---
description: Compose file deploy reference
keywords: fig, composition, compose, docker
title: Compose file deploy reference
toc_max: 4
toc_min: 2
---

Compose specification is a platform-neutral way to define multi-container applications. A Compose implementation supporting
deployment of application model MAY require some additional metadata as the Compose application model is way too abstract
to reflect actual infrastructure needs per service, or lifecycle constraints.

Compose Specification Deployment allows users to declare additional metadata on services so Compose implementations get
relevant data to allocate adequate resources on platform and configure them to match user's needs.

## Definitions

Compose Specification is extended to support an OPTIONAL `deploy` subsection on services. This section define runtime requirements
for a service.

### endpoint_mode

`endpoint_mode` specifies a service discovery method for external clients connecting to a service. Default and available values
are platform specific, anyway the Compose specification define two canonical values:

* `endpoint_mode: vip`: Assigns the service a virtual IP (VIP) that acts as the front end for clients to reach the service
  on a network. Platform routes requests between the client and nodes running the service, without client knowledge of how
  many nodes are participating in the service or their IP addresses or ports.

* `endpoint_mode: dnsrr`: Platform sets up DNS entries for the service such that a DNS query for the service name returns a
  list of IP addresses (DNS round-robin), and the client connects directly to one of these.

```yml
services:
  frontend:
    image: awesome/webapp
    ports:
      - "8080:80"
    deploy:
      mode: replicated
      replicas: 2
      endpoint_mode: vip
```

### labels

`labels` specifies metadata for the service. These labels MUST *only* be set on the service and *not* on any containers for the service.
This assumes the platform has some native concept of "service" that can match Compose application model.

```yml
services:
  frontend:
    image: awesome/webapp
    deploy:
      labels:
        com.example.description: "This label will appear on the web service"
```

### mode

`mode` define the replication model used to run the service on platform. Either `global` (exactly one container per physical node) or `replicated` (a specified number of containers). The default is `replicated`.

```yml
services:
  frontend:
    image: awesome/webapp
    deploy:
      mode: global
```

### placement

`placement` specifies constraints and preferences for platform to select a physical node to run service containers.

#### constraints

`constraints` defines a REQUIRED property the platform's node MUST fulfill to run service container. Can be set either
by a list or a map with string values.

```yml
deploy:
  placement:
    constraints:
      - disktype=ssd
```

```yml
deploy:
  placement:
    constraints:
      disktype: ssd
```

#### preferences

`preferences` defines a property the platform's node SHOULD fulfill to run service container. Can be set either
by a list or a map with string values.

```yml
deploy:
  placement:
    preferences:
      - datacenter=us-east
```

```yml
deploy:
  placement:
    preferences:
      datacenter: us-east
```

### replicas

If the service is `replicated` (which is the default), `replicas` specifies the number of containers that SHOULD be
running at any given time.

```yml
services:
  fronted:
    image: awesome/webapp
    deploy:
      mode: replicated
      replicas: 6
```

### resources

`resources` configures physical resource constraints for container to run on platform. Those constraints can be configured
as a:

- `limits`: The platform MUST prevent container to allocate more
- `reservations`: The platform MUST guarantee container can allocate at least the configured amount

```yml
services:
  frontend:
    image: awesome/webapp
    deploy:
      resources:
        limits:
          cpus: '0.50'
          memory: 50M
          pids: 1
        reservations:
          cpus: '0.25'
          memory: 20M
```

#### cpus

`cpus` configures a limit or reservation for how much of the available CPU resources (as number of cores) a container can use.

#### memory

`memory` configures a limit or reservation on the amount of memory a container
can allocate, set as a string expressing a
[byte value](index.md#specifying-byte-values).

#### pids

`pids` tunes a container’s PIDs limit, set as an integer.

#### devices

`devices` configures reservations of the devices a container can use. It contains a list of reservations, each set as an object with the following parameters: `capabilities`, `driver`, `count`, `device_ids` and `options`.

Devices are reserved using a list of capabilities, making `capabilities` the only required field. A device MUST satisfy all the requested capabilities for a successful reservation.

