# docker-compose.yml fields Our compose-file support is currently based on [version 2.4](https://docs.docker.com/compose/compose-file/compose-versioning/#version-24), as such any fields that were introduced in version 3 are not supported. ## Supported fields | Field | Details | | ------------------------------------------------------------------------------------------------- | -------------------------------------------------------------------------------------------------------------------------------------- | | [build](https://docs.docker.com/reference/compose-file/build/) | when using a path it must point to project/app subfolders. URLs to git repositories are not currently supported. | | [build.args](https://docs.docker.com/reference/compose-file/build/#args) | | | [build.cache\_from](https://docs.docker.com/reference/compose-file/build/#cache_from) | | | [build.context](https://docs.docker.com/reference/compose-file/build/#context) | must point to project/app subfolders. URLs to git repositories are not currently supported. | | [build.dockerfile](https://docs.docker.com/reference/compose-file/build/#dockerfile) | | | [build.extra\_hosts](https://docs.docker.com/reference/compose-file/build/#extra_hosts) | | | [build.labels](https://docs.docker.com/reference/compose-file/build/#labels) | | | [build.shm\_size](https://docs.docker.com/reference/compose-file/build/#shm_size) | | | [build.target](https://docs.docker.com/reference/compose-file/build/#target) | currently incompatible with [Livepush](https://docs.balena.io/learn/develop/local-mode#livepush) | | [cap\_add](https://docs.docker.com/reference/compose-file/services/#cap_add) | | | [cap\_drop](https://docs.docker.com/reference/compose-file/services/#cap_drop) | | | [cgroup\_parent](https://docs.docker.com/reference/compose-file/services/#cgroup_parent) | | | [command](https://docs.docker.com/reference/compose-file/services/#command) | | | [cpu\_quota](https://docs.docker.com/reference/compose-file/services/#cpu_quota) | | | [cpu\_shares](https://docs.docker.com/reference/compose-file/services/#cpu_shares) | | | [cpuset](https://docs.docker.com/reference/compose-file/services/#cpuset) | | | [depends\_on](https://docs.docker.com/reference/compose-file/services/#depends_on) | Only array form and `service_started` condition | | [devices](https://docs.docker.com/reference/compose-file/services/#devices) | | | [dns](https://docs.docker.com/reference/compose-file/services/#dns) | | | [dns\_opt](https://docs.docker.com/reference/compose-file/services/#dns_opt) | | | [dns\_search](https://docs.docker.com/reference/compose-file/services/#dns_search) | | | [domainname](https://docs.docker.com/reference/compose-file/services/#domainname) | | | [entrypoint](https://docs.docker.com/reference/compose-file/services/#entrypoint) | | | [environment](https://docs.docker.com/reference/compose-file/services/#environment) | | | [extra\_hosts](https://docs.docker.com/reference/compose-file/services/#extra_hosts) | | | [group\_add](https://docs.docker.com/reference/compose-file/services/#group_add) | | | [healthcheck](https://docs.docker.com/reference/compose-file/services/#healthcheck) | | | [hostname](https://docs.docker.com/reference/compose-file/services/#hostname) | | | [image](https://docs.docker.com/reference/compose-file/services/#image) | | | [ipc](https://docs.docker.com/reference/compose-file/services/#ipc) | | | [labels](https://docs.docker.com/reference/compose-file/services/#labels) | | | [mac\_address](https://docs.docker.com/reference/compose-file/services/#mac_address) | | | [mem\_limit](https://docs.docker.com/reference/compose-file/services/#mem_limit) | | | [mem\_reservation](https://docs.docker.com/reference/compose-file/services/#mem_reservation) | | | [network\_mode](https://docs.docker.com/reference/compose-file/services/#network_mode) | Only support `bridge`, `host`, `service:[service name]`, or none | | [networks](https://docs.docker.com/reference/compose-file/services/#networks) | Only support specifying network names | | [oom\_kill\_disable](https://docs.docker.com/reference/compose-file/services/#oom_kill_disable) | | | [oom\_score\_adj](https://docs.docker.com/reference/compose-file/services/#oom_score_adj) | | | [pid](https://docs.docker.com/reference/compose-file/services/#pid) | Only support `host` or none | | [pids\_limit](https://docs.docker.com/reference/compose-file/services/#pids_limit) | | | [ports](https://docs.docker.com/reference/compose-file/services/#ports) | | | [privileged](https://docs.docker.com/reference/compose-file/services/#privileged) | | | [read\_only](https://docs.docker.com/reference/compose-file/services/#read_only) | | | [restart](https://docs.docker.com/reference/compose-file/services/#restart) | Defaults