To configure QuantumLeap you can use the following environment variables:
||Max number of rows a query can retrieve|
||Whether to store original entity data|
||PostgreSQL default db|
||Pathname for tenant configuration|
||define the log level for all services (
DEFAULT_LIMIT. This variable specifies the upper limit L of rows a query
operation is allowed to fetch from the database and return to client. The
actual number of rows will be the least of L and the client-specified limit
or L if the client didn't specify a limit. If not set through this variable,
L defaults to 10,000. This variable is read in on each API call to query
endpoints so it can be set dynamically and it will affect every subsequent
query operation. The variable string value you set should be convertible to
an integer, if not, the default value of 10,000 will be used instead.
KEEP_RAW_ENTITY. If true, then each notified entity will be stored in its
entirety as JSON in an additional column of the corresponding entity table.
(This may result in the table needing up to 10x more storage.) If false, the
JSON will only be stored (as detailed earlier) in case the conversion from
JSON to tabular fails---typically this happens when the notified entity
contains a previously notified attribute whose type is now different than
it used to be in the past. This variable is read in on each API call to the
notify endpoint so it can be set dynamically and it will affect every
subsequent insert operation. Any of the following (case insensitive) values
will be interpreted as true: 'true', 'yes', '1', 't', 'y'. Anything else
counts for false, which is also the default value if the variable is not set.
Database selection per different tenant
QuantumLeap can use different time series databases to persist and query NGSI data. Currently both CrateDB and Timescale are supported as back ends, even though query functionality is not yet available for Timescale.
If no configuration is provided QuantumLeap assumes CrateDB is the back end to use and will store all incoming NGSI data in it. However, different back ends can be configured for specific tenants through a YAML configuration file. To use this feature, you have to set the environment variable below:
QL_CONFIG: absolute pathname of the QuantumLeap YAML configuration file. If not set, the default configuration will be used where only the Crate back end is available.
The YAML configuration file specifies what back end to use for which tenant as well as the default back end to use for any other tenant not explicitly mentioned in the file. Here's an example YAML configuration:
tenants: t1: backend: Timescale t2: backend: Crate t3: backend: Timescale default-backend: Crate
With this configuration, any NGSI entity coming in for tenant
t3 will be stored in Timescale whereas tenant
t2 will use
Crate. Any tenant other than
t3 gets the default
Crate back end.