobs don’t run on workers
  • hooks as the build hook must be the same and the deploy and post_deploy hooks don’t run on workers.

A worker named queue that was small and had a different start command could look like this:
        size: S
            start: |

For resource allocation, using workers in your project requires a Medium plan or larger.


The access dictionary has one allowed key:

Name Allowed values Default Description
ssh admin, contributor, or viewer contributor Defines the minimum role required to access app environments via SSH.

In the following example, only users with admin permissions for the given environment type can access the deployed environment via SSH:
    ssh: admin

Variables provides a number of ways to set variables. Variables set in your app configuration have the lowest precedence, meaning they’re overridden by any conflicting values provided elsewhere.

All variables set in your app configuration must have a prefix. Some prefixes have specific meanings.

Variables with the prefix env are available as a separate environment variable. All other variables are available in the $PLATFORM_VARIABLES environment variable.

The following example sets two variables:

  • A variable named env:AUTHOR with the value Juan that’s available in the environment as $AUTHOR
  • A variable named with the value My site rocks that’s available in the $PLATFORM_VARIABLES environment variable
        AUTHOR: 'Juan'
        "": 'My site rocks'

You can also define and access more complex values.


Tier availability

This feature is available for Elite and Enterprise customers. Compare the tiers on our pricing page, or contact our sales team for more information.

Set limits in outbound traffic from your app with no impact on inbound requests.

The outbound key is required and contains one or more rules. The rules define what traffic is allowed; anything unspecified is blocked.

Each rule has the following properties where at least one is required and ips and domains can’t be specified together:

Name Type Default Description
ips Array of strings [""] IP addresses in CIDR notation. See a CIDR format converter.
domains Array of strings Fully qualified domain names to specify specific destinations by hostname.
ports Array of integers Ports from 1 to 65535 that are allowed. If any ports are specified, all unspecified ports are blocked. If no ports are specified, all ports are allowed. Port 25, the SMTP port for sending email, is always blocked.

The default settings would look like this:
        - ips: [""]

Supported regions 

An outbound firewall is available on all regions except the legacy regions:


These regions will be upgraded in the future. If you’re on one of these regions and want a firewall now, migrate your project to a newer region.

Support for rules 

Where outbound rules for firewalls are supported in all environments. For Dedicated Gen 2 projects, contact support for configuration.

Multiple rules 

Multiple firewall rules can be specified. In such cases, a given outbound request is allowed if it matches any of the defined rules.

So in the following example requests to any IP on port 80 are allowed and requests to on either port 80 or 443 are allowed:
        - ips: [""]
          ports: [443]
        - ports: [80]

Outbound traffic to CDNs 

Be aware that many services are behind a content delivery network (CDN). For most CDNs, routing is done via domain name, not IP address, so thousands of domain names may share the same public IP addresses at the CDN. If you allow the IP address of a CDN, you are usually allowing many or all of the other customers hosted behind that CDN.

Outbound traffic by domain 

You can filter outbound traffic by domain. Using domains in your rules rather than IP addresses is generally more specific and secure. For example, if you use an IP address for a service with a CDN, you have to allow the IP address for the CDN. This means that you allow potentially hundreds or thousands of other servers also using the CDN.

An example rule filtering by domain:
    - protocol: tcp
      domains: ["", ""]
      ports: [80, 443]
    - protocol: tcp
      ips: ["",""]
      ports: [22]

Determine which domains to allow 

To determine which domains to include in your filtering rules, find the domains your site has requested the DNS to resolve. Run the following command to parse your server’s dns.log file and display all Fully Qualified Domain Names that have been requested:

awk '/query\[[^P]\]/ { print $6 | "sort -u" }' /var/log/dns.log

The output includes all DNS requests that were made, including those blocked by your filtering rules. It doesn’t include any requests made using an IP address.

Example output:


The only property of the build dictionary is flavor, which specifies a default set of build tasks to run. Flavors are language-specific.

