Dockerfile specified with -f not found within build context when cwd is a symlink

[jmanning2k]

Description of problem:
Symlinks appear to be resolved for the build context path (#15039), however they are not normalized/resolved when checking if a Dockerfile specified with '-f' is within the build context.

docker version:

docker version
Client:
 Version:      1.8.1
 API version:  1.20
 Go version:   go1.4.2
 Git commit:   d12ea79
 Built:        Thu Aug 13 02:32:18 UTC 2015
 OS/Arch:      linux/amd64

Server:
 Version:      1.8.1
 API version:  1.20
 Go version:   go1.4.2
 Git commit:   d12ea79
 Built:        Thu Aug 13 02:32:18 UTC 2015
 OS/Arch:      linux/amd64

docker info:

Containers: 18
Images: 719
Storage Driver: aufs
 Root Dir: /var/lib/docker/aufs
 Backing Filesystem: extfs
 Dirs: 755
 Dirperm1 Supported: false
Execution Driver: native-0.2
Logging Driver: json-file
Kernel Version: 3.13.0-57-generic
Operating System: Ubuntu precise (12.04.5 LTS)
CPUs: 2
Total Memory: 7.304 GiB
Name: lims-jmanning
ID: W2PD:YEXU:IOKW:BFAK:AXAJ:CQA5:TVRW:LMWI:TMFT:H6KR:4BVK:GH42
WARNING: No swap limit support

uname -a: Linux lims-jmanning 3.13.0-57-generic #95~precise1-Ubuntu SMP Mon Jun 22 09:43:07 UTC 2015 x86_64 x86_64 x86_64 GNU/Linux

Environment details (AWS, VirtualBox, physical, etc.):
Both on Ubuntu based AWS node and a docker-machine image on OSX

How reproducible:
Always, given recipe below.

Steps to Reproduce:

$ cd /home/test
$ ln -sf /tmp tmp
$ cd tmp
$ mkdir test-docker
$ cd test-docker
$ echo "FROM scratch" > Dockerfile
$ docker build .    ## WORKS
Sending build context to Docker daemon 2.048 kB
Step 0 : FROM scratch
 --->
No image was generated. Is your Dockerfile empty?
$ docker build -f Dockerfile .   ## FAILS
unable to prepare context: The Dockerfile (/home/test/tmp/test-docker/Dockerfile) must be within the build context (.)
$ docker build -f $(pwd)/Dockerfile $(pwd)  ## FAILS
unable to prepare context: The Dockerfile (/home/test/tmp/test-docker/Dockerfile) must be within the build context (/home/test/tmp/test-docker)
$ docker build -f $(pwd -P)/Dockerfile .    ## WORKS - pwd -P gives path with symlinks resolved
Sending build context to Docker daemon 2.048 kB
Step 0 : FROM scratch
 --->
No image was generated. Is your Dockerfile empty?
$echo docker build -f $(pwd -P)/Dockerfile $(pwd)
docker build -f /tmp/test-docker/Dockerfile /home/test/tmp/test-docker
$docker build -f $(pwd -P)/Dockerfile $(pwd)    ### WORKS even though paths are different
Sending build context to Docker daemon 2.048 kB
Step 0 : FROM scratch
 --->
No image was generated. Is your Dockerfile empty?

Actual Results:
Build fails unless I provide fully resolved path to Dockerfile regardless of if cwd is symlinked path or '.'
Error given is a variant of:
unable to prepare context: The Dockerfile (/home/test/tmp/test-docker/Dockerfile) must be within the build context (.)

Expected Results:
These commands should work regardless of symlinks. As noted in docker build -h it should be valid to specify docker build -f PATH/Dockerfile PATH
$ docker build -f Dockerfile . ## FAILS
$ docker build -f $(pwd)/Dockerfile $(pwd) ## FAILS

Additional info:
Our build uses symlinks for build folder in some environmentsso that dev builds and production builds can use the same filesystem paths throughout.
Related to #15037, probably caused by #15039 / bdc55be (build context dir is normalized for symlinks, but not a Dockerfile specified with '-f').

I think #14339 is the same issue, but mistakenly closed as duplicate of a similar but non-identical issue.

In the real world case, I am attempting to use '-f Dockerfile_base', which is why I can't simply omit the '-f' flag.

Same behavior seen on:
Docker version 1.8.1, build d12ea79 (ubuntu)
Docker version 1.8.2, build 0a8c2e3 (OSX)

EDIT: Updated to bug report template.

[rncry]

I'm having this issue but without symlinks being used.

[jmanning2k]

I can confirm there is an identical failure without symlinks when using docker-machine on OSX. Using any folder outside the folders mounted in the VM will give this error (only when '-f Dockerfile' is used, it works outside the build context when no Dockerfile is specified. Possibly the same cause.

