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Vitals with InfluxDB
Leveraging a time series database for Vitals data can improve request and Vitals performance in very-high traffic Kong Gateway Enterprise clusters (such as environments handling tens or hundreds of thousands of requests per second), without placing additional write load on the database backing the Kong cluster.
For information about using Kong Vitals with a database as the backend, refer to Kong Vitals.
Set up Kong Vitals with InfluxDB
Start an InfluxDB database
Production-ready InfluxDB installations should be deployed as a separate effort, but for proof-of-concept testing, running a local InfluxDB instance is possible with Docker.
-
Create a custom network to allow the containers to discover and communicate with each other.
docker network create kong-ee-net
-
Start a local InfluxDB instance with Docker.
docker run -d -p 8086:8086 \ --network=kong-ee-net \ --name influxdb \ -e INFLUXDB_DB=kong \ influxdb:1.8.4-alpine
You must use InfluxDB 1.8.4-alpine because InfluxDB 2.0 will not work.
Writing Vitals data to InfluxDB requires that the
kong
database is created, this is done using theINFLUXDB_DB
variable.
Install Kong Gateway
If you already have a Kong Gateway instance, skip to deploying a license.
If you have not installed Kong Gateway, a Docker installation will work for the purposes of this guide.
Pull the Kong Gateway Docker image
-
Pull the following Docker image.
docker pull kong/kong-gateway:3.3.1.1
Some older Kong Gateway images are not publicly accessible. If you need a specific patch version and can’t find it on Kong’s public Docker Hub page, contact Kong Support.
You should now have your Kong Gateway image locally.
-
Tag the image.
docker tag kong/kong-gateway:3.3.1.1 kong-ee
Start the database and Kong Gateway containers
-
Start a PostgreSQL container:
docker run -d --name kong-ee-database \ --network=kong-ee-net \ -p 5432:5432 \ -e "POSTGRES_USER=kong" \ -e "POSTGRES_DB=kong" \ -e "POSTGRES_PASSWORD=kong" \ postgres:9.6
-
Prepare the Kong database:
docker run --rm --network=kong-ee-net \ -e "KONG_DATABASE=postgres" \ -e "KONG_PG_HOST=kong-ee-database" \ -e "KONG_PG_PASSWORD=kong" \ -e "KONG_PASSWORD=kongpass" \ kong-ee kong migrations bootstrap
-
Start the gateway with Kong Manager and InfluxDB:
Important: The settings below are intended for non-production use only, as they override the default
admin_listen
setting to listen for requests from any source. Do not use these settings in environments directly exposed to the internet.
If you need to expose theadmin_listen
port to the internet in a production environment, secure it with authentication.docker run -d --name kong-ee --network=kong-ee-net \ -e "KONG_DATABASE=postgres" \ -e "KONG_PG_HOST=kong-ee-database" \ -e "KONG_PG_PASSWORD=kong" \ -e "KONG_PROXY_ACCESS_LOG=/dev/stdout" \ -e "KONG_ADMIN_ACCESS_LOG=/dev/stdout" \ -e "KONG_PROXY_ERROR_LOG=/dev/stderr" \ -e "KONG_ADMIN_ERROR_LOG=/dev/stderr" \ -e "KONG_ADMIN_LISTEN=0.0.0.0:8001" \ -e "KONG_ADMIN_GUI_URL=http://localhost:8002" \ -e "KONG_VITALS_STRATEGY=influxdb" \ -e "KONG_VITALS_TSDB_ADDRESS=influxdb:8086" \ -p 8000:8000 \ -p 8443:8443 \ -p 8001:8001 \ -p 8444:8444 \ -p 8002:8002 \ -p 8445:8445 \ -p 8003:8003 \ -p 8004:8004 \ kong-ee
Note: For
KONG_ADMIN_GUI_URL
, replacelocalhost
with with the DNS name or IP of the Docker host.KONG_ADMIN_GUI_URL
should have a protocol, for example,http://
.
Deploy a Kong Gateway license
If you already have a Kong Gateway Enterprise license attached to your Kong Gateway instance, skip to Configure Vitals with InfluxDB.
You will not be able to access the Kong Vitals functionality without a valid Kong Gateway Enterprise license attached to your Kong Gateway instance.