to `always` | | [security\_opt](https://docs.docker.com/reference/compose-file/services/#security_opt) | | | [shm\_size](https://docs.docker.com/reference/compose-file/services/#shm_size) | | | [stop\_grace\_period](https://docs.docker.com/reference/compose-file/services/#stop_grace_period) | | | [stop\_signal](https://docs.docker.com/reference/compose-file/services/#stop_signal) | | | [sysctls](https://docs.docker.com/reference/compose-file/services/#sysctls) | | | [tmpfs](https://docs.docker.com/reference/compose-file/services/#tmpfs) | | | [ulimits](https://docs.docker.com/reference/compose-file/services/#ulimits) | | | [user](https://docs.docker.com/reference/compose-file/services/#user) | | | [userns\_mode](https://docs.docker.com/reference/compose-file/services/#userns_mode) | | | [volumes](https://docs.docker.com/reference/compose-file/services/#volumes) | Only support short syntax and named volumes. Bind mounts are not supported, except for as allowed by balena specific [labels](#labels) | | [working\_dir](https://docs.docker.com/reference/compose-file/services/#working_dir) | | ## Known unsupported fields | Field | Details | | ------------------------------------------------------------------------------------------------------------------------------------------------------ | ---------------------------------------------------------------------------------- | | [blkio\_config](https://docs.docker.com/reference/compose-file/services/#blkio_config) | | | [build.isolation](https://docs.docker.com/reference/compose-file/build/#isolation) | | | [build.network](https://docs.docker.com/reference/compose-file/build/#network) | | | [container\_name](https://docs.docker.com/reference/compose-file/services/#container_name) | Used by the device supervisor | | [cpu\_count](https://docs.docker.com/reference/compose-file/services/#cpu_count) | | | [cpu\_percent](https://docs.docker.com/reference/compose-file/services/#cpu_percent) | | | [cpus](https://docs.docker.com/reference/compose-file/services/#cpus) | Introduced by Docker Compose v2.2 and therefore not working | | [env\_file and service.env\_file](https://docs.docker.com/compose/how-tos/environment-variables/set-environment-variables/#use-the-env_file-attribute) | | | [expose](https://docs.docker.com/reference/compose-file/services/#expose) | Informational only. Removed to prevent conflicts with other network configurations | | [external\_links](https://docs.docker.com/reference/compose-file/services/#external_links) | | | [isolation](https://docs.docker.com/reference/compose-file/services/#isolation) | | | [links](https://docs.docker.com/reference/compose-file/services/#links) | | | [logging](https://docs.docker.com/reference/compose-file/services/#logging) | | | [mem\_swappiness](https://docs.docker.com/reference/compose-file/services/#mem_swappiness) | | | [memswap\_limit](https://docs.docker.com/reference/compose-file/services/#memswap_limit) | | | [runtime](https://docs.docker.com/reference/compose-file/services/#runtime) | | | [scale](https://docs.docker.com/reference/compose-file/services/#scale) | | | [stdin\_open](https://docs.docker.com/reference/compose-file/services/#stdin_open) | | | [tty](https://docs.docker.com/reference/compose-file/services/#tty) | | | [volume\_driver](https://docs.docker.com/reference/compose-file/volumes/#driver) | | | [volumes\_from](https://docs.docker.com/reference/compose-file/services/#volumes_from) | | ## Known unsupported features | Feature | Details | | -------------------------------------------------------------------------------------------- | ------- | | [variable substitution](https://docs.docker.com/reference/dockerfile/#variable-substitution) | | ## Labels {% hint style="warning" %} 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. {% endhint %} | 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.extra-firmware | false | Enables the service to provide [extra firmware](https://docs.balena.io/learn/develop/extra-firmware) files to the host OS. Use this with the extra firmware block to add Linux firmware without depending on an OS release. | v17.5.2 | v6.10.7 | | 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](https://github.com/balena-os/meta-balena/blob/master/CHANGELOG.md). These labels are applied to a specific service with the `labels:` setting: ```yaml 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: '' ```