Ignoring .dockerignore

A colleague came to me and asked: "How to ignore .dockerignore



when building a docker image?"

After joint searches and checks, a simple solution was found, which consists of the following:

Assembled a test project:

And now, in more detail on the files:

1. Dockerfile

   
   
   
   
   
   
   

   FROM alpine
   COPY . .
   ENTRYPOINT cat data.txt
         
         
   
           
           
           
         
   
       
           
           
           
         
         
   
           
           
           
         
   
       
       

   
   
   

2. .dockerignore

   
   
   
   
   
   
   

   data.txt
   README.md
         
         
   
           
           
           
         
   
       
           
           
           
         
         
   
           
           
           
         
   
       
       

   
   
   

3. data.txt (the file that we will exclude during assembly)

   
   
   
   
   
   
   

   hello habr
         
         
   
           
           
           
         
   
       
           
           
           
         
         
   
           
           
           
         
   
       
       

   
   
   

4. Dockerfile.dev

   
   
   
   
   
   
   

   FROM alpine
   COPY . .
   ENTRYPOINT cat data.txt
         
         
   
           
           
           
         
   
       
           
           
           
         
         
   
           
           
           
         
   
       
       

   
   
   

   As you can see, it is no different from the previously created Dockerfile, but here we are interested in the postfix in the file name

   
   
   
   
   
   
   

5. Dockerfile.dev.dockerignore (ignore file for so called dev build)

   
   
   
   
   
   
   

   README.md
         
         
   
           
           
           
         
   
       
           
           
           
         
         
   
           
           
           
         
   
       
       

   
   
   

Now we have 2 identical Dockerfiles, with a difference only in the name, and each has its own .dockerignore, and for this to work, we need to set the DOCKER_BUILDKIT = 1 flag.

Well, now, you can check what happened:

ala prod-assembly

docker build -t with_ignore -f Dockerfile .

docker run --rm with_ignore
      
      

        
        
        
      

    
        
        
        
      
      

        
        
        
      

    
    

in the output we will see

cat: can't open 'data.txt': No such file or directory
      
      

        
        
        
      

    
        
        
        
      
      

        
        
        
      

    
    

test build

docker build -t without_ignore -f Dockerfile.dev .

docker run --rm without_ignore
      
      

        
        
        
      

    
        
        
        
      
      

        
        
        
      

    
    

in output

hello habr
      
      

        
        
        
      

    
        
        
        
      
      

        
        
        
      

    
    

PROFIT.

github