You can deploy a license file in one of the following ways:
Method | Supported deployment types |
---|---|
/licenses Admin API endpoint |
• Traditional database-backed deployment • Hybrid mode deployment |
File on the node filesystem ( license.json ) |
• Traditional database-backed deployment • DB-less mode |
Environment variable containing the full license ( KONG_LICENSE_DATA ) |
• Traditional database-backed deployment • DB-less mode |
Environment variable containing path to license file ( KONG_LICENSE_PATH ) |
• Traditional database-backed deployment • DB-less mode |
The recommended method is using the Admin API.
Important:
- If you deploy a license using the
/license
endpoint on the control plane, the control plane propagates the license to connected data planes automatically.- If you deploy a license using a
KONG_LICENSE_DATA
orKONG_LICENSE_PATH
environment variable, the control plane does not propagate the license to data plane nodes. You must add the license to each data plane node, and each node must start with the license. The license can’t be added after starting the node.We don’t recommend using this method in hybrid mode deployments.
Prerequisites
- You have received a
license.json
file from Kong. - Kong Gateway is installed.
Deploy the license
Configure Vitals with InfluxDB Kong Gateway
Note: If you used the configuration in Installing Kong Gateway on Docker, then you do not need to complete this step.
In addition to enabling Kong Vitals, Kong Gateway must be configured to use InfluxDB as the backing strategy for Vitals. The InfluxDB host and port must also be defined:
echo "KONG_VITALS_STRATEGY=influxdb KONG_VITALS_TSDB_ADDRESS=influxdb:8086 kong reload exit" \
| docker exec -i kong-ee /bin/sh
Note: In Hybrid Mode, configure
vitals_strategy
andvitals_tsdb_address
on both the control plane and all data planes.
Understanding Vitals data using InfluxDB measurements
Kong Vitals records metrics in two InfluxDB measurements:
-
kong_request
: Contains field values for request latencies and HTTP, and tags for various Kong entities associated with the requests (for example, the Route and Service in question). -
kong_datastore_cache
: Contains points about cache hits and misses.
To display the measurement schemas on your InfluxDB instance running in Docker:
-
Open command line in your InfluxDB Docker container.
docker exec -it influxdb /bin/sh
-
Log in to the InfluxDB CLI.
influx -precision rfc3339
-
Enter the InfluxQL query for returning a list of tag keys associated with the specified database.
> SHOW TAG KEYS ON kong
Example result:
name: kong_request tagKey ------ consumer hostname route service status_f wid workspace name: kong_datastore_cache tagKey ------ hostname wid
-
Enter the InfluxQL query for returning the field keys and the data type of their field values.
> SHOW FIELD KEYS ON kong
Example result:
name: kong_request fieldKey fieldType -------- --------- kong_latency integer proxy_latency integer request_latency integer status integer name: kong_datastore_cache fieldKey fieldType -------- --------- hits integer misses integer
The tag wid
is used to differentiate the unique worker ID per host, to avoid
duplicate metrics shipped at the same point in time.
As demonstrated above, the series cardinality of the kong_request
measurement
varies based on the cardinality of the Kong cluster configuration - a greater
number of Service/Route/Consumer/Workspace combinations handled by Kong results
in a greater series cardinality as written by Vitals.
Sizing an InfluxDB node/cluster for Vitals
Consult the InfluxDB sizing guidelines for reference on appropriately sizing an InfluxDB node/cluster.
Note: The query behavior when reading Vitals data falls under the “moderate” load category as defined by the InfluxDB sizing guidelines. Several
GROUP BY
statements and functions are used to generate the Vitals API responses, which can require significant CPU resources to execute when hundreds of thousands or millions of data points are present.
Query frequency and precision
Kong buffers Vitals metrics and writes InfluxDB points in batches to improve throughput in InfluxDB and reduce overhead in the Kong proxy path. Each Kong worker process flushes its buffer of metrics every 10 seconds or 5000 data points, whichever comes first.
Metrics points are written with microsecond (u
) precision. To comply with
the Vitals API, measurement
values are read back grouped by second.
Note: Because of limitations in the OpenResty API, writing values with microsecond precision requires an additional syscall per request.
Managing the retention policy of the Kong database
Vitals InfluxDB data points are not downsampled or managed by a
retention policy through Kong. InfluxDB operators are encouraged to manually manage
the retention policy of the kong
database to reduce the disk space and memory
needed to manage Vitals data points.