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[!Important]
Processing engine only works with Docker
The Processing engine is currently supported only in Docker x86 environments. Non-Docker support is coming soon. The engine, API, and developer experience are actively evolving and may change. Join our Discord for updates and feedback.
Use the {{% product-name %}} Processing engine to run code and perform tasks for different database events.
{{% product-name %}} provides the InfluxDB 3 Processing engine, an embedded Python VM that can dynamically load and trigger Python plugins in response to events in your database.
Plugins
[!Note]
Contribute and use community plugins
influxdata/influxdb3_plugins is a public repository on GitHub where you can find and contribute example plugins. You can reference plugins from the repository directly within a trigger configuration.
A Processing engine plugin is Python code you provide to run tasks, such as downsampling data, monitoring, creating alerts, or calling external services.
Triggers
A trigger is an InfluxDB 3 resource you create to associate a database event (for example, a WAL flush) with the plugin that should run. When an event occurs, the trigger passes configuration, optional arguments, and event data to the plugin.
The Processing engine provides four types of plugins and triggers--each type corresponds to an event type with event-specific configuration to let you handle events with targeted logic.
- WAL flush: Triggered when the write-ahead log (WAL) is flushed to the object store (default is every second)
- Parquet persistence (coming soon): Triggered when InfluxDB 3 persists data to object store Parquet files
- Scheduled tasks: Triggered on a schedule you specify using cron syntax
- On Request: Bound to the HTTP API
/api/v3/engine/<CUSTOM_PATH>endpoint and triggered by a GET or POST request to the endpoint.
Activate the Processing engine
To enable the Processing engine, start the {{% product-name %}} server with the --plugin-dir option and a path to your plugins directory (it doesn't need to exist yet)--for example:
influxdb3 serve --node-id node0 --plugin-dir /path/to/plugins
Shared API
All plugin types provide the InfluxDB 3 shared API for interacting with the database. The shared API provides access to the following:
LineBuilderto create Line Protocol lines for writing to the databasequeryto query data from any databaseinfo,warn, anderrorto log messages to the database log, which is output in the server logs and captured in system tables queryable by SQL
Line builder
The LineBuilder is a simple API for building lines of Line Protocol to write into the database. Writes are buffered while the plugin runs and are flushed when the plugin completes. The LineBuilder API is available in all plugin types.
The following example shows how to use the LineBuilder API:
# Build line protocol incrementally
line = LineBuilder("weather")
line.tag("location", "us-midwest")
line.float64_field("temperature", 82.5)
line.time_ns(1627680000000000000)
influxdb3_local.write(line)
# Output line protocol as a string ("weather,location=us-midwest temperature=82.5 1627680000000000000")
line_str = line.build()
Here is the Python implementation of the LineBuilder API:
from typing import Optional
from collections import OrderedDict
class InfluxDBError(Exception):
"""Base exception for InfluxDB-related errors"""
pass
class InvalidMeasurementError(InfluxDBError):
"""Raised when measurement name is invalid"""
pass
class InvalidKeyError(InfluxDBError):
"""Raised when a tag or field key is invalid"""
pass
class InvalidLineError(InfluxDBError):
"""Raised when a line protocol string is invalid"""
pass
class LineBuilder:
def __init__(self, measurement: str):
if ' ' in measurement:
raise InvalidMeasurementError("Measurement name cannot contain spaces")
self.measurement = measurement
self.tags: OrderedDict[str, str] = OrderedDict()
self.fields: OrderedDict[str, str] = OrderedDict()
self._timestamp_ns: Optional[int] = None
def _validate_key(self, key: str, key_type: str) -> None:
"""Validate that a key does not contain spaces, commas, or equals signs."""
if not key:
raise InvalidKeyError(f"{key_type} key cannot be empty")
if ' ' in key:
raise InvalidKeyError(f"{key_type} key '{key}' cannot contain spaces")
if ',' in key:
raise InvalidKeyError(f"{key_type} key '{key}' cannot contain commas")
if '=' in key:
raise InvalidKeyError(f"{key_type} key '{key}' cannot contain equals signs")
def tag(self, key: str, value: str) -> 'LineBuilder':
"""Add a tag to the line protocol."""
self._validate_key(key, "tag")
self.tags[key] = str(value)
return self
def uint64_field(self, key: str, value: int) -> 'LineBuilder':
"""Add an unsigned integer field to the line protocol."""
self._validate_key(key, "field")
if value < 0:
raise ValueError(f"uint64 field '{key}' cannot be negative")
self.fields[key] = f"{value}u"
return self
def int64_field(self, key: str, value: int) -> 'LineBuilder':
"""Add an integer field to the line protocol."""
