Truncate Nagios plugin output to 1024 bytes max

It appears that Nagios cannot ingest output which is larger than 1024
bytes so this change makes sure that the Nagios encoder complies with
this requirement.

Change-Id: I22c7186f0dc6edabe8c3372a8c06197b276a9d4d
Closes-Bug: #1517917
(cherry picked from commit ca031a41aa)

deployment_scripts/puppet/modules/lma_collector/files/plugins/common/lma_utils.lua

@@ -214,4 +214,25 @@ function chomp(s)
     return string.gsub(s, "\n$", "")
 end
 
+function truncate(str, max_length, delimiter)
+    if string.len(str) <= max_length then
+        return str
+    end
+
+    local pos = 1
+    while true do
+        local next_pos1, next_pos2 = string.find(str, delimiter, pos)
+        if not next_pos1 or next_pos1 - 1 > max_length then
+            pos = pos - string.len(delimiter) - 1
+            if pos < 1 then
+                pos = max_length
+            end
+            break
+        end
+        pos = next_pos2 + 1
+    end
+
+    return string.sub(str, 1, pos)
+end
+
 return M

deployment_scripts/puppet/modules/lma_collector/files/plugins/encoders/status_nagios.lua

@@ -71,7 +71,9 @@ function process_message()
             details[#details+1] = alarm
         end
     end
-    data['plugin_output'] = table.concat(details, nagios_break_line)
+    -- Nagios cannot accept 'plugin_output' parameter greater than 1024 bytes
+    -- See bug #1517917 for details
+    data['plugin_output'] = lma.truncate(table.concat(details, nagios_break_line), 1024, nagios_break_line)
 
     local params = {}
     for k, v in pairs(data) do

deployment_scripts/puppet/modules/lma_collector/tests/lua/test_lma_utils.lua

@@ -60,6 +60,36 @@ TestLmaUtils = {}
         assert(msg:match(': fail'))
     end
 
+    function TestLmaUtils:test_truncate_with_small_string()
+        local ret = lma_utils.truncate('foo', 10, '<BR/>')
+        assertEquals(ret, 'foo')
+    end
+
+    function TestLmaUtils:test_truncate_with_large_string()
+        local ret = lma_utils.truncate('foo and long string', 10, '<BR/>')
+        assertEquals(ret, 'foo and lo')
+    end
+
+    function TestLmaUtils:test_truncate_with_one_delimiter()
+        local ret = lma_utils.truncate('foo<BR/>longstring', 10, '<BR/>')
+        assertEquals(ret, 'foo')
+    end
+
+    function TestLmaUtils:test_truncate_with_several_delimiters_1()
+        local ret = lma_utils.truncate('foo<BR/>bar<BR/>longstring', 10, '<BR/>')
+        assertEquals(ret, 'foo')
+    end
+
+    function TestLmaUtils:test_truncate_with_several_delimiters_2()
+        local ret = lma_utils.truncate('foo<BR/>ba<BR/>longstring', 10, '<BR/>')
+        assertEquals(ret, 'foo<BR/>ba')
+    end
+
+    function TestLmaUtils:test_truncate_with_several_delimiters_3()
+        local ret = lma_utils.truncate('foo<BR/>ba<BR/>long<BR/>string', 12, '<BR/>')
+        assertEquals(ret, 'foo<BR/>ba')
+    end
+
 lu = LuaUnit
 lu:setVerbosity( 1 )
 os.exit( lu:run() )