github.com/brahmaroutu/docker@v1.2.1-0.20160809185609-eb28dde01f16/docs/reference/commandline/build.md

<!--[metadata]>
+++
title = "build"
description = "The build command description and usage"
keywords = ["build, docker, image"]
[menu.main]
parent = "smn_cli"
+++
<![end-metadata]-->

# build

```markdown
Usage:  docker build [OPTIONS] PATH | URL | -

Build an image from a Dockerfile

Options:
      --build-arg value         Set build-time variables (default [])
      --cgroup-parent string    Optional parent cgroup for the container
      --cpu-period int          Limit the CPU CFS (Completely Fair Scheduler) period
      --cpu-quota int           Limit the CPU CFS (Completely Fair Scheduler) quota
  -c, --cpu-shares int          CPU shares (relative weight)
      --cpuset-cpus string      CPUs in which to allow execution (0-3, 0,1)
      --cpuset-mems string      MEMs in which to allow execution (0-3, 0,1)
      --disable-content-trust   Skip image verification (default true)
  -f, --file string             Name of the Dockerfile (Default is 'PATH/Dockerfile')
      --force-rm                Always remove intermediate containers
      --help                    Print usage
      --isolation string        Container isolation technology
      --label value             Set metadata for an image (default [])
  -m, --memory string           Memory limit
      --memory-swap string      Swap limit equal to memory plus swap: '-1' to enable unlimited swap
      --no-cache                Do not use cache when building the image
      --pull                    Always attempt to pull a newer version of the image
  -q, --quiet                   Suppress the build output and print image ID on success
      --rm                      Remove intermediate containers after a successful build (default true)
      --shm-size string         Size of /dev/shm, default value is 64MB.
                                The format is `<number><unit>`. `number` must be greater than `0`.
                                Unit is optional and can be `b` (bytes), `k` (kilobytes), `m` (megabytes),
                                or `g` (gigabytes). If you omit the unit, the system uses bytes.
  -t, --tag value               Name and optionally a tag in the 'name:tag' format (default [])
      --ulimit value            Ulimit options (default [])
```

Builds Docker images from a Dockerfile and a "context". A build's context is
the files located in the specified `PATH` or `URL`. The build process can refer
to any of the files in the context. For example, your build can use an
[*ADD*](../builder.md#add) instruction to reference a file in the
context.

The `URL` parameter can specify the location of a Git repository; the repository
acts as the build context. The system recursively clones the repository and its
submodules using a `git clone --depth 1 --recursive` command. This command runs
in a temporary directory on your local host. After the command succeeds, the
directory is sent to the Docker daemon as the context. Local clones give you the
ability to access private repositories using local user credentials, VPNs, and
so forth.

Git URLs accept context configuration in their fragment section, separated by a
colon `:`.  The first part represents the reference that Git will check out,
this can be either a branch, a tag, or a commit SHA. The second part represents
a subdirectory inside the repository that will be used as a build context.

For example, run this command to use a directory called `docker` in the branch
`container`:

```bash
$ docker build https://github.com/docker/rootfs.git#container:docker
```

The following table represents all the valid suffixes with their build
contexts:

Build Syntax Suffix             | Commit Used           | Build Context Used
--------------------------------|-----------------------|-------------------
`myrepo.git`                    | `refs/heads/master`   | `/`
`myrepo.git#mytag`              | `refs/tags/mytag`     | `/`
`myrepo.git#mybranch`           | `refs/heads/mybranch` | `/`
`myrepo.git#abcdef`             | `sha1 = abcdef`       | `/`
`myrepo.git#:myfolder`          | `refs/heads/master`   | `/myfolder`
`myrepo.git#master:myfolder`    | `refs/heads/master`   | `/myfolder`
`myrepo.git#mytag:myfolder`     | `refs/tags/mytag`     | `/myfolder`
`myrepo.git#mybranch:myfolder`  | `refs/heads/mybranch` | `/myfolder`
`myrepo.git#abcdef:myfolder`    | `sha1 = abcdef`       | `/myfolder`

Instead of specifying a context, you can pass a single Dockerfile in the `URL`
or pipe the file in via `STDIN`. To pipe a Dockerfile from `STDIN`:

```bash
$ docker build - < Dockerfile
```

With Powershell on Windows, you can run:

```powershell
Get-Content Dockerfile | docker build -
```

If you use STDIN or specify a `URL`, the system places the contents into a file
called `Dockerfile`, and any `-f`, `--file` option is ignored. In this
scenario, there is no context.