See what the build flavor is for your language:

In all languages, you can also specify a flavor of none to take no action at all (which is the default for any language other than PHP and Node.js).
    flavor: none


Installs global dependencies as part of the build process. They’re independent of your app’s dependencies and are available in the PATH during the build process and in the runtime environment. They’re installed before the build hook runs using a package manager for the language.

Language Key name Package manager
PHP php Composer
Python 2 python or python2 Pip 2
Python 3 python3 Pip 3
Ruby ruby Bundler
Node.js nodejs npm (see how to use yarn)
Java java Apache Maven, Gradle, or Apache Ant

The format for package names and version constraints are defined by the specific package manager.

An example of dependencies in multiple languages:
    php: # Specify one Composer package per line.
        drush/drush: '8.0.0'
        composer/composer: '^2'
    python: # Specify one Python 2 package per line.
        behave: '*'
    python2: # Specify one Python 2 package per line.
        requests: '*'
    python3: # Specify one Python 3 package per line.
        numpy: '*'
    ruby: # Specify one Bundler package per line.
        sass: '3.4.7'
    nodejs: # Specify one NPM package per line.
        pm2: '^4.5.0'


There are three different hooks that run as part of the process of building and deploying your app. These are places where you can run custom scripts. They are: the build hook, the deploy hook, and the post_deploy hook. Only the build hook is run for worker instances, while web instances run all three.

The process is ordered as:

  1. Variables accessible at build time become available.
  2. Build flavor runs if applicable.
  3. Any dependencies are installed.
  4. The build hook is run.
  5. The file system is changed to read only (except for any mounts).
  6. The app container starts. Variables accessible at runtime and services become available.
  7. The deploy hook is run.
  8. The app container begins accepting requests.
  9. The post_deploy hook is run.

Note that if an environment changes by no code changes, only the last step is run. If you want the entire process to run, see how to manually trigger builds.

Writable directories during build 

During the build hook, there are three writeable directories:

  • $PLATFORM_APP_DIR: Where your code is checked out and the working directory when the build hook starts. Becomes the app that gets deployed.
  • $PLATFORM_CACHE_DIR: Persists between builds, but isn’t deployed. Shared by all builds on all branches.
  • /tmp: Isn’t deployed and is wiped between each build.

Hook failure 

Each hook is executed as a single script, so they’re considered to have failed only if the final command in them fails. To cause them to fail on the first failed command, add set -e to the beginning of the hook.

If a build hook fails for any reason, the build is aborted and the deploy doesn’t happen. Note that this only works for build hooks – if other hooks fail, the app is still deployed.


The keys of the crons definition are the names of the cron jobs. The names must be unique.

If an application defines both a web instance and worker instances, cron jobs run only on the web instance.

See how to get cron logs.

The following table shows the properties for each job:

Name Type Required Description
spec string Yes The cron specification. To prevent competition for resources that might hurt performance, use H in definitions to indicate an unspecified but invariant time. For example, instead of using 0 * * * * to indicate the cron job runs at the start of every hour, you can use H * * * * to indicate it runs every hour, but not necessarily at the start. This prevents multiple cron jobs from trying to start at the same time.
commands A cron commands dictionary Yes A definition of what commands to run when starting and stopping the cron job.
shutdown_timeout integer No When a cron is canceled, this represents the number of seconds after which a SIGKILL signal is sent to the process to force terminate it. The default is 10 seconds.
timeout integer No The maximum amount of time a cron can run before it’s terminated. Defaults to the maximum allowed value of 86400 seconds (24 hours).

