enh: allow moving the cache folder with an environment variable

Resolves: #1029.

mriqc/cli/version.py

@@ -24,11 +24,10 @@
 
 from contextlib import suppress
 from datetime import datetime, timezone
-from pathlib import Path
 
 import requests
 
-from mriqc import __version__
+from mriqc import __version__, config
 
 RELEASE_EXPIRY_DAYS = 14
 DATE_FMT = '%Y%m%d'
@@ -42,7 +41,7 @@ def check_latest():
     latest = None
     date = None
     outdated = None
-    cachefile = Path.home() / '.cache' / 'mriqc' / 'latest'
+    cachefile = config.environment.cache_path / 'latest'
     try:
         cachefile.parent.mkdir(parents=True, exist_ok=True)
     except OSError:

mriqc/config.py

@@ -212,6 +212,11 @@
     else '18480913-163000_PhineasG-ageh-adhi-sacc-ident9b1ab0f'
 )
 
+_mriqc_cache = Path(os.getenv(
+    'MRIQC_CACHE_PATH',
+    str(Path.home() / '.cache' / 'mriqc')
+)).absolute()
+
 
 class _Config:
     """An abstract class forbidding instantiation."""
@@ -283,6 +288,8 @@ class environment(_Config):
 
     """
 
+    cache_path = _mriqc_cache
+    """Path to the location of the cache directory."""
     cpu_count = os.cpu_count()
     """Number of available CPUs."""
     exec_docker_version = _docker_ver