uncloud/website/docs/8-compose-file-reference/1-support-matrix.md

Compose support matrix

Uncloud supports a subset of the Compose specification with some extensions and limitations. The following table shows the support status for main Compose features:

Feature	Support Status	Notes
Services
build	✅ Supported	Build context and Dockerfile
cap_add	✅ Supported	Additional kernel capabilities
cap_drop	✅ Supported	Which kernel capabilities to drop
command	✅ Supported	Override container command
configs	✅ Supported	File-based and inline configs
cpus	✅ Supported	CPU limit
depends_on	⚠️ Limited	Services deployed in order but conditions not checked
devices	✅ Supported	Device mappings
dns	❌ Not supported	Built-in service discovery
dns_search	❌ Not supported	Built-in service discovery
entrypoint	✅ Supported	Override container entrypoint
env_file	✅ Supported	Environment file
environment	✅ Supported	Environment variables
gpus	✅ Supported	GPU device access
healthcheck	✅ Supported	Health check configuration
image	✅ Supported	Container image specification
init	✅ Supported	Run init process in container
labels	❌ Not supported
links	❌ Not supported	Use service names for communication
logging	✅ Supported	Defaults to local log driver
mem_limit	✅ Supported	Memory limit
mem_reservation	✅ Supported	Memory reservation
mem_swappiness	❌ Not supported
memswap_limit	❌ Not supported
networks	❌ Not supported	All containers share cluster network
ports	⚠️ Limited	mode: host only, use x-ports for HTTP/HTTPS
privileged	✅ Supported	Run containers in privileged mode
pull_policy	✅ Supported	always, missing, never
secrets	❌ Not supported	Use configs or environment variables
security_opt	❌ Not supported
storage_opt	❌ Not supported
sysctls	✅ Supported	Namespaced kernel parameters
user	✅ Supported	Set container user
volumes	✅ Supported	Named volumes, bind mounts, tmpfs
Deploy
labels	❌ Not supported
mode	✅ Supported	Either global or replicated
placement	❌ Not supported	Use x-machines extension
replicas	✅ Supported	Number of container replicas
resources	⚠️ Limited	CPU, memory limits and device reservations
restart_policy	❌ Not supported	Defaults to unless-stopped
rollback_config	❌ Not supported	See #151
update_config	⚠️ Limited	Only order supported (defaults to start-first). See deployment strategies
Volumes
Named volumes	✅ Supported	Docker volumes
Bind mounts	✅ Supported	Host path binding
Tmpfs mounts	✅ Supported	In-memory filesystems
Volume labels	✅ Supported	Custom labels
External volumes	✅ Supported	Must exist before deployment
Volume drivers	⚠️ Limited	Local driver only
Configs
File-based configs	✅ Supported	Read from file
Inline configs	✅ Supported	Defined in compose file
External configs	❌ Not supported	Not supported
Short syntax	❌ Not supported	Use long syntax only
Extensions
x-caddy	✅ Uncloud-specific	Custom Caddy configuration
x-machines	✅ Uncloud-specific	Machine placement constraints
x-ports	✅ Uncloud-specific	Service port publishing

Legend

• ✅ Supported: Feature works as documented
• ⚠️ Limited: Partial support or with restrictions
• ❌ Not supported: Feature is not (yet) available

Uncloud extensions

Uncloud provides several custom extensions to enhance the Compose experience:

x-ports

Expose HTTP/HTTPS service ports via the Caddy reverse proxy, or bind TCP/UDP ports directly to the host:

services:
  web:
    image: nginx
    x-ports:
      - 80/https
      - example.com:80/https
      - 8080:80/tcp@host

See Publishing services for more details.

x-caddy

Custom Caddy reverse proxy configuration for a service:

services:
  web:
    image: nginx
    x-caddy: |
      example.com {
        reverse_proxy {{upstreams 80}}
      }

See Publishing services for more details.

x-machines

Restrict which machines can run your service. If you deploy multiple replicas, Uncloud automatically spreads them across the specified machines.

services:
  web:
    image: nginx
    x-machines:
      - machine-1
      - machine-2
    # Short syntax for a single machine
    # x-machines: machine-1