Cron commands 

Name Type Required Description
start string Yes The command that’s run. It’s run in Dash.
stop string No The command that’s issued to give the cron command a chance to shutdown gracefully, such as to finish an active item in a list of tasks. Issued when a cron task is interrupted by a user through the CLI or Console. If not specified, a SIGTERM signal is sent to the process.
        spec: 'H * * * *'
            start: sleep 60 && echo sleep-60-finished && date
            stop: killall sleep
        shutdown_timeout: 18

Example cron jobs 

    # Run Drupal's cron tasks every 19 minutes.
        spec: '*/19 * * * *'
            start: 'cd web ; drush core-cron'
    # But also run pending queue tasks every 7 minutes.
    # Use an odd number to avoid running at the same time as the `drupal` cron.
        spec: '*/7 * * * *'
            start: 'cd web ; drush queue-run aggregator_feeds'

        spec: '*/19 * * * *'
            start: 'bundle exec rake some:task'

Cron job timing 

Minimum time between cron jobs being triggered:

Plan Time
Professional 5 minutes
Elite or Enterprise 1 minute

For each app container, only one cron job can run at a time. If a new job is triggered while another is running, the new job is paused until the other completes.

To minimize conflicts, a random offset is applied to all triggers. The offset is a random number of seconds up to 20 minutes or the cron frequency, whichever is smaller.

Crons are also paused while activities such as backups are running. The crons are queued to run after the other activity finishes.

To run cron jobs in a timezone other than UTC, set the timezone property.

Paused crons 

Development environments are often used for a limited time and then abandoned. While it’s useful for environments under active development to have scheduled tasks, unused environments don’t need to run cron jobs. To minimize unnecessary resource use, crons on environments with no deployments are paused.

This affects all environments that aren’t live environments. This means all environments on Development plans and all non-Production environments on higher plans.

Such environments with deployments within 14 days have crons with the status running. If there haven’t been any deployments within 14 days, the status is paused.

You can see the status in the Console or using the CLI by running platform environment:info and looking under deployment_state.

Supported regions 

Paused crons are available on all regions except the legacy regions:


These regions will be upgraded in the future. If you’re on one of these regions and want paused crons now, migrate your project to a newer region.

Restarting paused crons 

If the crons on your development environment are paused but you’re still using them, you can push changes to the environment or redeploy it.

To restart crons without changing anything:

  1. In the Console, navigate to your project.
  2. Open the environment where you’d like the crons to run.
  3. Click Redeploy next to the cron status of Paused.

Run the following command:

platform redeploy


The following table presents the various possible modifications to your PHP or Lisp runtime:

Name Type Language Description
extensions List of strings OR extensions definitions PHP PHP extensions to enable.
disabled_extensions List of strings PHP PHP extensions to disable.
request_terminate_timeout integer PHP The timeout for serving a single request after which the PHP-FPM worker process is killed.
sizing_hints A sizing hints definition PHP The assumptions for setting the number of workers in your PHP-FPM runtime.
xdebug An Xdebug definition PHP The setting to turn on Xdebug.
quicklisp Distribution definitions Lisp Distributions for QuickLisp to use.


You can enable PHP extensions just with a list of extensions:
    - geoip
    - tidy

Alternatively, if you need to include configuration options, use a dictionary for that extension:
    - geoip
    - name: blackfire
          server_id: foo
          server_token: bar

In this case, the name property is required.

Sizing hints 

The following table shows the properties that can be set in sizing_hints:

Name Type Default Minimum Description
request_memory integer 45 10 The average memory consumed per request in MB.
reserved_memory integer 70 70 The amount of memory reserved in MB.

See more about PHP-FPM workers and sizing.


The following table shows the properties that can be set in source:

Name Type Required Description
operations An operations dictionary Operations that can be applied to the source code. See source operations
root string The path where the app code lives. Defaults to the directory of the file. Useful for multi-app setups.

Additional hosts 

If you’re using a private network with specific IP addresses you need to connect to, you might want to map those addresses to hostnames to better remember and organize them. In such cases, you can add a map of those IP addresses to whatever hostnames you like. Then when your app tries to access the hostname, it’s sent to the proper IP address.

So in the following example, if your app tries to access, it’s sent to
additional_hosts: "" ""

This is equivalent to adding the mapping to the /etc/hosts file for the container.