docker-compose.yml fields

Our compose-file support is currently based on version 2.4, as such any fields that were introduced in version 3 are not supported.

Supported fields

Field
Details

build
when using a path it must point to project/app subfolders. URLs to git repositories are not currently supported.

build.context
must point to project/app subfolders. URLs to git repositories are not currently supported.

build.dockerfile
build.args
build.cache_from
build.extra_hosts
build.labels
build.shm_size
build.target
currently incompatible with Livepush
cap_add
cap_drop
cgroup_parent
command
cpu_shares
cpu_quota
cpuset
devices
depends_on
Only array form and service_started condition

dns
dns_opt
dns_search
domainname
entrypoint
environment
expose
extra_hosts
group_add
healthcheck
hostname
image
ipc
labels
mac_address
mem_limit
mem_reservation
network_mode
Only support bridge, host, service:[service name], or none

networks
Only support specifying network names

oom_kill_disable
oom_score_adj
pid
Only support host or none

pids_limit
ports
privileged
read_only
restart
Defaults to always
security_opt
shm_size
stop_grace_period
stop_signal
sysctls
tmpfs
ulimits
user
userns_mode
volumes
Only support short syntax and named volumes. Bind mounts are not supported, except for as allowed by balena specific labels
working_dir

Known unsupported fields

Field
Details

build.isolation
build.network
blkio_config
container_name
Used by the device supervisor

cpu_count
cpu_percent
cpus
Introduced by Docker Compose v2.2 and therefore not working

external_links
isolation
links
logging
memswap_limit
mem_swappiness
runtime
scale
stdin_open
tty
volume_driver
volumes_from

Known unsupported features

Feature
Details

variable substitution

Labels

Note: If you have devices in your app that have a supervisor version lower than 7.22.0, then you should use the io.resin.features. form of the labels to ensure that all devices obey the label. Earlier supervisor versions will not understand the io.balena.features label.

Label
Default
Description
Supervisor
balenaOS*

io.balena.features.balena-socket
false
Bind mounts the balena container engine socket into the container and sets the environment variable DOCKER_HOST with the socket location for use by docker clients.
v7.23.0
v2.21.0

io.balena.features.dbus
false
Bind mounts the host OS dbus into the container using /run/dbus:/host/run/dbus.
v7.23.0
v2.21.0

io.balena.features.sysfs
false
Bind mounts the host OS /sys into the container.
v10.8.0
v2.48.0

io.balena.features.procfs
false
Bind mounts the host OS /proc into the container.
v10.8.0
v2.48.0

io.balena.features.kernel-modules
false
Bind mounts the host OS /lib/modules into the container (i.e. /lib/modules:/lib/modules).
v7.23.0
v2.21.0

io.balena.features.firmware
false
Bind mounts the host OS /lib/firmware into the container.
v7.23.0
v2.21.0

io.balena.features.journal-logs
false
Bind mounts journal log directories /var/log/journal and /run/log/journal as well as /etc/machine-id in read only mode. Required by some logging agents such as promtail. Journal logs can be read using libraries such as sd-journal in C or sdjournal in Go.
v12.0.1
v2.61.0

io.balena.features.supervisor-api
false
Ensures that BALENA_SUPERVISOR_HOST, BALENA_SUPERVISOR_PORT, BALENA_SUPERVISOR_ADDRESS, and BALENA_SUPERVISOR_API_KEY are added to the container environment variables, so the supervisor API can be used.
v7.23.0
v2.21.0

io.balena.features.balena-api
false
When enabled, it will make sure that BALENA_API_KEY is added to the container environment variables.
v7.23.0
v2.21.0

io.balena.update.strategy
download-then-kill
Set the fleet update strategy.
v7.23.0
v2.21.0

io.balena.update.handover-timeout
60000
Time, in milliseconds, before an old container is automatically killed. Only used with the hand-over update strategy.
v7.23.0
v2.21.0

* balenaOS versions that ship with a compatible device supervisor version as per
balenaOS Changelog.

These labels are applied to a specific service with the labels: setting:

labels:
      io.balena.features.balena-socket: '1'
      io.balena.features.kernel-modules: '1'
      io.balena.features.firmware: '1'
      io.balena.features.dbus: '1'
      io.balena.features.sysfs: '1'
      io.balena.features.procfs: '1'
      io.balena.features.journal-logs: '1'
      io.balena.features.supervisor-api: '1'
      io.balena.features.balena-api: '1'
      io.balena.update.strategy: download-then-kill
      io.balena.update.handover-timeout: ''