Make local.env creation idempotent in task setup

Taskfile.yml

@@ -30,10 +30,10 @@ tasks:
     deps: [ setup-win, setup-unix ]
     cmds:
       - git config blame.ignoreRevsFile .git-blame-ignore-revs
-      - echo "HONEYCOMB_API_KEY=__REPLACE__" >> deployment/local-dev/local.env
-      - echo "#OTEL_SDK_DISABLED=true" >> deployment/local-dev/local.env
-      - echo "GOOGLE_OAUTH_CLIENT_ID=__REPLACE__.apps.googleusercontent.com" >> deployment/local-dev/local.env
-      - echo "GOOGLE_OAUTH_CLIENT_SECRET=__REPLACE__" >> deployment/local-dev/local.env
+      - ./ensure.py deployment/local-dev/local.env HONEYCOMB_API_KEY __REPLACE__
+      - ./ensure.py deployment/local-dev/local.env '#OTEL_SDK_DISABLED' true
+      - ./ensure.py deployment/local-dev/local.env GOOGLE_OAUTH_CLIENT_ID __REPLACE__.apps.googleusercontent.com
+      - ./ensure.py deployment/local-dev/local.env GOOGLE_OAUTH_CLIENT_SECRET __REPLACE__
       - kubectl --context=docker-desktop apply -f deployment/setup/namespace.yaml
   setup-win:
     platforms: [ windows ]

ensure.py

@@ -0,0 +1,40 @@
+#!/usr/bin/env python3
+
+import os
+import sys
+
+def usage():
+    name = os.path.basename(sys.argv[0])
+    print(f"Usage: {name} file key value")
+    print("")
+    print(f"E.g., {name} local.env HONEYCOMB_API_KEY __REPLACE__")
+
+def ensure(fname, search_str, replace_str):
+    # Ensure search_str is present. If not found, add replace_str to end of file
+    found = False
+    try:
+        with open(fname, encoding='utf-8') as f:
+            lines = f.readlines()
+            for line in lines:
+                if search_str in line:
+                    found = True
+                    break
+    except FileNotFoundError:
+        lines = []
+    need_extra_newline = False
+    if lines and lines[-1] and not lines[-1].endswith('\n'):
+        need_extra_newline = True
+    if not found:
+        if need_extra_newline:
+            lines[-1] = lines[-1] + '\n'
+        lines.append(replace_str + '\n')
+        with open(fname, 'w', encoding='utf-8') as f:
+            f.writelines(lines)
+
+if __name__ == '__main__':
+    if (len(sys.argv) < 4):
+        usage()
+    (fname, key, value) = sys.argv[1:4]
+    search_str = f"{key}="
+    replace_str = f"{key}={value}"
+    ensure(fname, search_str, replace_str)