Add env var for version cache timeout

As part of the Newton midcycle, it was discussed that it might
be nice to be able to specify the version cache timeout value
via an environment variable, rather than the current hard-coded
value.

Fixes-bug: #1596734
Change-Id: I2bc77c64b764f6c22574a30b0e5af4ca6feff29f

1 files changed, 20 insertions, 2 deletions

diff --git a/ironicclient/common/filecache.py b/ironicclient/common/filecache.py
index a3d39b8..f85a69c 100644
--- a/ironicclient/common/filecache.py
+++ b/ironicclient/common/filecache.py
@@ -14,18 +14,23 @@
 #    License for the specific language governing permissions and limitations
 #    under the License.
 
+import logging
 import os
 
 import appdirs
 import dogpile.cache
 
+from ironicclient.common.i18n import _LW
+
+LOG = logging.getLogger(__name__)
 
 AUTHOR = 'openstack'
 PROGNAME = 'python-ironicclient'
 
+CACHE = None
 CACHE_DIR = appdirs.user_cache_dir(PROGNAME, AUTHOR)
+CACHE_EXPIRY_ENV_VAR = 'IRONICCLIENT_CACHE_EXPIRY'  # environment variable
 CACHE_FILENAME = os.path.join(CACHE_DIR, 'ironic-api-version.dbm')
-CACHE = None
 DEFAULT_EXPIRY = 300  # seconds
 
 
@@ -38,9 +43,22 @@ def _get_cache():
         if not os.path.exists(CACHE_DIR):
             os.makedirs(CACHE_DIR)
 
+        # Use the cache expiry if specified in an env var
+        expiry_time = os.environ.get(CACHE_EXPIRY_ENV_VAR, DEFAULT_EXPIRY)
+        try:
+            expiry_time = int(expiry_time)
+        except ValueError:
+            LOG.warning(_LW("Environment variable %(env_var)s should be an "
+                            "integer (not '%(curr_val)s') using default "
+                            "timeout of %(default)s instead"),
+                        {'env_var': CACHE_EXPIRY_ENV_VAR,
+                         'curr_val': expiry_time,
+                         'default': DEFAULT_EXPIRY})
+            expiry_time = DEFAULT_EXPIRY
+
         CACHE = dogpile.cache.make_region(key_mangler=str).configure(
             'dogpile.cache.dbm',
-            expiration_time=DEFAULT_EXPIRY,
+            expiration_time=expiry_time,
             arguments={
                 "filename": CACHE_FILENAME,
             }