Prometheus parser 0.22.0 raises `ValueError` when parsing HELP, INFO comments with double spaces

[gdmachado]

Issue

Starting with version 0.22.0, comment lines that are INFO, HELP will fail to parse if they contain double spaces between parts.

Example:

We have a particular service which exposes metrics in this format:

# HELP  jvm_heap_size_bytes jvm heap stat
# TYPE  jvm_heap_size_bytes gauge
jvm_heap_size_bytes{type="max"} 8589934592
jvm_heap_size_bytes{type="committed"} 1736441856
jvm_heap_size_bytes{type="used"} 1123733504

Expected behaviour:

Metrics of this service are successfully parsed.

list(text_fd_to_metric_families(fd)) should result with

[Metric(jvm_heap_size_bytes, jvm heap stat, gauge, , [Sample(name='jvm_heap_size_bytes', labels={'type': 'max'}, value=8589934592.0, timestamp=None, exemplar=None), Sample(name='jvm_heap_size_bytes', labels={'type': 'committed'}, value=1736441856.0, timestamp=None, exemplar=None), Sample(name='jvm_heap_size_bytes', labels={'type': 'used'}, value=1123733504.0, timestamp=None, exemplar=None)])]

(the behavior in 0.21.1)

Current behaviour:

Metrics for this service are not collected anymore since upgrading to 0.22 because of the ValueError raised during parse.

A ValueError is raised for the second and third comment lines above, as because of the double spaces, the second part becomes an empty string

[csmarchbanks]

Thank you for the report, I have opened up a fix in #1134 and will cut a patch release after it is merged.