OSX via dockermachine:

docker-machine version 0.4.1 (e2c88d6)
Docker version 1.8.2, build 0a8c2e3

#
$ mkdir /tmp/test-docker2 # not a symlink
$ cd /tmp/test-docker2
$ echo "FROM scratch" > Dockerfile
$ docker build -f Dockerfile .
unable to prepare context: The Dockerfile (/tmp/test-docker2/Dockerfile) must be within the build context (.)
$ docker build .
Sending build context to Docker daemon 2.048 kB
Step 0 : FROM scratch
(... WORKS)

This (original) error occurs on Linux only with symlinks involved. I cannot reproduce on Linux without symlinks.

[AaronDMarasco-VSI]

Seeings same problem on CentOS 7 (Docker version 1.8.2, build 0a8c2e3).

Worked around it using "realpath":

[amarasco@server releng]$ touch Dockerfile
[amarasco@server releng]$ ls -alF ~/work
lrwxrwxrwx. 1 amarasco amarasco 15 Sep 29 15:36 /home/amarasco/work -> /data/amarasco//
[amarasco@server releng]$ docker build -t image_81410_6 -f ./Dockerfile .
unable to prepare context: The Dockerfile (/home/amarasco/work/releng/Dockerfile) must be within the build context (.)
[amarasco@server releng]$ docker build -t image_81410_6 -f $(realpath .)/Dockerfile .
Sending build context to Docker daemon 91.65 kB
Error response from daemon: The Dockerfile (Dockerfile) cannot be empty

[Crazykev]

I want to take a shot at this one.

[Crazykev]

@thaJeztah I misunderstood the issue yesterday. Today I just can't reproduce this using 'master' and 'bf80ade'. It seems this issue has been fixed.

Here is the steps: (almost same as @jmanning2k did)

$ mkdir $HOME/test
$ cd $HOME/test
$ ln -sf /tmp tmp
$ cd tmp
$ mkdir test-docker
$ cd test-docker/
$ echo "FROM ubuntu" > Dockerfile
$ docker-1.9.0-dev build .
Sending build context to Docker daemon 2.048 kB
Step 1 : FROM ubuntu
 ---> cdd474520b8c
Successfully built cdd474520b8c
$ docker-1.9.0-dev build -f Dockerfile .
Sending build context to Docker daemon 2.048 kB
Step 1 : FROM ubuntu
 ---> cdd474520b8c
Successfully built cdd474520b8c
$ docker-1.9.0-dev build -f $(pwd)/Dockerfile $(pwd)
Sending build context to Docker daemon 2.048 kB
Step 1 : FROM ubuntu
 ---> cdd474520b8c
Successfully built cdd474520b8c
$ docker-1.9.0-dev build -f $(pwd -P)/Dockerfile .
Sending build context to Docker daemon 2.048 kB
Step 1 : FROM ubuntu
 ---> cdd474520b8c
Successfully built cdd474520b8c
$ docker-1.9.0-dev build -f $(pwd -P)/Dockerfile $(pwd)
Sending build context to Docker daemon 2.048 kB
Step 1 : FROM ubuntu
 ---> cdd474520b8c
Successfully built cdd474520b8c
$ docker-1.9.0-dev build -f $(pwd)/Dockerfile $(pwd -P)
Sending build context to Docker daemon 2.048 kB
Step 1 : FROM ubuntu
 ---> cdd474520b8c
Successfully built cdd474520b8c

@jmanning2k It seems this issue has been fixed. Can you still reproduce this using current 'master' ?

[djui]

I have this issue as well, running Docker 1.8.3. The symptom is when trying to build an image using -f in the temp directory ($TMPDIR) on OS X 10.11 the reported "out of context" error occurs. On OS X (Darwin) $TMPDIR resolves to /var/folders/.../.../... but /var is symlink'd /private/var. And using /tmp would also not work as it's symlink'd to /private/tmp.

One temporary solution is:

- cd ${TMPDIR:-/tmp}
+ cd -P ${TMPDIR:-/tmp}

  docker build --file=Dockerfile

[jmanning2k]

Finally had a chance to test with 1.9.0 on linux and OSX, both working, no longer showing this error.

[thaJeztah]

Thanks @jmanning2k! Good to hear it's resolved

[Boulboulouboule]

Thanks !
docker build --file=Dockerfile
works for me too :)

[rajiv180984]

I faced the same issue. I am using docker version:17.09.0-ce. I follow below steps.
Step 1: create Dockerfile and added commands for creating docker image
Step 2: go to directory where we have created Dockfile
Step 3: execute below command
$sudo docker build -t ubuntu-test:latest .
It resolved issue and image created successsfully
Note: build command depend on docker version as well as which build option we are using. :)