By default the `docker build` command will look for a `Dockerfile` at the root
of the build context. The `-f`, `--file`, option lets you specify the path to
an alternative file to use instead. This is useful in cases where the same set
of files are used for multiple builds. The path must be to a file within the
build context. If a relative path is specified then it must to be relative to
the current directory.

In most cases, it's best to put each Dockerfile in an empty directory. Then,
add to that directory only the files needed for building the Dockerfile. To
increase the build's performance, you can exclude files and directories by
adding a `.dockerignore` file to that directory as well. For information on
creating one, see the [.dockerignore file](../builder.md#dockerignore-file).

If the Docker client loses connection to the daemon, the build is canceled.
This happens if you interrupt the Docker client with `CTRL-c` or if the Docker
client is killed for any reason. If the build initiated a pull which is still
running at the time the build is cancelled, the pull is cancelled as well.

## Return code

On a successful build, a return code of success `0` will be returned.  When the
build fails, a non-zero failure code will be returned.

There should be informational output of the reason for failure output to
`STDERR`:

```bash
$ docker build -t fail .

Sending build context to Docker daemon 2.048 kB
Sending build context to Docker daemon
Step 1 : FROM busybox
 ---> 4986bf8c1536
Step 2 : RUN exit 13
 ---> Running in e26670ec7a0a
INFO[0000] The command [/bin/sh -c exit 13] returned a non-zero code: 13
$ echo $?
1
```

See also:

[*Dockerfile Reference*](../builder.md).

## Examples

### Build with PATH

```bash
$ docker build .

Uploading context 10240 bytes
Step 1 : FROM busybox
Pulling repository busybox
 ---> e9aa60c60128MB/2.284 MB (100%) endpoint: https://cdn-registry-1.docker.io/v1/
Step 2 : RUN ls -lh /
 ---> Running in 9c9e81692ae9
total 24
drwxr-xr-x    2 root     root        4.0K Mar 12  2013 bin
drwxr-xr-x    5 root     root        4.0K Oct 19 00:19 dev
drwxr-xr-x    2 root     root        4.0K Oct 19 00:19 etc
drwxr-xr-x    2 root     root        4.0K Nov 15 23:34 lib
lrwxrwxrwx    1 root     root           3 Mar 12  2013 lib64 -> lib
dr-xr-xr-x  116 root     root           0 Nov 15 23:34 proc
lrwxrwxrwx    1 root     root           3 Mar 12  2013 sbin -> bin
dr-xr-xr-x   13 root     root           0 Nov 15 23:34 sys
drwxr-xr-x    2 root     root        4.0K Mar 12  2013 tmp
drwxr-xr-x    2 root     root        4.0K Nov 15 23:34 usr
 ---> b35f4035db3f
Step 3 : CMD echo Hello world
 ---> Running in 02071fceb21b
 ---> f52f38b7823e
Successfully built f52f38b7823e
Removing intermediate container 9c9e81692ae9
Removing intermediate container 02071fceb21b
```

This example specifies that the `PATH` is `.`, and so all the files in the
local directory get `tar`d and sent to the Docker daemon. The `PATH` specifies
where to find the files for the "context" of the build on the Docker daemon.
Remember that the daemon could be running on a remote machine and that no
parsing of the Dockerfile happens at the client side (where you're running
`docker build`). That means that *all* the files at `PATH` get sent, not just
the ones listed to [*ADD*](../builder.md#add) in the Dockerfile.

The transfer of context from the local machine to the Docker daemon is what the
`docker` client means when you see the "Sending build context" message.

If you wish to keep the intermediate containers after the build is complete,
you must use `--rm=false`. This does not affect the build cache.

### Build with URL

```bash
$ docker build github.com/creack/docker-firefox
```

This will clone the GitHub repository and use the cloned repository as context.
The Dockerfile at the root of the repository is used as Dockerfile. Note that
you can specify an arbitrary Git repository by using the `git://` or `git@`
scheme.

### Build with -

```bash
$ docker build - < Dockerfile
```

This will read a Dockerfile from `STDIN` without context. Due to the lack of a
context, no contents of any local directory will be sent to the Docker daemon.
Since there is no context, a Dockerfile `ADD` only works if it refers to a
remote URL.

```bash
$ docker build - < context.tar.gz
```

This will build an image for a compressed context read from `STDIN`.  Supported
formats are: bzip2, gzip and xz.

