`args` define build arguments, that is Dockerfile `ARG` values.

Using the following Dockerfile as an example:

```Dockerfile
ARG GIT_COMMIT
RUN echo "Based on commit: $GIT_COMMIT"
```

`args` can be set in the Compose file under the `build` key to define `GIT_COMMIT`. `args` can be set as a mapping or a list:

```yml
build:
  context: .
  args:
    GIT_COMMIT: cdc3b19
```

```yml
build:
  context: .
  args:
    - GIT_COMMIT=cdc3b19
```

Values can be omitted when specifying a build argument, in which case its value at build time must be obtained by user interaction,
otherwise the build argument won't be set when building the Docker image.

```yml
args:
  - GIT_COMMIT
```

### `context`

`context` defines either a path to a directory containing a Dockerfile, or a URL to a Git repository.

When the value supplied is a relative path, it is interpreted as relative to the project directory.
Compose warns you about the absolute path used to define the build context as those prevent the Compose file
from being portable.

```yml
build:
  context: ./dir
```

```yml
services:
  webapp:
    build: https://github.com/mycompany/webapp.git
```

If not set explicitly, `context` defaults to project directory (`.`). 

### `cache_from`

`cache_from` defines a list of sources the image builder should use for cache resolution.

Cache location syntax follows the global format `[NAME|type=TYPE[,KEY=VALUE]]`. Simple `NAME` is actually a shortcut notation for `type=registry,ref=NAME`.

Compose Build implementations may support custom types, the Compose Specification defines canonical types which must be supported:

- `registry` to retrieve build cache from an OCI image set by key `ref`


```yml
build:
  context: .
  cache_from:
    - alpine:latest
    - type=local,src=path/to/cache
    - type=gha
```

Unsupported caches are ignored and don't prevent you from building images.

### `cache_to`

`cache_to` defines a list of export locations to be used to share build cache with future builds.

```yml
build:
  context: .
  cache_to:
   - user/app:cache
   - type=local,dest=path/to/cache
```

Cache target is defined using the same `type=TYPE[,KEY=VALUE]` syntax defined by [`cache_from`](#cache_from).

Unsupported caches are ignored and don't prevent you from building images.

### `dockerfile`

`dockerfile` sets an alternate Dockerfile. A relative path is resolved from the build context.
Compose warns you about the absolute path used to define the Dockerfile as it prevents Compose files
from being portable.

When set, `dockerfile_inline` attribute is not allowed and Compose
rejects any Compose file having both set.

```yml
build:
  context: .
  dockerfile: webapp.Dockerfile
```

### `dockerfile_inline`

{{< summary-bar feature_name="Build dockerfile inline" >}}

`dockerfile_inline` defines the Dockerfile content as an inlined string in a Compose file. When set, the `dockerfile`
attribute is not allowed and Compose rejects any Compose file having both set.

Use of YAML multi-line string syntax is recommended to define the Dockerfile content:

```yml
build:
  context: .
  dockerfile_inline: |
    FROM baseimage
    RUN some command
```

### `entitlements`

{{< summary-bar feature_name="Build entitlements" >}}

`entitlements` defines extra privileged entitlements to be allowed during the build.

 ```yaml
 entitlements:
   - network.host
   - security.insecure
 ```

### `extra_hosts`

`extra_hosts` adds hostname mappings at build-time. Use the same syntax as [`extra_hosts`](services.md#extra_hosts).

```yml
extra_hosts:
  - "somehost=162.242.195.82"
  - "otherhost=50.31.209.229"
  - "myhostv6=::1"
```
IPv6 addresses can be enclosed in square brackets, for example:

```yml
extra_hosts:
  - "myhostv6=[::1]"
```

The separator `=` is preferred, but `:` can also be used. Introduced in Docker Compose version [2.24.1](/manuals/compose/releases/release-notes.md#2241). For example:

```yml
extra_hosts:
  - "somehost:162.242.195.82"
  - "myhostv6:::1"
```

Compose creates matching entry with the IP address and hostname in the container's network