This buildpack aims at deploying a Promscale instance on the Scalingo PaaS platform.
The buildpack is expecting a PostgreSQL database with TimescaleDB Community Edition enabled. TimescaleDB Community Edition must be manually enabled on the database by an operator on the database administration panel.
The credentials to connect to the database must be defined in the environment variable SCALINGO_POSTGRESQL_URL. The default Scalingo user does not work out of the box for Promscale. You should add it the privilege CREATEROLE. The SQL query, by replacing username with the actual username, is:
ALTER ROLE username WITH CREATEROLE;This is also mandatory to update the connection string in the environment variable SCALINGO_POSTGRESQL_URL. The SSL mode must be require.
After the initial start of Promscale, it is safe to remove the CREATEROLE attribute:
ALTER ROLE username WITH NOCREATEROLE;This buildpack makes it mandatory to enable a Basic Auth protection. The application must define the PROMSCALE_WEB_AUTH_USERNAME and PROMSCALE_WEB_AUTH_PASSWORD environment variables with the credentials.
By default, Promscale tries to use 80% of the maximum connections that the database can handle. This might be too much and you may want to reduce the number of connections used by Promscale. You may see the following error messages:
FATAL: remaining connection slots are reserved for non-replication superuser connections (SQLSTATE 53300)
Define the environment variable PROMSCALE_DB_CONNECTIONS_MAX to limit the amount of connections used by Promscale.
Promscale requires the TimescaleDB extension to work. It is also possible to install a Promscale extension to improve the performance. Those can't be enabled by the default PostgreSQL user. Hence, disable them on Promscale by setting these environment variables: PROMSCALE_STARTUP_INSTALL_EXTENSIONS=false and PROMSCALE_STARTUP_UPGRADE_EXTENSIONS=false.
By default we're installing the version of Promscale declared in the bin/compile file. But if you want to use a specific version, you can define the environment variable PROMSCALE_VERSION.
scalingo env-set PROMSCALE_VERSION=0.10.0Upgrading Promscale may require to execute a migration script on the database. In this case, you may face the error:
Failed to acquire the migration lock to upgrade the schema version and unable to run with the old version. Please ensure that no other Promscale connectors with the old schema version are running.
To fix this issue, you first need to scale the Promscale application down to 0 container, then deploy the new version, and last scale the Promscale back up.