doc: initial documentation for gRPC

Give the FRR users some examples of gRPC usage in scripts to let them
start experimenting with the new configuration interface provided by
YANG/northbound.

Signed-off-by: Rafael Zalamena <rzalamena@opensourcerouting.org>

doc/developer/grpc.rst

@@ -0,0 +1,249 @@
+.. _grpc-dev:
+
+***************
+Northbound gRPC
+***************
+
+.. _grpc-languages-bindings:
+
+Programming Language Bindings
+=============================
+
+The gRPC supported programming language bindings can be found here:
+https://grpc.io/docs/languages/
+
+After picking a programming language that supports gRPC bindings, the
+next step is to generate the FRR northbound bindings. To generate the
+northbound bindings you'll need the programming language binding
+generator tools and those are language specific.
+
+Next sections will use Ruby as an example for writing scripts to use
+the northbound.
+
+
+.. _grpc-ruby-generate:
+
+Generating Ruby FRR Bindings
+----------------------------
+
+Generating FRR northbound bindings for Ruby example:
+
+::
+
+   # Install the required gems:
+   # - grpc: the gem that will talk with FRR's gRPC plugin.
+   # - grpc-tools: the gem that provides the code generator.
+   gem install grpc
+   gem install grpc-tools
+
+   # Create your project/scripts directory:
+   mkdir /tmp/frr-ruby
+
+   # Go to FRR's grpc directory:
+   cd grpc
+
+   # Generate the ruby bindings:
+   grpc_tools_ruby_protoc \
+     --ruby_out=/tmp/frr-ruby \
+     --grpc_out=/tmp/frr-ruby \
+     frr-northbound.proto
+
+
+.. _grpc-ruby-if-sample:
+
+Using Ruby To Get Interfaces State
+----------------------------------
+
+Here is a sample script to print all interfaces FRR discovered:
+
+::
+
+   require 'frr-northbound_services_pb'
+
+   # Create the connection with FRR's gRPC:
+   stub = Frr::Northbound::Stub.new('localhost:50051', :this_channel_is_insecure)
+
+   # Create a new state request to get interface state:
+   request = Frr::GetRequest.new
+   request.type = :STATE
+   request.path.push('/frr-interface:lib')
+
+   # Ask FRR.
+   response = stub.get(request)
+
+   # Print the response.
+   response.each do |result|
+     result.data.data.each_line do |line|
+       puts line
+     end
+   end
+
+
+.. note::
+
+   The generated files will assume that they are in the search path (e.g.
+   inside gem) so you'll need to either edit it to use ``require_relative`` or
+   tell Ruby where to look for them. For simplicity we'll use ``-I .`` to tell
+   it is in the current directory.
+
+
+The previous script will output something like this:
+
+::
+
+   $ cd /tmp/frr-ruby
+   # Add `-I.` so ruby finds the FRR generated file locally.
+   $ ruby -I. interface.rb
+   {
+     "frr-interface:lib": {
+       "interface": [
+         {
+           "name": "eth0",
+           "vrf": "default",
+           "state": {
+             "if-index": 2,
+             "mtu": 1500,
+             "mtu6": 1500,
+             "speed": 1000,
+             "metric": 0,
+             "phy-address": "11:22:33:44:55:66"
+           },
+           "frr-zebra:zebra": {
+             "state": {
+               "up-count": 0,
+               "down-count": 0
+             }
+           }
+         },
+         {
+           "name": "lo",
+           "vrf": "default",
+           "state": {
+             "if-index": 1,
+             "mtu": 0,
+             "mtu6": 65536,
+             "speed": 0,
+             "metric": 0,
+             "phy-address": "00:00:00:00:00:00"
+           },
+           "frr-zebra:zebra": {
+             "state": {
+               "up-count": 0,
+               "down-count": 0
+             }
+           }
+         }
+       ]
+     }
+   }
+
+
+.. _grpc-ruby-bfd-profile-sample:
+
+Using Ruby To Create BFD Profiles
+---------------------------------
+
+In this example you'll learn how to edit configuration using JSON
+and programmatic (XPath) format.
+
+::
+
+   require 'frr-northbound_services_pb'
+
+   # Create the connection with FRR's gRPC:
+   stub = Frr::Northbound::Stub.new('localhost:50051', :this_channel_is_insecure)
+
+   # Create a new candidate configuration change.
+   new_candidate = stub.create_candidate(Frr::CreateCandidateRequest.new)
+
+   # Use JSON to configure.
+   request = Frr::LoadToCandidateRequest.new
+   request.candidate_id = new_candidate.candidate_id
+   request.type = :MERGE
+   request.config = Frr::DataTree.new
+   request.config.encoding = :JSON
+   request.config.data = <<-EOJ
+   {
+     "frr-bfdd:bfdd": {
+       "bfd": {
+         "profile": [
+           {
+             "name": "test-prof",
+             "detection-multiplier": 4,
+             "required-receive-interval": 800000
+           }
+         ]
+       }
+     }
+   }
+   EOJ
+
+   # Load configuration to candidate.
+   stub.load_to_candidate(request)
+
+   # Commit candidate.
+   stub.commit(
+     Frr::CommitRequest.new(
+       candidate_id: new_candidate.candidate_id,
+       phase: :ALL,
+       comment: 'create test-prof'
+     )
+   )
+
+   #
+   # Now lets delete the previous profile and create a new one.
+   #
+
+   # Create a new candidate configuration change.
+   new_candidate = stub.create_candidate(Frr::CreateCandidateRequest.new)
+
+   # Edit the configuration candidate.
+   request = Frr::EditCandidateRequest.new
+   request.candidate_id = new_candidate.candidate_id
+
+   # Delete previously created profile.
+   request.delete.push(
+     Frr::PathValue.new(
+       path: "/frr-bfdd:bfdd/bfd/profile[name='test-prof']",
+     )
+   )
+
+   # Add new profile with two configurations.
+   request.update.push(
+     Frr::PathValue.new(
+       path: "/frr-bfdd:bfdd/bfd/profile[name='test-prof-2']/detection-multiplier",
+       value: 5.to_s
+     )
+   )
+   request.update.push(
+     Frr::PathValue.new(
+       path: "/frr-bfdd:bfdd/bfd/profile[name='test-prof-2']/desired-transmission-interval",
+       value: 900_000.to_s
+     )
+   )
+
+   # Modify the candidate.
+   stub.edit_candidate(request)
+
+   # Commit the candidate configuration.
+   stub.commit(
+     Frr::CommitRequest.new(
+       candidate_id: new_candidate.candidate_id,
+       phase: :ALL,
+       comment: 'replace test-prof with test-prof-2'
+     )
+   )
+
+
+And here is the new FRR configuration:
+
+::
+
+   $ sudo vtysh -c 'show running-config'
+   ...
+   bfd
+    profile test-prof-2
+     detect-multiplier 5
+     transmit-interval 900
+    !
+   !

