api: add an InfluxDB API endpoint

This provides a new InfluxDB-compatible endpoint to write data to Gnocchi at
`/v1/influxdb'.

doc/source/index.rst

@@ -24,6 +24,7 @@ Gnocchi's main features are:
 - Nagios/Icinga support
 - Statsd protocol support
 - Collectd plugin support
+- InfluxDB line protocol ingestion support
 
 Community
 ---------
@@ -123,6 +124,7 @@ Documentation
    grafana
    nagios
    collectd
+   influxdb
    glossary
    releasenotes/index.rst
    contributing

doc/source/influxdb.rst

@@ -0,0 +1,43 @@
+============================
+ InfluxDB ingestion support
+============================
+
+Gnocchi implements some part of the InfluxDB REST API. That allows tool that
+are used to write to InfluxDB to write directly to Gnocchi instead, such as
+`Telegraf`_.
+
+The endpoint is available at `/v1/influxdb`. It supports:
+
+* `GET /v1/influxdb/ping`
+* `POST /v1/influxdb/query` where the only query that is handled is `CREATE
+  DATABASE <db>`. That will create a new resource type named after the database
+  handle.
+* `POST /v1/influxdb/write?db=<db>`. The `db` parameter should be an existing
+  resource type that does not require any attributes to be set. The body should
+  follow the `InfluxDB line protocol`_.
+
+In order to map InfluxDB data to Gnocchi data model, the following
+transformation happen when writing metrics:
+
+* For each measure sent, one of the tag value is used as the original resource
+  id. By default the `host` tag is used. This can be overriden by passing the
+  `X-Gnocchi-InfluxDB-Tag-Resource-ID` HTTP header.
+
+* The metric names associated to the resource have the format:
+  `<measurement>.<field_key>[@<tag_key>=<tag_value>,…]`. The tag are sorted
+  by keys.
+
+
+Telegraf configuration
+======================
+
+In order to use `Telegraf`_ with Gnocchi, you can use the following
+configuration example::
+
+  [[outputs.influxdb]]
+    urls = ["http://admin:localhost:8041/v1/influxdb"]
+    http_headers = {"X-Gnocchi-InfluxDB-Tag-Resource-ID" = "host"}
+
+
+.. _`Telegraf`: https://github.com/influxdata/telegraf
+.. _`InfluxDB line protocol`: https://docs.influxdata.com/influxdb/v1.3/write_protocols/line_protocol_reference/

gnocchi/incoming/__init__.py

@@ -118,8 +118,9 @@ def add_measures(self, metric, measures):
     def add_measures_batch(self, metrics_and_measures):
         """Add a batch of measures for some metrics.
 
-        :param metrics_and_measures: A dict where keys
-        are metrics and value are measure.
+        :param metrics_and_measures: A dict where keys are metric objects
+                                     and values are a list of
+                                     :py:class:`gnocchi.incoming.Measure`.
         """
         utils.parallel_map(
             self._store_new_measures,

gnocchi/indexer/__init__.py

@@ -115,6 +115,12 @@ def __init__(self, type):
             "Resource type %s does not exist" % type)
         self.type = type
 
+    def jsonify(self):
+        return {
+            "cause": "Resource type does not exist",
+            "detail": self.type,
+        }
+
 
 class NoSuchMetric(IndexerException):
     """Error raised when a metric does not exist."""
@@ -224,6 +230,10 @@ def __init__(self, resource):
             "Resource %s already exists" % resource)
         self.resource = resource
 
+    def jsonify(self):
+        return {"cause": "Resource already exists",
+                "detail": self.resource}
+
 
 class ResourceTypeAlreadyExists(IndexerException):
     """Error raised when a resource type already exists."""

gnocchi/rest/api.py

@@ -1895,6 +1895,7 @@ class V1Controller(object):
     def __init__(self):
         # FIXME(sileht): split controllers to avoid lazy loading
         from gnocchi.rest.aggregates import api as agg_api
+        from gnocchi.rest import influxdb
 
         self.sub_controllers = {
             "search": SearchController(),
@@ -1908,6 +1909,7 @@ def __init__(self):
             "capabilities": CapabilityController(),
             "status": StatusController(),
             "aggregates": agg_api.AggregatesController(),
+            "influxdb": influxdb.InfluxDBController(),
         }
         for name, ctrl in self.sub_controllers.items():
             setattr(self, name, ctrl)