start work on 'check-grid' target, for use in an automated prodnet tester. Just a docstring so far.

Makefile

@@ -253,6 +253,18 @@ check-speed: .built
 	$(PYTHON) src/allmydata/test/check_speed.py $(TESTCLIENTDIR)
 	$(PYTHON) bin/tahoe stop $(TESTCLIENTDIR)
 
+# This target also uses a pre-established client node, along with a long-term
+# directory that contains some well-known files. See the docstring in
+# src/allmydata/test/check_grid.py to see how to set this up.
+check-grid: .built
+	if [ -z '$(TESTCLIENTDIR)' ]; then exit 1; fi
+	@echo "stopping any leftover client code"
+	-$(PYTHON) bin/tahoe stop $(TESTCLIENTDIR)
+	$(PYTHON) bin/tahoe start $(TESTCLIENTDIR)
+	sleep 5
+	$(PYTHON) src/allmydata/test/check_grid.py $(TESTCLIENTDIR)
+	$(PYTHON) bin/tahoe stop $(TESTCLIENTDIR)
+
 # 'make repl' is a simple-to-type command to get a Python interpreter loop
 # from which you can type 'import allmydata'
 repl:

src/allmydata/test/check_grid.py

@@ -0,0 +1,52 @@
+#! /usr/bin/python
+
+"""
+Test an existing Tahoe grid, both to see if the grid is still running and to
+see if the client is still compatible with it. This script is suitable for
+running from a periodic monitoring script, perhaps by an hourly cronjob.
+
+This script uses a pre-established client node (configured to connect to the
+grid being tested) and a pre-established directory (stored as the 'testgrid:'
+alias in that client node's aliases file). It then performs a number of
+uploads and downloads to exercise compatibility in various directions (new
+client vs old data).
+
+This script expects that the client node will be running before the script
+starts.
+
+To set up the client node, do the following:
+
+  tahoe create-client DIR
+  touch DIR/no_storage
+  populate DIR/introducer.furl
+  tahoe start DIR
+  tahoe -d DIR add-alias testgrid `tahoe -d DIR mkdir`
+  pick a 10kB-ish test file, compute its md5sum
+  tahoe -d DIR put FILE testgrid:old.MD5SUM
+  tahoe -d DIR put FILE testgrid:recent.MD5SUM
+  tahoe -d DIR put FILE testgrid:recentdir/recent.MD5SUM
+  echo "" | tahoe -d DIR put --mutable testgrid:log
+  echo "" | tahoe -d DIR put --mutable testgrid:recentlog
+
+This script will perform the following steps (the kind of compatibility that
+is being tested is in [brackets]):
+
+ read old.* and check the md5sums [confirm that new code can read old files]
+ read all recent.* files and check md5sums [read recent files]
+ delete all recent.* files and verify they're gone [modify an old directory]
+ read recentdir/recent.* files and check [read recent directory]
+ delete recentdir/recent.* and verify [modify recent directory]
+ delete recentdir and verify (keep the directory from growing unboundedly)
+ mkdir recentdir
+ upload random 10kB file to recentdir/recent.MD5SUM (prepare for next time)
+ upload random 10kB file to recent.MD5SUM [new code can upload to old servers]
+ append one-line timestamp to log [read/write old mutable files]
+ append one-line timestamp to recentlog [read/write recent mutable files]
+ delete recentlog
+ upload small header to new mutable recentlog [create mutable files]
+
+This script will also keep track of speeds and latencies and will write them
+in a machine-readable logfile.
+
+"""
+