self._validate_key(key, "field")
self.fields[key] = f"{value}i"
return self
def float64_field(self, key: str, value: float) -> 'LineBuilder':
"""Add a float field to the line protocol."""
self._validate_key(key, "field")
# Check if value has no decimal component
self.fields[key] = f"{int(value)}.0" if value % 1 == 0 else str(value)
return self
def string_field(self, key: str, value: str) -> 'LineBuilder':
"""Add a string field to the line protocol."""
self._validate_key(key, "field")
# Escape quotes and backslashes in string values
escaped_value = value.replace('"', '\\"').replace('\\', '\\\\')
self.fields[key] = f'"{escaped_value}"'
return self
def bool_field(self, key: str, value: bool) -> 'LineBuilder':
"""Add a boolean field to the line protocol."""
self._validate_key(key, "field")
self.fields[key] = 't' if value else 'f'
return self
def time_ns(self, timestamp_ns: int) -> 'LineBuilder':
"""Set the timestamp in nanoseconds."""
self._timestamp_ns = timestamp_ns
return self
def build(self) -> str:
"""Build the line protocol string."""
# Start with measurement name (escape commas only)
line = self.measurement.replace(',', '\\,')
# Add tags if present
if self.tags:
tags_str = ','.join(
f"{k}={v}" for k, v in self.tags.items()
)
line += f",{tags_str}"
# Add fields (required)
if not self.fields:
raise InvalidLineError(f"At least one field is required: {line}")
fields_str = ','.join(
f"{k}={v}" for k, v in self.fields.items()
)
line += f" {fields_str}"
# Add timestamp if present
if self._timestamp_ns is not None:
line += f" {self._timestamp_ns}"
return line
Query
The shared API query function executes an SQL query with optional parameters (a parameterized query) and returns results as a List of Dict[String, Any] where the key is the column name and the value is the column value. The query function is available in all plugin types.
The following examples show how to use the query function:
influxdb3_local.query("SELECT * from foo where bar = 'baz' and time > now() - 'interval 1 hour'")
# Or using parameterized queries
args = {"bar": "baz"}
influxdb3_local.query("SELECT * from foo where bar = $bar and time > now() - 'interval 1 hour'", args)
Logging
The shared API info, warn, and error functions log messages to the database log, which is output in the server logs and captured in system tables queryable by SQL.
The info, warn, and error functions are available in all plugin types. The functions take an arbitrary number of arguments, convert them to strings, and then join them into a single message separated by a space.
The following examples show to use the info, warn, and error logging functions:
ifluxdb3_local.info("This is an info message")
influxdb3_local.warn("This is a warning message")
influxdb3_local.error("This is an error message")
# Log a message that contains a data object
obj_to_log = {"hello": "world"}
influxdb3_local.info("This is an info message with an object", obj_to_log)
Trigger arguments
Every plugin type can receive arguments from the configuration of the trigger that runs it. You can use this to provide runtime configuration and drive behavior of a plugin--for example:
- threshold values for monitoring
- connection properties for connecting to third-party services
The arguments are passed as a Dict[str, str] where the key is the argument name and the value is the argument value.
The following example shows how to use an argument in a WAL plugin:
def process_writes(influxdb3_local, table_batches, args=None):
if args and "threshold" in args:
threshold = int(args["threshold"])
influxdb3_local.info(f"Threshold is {threshold}")
else:
influxdb3_local.warn("No threshold provided")
The args parameter is optional and can be omitted from the trigger definition if the plugin doesn't need to use arguments.
Import plugin dependencies
Use the influxdb3 install command to download and install Python packages that your plugin depends on.
influxdb3 install package <PACKAGE_NAME>
Use influxdb3 install with Docker
-
Start the server
docker run \ --name CONTAINER_NAME \ -v /path/to/.influxdb3/data:/data \ -v /path/to/.influxdb3/plugins:/plugins \ quay.io/influxdb/influxdb3-{{< product-key >}}:latest \ serve --node-id=node0 \ --object-store=file \ --data-dir=/data \ --http-bind=localhost:8183 \ --plugin-dir=/plugins -
Use
docker execto run theinfluxdb3 installcommand:docker exec -it CONTAINER_NAME influxdb3 install package pandas
The result is an active Python virtual environment with the package installed in <PLUGINS_DIR>/.venv.
You can pass additional options to use a requirements.txt file or a custom virtual environment path.
For more information, see the influxdb3 CLI help:
influxdb3 install package --help
WAL flush plugin
When a WAL flush plugin is triggered, the plugin receives a list of table_batches filtered by the trigger configuration (either all tables in the database or a specific table).
