mixin: Add fallback for MemAvailable
Add a fallback to Buffers+Cached+MemFree+Slab for older Linux kernels
where the MemAvailable metric is not available for memory utilization.
expr: |||
1 - (
node_memory_MemAvailable_bytes{%(nodeExporterSelector)s}
+ or
+ (
+ node_memory_Buffers_bytes{%(nodeExporterSelector)s}
+ +
+ node_memory_Cached_bytes{%(nodeExporterSelector)s}
+ +
+ node_memory_MemFree_bytes{%(nodeExporterSelector)s}
+ +
+ node_memory_Slab_bytes{%(nodeExporterSelector)s}
+ )
/
node_memory_MemTotal_bytes{%(nodeExporterSelector)s}
)
