Datastore reference

Sensu stores the most recent event for each entity and check pair using either an etcd (default) or PostgreSQL database. You can access observability event data with the Sensu web UI Events page, sensuctl event commands, and the events API. For longer retention of observability event data, integrate Sensu with a time-series database like InfluxDB or a searchable index like ElasticSearch or Splunk.

Use default event storage

By default, Sensu uses its embedded etcd database to store configuration and event data. This embedded database allows you to get started with Sensu without deploying a complete, scalable architecture. Sensu’s default embedded etcd configuration listens for unencrypted communication on ports 2379 (client requests) and 2380 (peer communication).

Sensu can be configured to disable the embedded etcd database and use one or more external etcd nodes for configuration and event storage instead. To stand up an external etcd cluster, follow etcd’s clustering guide using the same store configuration. Do not configure external etcd in Sensu via backend command line flags or the backend configuration file (/etc/sensu/backend.yml).

As your deployment grows beyond the proof-of-concept stage, review Deployment architecture for Sensu for more information about deployment considerations and recommendations for a production-ready Sensu deployment.

Sensu requires at least etcd 3.3.2 and is tested against etcd 3.5. etcd version 3.4.0 is compatible with Sensu but may result in slower performance.

Scale event storage

COMMERCIAL FEATURE: Access enterprise-scale event storage in the packaged Sensu Go distribution. For more information, read Get started with commercial features.

Sensu supports using an external PostgreSQL instance for event storage in place of etcd. PostgreSQL can handle significantly higher volumes of Sensu events, which allows you to scale Sensu beyond etcd’s 8GB limit.

When configured with a PostgreSQL event store, Sensu connects to PostgreSQL to store and retrieve event data in place of etcd. Etcd continues to store Sensu entity and configuration data. You can access event data stored in PostgreSQL using the same Sensu web UI, API, and sensuctl processes as etcd-stored events.

PostgreSQL requirements

Sensu supports PostgreSQL 9.5 and later, including Amazon Relational Database Service (Amazon RDS) when configured with the PostgreSQL engine. Read the PostgreSQL documentation to install and configure PostgreSQL.

For optimal performance, we recommend the following PostgreSQL configuration parameters and settings as a starting point for your postgresql.conf file:

max_connections = 200

shared_buffers = 10GB

maintenance_work_mem = 1GB

vacuum_cost_delay = 10ms
vacuum_cost_limit = 10000

bgwriter_delay = 50ms
bgwriter_lru_maxpages = 1000

max_worker_processes = 8
max_parallel_maintenance_workers = 2
max_parallel_workers_per_gather = 2
max_parallel_workers = 8

synchronous_commit = off

wal_sync_method = fdatasync
wal_writer_delay = 5000ms
max_wal_size = 5GB
min_wal_size = 1GB

checkpoint_completion_target = 0.9

autovacuum_naptime = 10s
autovacuum_vacuum_scale_factor = 0.05
autovacuum_analyze_scale_factor = 0.025

Adjust the parameters and settings as needed based on your hardware and the performance you observe. Read the PostgreSQL parameters documentation for information about setting parameters.

Configure the PostgreSQL event store

At the time when you enable the PostgreSQL event store, event data cuts over from etcd to PostgreSQL. This results in a loss of recent event history. No restarts or Sensu backend configuration changes are required to enable the PostgreSQL event store.

When you successfully enable PostgreSQL as the Sensu Go event store, the Sensu backend log will include a message like this:

Mar 10 17:44:45 sensu-centos sensu-backend[1365]: {"component":"store-providers","level":"warning","msg":"switched event store to postgres","time":"2020-03-10T17:44:45Z"}

After you install and configure PostgreSQL, configure Sensu by creating a PostgresConfig resource like the following example. Review the datastore specification for more information.

---
type: PostgresConfig
api_version: store/v1
metadata:
  name: my-postgres
spec:
  batch_buffer: 0
  batch_size: 1
  batch_workers: 0
  dsn: "postgresql://user:secret@host:port/dbname"
  max_conn_lifetime: 5m
  max_idle_conns: 2
  pool_size: 20
  strict: true
  enable_round_robin: true
{
  "type": "PostgresConfig",
  "api_version": "store/v1",
  "metadata": {
    "name": "my-postgres"
  },
  "spec": {
    "batch_buffer": 0,
    "batch_size": 1,
    "batch_workers": 0,
    "dsn": "postgresql://user:secret@host:port/dbname",
    "max_conn_lifetime": "5m",
    "max_idle_conns": 2,
    "pool_size": 20,
    "strict": true,
    "enable_round_robin": true
  }
}

Save your PostgresConfig resource definition to a file (in this example, postgres.yml or postgres.json). Then, use sensuctl configured as the admin user to activate the PostgreSQL event store.

sensuctl create --file postgres.yml
sensuctl create --file postgres.json

To update your Sensu PostgreSQL configuration, repeat the sensuctl create process. You can expect PostgreSQL status updates in the Sensu backend logs at the warn log level and PostgreSQL error messages in the Sensu backend logs at the error log level.

Disable the PostgreSQL event store

To disable the PostgreSQL event store, use sensuctl delete with your PostgresConfig resource definition file:

sensuctl delete --file postgres.yml
sensuctl delete --file postgres.json

The Sensu backend log will include a message to record that you successfully disabled PostgreSQL as the Sensu Go event store:

Mar 10 17:35:04 sensu-centos sensu-backend[1365]: {"component":"store-providers","level":"warning","msg":"switched event store to etcd","time":"2020-03-10T17:35:04Z"}

When you disable the PostgreSQL event store, event data cuts over from PostgreSQL to etcd, which results in a loss of recent event history. No restarts or Sensu backend configuration changes are required to disable the PostgreSQL event store.

