clickhouse: add a new Clickhouse component to help setting Clickhouse

docs/configuration.md

@@ -10,6 +10,7 @@ configured through a different section:
 - `snmp`: [SNMP poller](#snmp)
 - `geoip`: [GeoIP database](#geoip)
 - `kafka`: [Kafka broker](#kafka)
+- `clickhouse`: [Clickhouse helper](#clickhouse)
 - `core`: [Core](#core)
 
 You can get the default configuration with `./akvorado --dump --check`.
@@ -154,6 +155,11 @@ kafka:
       cleanup.policy: delete
 ```
 
+## Clickhouse
+
+The Clickhouse component exposes some useful HTTP endpoints to
+configure a Clickhouse database. It takes no configuration.
+
 ## Core
 
 The core orchestrates the remaining components. It receives the flows

docs/integration.md

@@ -0,0 +1,33 @@
+# Integrations
+
+*Akvorado* needs some integration with external components to be
+useful. The most important one is Kafka, but it can also integrate
+with Clickhouse and Grafana.
+
+## Kafka
+
+The Kafka component sends flows to Kafka. Its
+[configuration](configuration.md#kafka) mostly needs a topic name and a list
+of brokers. It is possible to let *Akvorado* manage the topic with the
+appropriate settings (number of partitions, replication factor and
+additional configuration entries). If the topic exists, *Akvorado*
+won't update the number of partitions and the replication factor but
+other settings will be updated.
+
+## Clickhouse
+
+Clickhouse can collect the data from Kafka. To help its configuration,
+*Akvorado* exposes a few HTTP endpoint:
+
+- `/api/v0/clickhouse/flow.proto` contains the schema
+- `/api/v0/clickhouse/init.sh` contains the schema in the form of a
+  script to execute during initialization
+- `/api/v0/clickhouse/protocols.csv` contains a CSV with the mapping
+  between protocol numbers and names
+- `/api/v0/clickhouse/asns.csv` contains a CSV with the mapping
+  between AS numbers and organization names
+
+## Grafana
+
+No integration is currently done for Grafana, except a reverse proxy
+configured in the [web section](configuration.md#web).

docs/usage.md

@@ -27,12 +27,11 @@ with `--check` if you don't want *Akvorado* to start.
 ### Exposed HTTP endpoints
 
 The embedded HTTP server contains the endpoints listed on the [home
-page](/). The [`/api/v0/flows`](/api/v0/flows?limit=1) continously
-printed flows sent to Kafka (using [ndjson]()). It also accepts a
-`limit` argument to stops after emitting the specified number of
-flows. This endpoint should not be used for anything else other than
-debug: it can skips some flows and if there are several users, flows
-will be dispatched between them.
+page](index.md). The [`/api/v0/flows`](/api/v0/flows?limit=1)
+continously printed flows sent to Kafka (using [ndjson]()). It also
+accepts a `limit` argument to stops after emitting the specified
+number of flows. This endpoint should not be used for anything else
+other than debug: it can skips some flows and if there are several
+users, flows will be dispatched between them.
 
 [ndjson]: http://ndjson.org/
-