Add a cluster architecture diagram

This adds a simple diagram for the cluster architecture and also adds a
dependency on graphviz (both doc and in configure).

Reviewed-by: imsnah

.gitignore

@@ -32,6 +32,7 @@
 /doc/*.html
 /doc/*.in
 /doc/*.pdf
+/doc/*.png
 /doc/rapi-resources.sgml
 
 # doc/examples

DEVNOTES

@@ -9,6 +9,8 @@ Most dependencies from INSTALL, plus:
    http://sources.redhat.com/docbook-tools/
  - rst2html from Docutils
    http://docutils.sourceforge.net/
+ - graphviz
+   http://www.graphviz.org/
 
 
 Configuring for development

Makefile.am

@@ -232,6 +232,11 @@ doc/%.html: doc/%.in $(DOCBOOK_WRAPPER)
 doc/%.html: doc/%.rst
 	$(RST2HTML) $< $@
 
+doc/%.png: doc/%.dot
+	$(DOT) -Tpng -o $@ $<
+
+doc/design-2.0.html: doc/design-2.0.rst doc/arch-2.0.png
+
 doc/rapi.pdf doc/rapi.html doc/rapi.in: doc/rapi-resources.sgml
 
 doc/rapi-resources.sgml: $(BUILD_RAPI_RESOURCE_DOC) lib/rapi/connector.py

configure.ac

@@ -133,6 +133,14 @@ then
   AC_MSG_ERROR([rst2html not found])
 fi
 
+# Check for graphviz (dot)
+AC_ARG_VAR(DOT, [dot path])
+AC_PATH_PROG(DOT, [dot], [])
+if test -z "$DOT"
+then
+  AC_MSG_ERROR([dot (from the graphviz suite) not found])
+fi
+
 # Check for Python
 AM_PATH_PYTHON(2.4)
 

doc/arch-2.0.dot

+digraph "ganeti-2.0-architecture" {
+  compound=false
+  concentrate=true
+  mclimit=100.0
+  nslimit=100.0
+  edge[fontsize="8" fontname="Helvetica-Oblique"]
+  node[width="0" height="0" fontsize="12" fontcolor="black" shape=rect]
+
+  subgraph outside {
+    rclient[label="external clients"]
+    label="Outside the cluster"
+  }
+
+  subgraph cluster_inside {
+    label="ganeti cluster"
+    labeljust=l
+    subgraph cluster_master_node {
+      label="master node"
+      rapi[label="RAPI daemon"]
+      cli[label="CLI"]
+      watcher[label="Watcher"]
+      burnin[label="Burnin"]
+      masterd[shape=record style=filled label="{ <luxi> luxi endpoint | master I/O thread | job queue | {<w1> worker| <w2> worker | <w3> worker }}"]
+      {rapi;cli;watcher;burnin} -> masterd:luxi [label="LUXI" labelpos=100]
+    }
+
+    subgraph cluster_nodes {
+        label="nodes"
+        noded1 [shape=record label="{ RPC listener | Disk management | Network management | Hypervisor } "]
+        noded2 [shape=record label="{ RPC listener | Disk management | Network management | Hypervisor } "]
+        noded3 [shape=record label="{ RPC listener | Disk management | Network management | Hypervisor } "]
+    }
+    masterd:w2 -> {noded1;noded2;noded3} [label="node RPC"]
+    cli -> {noded1;noded2;noded3} [label="SSH"]
+  }
+
+  rclient -> rapi [label="RAPI protocol"]
+}

doc/design-2.0.rst

@@ -85,6 +85,14 @@ design of Ganeti is required. While the cluster operations themselves
 won't change (e.g. start instance will do the same things, the way
 these operations are scheduled internally will change radically.
 
+The new design will change the cluster architecture to:
+
+.. image:: arch-2.0.png
+
+This differs from the 1.2 architecture by the addition of the master
+daemon, which will be the only entity to talk to the node daemons.
+
+
 Detailed design
 ===============