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nvme_metrics: refactor Python collector to support nvme-cli v2.11+
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nvme-cli v2.11 introduced a breaking change by forcing JSON output to
always be verbose, resulting in a significantly different output
structure.

Fixes: #226

Signed-off-by: Daniel Swarbrick <[email protected]>
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@dswarbrick
dswarbrick committed Nov 19, 2024
1 parent 39b36d0 commit b518891
Showing 1 changed file with 72 additions and 44 deletions.
116 changes: 72 additions & 44 deletions nvme_metrics.py
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Original file line number Diff line number Diff line change
Expand Up @@ -74,6 +74,9 @@
"Device error log entry count",
["device"], namespace=namespace, registry=registry,
),
# FIXME: The "nvmecli" metric ought to be an Info type, not a Gauge. However, making this change
# will result in the metric having a "_info" suffix automatically appended, which is arguably
# a breaking change.
"nvmecli": Gauge(
"nvmecli",
"nvme-cli tool information",
Expand Down Expand Up @@ -142,7 +145,11 @@ def exec_nvme_json(*args):
"""
Execute nvme CLI tool with specified arguments and return parsed JSON output.
"""
output = exec_nvme(*args, "--output-format", "json")
# Note: nvme-cli v2.11 effectively introduced a breaking change by forcing JSON output to always
# be verbose. Older versions of nvme-cli optionally produced verbose output if the --verbose
# flag was specified. In order to avoid having to handle two different JSON schemas, always
# add the --verbose flag.
output = exec_nvme(*args, "--output-format", "json", "--verbose")
return json.loads(output)


Expand All @@ -157,49 +164,70 @@ def main():
device_list = exec_nvme_json("list")

for device in device_list["Devices"]:
device_path = device["DevicePath"]
device_name = os.path.basename(device_path)

metrics["device_info"].labels(
device_name,
device["ModelNumber"],
device["Firmware"],
device["SerialNumber"].strip(),
)

metrics["sector_size"].labels(device_name).set(device["SectorSize"])
metrics["physical_size"].labels(device_name).set(device["PhysicalSize"])
metrics["used_bytes"].labels(device_name).set(device["UsedBytes"])

smart_log = exec_nvme_json("smart-log", device_path)

# Various counters in the NVMe specification are 128-bit, which would have to discard
# resolution if converted to a JSON number (i.e., float64_t). Instead, nvme-cli marshals
# them as strings. As such, they need to be explicitly cast to int or float when using them
# in Counter metrics.
metrics["data_units_read"].labels(device_name).inc(int(smart_log["data_units_read"]))
metrics["data_units_written"].labels(device_name).inc(int(smart_log["data_units_written"]))
metrics["host_read_commands"].labels(device_name).inc(int(smart_log["host_read_commands"]))
metrics["host_write_commands"].labels(device_name).inc(
int(smart_log["host_write_commands"])
)
metrics["avail_spare"].labels(device_name).set(smart_log["avail_spare"] / 100)
metrics["spare_thresh"].labels(device_name).set(smart_log["spare_thresh"] / 100)
metrics["percent_used"].labels(device_name).set(smart_log["percent_used"] / 100)
metrics["critical_warning"].labels(device_name).set(smart_log["critical_warning"])
metrics["media_errors"].labels(device_name).inc(int(smart_log["media_errors"]))
metrics["num_err_log_entries"].labels(device_name).inc(
int(smart_log["num_err_log_entries"])
)
metrics["power_cycles"].labels(device_name).inc(int(smart_log["power_cycles"]))
metrics["power_on_hours"].labels(device_name).inc(int(smart_log["power_on_hours"]))
metrics["controller_busy_time"].labels(device_name).inc(
int(smart_log["controller_busy_time"])
)
metrics["unsafe_shutdowns"].labels(device_name).inc(int(smart_log["unsafe_shutdowns"]))

# NVMe reports temperature in kelvins; convert it to degrees Celsius.
metrics["temperature"].labels(device_name).set(smart_log["temperature"] - 273)
for subsys in device["Subsystems"]:
for ctrl in subsys["Controllers"]:
for ns in ctrl["Namespaces"]:
device_name = ns["NameSpace"]

# FIXME: This metric ought to be refactored into a "controller_info" metric,
# since it contains information that is not unique to the namespace. However,
# previous versions of this collector erroneously referred to namespaces, e.g.
# "nvme0n1", as devices, so preserve the former behaviour for now.
metrics["device_info"].labels(
device_name,
ctrl["ModelNumber"],
ctrl["Firmware"],
ctrl["SerialNumber"].strip(),
)

metrics["sector_size"].labels(device_name).set(ns["SectorSize"])
metrics["physical_size"].labels(device_name).set(ns["PhysicalSize"])
metrics["used_bytes"].labels(device_name).set(ns["UsedBytes"])

# FIXME: The smart-log should only need to be fetched once per controller, not
# per namespace. However, in order to preserve legacy metric labels, fetch it
# per namespace anyway. Most consumer grade SSDs will only have one namespace.
smart_log = exec_nvme_json("smart-log", os.path.join("/dev", device_name))

# Various counters in the NVMe specification are 128-bit, which would have to
# discard resolution if converted to a JSON number (i.e., float64_t). Instead,
# nvme-cli marshals them as strings. As such, they need to be explicitly cast
# to int or float when using them in Counter metrics.
metrics["data_units_read"].labels(device_name).inc(
int(smart_log["data_units_read"])
)
metrics["data_units_written"].labels(device_name).inc(
int(smart_log["data_units_written"])
)
metrics["host_read_commands"].labels(device_name).inc(
int(smart_log["host_read_commands"])
)
metrics["host_write_commands"].labels(device_name).inc(
int(smart_log["host_write_commands"])
)
metrics["avail_spare"].labels(device_name).set(smart_log["avail_spare"] / 100)
metrics["spare_thresh"].labels(device_name).set(smart_log["spare_thresh"] / 100)
metrics["percent_used"].labels(device_name).set(smart_log["percent_used"] / 100)
metrics["critical_warning"].labels(device_name).set(
smart_log["critical_warning"]["value"]
)
metrics["media_errors"].labels(device_name).inc(int(smart_log["media_errors"]))
metrics["num_err_log_entries"].labels(device_name).inc(
int(smart_log["num_err_log_entries"])
)
metrics["power_cycles"].labels(device_name).inc(int(smart_log["power_cycles"]))
metrics["power_on_hours"].labels(device_name).inc(
int(smart_log["power_on_hours"])
)
metrics["controller_busy_time"].labels(device_name).inc(
int(smart_log["controller_busy_time"])
)
metrics["unsafe_shutdowns"].labels(device_name).inc(
int(smart_log["unsafe_shutdowns"])
)

# NVMe reports temperature in kelvins; convert it to degrees Celsius.
metrics["temperature"].labels(device_name).set(smart_log["temperature"] - 273)


if __name__ == "__main__":
Expand Down

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