Allow a specific cache directory or no cache

If the env var XDG_CACHE_HOME is set, the cache directory is
"$XDG_CACHE_HOME/ianardap", else if HOME is set, it is
"$HOME/.ianardapcaches", else no cache is used but a loud
warning is displayed at the end of the result to encourage
users to set a cache directory.

Adapted pytest tests, no change needed on test_exe_matrix. They are
obviously slower with no cache. NB: two tests now fail independently
of this change.

Issue: #4

.gitignore

@@ -0,0 +1 @@
+__pycache__/

README.md

@@ -19,6 +19,8 @@ You need Python 3 and [Requests](http://python-requests.org/). You can install R
 
 Then, copy the script `check_expire` and the file `ianardap.py`to the directory of local plugins.
 
+The use of a cache directory is not mandatory, but highly recommended. It can be either `$XDG_CACHE_HOME/ianardap` or `$HOME/.ianardapcaches` depending on the environment variables set.
+
 ## Icinga configuration
 
 If you use Icinga, here is a possible definition of the command:
@@ -35,6 +37,7 @@ object CheckCommand "expiration" {
       "-v" = { set_if = "$expiration_verbose$" }
   }
 
+  env.XDG_CACHE_HOME = "/var/cache/nagios"
 }
 
 apply Service "expiration" {
@@ -60,6 +63,13 @@ object Host "bortzmeyer-org" {
 }
 ```
 
+If needed, create the cache directory accordingly:
+
+```
+mkdir /var/cache/nagios
+chown nagios: /var/cache/nagios
+```
+
 ## Zabbix configuration
 
 For monitoring systems that do not rely on exit codes but on calculation mechanism based on the metric they receive you can use the `-u` option that will only return the expiration date in unixtime format.

check_expire

@@ -53,6 +53,8 @@ def usage(msg=None):
         print("")
 
 def details():
+    if database and not database.cachefile:
+        print(" (WARNING: no cache directory used, please set environement variable XDG_CACHE_HOME or HOME.)", end="")
     if verbose:
         print(" RDAP database \"%s\", version %s published on %s, retrieved on %s, RDAP server is %s" % \
               (database.description, database.version, database.publication, database.retrieved, server))

ianardap.py

@@ -21,7 +21,8 @@ IANABASES = {"domains": "https://data.iana.org/rdap/dns.json",
              "v6prefixes": "https://data.iana.org/rdap/ipv6.json",
              "as": "https://data.iana.org/rdap/asn.json",
              "objects": "https://data.iana.org/rdap/object-tags.json"}
-CACHE = os.environ["HOME"] + "/.ianardapcaches" 
+CACHE = os.environ["XDG_CACHE_HOME"] + "/ianardap" if "XDG_CACHE_HOME" in os.environ else \
+        (os.environ["HOME"] + "/.ianardapcaches" if "HOME" in os.environ else None)
 MAXAGE = 24 # Hours. Used only if the server no longer gives the information.
 IANATIMEOUT = 10 # Seconds
 MAXTESTS = 3 # Maximum attempts to get the database
@@ -60,9 +61,13 @@ file (see the documentation of the module).
         """
         
         cache_valid = False
+        self.category = category
+        self.cachefile = None
+        self.lockname = None
+        self.expirationfile = None
+        if cachedir:
             if not os.path.exists(cachedir):
                 os.mkdir(cachedir)
-        self.category = category
             cachefile = os.path.join(cachedir, category)
             if pickleformat:
                 self.cachefile = cachefile + ".pickle"
@@ -71,9 +76,10 @@ file (see the documentation of the module).
             self.lockname = self.cachefile + ".lock"
             self.expirationfile = self.cachefile + ".expires"
         if maxage is not None:
-            with open(self.expirationfile, 'w'):
             self.expirationtime = time.mktime((datetime.datetime.now() + \
                                               datetime.timedelta(hours=maxage)).timetuple())
+            if self.expirationfile:
+                with open(self.expirationfile, 'w'):
                     os.utime(self.expirationfile,
                              times = (self.expirationtime, self.expirationtime))
         loaded = False
@@ -81,7 +87,7 @@ file (see the documentation of the module).
         errmsg = "No error"
         while not loaded and tests < MAXTESTS:
             self.lock()
-            if os.path.exists(self.cachefile) and \
+            if self.cachefile and os.path.exists(self.cachefile) and \
                (pathlib.Path(self.expirationfile).exists() and \
                 datetime.datetime.fromtimestamp(os.path.getmtime(self.expirationfile)) > \
                 datetime.datetime.now()):
@@ -139,6 +145,7 @@ file (see the documentation of the module).
                 try:
                     content = response.content
                     database = json.loads(content)
+                    if self.expirationfile:
                         with open(self.expirationfile, 'w'):
                             os.utime(self.expirationfile,
                                      times = (self.expirationtime, self.expirationtime))
@@ -173,7 +180,7 @@ file (see the documentation of the module).
         else: # IP addresses will be complicated, because of the
               # longest prefix rule.
             raise Exception("Unsupported category %s" % self.category)
-        if not cache_valid:
+        if self.cachefile and not cache_valid:
             self.lock()
             cache = open(self.cachefile, "wb")
             if pickleformat:
@@ -184,10 +191,12 @@ file (see the documentation of the module).
             self.unlock()
         
     def lock(self):
+        if self.lockname:
             self.lockhandle = open(self.lockname, 'w')
             fcntl.lockf(self.lockhandle, fcntl.LOCK_EX)
 
     def unlock(self):
+        if self.lockname:
             fcntl.lockf(self.lockhandle, fcntl.LOCK_UN)
             self.lockhandle.close()
 

test_ianardap.py

@@ -29,8 +29,9 @@ def test_refresh():
     # Force a resfresh
     database = ianardap.IanaRDAPDatabase(maxage=0)
     assert (database.retrieved > (datetime.datetime.now() - datetime.timedelta(minutes=1))) and \
+        ((not database.cachefile) or \
         (datetime.datetime.fromtimestamp(os.path.getmtime(database.cachefile)) > \
-        (datetime.datetime.now() - datetime.timedelta(minutes=1)))
+        (datetime.datetime.now() - datetime.timedelta(minutes=1))))
 
 def test_find_exists():
     database = ianardap.IanaRDAPDatabase()