The following example shows a simple WAL flush plugin:
def process_writes(influxdb3_local, table_batches, args=None):
for table_batch in table_batches:
# Skip the batch if table_name is write_reports
if table_batch["table_name"] == "write_reports":
continue
row_count = len(table_batch["rows"])
# Double the row count if table name matches args table_name
if args and "double_count_table" in args and table_batch["table_name"] == args["double_count_table"]:
row_count *= 2
# Use the LineBuilder API to write data
line = LineBuilder("write_reports")\
.tag("table_name", table_batch["table_name"])\
.int64_field("row_count", row_count)
influxdb3_local.write(line)
influxdb3_local.info("wal_plugin.py done")
WAL flush trigger Configuration
When you create a trigger, you associate it with a database and provide configuration specific to the trigger type.
For a WAL flush trigger you specify a trigger-spec, which determines when the plugin is triggered (and what table data it receives):
all-tables: triggers the plugin on every write to the associated databasetable:<table_name>triggers the plugin function only for writes to the specified table.
The following example creates a WAL flush trigger for the gh:examples/wal_plugin/wal_plugin.py plugin.
influxdb3 create trigger \
--trigger-spec "table:TABLE_NAME" \
--plugin-filename "gh:examples/wal_plugin/wal_plugin.py" \
--database DATABASE_NAME TRIGGER_NAME
The gh: prefix lets you fetch a plugin file directly from the influxdata/influxdb3_plugins repository in GitHub.
Without the prefix, the server looks for the file inside of the plugins directory.
To provide additional configuration to your plugin, pass a list of key-value pairs in the --trigger-arguments option and, in your plugin, use the args parameter to receive the arguments.
For more information about trigger arguments, see the CLI help:
influxdb3 create trigger help
Schedule Plugin
Schedule plugins run on a schedule specified in cron syntax. The plugin will receive the local API, the time of the trigger, and any arguments passed in the trigger definition. Here's an example of a simple schedule plugin:
# see if a table has been written to in the last 5 minutes
def process_scheduled_call(influxdb3_local, time, args=None):
if args and "table_name" in args:
table_name = args["table_name"]
result = influxdb3_local.query(f"SELECT * FROM {table_name} WHERE time > now() - 'interval 5m'")
# write an error log if the result is empty
if not result:
influxdb3_local.error(f"No data in {table_name} in the last 5 minutes")
else:
influxdb3_local.error("No table_name provided for schedule plugin")
Schedule Trigger Configuration
Schedule plugins are set with a trigger-spec of schedule:<cron_expression> or every:<duration>. The args parameter can be used to pass configuration to the plugin. For example, if we wanted to use the system-metrics example from the Github repo and have it collect every 10 seconds we could use the following trigger definition:
influxdb3 create trigger \
--trigger-spec "every:10s" \
--plugin-filename "gh:examples/schedule/system_metrics/system_metrics.py" \
--database mydb system-metrics
On Request Plugin
On Request plugins are triggered by a request to a specific endpoint under /api/v3/engine. The plugin will receive the local API, query parameters Dict[str, str], request headers Dict[str, str], request body (as bytes), and any arguments passed in the trigger definition. Here's an example of a simple On Request plugin:
import json
def process_request(influxdb3_local, query_parameters, request_headers, request_body, args=None):
for k, v in query_parameters.items():
influxdb3_local.info(f"query_parameters: {k}={v}")
for k, v in request_headers.items():
influxdb3_local.info(f"request_headers: {k}={v}")
request_data = json.loads(request_body)
influxdb3_local.info("parsed JSON request body:", request_data)
# write the data to the database
line = LineBuilder("request_data").tag("tag1", "tag1_value").int64_field("field1", 1)
# get a string of the line to return as the body
line_str = line.build()
influxdb3_local.write(line)
return 200, {"Content-Type": "application/json"}, json.dumps({"status": "ok", "line": line_str})
On Request Trigger Configuration
On Request plugins are set with a trigger-spec of request:<endpoint>. The args parameter can be used to pass configuration to the plugin. For example, if we wanted the above plugin to run on the endpoint /api/v3/engine/my_plugin, we would use request:my_plugin as the trigger-spec.
Trigger specs must be unique across all configured plugins, regardless of which database they are tied to, given the path is the same. Here's an example to create a request trigger tied to the "hello-world' path using a plugin in the plugin-dir:
influxdb3 create trigger \
--trigger-spec "request:hello-world" \
--plugin-filename "hellp/hello_world.py" \
--database mydb hello-world