Show app version (#77)

Dockerfile

@@ -7,6 +7,7 @@ RUN apt-get update \
       build-essential \
       curl \
       software-properties-common \
+      git \
     && rm -rf /var/lib/apt/lists/*
 
 COPY . .

ngm/app.py

@@ -1,3 +1,6 @@
+import subprocess
+from typing import Optional
+
 import altair as alt
 import numpy as np
 import polars as pl
@@ -198,6 +201,21 @@ def summarize_scenario(
     c.altair_chart(chart, use_container_width=True)
 
 
+def get_commit(length: int = 15) -> Optional[str]:
+    try:
+        x = subprocess.run(
+            ["git", "rev-parse", f"--short={length}", "HEAD"], capture_output=True
+        )
+        if x.returncode == 0:
+            commit = x.stdout.decode().strip()
+            assert len(commit) == length
+            return commit
+        else:
+            return None
+    except FileNotFoundError:
+        return None
+
+
 def app():
     st.info(
         "This interactive application is a prototype designed for software testing and educational purposes."
@@ -275,6 +293,10 @@ def app():
                 help="Values are reported only to this many significant figures.",
             )
 
+        commit = get_commit()
+        if commit is not None:
+            st.caption(f"App version: {commit}")
+
     # # make and run scenarios ------------------------------------------------------------
     group_names = params["Group name"]
     N = params["Pop. size"].to_numpy()