##### capabilities

`capabilities` are set as a list of strings, expressing both generic and driver specific capabilities.
The following generic capabilities are recognized today:

- `gpu`: Graphics accelerator
- `tpu`: AI accelerator

To avoid name clashes, driver specific capabilities MUST be prefixed with the driver name.
For example, reserving an nVidia CUDA-enabled accelerator might look like this:

```yml
deploy:
  resources:
    reservations:
      devices:
        - capabilities: ["nvidia-compute"]
```

##### driver

A different driver for the reserved device(s) can be requested using `driver` field. The value is specified as a string.

```yml
deploy:
  resources:
    reservations:
      devices:
        - capabilities: ["nvidia-compute"]
          driver: nvidia
```

##### count

If `count` is set to `all` or not specified, Compose implementations MUST reserve all devices that satisfy the requested capabilities. Otherwise, Compose implementations MUST reserve at least the number of devices specified. The value is specified as an integer.

```yml
deploy:
  resources:
    reservations:
      devices:
        - capabilities: ["tpu"]
          count: 2
```

`count` and `device_ids` fields are exclusive. Compose implementations MUST return an error if both are specified.

##### device_ids

If `device_ids` is set, Compose implementations MUST reserve devices with the specified IDs providing they satisfy the requested capabilities. The value is specified as a list of strings.

```yml
deploy:
  resources:
    reservations:
      devices:
        - capabilities: ["gpu"]
          device_ids: ["GPU-f123d1c9-26bb-df9b-1c23-4a731f61d8c7"]
```

`count` and `device_ids` fields are exclusive. Compose implementations MUST return an error if both are specified.

##### options

Driver specific options can be set with `options` as key-value pairs.

```yml
deploy:
  resources:
    reservations:
      devices:
        - capabilities: ["gpu"]
          driver: gpuvendor
          options:
            virtualization: false
```

### restart_policy

`restart_policy` configures if and how to restart containers when they exit. If `restart_policy` is not set, Compose implementations MUST consider `restart` field set by service configuration.

- `condition`: One of `none`, `on-failure` or `any` (default: `any`).
- `delay`: How long to wait between restart attempts, specified as a [duration](index.md#specifying-durations) (default: 0).
- `max_attempts`: How many times to attempt to restart a container before giving up (default: never give up). If the restart does not
  succeed within the configured `window`, this attempt doesn't count toward the configured `max_attempts` value.
  For example, if `max_attempts` is set to '2', and the restart fails on the first attempt, more than two restarts MUST be attempted.
- `window`: How long to wait before deciding if a restart has succeeded, specified as a [duration](index.md#specifying-durations) (default:
  decide immediately).

```yml
deploy:
  restart_policy:
    condition: on-failure
    delay: 5s
    max_attempts: 3
    window: 120s
```

### rollback_config

`rollback_config` configures how the service should be rollbacked in case of a failing update.

- `parallelism`: The number of containers to rollback at a time. If set to 0, all containers rollback simultaneously.
- `delay`: The time to wait between each container group's rollback (default 0s).
- `failure_action`: What to do if a rollback fails. One of `continue` or `pause` (default `pause`)
- `monitor`: Duration after each task update to monitor for failure `(ns|us|ms|s|m|h)` (default 0s).
- `max_failure_ratio`: Failure rate to tolerate during a rollback (default 0).
- `order`: Order of operations during rollbacks. One of `stop-first` (old task is stopped before starting new one),
   or `start-first` (new task is started first, and the running tasks briefly overlap) (default `stop-first`).

### update_config

`update_config` configures how the service should be updated. Useful for configuring rolling updates.

- `parallelism`: The number of containers to update at a time.
- `delay`: The time to wait between updating a group of containers.
- `failure_action`: What to do if an update fails. One of `continue`, `rollback`, or `pause` (default: `pause`).
- `monitor`: Duration after each task update to monitor for failure `(ns|us|ms|s|m|h)` (default 0s).
- `max_failure_ratio`: Failure rate to tolerate during an update.
- `order`: Order of operations during updates. One of `stop-first` (old task is stopped before starting new one),
   or `start-first` (new task is started first, and the running tasks briefly overlap) (default `stop-first`).

```yml
deploy:
  update_config:
    parallelism: 2
    delay: 10s
    order: stop-first
```
