Docker build gives unable to prepare context context must be a directory Users tempUser git docker Dockerfile

Question

I have a Dockerfile that is supposed to build an Ubuntu image  But whenever I run docker build -t ubuntu-test latest   Dockerfile  it shows the following error on the console  unable to prepare context  context must be a directory   Users tempUser git docker Dockerfile  I m on Mac OsX  I tried to sudo as well  Nothing works

User · Answer

You can also run docker build with -f option   docker build -t ubuntu-test latest -f Dockerfile custom

User · Answer

It s simple  whenever Docker build is run  docker wants to know  what s the image name  so we need to pass -t     Now make sure you are in the same directory where you have your Dockerfile and run   docker build -t  lt image name gt   lt version gt    Example  docker build -t my apache latest   assuming you are in the same directory as your Dockerfile otherwise pass -f flag and the Dockerfile   docker build -t my apache latest -f   Users documents myapache Dockerfile

User · Answer

I face the same issue  I am using docker version 17 09 0-ce    I follow below steps    Create Dockerfile and added commands for creating docker image Go to directory where we have created Dockfile 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

User · Answer

You need to point to the directory instead  You must not specify the dockerfile    docker build -t ubuntu-test latest   does work    docker build -t ubuntu-test latest   Dockerfile does not work

User · Answer

Understand contexts  The docker build command  The basic syntax of docker s build command is  docker build -t imagename imagetag context dir   The context  The context is a directory and determines what the docker build process is going to see  From the Dockerfile s point of view  any file context dir mydir myfile in your filesystem will become  mydir myfile in the Dockerfile and hence during the build process   The dockerfile  If the dockerfile is called Dockerfile and lives in the context  it will be found implicitly by naming convention  That s nice  because it means you can usually find the Dockerfile in any docker container immediately   If you insist on using different name  say   tmp mydockerfile   you can use -f like this   docker build -t imagename imagetag -f  tmp mydockerfile context dir   but then the dockerfile will not be in the same folder or at least will be harder to find

User · Answer

To specify a Dockerfile when build  you can use   docker build -t ubuntu-test latest -  lt   path to your Dockerfile   But it ll fail if there s ADD or COPY command that depends on relative path  There re many ways to specify a context for docker build  you can refer to docs of docker build for more info

User · Answer

One of the reasons for me getting an error was the file name make sure the file  name is Dockerfile So i figured it out  hope it might help someone

[docker] Docker build gives "unable to prepare context: context must be a directory: /Users/tempUser/git/docker/Dockerfile"

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