General improvements

[gdm-maha]

What

Fix hover tooltip values and graph clipping in the Prometheus backend.

Why

Prometheus encodes all sample values as JSON strings (e.g. "4114608128"). The Transformer stored them as-is, so uPlot received strings instead of numbers and could not populate the hover tooltip or correctly calculate the Y-axis range, causing the top of the graph to be clipped.

The threshold timestamp lookup also used array_column() with raw JSON-decoded keys, which caused type mismatches (int vs float) and silently returned null for all threshold values — hiding warning and critical lines.

Finally, calculateSteps() had a hardcoded 60-second minimum step. This caused repeated identical data points within a single check interval due to Prometheus gap-filling. The step now uses check_interval from the PerfdataRequest as its minimum.

Changes

• Transformer: cast sample values to float (or null) and timestamps to int
• Transformer: replace array_column() threshold lookup with explicit int-keyed loop
• Prometheus: pass $checkInterval through getMetrics() to calculateSteps()
• PerfdataSource: pass $req->getCheckInterval() to getMetrics()

Before / After

Before — tooltip empty, graph top clipped:

After — tooltip populated, graph fully visible:

[gdm-maha]

fyi using VictoriaMetrics as backend :)

[martialblog]

Hi, thanks for the PR. I'll have a look at it.

[martialblog]

Hi, the changes look good. The only change I would make is the following.

The getCheckInterval method is only available since 0.4.0 so we need to update the module.info to reflect the dependency.

Modules: perfdatagraphs (>=0.4.0)