### Usage of .dockerignore

```bash
$ docker build .

Uploading context 18.829 MB
Uploading context
Step 1 : FROM busybox
 ---> 769b9341d937
Step 2 : CMD echo Hello world
 ---> Using cache
 ---> 99cc1ad10469
Successfully built 99cc1ad10469
$ echo ".git" > .dockerignore
$ docker build .
Uploading context  6.76 MB
Uploading context
Step 1 : FROM busybox
 ---> 769b9341d937
Step 2 : CMD echo Hello world
 ---> Using cache
 ---> 99cc1ad10469
Successfully built 99cc1ad10469
```

This example shows the use of the `.dockerignore` file to exclude the `.git`
directory from the context. Its effect can be seen in the changed size of the
uploaded context. The builder reference contains detailed information on
[creating a .dockerignore file](../builder.md#dockerignore-file)

### Tag image (-t)

```bash
$ docker build -t vieux/apache:2.0 .
```

This will build like the previous example, but it will then tag the resulting
image. The repository name will be `vieux/apache` and the tag will be `2.0`.
[Read more about valid tags](tag.md).

You can apply multiple tags to an image. For example, you can apply the `latest`
tag to a newly built image and add another tag that references a specific
version.
For example, to tag an image both as `whenry/fedora-jboss:latest` and
`whenry/fedora-jboss:v2.1`, use the following:

```bash
$ docker build -t whenry/fedora-jboss:latest -t whenry/fedora-jboss:v2.1 .
```
### Specify Dockerfile (-f)

```bash
$ docker build -f Dockerfile.debug .
```

This will use a file called `Dockerfile.debug` for the build instructions
instead of `Dockerfile`.

```bash
$ docker build -f dockerfiles/Dockerfile.debug -t myapp_debug .
$ docker build -f dockerfiles/Dockerfile.prod  -t myapp_prod .
```

The above commands will build the current build context (as specified by the
`.`) twice, once using a debug version of a `Dockerfile` and once using a
production version.

```bash
$ cd /home/me/myapp/some/dir/really/deep
$ docker build -f /home/me/myapp/dockerfiles/debug /home/me/myapp
$ docker build -f ../../../../dockerfiles/debug /home/me/myapp
```

These two `docker build` commands do the exact same thing. They both use the
contents of the `debug` file instead of looking for a `Dockerfile` and will use
`/home/me/myapp` as the root of the build context. Note that `debug` is in the
directory structure of the build context, regardless of how you refer to it on
the command line.

> **Note:**
> `docker build` will return a `no such file or directory` error if the
> file or directory does not exist in the uploaded context. This may
> happen if there is no context, or if you specify a file that is
> elsewhere on the Host system. The context is limited to the current
> directory (and its children) for security reasons, and to ensure
> repeatable builds on remote Docker hosts. This is also the reason why
> `ADD ../file` will not work.

### Optional parent cgroup (--cgroup-parent)

When `docker build` is run with the `--cgroup-parent` option the containers
used in the build will be run with the [corresponding `docker run`
flag](../run.md#specifying-custom-cgroups).

### Set ulimits in container (--ulimit)

Using the `--ulimit` option with `docker build` will cause each build step's
container to be started using those [`--ulimit`
flag values](./run.md#set-ulimits-in-container-ulimit).

### Set build-time variables (--build-arg)

You can use `ENV` instructions in a Dockerfile to define variable
values. These values persist in the built image. However, often
persistence is not what you want. Users want to specify variables differently
depending on which host they build an image on.

A good example is `http_proxy` or source versions for pulling intermediate
files. The `ARG` instruction lets Dockerfile authors define values that users
can set at build-time using the  `--build-arg` flag:

```bash
$ docker build --build-arg HTTP_PROXY=http://10.20.30.2:1234 .
```

This flag allows you to pass the build-time variables that are
accessed like regular environment variables in the `RUN` instruction of the
Dockerfile. Also, these values don't persist in the intermediate or final images
like `ENV` values do.

Using this flag will not alter the output you see when the `ARG` lines from the
Dockerfile are echoed during the build process.

For detailed information on using `ARG` and `ENV` instructions, see the
[Dockerfile reference](../builder.md).

### Specify isolation technology for container (--isolation)

This option is useful in situations where you are running Docker containers on
Windows. The `--isolation=<value>` option sets a container's isolation
technology. On Linux, the only supported is the `default` option which uses
Linux namespaces. On Microsoft Windows, you can specify these values:


| Value     | Description                                                                                                                                                   |
|-----------|---------------------------------------------------------------------------------------------------------------------------------------------------------------|
| `default` | Use the value specified by the Docker daemon's `--exec-opt` . If the `daemon` does not specify an isolation technology, Microsoft Windows uses `process` as its default value.  |
| `process` | Namespace isolation only.                                                                                                                                     |
| `hyperv`  | Hyper-V hypervisor partition-based isolation.                                                                                                                 |

Specifying the `--isolation` flag without a value is the same as setting `--isolation="default"`.