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dockerdockerignore
Ilia Barahovsky
Ilia Barahovsky

Reputation: 10498

.dockerignore pattern to exclude files in all subdirectories

How can I exclude python generated files like *.pyc in all subdirectories from the docker image?

I added .dockerignore at the root of the context directory:

# Ignore generated files
*.pyc

Alas docker build ignores this at least for subdirectories and copies the entire directory tree that looks like the following:

/contextdir/
|-- Dockerfile
\-- src/
    |-- a.py   # this is copied - all right
    \-- a.pyc  # this should be ignored, but is copied too. Why?

Upvotes: 63

Views: 44219

Answers (2)

Ilia Barahovsky
Ilia Barahovsky

Reputation: 10498

Patterns like *.pyc are matched only at the beginning of the path, or for the files directly below the context directory, but not recursively. To make it work recursively the **/ syntax must be used:

# Ignore generated files
**/*.pyc

The reference at How to create a dockerignore file doesn't put that clear enough.

Finally, I understood that trick. For some reason, I wasn't able to find any mention of this and haven't found any example Dockerfile with such construct, so documenting it here. Was it trivial for everybody else?

Upvotes: 134

Elton Stoneman
Elton Stoneman

Reputation: 19154

The docs for .dockerignore state that the .dockerignore file is interpreted as a list of patterns similar to the file globs of Unix shells. The pattern matching use's Go's filepath matching logic. The docs also cover the recursive pattern:

Beyond Go’s filepath.Match rules, Docker also supports a special wildcard string ** that matches any number of directories (including zero). For example, **/*.go will exclude all files that end with .go that are found in all directories, including the root of the build context.

Upvotes: 11

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