perf: eliminate slow chown operations in Docker builds (~41min → seconds) (#12256)

Co-authored-by: Pranjal Gupta <19pran@gmail.com>

openhands/runtime/utils/runtime_templates/Dockerfile.j2

@@ -223,12 +223,12 @@ RUN \
     # Set environment variables (requires root)
     /openhands/micromamba/bin/micromamba run -n openhands poetry run python -c "import sys; print('OH_INTERPRETER_PATH=' + sys.executable)" >> /etc/environment && \
     # Set permissions for shared read-only access
+    # Note: chown -R operations removed - files are now created with correct ownership
+    # by running micromamba/poetry as openhands user (see install_dependencies_user)
     chmod -R 755 /openhands/poetry && \
     chmod -R 755 /openhands/micromamba && \
-    chown -R openhands:openhands /openhands/poetry && \
     mkdir -p /openhands/workspace && chmod -R g+rws,o+rw /openhands/workspace && \
     chown -R openhands:openhands /openhands/workspace && \
-    chown -R openhands:openhands /openhands/micromamba && \
     # Ensure PATH includes system binaries early in startup
     echo 'export PATH="/usr/bin:/bin:/usr/sbin:/sbin:$PATH"' >> /etc/environment && \
     echo 'export PATH="/usr/bin:/bin:/usr/sbin:/sbin:$PATH"' >> /etc/bash.bashrc && \
@@ -290,8 +290,11 @@ RUN mkdir -p /openhands/micromamba/bin && \
     echo 'export PATH="/openhands/micromamba/bin:$PATH"' >> /etc/environment
 
 # Create the openhands virtual environment and install poetry and python
+# Run as openhands user to avoid expensive chown -R operations later
+USER openhands
 RUN /openhands/micromamba/bin/micromamba create -n openhands -y && \
     /openhands/micromamba/bin/micromamba install -n openhands -c conda-forge poetry python=3.12 -y
+USER root
 
 # Create a clean openhands directory including only the pyproject.toml, poetry.lock and openhands/__init__.py
 RUN \