@@ -123,6 +123,7 @@ This section lists each version from latest to oldest.  Each listing includes a

 * `POST /containers/create/` and `POST /containers/(name)/update` now validates restart policies.

 * `POST /containers/create` now validates IPAMConfig in NetworkingConfig, and returns error for invalid IPv4 and IPv6 addresses (`--ip` and `--ip6` in `docker create/run`).

 * `POST /containers/create` now takes a `Mounts` field in `HostConfig` which replaces `Binds` and `Volumes`. *note*: `Binds` and `Volumes` are still available but are exclusive with `Mounts`

+* `POST /build` now performs a preliminary validation of the `Dockerfile` before starting the build, and returns an error if the syntax is incorrect. Note that this change is _unversioned_ and applied to all API versions.

 ### v1.24 API changes

@@ -1201,6 +1201,10 @@ The archive may include any number of other files,

 which are accessible in the build context (See the [*ADD build

 command*](../../reference/builder.md#add)).

+The Docker daemon performs a preliminary validation of the `Dockerfile` before

+starting the build, and returns an error if the syntax is incorrect. After that,

+each instruction is run one-by-one until the ID of the new image is output.

+

 The build is canceled if the client drops the connection by quitting

 or being killed.

@@ -1243,6 +1243,10 @@ The archive may include any number of other files,

 which are accessible in the build context (See the [*ADD build

 command*](../../reference/builder.md#add)).

+The Docker daemon performs a preliminary validation of the `Dockerfile` before

+starting the build, and returns an error if the syntax is incorrect. After that,

+each instruction is run one-by-one until the ID of the new image is output.

+

 The build is canceled if the client drops the connection by quitting

 or being killed.

@@ -1370,6 +1370,10 @@ The archive may include any number of other files,

 which are accessible in the build context (See the [*ADD build

 command*](../../reference/builder.md#add)).

+The Docker daemon performs a preliminary validation of the `Dockerfile` before

+starting the build, and returns an error if the syntax is incorrect. After that,

+each instruction is run one-by-one until the ID of the new image is output.

+

 The build is canceled if the client drops the connection by quitting

 or being killed.

@@ -1448,6 +1448,10 @@ The archive may include any number of other files,

 which are accessible in the build context (See the [*ADD build

 command*](../../reference/builder.md#add)).

+The Docker daemon performs a preliminary validation of the `Dockerfile` before

+starting the build, and returns an error if the syntax is incorrect. After that,

+each instruction is run one-by-one until the ID of the new image is output.

+

 The build is canceled if the client drops the connection by quitting

 or being killed.

@@ -1625,6 +1625,10 @@ The archive may include any number of other files,

 which are accessible in the build context (See the [*ADD build

 command*](../../reference/builder.md#add)).

+The Docker daemon performs a preliminary validation of the `Dockerfile` before

+starting the build, and returns an error if the syntax is incorrect. After that,

+each instruction is run one-by-one until the ID of the new image is output.

+

 The build is canceled if the client drops the connection by quitting

 or being killed.

@@ -1658,6 +1658,10 @@ The archive may include any number of other files,

 which are accessible in the build context (See the [*ADD build

 command*](../../reference/builder.md#add)).

+The Docker daemon performs a preliminary validation of the `Dockerfile` before

+starting the build, and returns an error if the syntax is incorrect. After that,

+each instruction is run one-by-one until the ID of the new image is output.

+

 The build is canceled if the client drops the connection by quitting

 or being killed.

@@ -1661,6 +1661,10 @@ The archive may include any number of other files,

 which are accessible in the build context (See the [*ADD build

 command*](../../reference/builder.md#add)).

+The Docker daemon performs a preliminary validation of the `Dockerfile` before

+starting the build, and returns an error if the syntax is incorrect. After that,

+each instruction is run one-by-one until the ID of the new image is output.

+

 The build is canceled if the client drops the connection by quitting

 or being killed.

@@ -1682,6 +1682,10 @@ The archive may include any number of other files,

 which are accessible in the build context (See the [*ADD build

 command*](../../reference/builder.md#add)).

+The Docker daemon performs a preliminary validation of the `Dockerfile` before

+starting the build, and returns an error if the syntax is incorrect. After that,

+each instruction is run one-by-one until the ID of the new image is output.

+

 The build is canceled if the client drops the connection by quitting

 or being killed.

@@ -68,6 +68,13 @@ add multiple `-t` parameters when you run the `build` command:

     $ docker build -t shykes/myapp:1.0.2 -t shykes/myapp:latest .

+Before the Docker daemon runs the instructions in the `Dockerfile`, it performs

+a preliminary validation of the `Dockerfile` and returns an error if the syntax is incorrect:

+

+    $ docker build -t test/myapp .

+    Sending build context to Docker daemon 2.048 kB

+    Error response from daemon: Unknown instruction: RUNCMD

+

 The Docker daemon runs the instructions in the `Dockerfile` one-by-one,

 committing the result of each instruction

 to a new image if necessary, before finally outputting the ID of your