Datastore specification

Top-level attributes

type
description Top-level attribute that specifies the sensuctl create resource type. PostgreSQL datastore configs should always be type PostgresConfig.
required true
type String
example
type: PostgresConfig
{
  "type": "PostgresConfig"
}
api_version
description Top-level attribute that specifies the Sensu API group and version. For PostgreSQL datastore configs, the api_version should be store/v1.
required true
type String
example
api_version: store/v1
{
  "api_version": "store/v1"
}
metadata
description Top-level scope that contains the PostgreSQL datastore name and created_by field.
required true
type Map of key-value pairs
example
metadata:
  name: my-postgres
  created_by: admin
{
  "metadata": {
    "name": "my-postgres",
    "created_by": "admin"
  }
}
spec
description Top-level map that includes the PostgreSQL datastore config spec attributes.
required true
type Map of key-value pairs
example
spec:
  batch_buffer: 0
  batch_size: 1
  batch_workers: 0
  dsn: 'postgresql://user:secret@host:port/dbname'
  max_conn_lifetime: 5m
  max_idle_conns: 2
  pool_size: 20
  strict: true
  enable_round_robin: true
{
  "spec": {
    "batch_buffer": 0,
    "batch_size": 1,
    "batch_workers": 0,
    "dsn": "postgresql://user:secret@host:port/dbname",
    "max_conn_lifetime": "5m",
    "max_idle_conns": 2,
    "pool_size": 20,
    "strict": true,
    "enable_round_robin": true
  }
}

Metadata attributes

name
description PostgreSQL datastore name used internally by Sensu.
required true
type String
example
name: my-postgres
{
  "name": "my-postgres"
}
created_by
description Username of the Sensu user who created the datastore or last updated the datastore. Sensu automatically populates the created_by field when the datastore is created or updated.
required false
type String
example
created_by: admin
{
  "created_by": "admin"
}

Spec attributes

batch_buffer
description Maximum number of requests to buffer in memory.

WARNING: The batcher is sensitive to configuration values, and some batch_buffer, batch_size, and batch_workers combinations will not work optimally. We do not recommend configuring this attribute while we are testing and improving it.

required false
default 0
type Integer
example
batch_buffer: 0
{
  "batch_buffer": 0
}
batch_size
description Number of requests in each PostgreSQL write transaction, as specified in the PostgreSQL configuration.

WARNING: The batcher is sensitive to configuration values, and some batch_buffer, batch_size, and batch_workers combinations will not work optimally. We do not recommend configuring this attribute while we are testing and improving it.

required false
default 1
type Integer
example
batch_size: 1
{
  "batch_size": 1
}
batch_workers
description Number of Goroutines sending data to PostgreSQL, as specified in the PostgreSQL configuration.

WARNING: The batcher is sensitive to configuration values, and some batch_buffer, batch_size, and batch_workers combinations will not work optimally. We do not recommend configuring this attribute while we are testing and improving it.

required false
default Current PostgreSQL pool size
type Integer
example
batch_workers: 0
{
  "batch_workers": 0
}
dsn
description Data source names. Specified as a URL or PostgreSQL connection string. The Sensu backend uses the Go pq library, which supports a subset of the PostgreSQL libpq connection string parameters.
required true
type String
example
dsn: 'postgresql://user:secret@host:port/dbname'
{
  "dsn": "postgresql://user:secret@host:port/dbname"
}
max_conn_lifetime
description Maximum time a connection can persist before being destroyed. Specify values with a numeral and a letter indicator: s to indicate seconds, m to indicate minutes, and h to indicate hours. For example, 1m, 2h, and 2h1m3s are valid.
required false
type String
example
max_conn_lifetime: 5m
{
  "max_conn_lifetime": "5m"
}
max_idle_conns
description Maximum number of number of idle connections to retain.
required false
default 2
type Integer
example
max_idle_conns: 2
{
  "max_idle_conns": 2
}
pool_size
description Maximum number of connections to hold in the PostgreSQL connection pool. We recommend 20 for most instances.
required false
default 0 (unlimited)
type Integer
example
pool_size: 20
{
  "pool_size": 20
}

strict
description If true, when the PostgresConfig resource is created, configuration validation will include connecting to the PostgreSQL database and executing a query to confirm whetherthe connected user has permission to create database tables. Otherwise, false.

We recommend setting strict: true in most cases. If the connection fails or the user does not have permission to create database tables, resource configuration will fail and the configuration will not be persisted. This extended configuration is useful for debugging when you are not sure whether the configuration is correct or the database is working properly.
required false
default false
type Boolean
example
strict: true
{
  "strict": true
}

enable_round_robin
description If true, enables round robin scheduling on PostgreSQL. Any existing round robin scheduling will stop and migrate to PostgreSQL as entities check in with keepalives. Sensu will gradually delete the existing etcd scheduler state as keepalives on the etcd scheduler keys expire over time. Otherwise, false.

We recommend using PostgreSQL rather than etcd for round robin scheduling because etcd leases are not reliable enough to produce precise round robin behavior.
required false
default false
type Boolean
example
enable_round_robin: true
{
  "enable_round_robin": true
}