varnish module: add instance_name option (#5264)

* add instance_name option

* add timeout

* minor

3 files changed, 30 insertions, 6 deletions

diff --git a/collectors/python.d.plugin/varnish/README.md b/collectors/python.d.plugin/varnish/README.md
index 102a5103de..44d64efe11 100644
--- a/collectors/python.d.plugin/varnish/README.md
+++ b/collectors/python.d.plugin/varnish/README.md
@@ -64,7 +64,13 @@ It produces:
 
 ### configuration
 
-No configuration is needed.
+Only one parameter is supported:
+
+```yaml
+instance_name: 'name'
+```
+
+The name of the varnishd instance to get logs from. If not specified, the host name is used.
 
 ---
 
diff --git a/collectors/python.d.plugin/varnish/varnish.chart.py b/collectors/python.d.plugin/varnish/varnish.chart.py
index 6146ce66e0..da67815762 100644
--- a/collectors/python.d.plugin/varnish/varnish.chart.py
+++ b/collectors/python.d.plugin/varnish/varnish.chart.py
@@ -136,6 +136,8 @@ CHARTS = {
     }
 }
 
+VARNISHSTAT = 'varnishstat'
+
 
 class Parser:
     _backend_new = re.compile(r'VBE.([\d\w_.]+)\(.*?\).(beresp[\w_]+)\s+(\d+)')
@@ -172,19 +174,31 @@ class Service(ExecutableService):
         ExecutableService.__init__(self, configuration=configuration, name=name)
         self.order = ORDER
         self.definitions = CHARTS
-        varnishstat = find_binary('varnishstat')
-        self.command = [varnishstat, '-1'] if varnishstat else None
+        self.instance_name = configuration.get('instance_name')
         self.parser = Parser()
+        self.command = None
+
+    def create_command(self):
+        varnishstat = find_binary(VARNISHSTAT)
+
+        if not varnishstat:
+            self.error("can't locate '{0}' binary or binary is not executable by user netdata".format(VARNISHSTAT))
+            return False
+
+        if self.instance_name:
+            self.command = [varnishstat, '-1', '-n', self.instance_name, '-t', '1']
+        else:
+            self.command = [varnishstat, '-1', '-t', '1']
+        return True
 
     def check(self):
-        if not self.command:
-            self.error("Can't locate 'varnishstat' binary or binary is not executable by user netdata")
+        if not self.create_command():
             return False
 
         # STDOUT is not empty
         reply = self._get_raw_data()
         if not reply:
-            self.error("No output from 'varnishstat'. Not enough privileges?")
+            self.error("No output from 'varnishstat'. Is it running? Not enough privileges?")
             return False
 
         self.parser.init(reply)
diff --git a/collectors/python.d.plugin/varnish/varnish.conf b/collectors/python.d.plugin/varnish/varnish.conf
index 9d582f7def..54bfe4deee 100644
--- a/collectors/python.d.plugin/varnish/varnish.conf
+++ b/collectors/python.d.plugin/varnish/varnish.conf
@@ -59,4 +59,8 @@
 #     penalty: yes            # the JOB's penalty
 #     autodetection_retry: 0  # the JOB's re-check interval in seconds
 #
+# Additionally to the above, varnish also supports the following:
+#
+#     instance_name: 'name'       # the name of the varnishd instance to get logs from. If not specified, the host name is used.
+#
 # ----------------------------------------------------------------------