DockerCLI/docs/reference/commandline/build.md

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title = "build"
description = "The build command description and usage"
keywords = ["build, docker, image"]
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parent = "smn_cli"
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# build
Usage: docker build [OPTIONS] PATH | URL | -
Build a new image from the source code at PATH
-f, --file="" Name of the Dockerfile (Default is 'PATH/Dockerfile')
--force-rm=false Always remove intermediate containers
--no-cache=false Do not use cache when building the image
--pull=false Always attempt to pull a newer version of the image
-q, --quiet=false Suppress the verbose output generated by the containers
--rm=true Remove intermediate containers after a successful build
-t, --tag="" Repository name (and optionally a tag) for the image
-m, --memory="" Memory limit for all build containers
--memory-swap="" Total memory (memory + swap), `-1` to disable swap
-c, --cpu-shares CPU Shares (relative weight)
--cpuset-mems="" MEMs in which to allow execution, e.g. `0-3`, `0,1`
--cpuset-cpus="" CPUs in which to allow execution, e.g. `0-3`, `0,1`
--cgroup-parent="" Optional parent cgroup for the container
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*](/reference/builder/#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`:
$ 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`:
docker build - < Dockerfile
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](/reference/builder#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.
> **Note:**
> Currently only the "run" phase of the build can be canceled until pull
> cancellation is implemented).
## 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`:
$ docker build -t fail .
Sending build context to Docker daemon 2.048 kB
Sending build context to Docker daemon
Step 0 : FROM busybox
---> 4986bf8c1536
Step 1 : 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*](/reference/builder).
## Examples
$ 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*](/reference/builder/#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.
$ docker build .
Uploading context 18.829 MB
Uploading context
Step 0 : FROM busybox
---> 769b9341d937
Step 1 : CMD echo Hello world
---> Using cache
---> 99cc1ad10469
Successfully built 99cc1ad10469
$ echo ".git" > .dockerignore
$ docker build .
Uploading context 6.76 MB
Uploading context
Step 0 : FROM busybox
---> 769b9341d937
Step 1 : 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/#dockerignore-file)
$ 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`
$ 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.
$ docker build - < context.tar.gz
This will build an image for a compressed context read from `STDIN`. Supported
formats are: bzip2, gzip and xz.
$ 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@`
schema.
$ docker build -f Dockerfile.debug .
This will use a file called `Dockerfile.debug` for the build instructions
instead of `Dockerfile`.
$ 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.
$ 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.
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](/reference/run/#specifying-custom-cgroups).