shell: Ensure the history file always exists

CHANGES.md

@@ -13,6 +13,13 @@ development source code and as such may not be routinely kept up to date.
 
 # __NEXT__
 
+## Bug fixes
+
+* `nextstrain shell` no longer errors when its history file, e.g.
+  _~/.nextstrain/shell-history_, doesn't exist.  This primarily affected the
+  Docker runtime and was a regression from 4.2.0 introduced in 5.0.0.
+  ([#232](https://github.com/nextstrain/cli/pull/232))
+
 
 # 5.0.0 (25 October 2022)
 

nextstrain/cli/command/shell.py

@@ -80,7 +80,20 @@ def run(opts):
     print()
 
     with resources.as_file("bashrc") as bashrc:
-        history_file = SHELL_HISTORY
+        # Ensure the history file exists to pass checks the Docker runner
+        # performs for mounted volumes.  This also makes sure that the file is
+        # writable by the Conda runtime too by ensuring the parent directory
+        # exists.
+        #
+        # Don't use strict=True because it's ok if it doesn't exist yet!
+        history_file = SHELL_HISTORY.resolve()
+        history_file.parent.mkdir(parents = True, exist_ok = True)
+
+        try:
+            # Don't use exist_ok=True so we don't touch the mtime unnecessarily
+            history_file.touch()
+        except FileExistsError:
+            pass
 
         if opts.__runner__ is conda:
             opts.default_exec_args = [