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Remove sequential route blocks from traffic splitting #445

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Feb 8, 2017
Merged

Remove sequential route blocks from traffic splitting #445

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2 changes: 1 addition & 1 deletion docs/configuration/http_conn_man/route_config/route.rst
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Expand Up @@ -49,7 +49,7 @@ cluster
*path_redirect* is not specified), one of *cluster* or *weighted_clusters* must be specified.
With the *weighted_clusters* option, multiple upstream clusters can be specified for a given route.
The request is forwarded to one of the upstream clusters based on weights assigned
to each cluster. See :ref:`traffic splitting <config_http_conn_man_route_table_traffic_splitting_split_percentages>`
to each cluster. See :ref:`traffic splitting <config_http_conn_man_route_table_traffic_splitting_split>`
for additional documentation.

.. _config_http_conn_man_route_table_route_host_redirect:
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79 changes: 9 additions & 70 deletions docs/configuration/http_conn_man/route_config/traffic_splitting.rst
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Expand Up @@ -92,18 +92,15 @@ accomplish the task.
Traffic splitting across multiple upstreams
-------------------------------------------

Consider the ``helloworld`` example again with three versions (v1, v2 and
v3). Envoy provides two ways to split traffic evenly across the three
versions (i.e., ``33%, 33%, 34%``):

.. _config_http_conn_man_route_table_traffic_splitting_split_percentages:

(a) Weight-based cluster selection
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

The first option is to use a **single** :ref:`route <config_http_conn_man_route_table_route>` with
:ref:`weighted_clusters <config_http_conn_man_route_table_route_weighted_clusters>`,
where multiple upstream cluster targets are specified for a single route,
Consider the ``helloworld`` example again, now with three versions (v1, v2 and
v3) instead of two. To split traffic evenly across the three versions
(i.e., ``33%, 33%, 34%``), the ``weighted_clusters`` option can be used to
specify the weight for each upstream cluster.

Unlike the previous example, a **single** :ref:`route
<config_http_conn_man_route_table_route>` entry is sufficient. The
:ref:`weighted_clusters <config_http_conn_man_route_table_route_weighted_clusters>`
configuration block in a route can be used to specify multiple upstream clusters
along with weights that indicate the **percentage** of traffic to be sent
to each upstream cluster.

Expand Down Expand Up @@ -137,61 +134,3 @@ The weights assigned to each cluster can be dynamically adjusted using the
following runtime variables: ``routing.traffic_split.helloworld.helloworld_v1``,
``routing.traffic_split.helloworld.helloworld_v2`` and
``routing.traffic_split.helloworld.helloworld_v3``.

.. _config_http_conn_man_route_table_traffic_splitting_split_probabilities:

(b) Probabilistic route selection
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

The second option is to use **multiple** :ref:`routes <config_http_conn_man_route_table_route>`
as shown in the traffic shifting example, with :ref:`runtimes <config_http_conn_man_route_table_route_runtime>`
that specify the **probability** of selecting a route.
Since Envoy matches routes with a :ref:`first match <config_http_conn_man_route_table_route_matching>`
policy, the related routes (one for each upstream cluster) must be placed back-to-back,
along with a runtime in all but the last route.

.. code-block:: json

{
"route_config": {
"virtual_hosts": [
{
"name": "helloworld",
"domains": ["*"],
"routes": [
{
"prefix": "/",
"cluster": "helloworld_v1",
"runtime": {
"key": "routing.traffic_split.helloworld.helloworld_v1",
"default": 33
}
},
{
"prefix": "/",
"cluster": "helloworld_v2",
"runtime": {
"key": "routing.traffic_split.helloworld.helloworld_v2",
"default": 50
}
},
{
"prefix": "/",
"cluster": "helloworld_v3",
}
]
}
]
}
}

In the configuration above,

1. ``routing.traffic_split.helloworld.helloworld_v1`` is set to ``33``, so that there is a
*33\% probability* that the v1 route will be selected by Envoy.
2. ``routing.traffic_split.helloworld.helloworld_v2`` is set to ``50``, so that if the v1 route
is not selected, between v2 and v3, there is a *50\% probability* that the v2 route will
be selected by Envoy. If v2 is not selected the traffic falls through to the v3 route.

This distribution of probabilities ensures that the traffic will be split evenly across
all three routes (i.e. ``33%, 33%, 34%``).
8 changes: 4 additions & 4 deletions docs/intro/arch_overview/http_routing.rst
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Expand Up @@ -27,10 +27,10 @@ request. The router filter supports the following features:
* Request timeout specified either via :ref:`HTTP
header <config_http_filters_router_headers>` or via :ref:`route configuration
<config_http_conn_man_route_table_route_timeout>`.
* Probability-based route selection via :ref:`runtime values <config_http_conn_man_route_table_route_runtime>`
(see :ref:`traffic shifting/shifting <config_http_conn_man_route_table_traffic_splitting>`).
* :ref:`Weight/percentage-based <config_http_conn_man_route_table_route_weighted_clusters>` upstream cluster selection
for a given route (see :ref:`traffic shifting/splitting <config_http_conn_man_route_table_traffic_splitting_split>`).
* Traffic shifting from one upstream cluster to another via :ref:`runtime values <config_http_conn_man_route_table_route_runtime>`
(see :ref:`traffic shifting/splitting <config_http_conn_man_route_table_traffic_splitting>`).
* Traffic splitting across multiple upstream clusters using :ref:`weight/percentage-based routing<config_http_conn_man_route_table_route_weighted_clusters>`
(see :ref:`traffic shifting/splitting <config_http_conn_man_route_table_traffic_splitting_split>`).
* Arbitrary headers :ref:`routing rules <config_http_conn_man_route_table_route_headers>`.
* Virtual cluster specifications. A virtual cluster is specified at the virtual host level and is
used by Envoy to generate additional statistics on top of the standard cluster level ones. Virtual
Expand Down