doc/developer/index.rst

@@ -12,6 +12,7 @@ FRRouting Developer's Guide
    testing
    bgpd
    fpm
+   grpc
    ospf
    zebra
    vtysh

doc/developer/subdir.am

@@ -28,6 +28,7 @@ dev_RSTFILES = \
 	doc/developer/cli.rst \
 	doc/developer/conf.py \
 	doc/developer/frr-release-procedure.rst \
+	doc/developer/grpc.rst \
 	doc/developer/hooks.rst \
 	doc/developer/include-compile.rst \
 	doc/developer/index.rst \

doc/user/grpc.rst

@@ -0,0 +1,66 @@
+.. _grpc:
+
+***************
+Northbound gRPC
+***************
+
+.. program:: configure
+
+*gRPC* provides a combined front end to all FRR daemons using the YANG
+northbound. It is currently disabled by default due its experimental
+stage, but it can be enabled with :option:`--enable-grpc` option in the
+configure script.
+
+
+.. _grpc-features:
+
+Northbound gRPC Features
+========================
+
+* Get/set configuration using JSON/XML/XPath encondings.
+* Execute YANG RPC calls.
+* Lock/unlock configuration.
+* Create/edit/load/update/commit candidate configuration.
+* List/get transactions.
+
+
+.. note::
+
+   There is currently no support for YANG notifications.
+
+
+.. note::
+
+   You can find more information on how to code programs to interact
+   with FRR by reading the gRPC Programming Language Bindings section
+   in the `developer's documentation
+   <http://docs.frrouting.org/projects/dev-guide/en/latest/grpc.html>`_.
+
+
+.. _grpc-config:
+
+Daemon gRPC Configuration
+=========================
+
+The *gRPC* module accepts the following run time option:
+
+- ``port``: the port to listen to (defaults to ``50051``).
+
+
+.. note::
+
+   At the moment only localhost connections with no SSL/TLS are
+   supported.
+
+
+To configure FRR daemons to listen to gRPC you need to append the
+following parameter to the daemon's command line: ``-M grpc``
+(optionally ``-M grpc:PORT`` to specify listening port).
+
+To do that in production you need to edit the ``/etc/frr/daemons`` file
+so the daemons get started with the command line argument. Example:
+
+::
+
+   # other daemons...
+   bfdd_options="  --daemon -A 127.0.0.1 -M grpc"

doc/user/index.rst

@@ -23,6 +23,7 @@ Basics
 
    basic
    vtysh
+   grpc
    filter
    routemap
    ipv6

doc/user/subdir.am

@@ -15,6 +15,7 @@ user_RSTFILES = \
 	doc/user/filter.rst \
 	doc/user/frr-reload.rst \
 	doc/user/glossary.rst \
+	doc/user/grpc.rst \
 	doc/user/index.rst \
 	doc/user/installation.rst \
 	doc/user/ipv6.rst \