CC-1333 Add repository aware caching

dockerfiles/go-1.19.Dockerfile

@@ -1,10 +1,15 @@
+# syntax=docker/dockerfile:1.7-labs
 FROM golang:1.19-alpine
 
 ENV CODECRAFTERS_DEPENDENCY_FILE_PATHS="go.mod,go.sum"
 
 WORKDIR /app
 
-COPY go.mod go.sum ./
+# .git & README.md are unique per-repository. We ignore them on first copy to prevent cache misses
+COPY --exclude=.git --exclude=README.md . /app
 
 RUN go mod graph | awk '{if ($1 !~ "@") print $2}' | xargs -r go get
 
+
+# Once the heave steps are done, we can copy all files back
+COPY . /app

dockerfiles/python-3.11.Dockerfile

@@ -1,11 +1,12 @@
+# syntax=docker/dockerfile:1.7-labs
 FROM python:3.11-alpine
 
 RUN pip install pipenv
 
-COPY Pipfile /app/Pipfile
-COPY Pipfile.lock /app/Pipfile.lock
 
 WORKDIR /app
+# .git & README.md are unique per-repository. We ignore them on first copy to prevent cache misses
+COPY --exclude=.git --exclude=README.md . /app
 
 ENV WORKON_HOME=/venvs
 
@@ -14,4 +15,6 @@ RUN pipenv install
 # Force environment creation
 RUN pipenv run python3 -c "1+1"
 
-ENV CODECRAFTERS_DEPENDENCY_FILE_PATHS="Pipfile,Pipfile.lock"
+ENV CODECRAFTERS_DEPENDENCY_FILE_PATHS="Pipfile,Pipfile.lock"
+# Once the heave steps are done, we can copy all files back
+COPY . /app

dockerfiles/rust-1.70.Dockerfile

@@ -1,12 +1,13 @@
+# syntax=docker/dockerfile:1.7-labs
 FROM rust:1.70-buster
 
-COPY Cargo.toml /app/Cargo.toml
-COPY Cargo.lock /app/Cargo.lock
 
 RUN mkdir /app/src
 RUN echo 'fn main() { println!("Hello World!"); }' > /app/src/main.rs
 
 WORKDIR /app
+# .git & README.md are unique per-repository. We ignore them on first copy to prevent cache misses
+COPY --exclude=.git --exclude=README.md . /app
 RUN cargo build --release --target-dir=/tmp/codecrafters-grep-target
 
 RUN cargo clean -p grep-starter-rust --release --target-dir=/tmp/codecrafters-grep-target
@@ -18,3 +19,6 @@ RUN chmod +x /codecrafters-precompile.sh
 
 ENV CODECRAFTERS_DEPENDENCY_FILE_PATHS="Cargo.toml,Cargo.lock"
 
+
+# Once the heave steps are done, we can copy all files back
+COPY . /app