Add Multi-version Capability

Adds support for having multiple evaluation python versions installed in
the docker container. A utility to automatically generate correct
dockerfile instructions and nsjail mounts based on the available
versions is also included.

Signed-off-by: Hassan Abouelela <[email protected]>

1 files changed, 68 insertions, 0 deletions

diff --git a/scripts/set_versions.py b/scripts/set_versions.py
new file mode 100644
index 0000000..f98c52c
--- /dev/null
+++ b/scripts/set_versions.py
@@ -0,0 +1,68 @@
+"""Generate a Dockerfile from in.Dockerfile and a version JSON file, and write version info."""
+
+import re
+from pathlib import Path
+from textwrap import dedent
+
+from scripts import python_version
+
+DOCKERFILE_TEMPLATE = Path("scripts/in.Dockerfile").read_text("utf-8")
+DOCKERFILE = Path("Dockerfile")
+JAIL_CONFIG = Path("config/snekbox.cfg")
+
+versions, main_version = python_version.get_all_versions()
+
+# Download and copy multiple python images into one layer
+python_build = ""
+jail_mounts = ""
+previous_layer = "first"
+
+for version in versions:
+    # Configure NSJail mounts
+    jail_mounts += dedent(
+        f"""
+        mount {{
+            src: "/usr/local/bin/python{version.version_name}"
+            dst: "/usr/local/bin/python{version.version_name}"
+            is_bind: true
+            rw: false
+        }}
+    """
+    )
+
+    if version.is_main:
+        # Main is handled separately later
+        continue
+
+    # Add the current version to the Dockerfile
+    layer_name = version.version_name.replace(".", "-")  # Dots aren't valid in layer names
+    python_build += dedent(
+        f"""
+        FROM python:{version.image_tag} as base-{layer_name}
+        COPY --from=base-{previous_layer} / /
+    """
+    )
+    previous_layer = layer_name
+
+# Main version is installed twice, once at the very beginning to make sure
+# its files aren't overwritten, and once at the end which actually makes use of the version
+python_build = f"FROM python:{main_version.image_tag} as base-first\n" + python_build
+
+# Update mounts for python binaries in the NSJail config
+new_config = re.sub(
+    r"(?<=# mount-section-key)[\s\S]+(?=# mount-section-key-end)",
+    jail_mounts,
+    JAIL_CONFIG.read_text("utf-8"),
+)
+JAIL_CONFIG.write_text(new_config, "utf-8")
+
+# Write new dockerfile
+DOCKERFILE.write_text(
+    "# THIS FILE IS AUTOGENERATED, DO NOT MODIFY! #\n"
+    + DOCKERFILE_TEMPLATE.replace("{python_install_commands}", python_build)
+    .replace("{final_base}", previous_layer)
+    .replace("{main_version_tag}", main_version.image_tag),
+    "utf-8",
+)
+
+print("Finished!")