Docker: unable to prepare context: unable to evaluate symlinks in Dockerfile path: GetFileAttributesEx

Question

I just downloaded Docker Toolbox for Windows 10 64bit today. I'm going through the tutorial. I'm receving the following error when trying to build an image using a Dockerfile.

Steps:

• Launched Docker Quickstart terminal.
• testdocker after creating it.
• Prepare Dockerfile as documented in "Build your own image" web link
• ran below command

docker build -t docker-whale .

Error: $ docker build -t docker-whale .

unable to prepare context: unable to evaluate symlinks in Dockerfile path: GetFileAttributesEx C:\Users\Villanueva\Test\testdocker\Dockerfile: The system cannot find the file specified.

BTW: I tried several options mentioned @ https://github.com/docker/docker/issues/14339

    $ docker info
    Containers: 4
     Running: 0
     Paused: 0
     Stopped: 4
    Images: 2
    Server Version: 1.10.1
    Storage Driver: aufs
     Root Dir: /mnt/sda1/var/lib/docker/aufs
     Backing Filesystem: extfs
     Dirs: 20
     Dirperm1 Supported: true
    Execution Driver: native-0.2
    Logging Driver: json-file
    Plugins:
     Volume: local
     Network: bridge null host
    Kernel Version: 4.1.17-boot2docker
    Operating System: Boot2Docker 1.10.1 (TCL 6.4.1); master : b03e158 - Thu Feb 11 22:34:01 UTC 2016
    OSType: linux
    Architecture: x86_64
    CPUs: 1
    Total Memory: 996.2 MiB
    Name: default
    ID: C7DS:CIAJ:FTSN:PCGD:ZW25:MQNG:H3HK:KRJL:G6FC:VPRW:SEWW:KP7B
    Debug mode (server): true
     File Descriptors: 32
     Goroutines: 44
     System Time: 2016-02-19T17:37:37.706076803Z
     EventsListeners: 0
     Init SHA1:
     Init Path: /usr/local/bin/docker
     Docker Root Dir: /mnt/sda1/var/lib/docker
    Labels:
     provider=virtualbox

Solution 1

while executing following command:

docker build -t docker-whale .

check that Dockerfile is present in your current working directory.

Solution 2

The error message is misleading. The problem has nothing to do with symlinks really. It is usually only that docker cannot find the Dockerfile describing the build.

Typical reasons are these:

• Dockerfile has wrong name.
  It must be called Dockerfile. If it is called, for instance, dockerfile, .Dockerfile, Dockerfile.txt, or other, it will not be found.
• Dockerfile is not in context.
  If you say docker build contextdir, the Dockerfile must be at contextdir/Dockerfile. If you have it in, say, ./Dockerfile instead, it will not be found.
• Dockerfile does not exist at all.
  Sounds silly? Well, I got the above error message from my GitLab CI after I had written a nice Dockerfile, but forgotten to check it in. Silly? Sure. Unlikely? No.

Solution 3

If you are working on windows 8 you would be using Docker toolbox. From the mydockerbuild directory run the below command as your Dockerfile is a textfile

docker build -t docker-whale -f ./Dockerfile.txt .

Solution 4

The name of the file should be Dockerfile and not .Dockerfile. The file should not have any extension.

Solution 5

1. Make sure you moved to the directory where Dockerfile is located.
2. Make sure your Dockerfile is extension-less. That is, not Dockerfile.txt, Dockerfile.rtf, or any other.
3. Make sure you named Dockerfile, and not DockerFile, dockerfile or any other.

View more solutions

Comments

[villanux]

Update: docker build -t XXX --file ./Dockefile . worked. Docker may want to update their documentation for Windows users.

[eXa]

If docker build -t XXX --file ./Dockefile it might be because you got the filename wrong it's missing the R.

[RichVel]

This is an amazingly bad error message, it just means "cannot open file" - same on Linux and macOS.

[lmat - Reinstate Monica]

Mind-blowingly bad error message.

[IanGSY]

Thanks. My issue was I had created my Dockerfile in Notepad and it had automatically appended .txt to the filename.

[Sumi Straessle]

You may also explicitly write the Dockerfile name with the fflag, as in docker build -f Dockerfile-dev.yaml -t my_container . This may prove useful if you have several Dockerfile in your project, one per environment, for example. The same applies to docker-compose. Putting them in different subdirectories will not work, since the context (.) will not match.

[sebagomez]

not anymore (if ever) docker build -t docker-whale . is a valid command

[K. Brafford]

@IanGSY I wish I could give you more points for that. That was exactly my problem too!

[Alex]

for future reference if you need to do this it is because your Dockerfile has an extension whereas by default Docker expects it not too. Setting the file manually with the extension adds headaches you do not need. You should set Windows explorer to show extensions and then remove the extension.

[Per Lundberg]

Notepad is an excessively evil program.

[Mike Kellogg]

if you're following along on the docker documentation "getting started" tutorial you would use this: docker build -t friendlyhello -f ./Dockerfile.txt .

[myloginid]

Its really bad semantics that you have to specify the file name and the dummy path also. and/or always name your file as Dockerfile.. :-(

[Lawrence Lee]

This worked for me! I only installed Docker Toolbox and didn't install it in WSL; instead, I'm using the windows executables directly, since WSL can do that now.

[Sachidananda Naik]

This saved my day. By the way, I'm using a Mac machine. But the catch here is that the Dockerfile was created a plain text file. Thanks buddy for the help.

[Paul Gear]

I think this would be a lot stronger (and more relevant) an answer without the 2nd half.

[leon.io]

Great answer, and thanks for the background information

[Donald Shahini]

Dockerfile is not a .txt file. If you have it as a .txt file it will give error again.

[Purplejacket]

It's also necessary to have the . (dot) at the end of the line, as the above shows.

[Purplejacket]

Documentation for docker build is here: docs.docker.com/engine/reference/commandline/build

[Ayyappa]

I cloned a json file instead of creating a new file. Once i renamed it to Dockerfile and updated it contents, it didn't show .json extension and later realised thats the culprit! Thanks for the note!

[Junaid]

Filename did the trick for me. I had to change DockerFile to Dockerfile

[Saites]

Likewise, check for simple spelling errors. I landed here because Dockefile is certainly not the same as Dockerfile :facepalm: Since building with docker build -f <tab-completed filename> . worked, I looked closer and realized I had mistyped it.

[Kraken]

When you need a reminder that you're calling from the wrong directory xD

[Christopher Markieta]

Copied something weird after the trailing period, removing this helped.

[Ukrainian-serge]

big help on the Dockerfile instead of DockerFile