Logging and Observability

Metric Counter

Emit a Count

Scripts can emit small metric lines after work completes. A counter is simple to graph when the metric name and value shape stay fixed.

Program

Play the script to choose the count and see the metric line.

count
metric_counter_line.sh
Replay: real traced execution (multi-file project)
#!/usr/bin/env bash

count=3
metric="jobs_processed"
line="$metric=$count"
echo "$line"

#!/usr/bin/env bash

count=5
metric="jobs_processed"
line="$metric=$count"
echo "$line"

  1. count ← 3

    3count=34metric="jobs_processed"
    values this step3count

  2. metric ← jobs_processed

    3count=34metric="jobs_processed"5line="$metric=$count"
    values this stepjobs_processedmetric

  3. line ← jobs_processed=3

    4metric="jobs_processed"5line="$metric=$count"6echo "$line"
    values this stepjobs_processed=3linejobs_processedmetric3count

  4. echo "$line"

    5line="$metric=$count"6echo "$line"
    outputjobs_processed=3
    values this stepjobs_processed=3line

  1. count ← 5

    3count=54metric="jobs_processed"
    values this step5count

  2. metric ← jobs_processed

    3count=54metric="jobs_processed"5line="$metric=$count"
    values this stepjobs_processedmetric

  3. line ← jobs_processed=5

    4metric="jobs_processed"5line="$metric=$count"6echo "$line"
    values this stepjobs_processed=5linejobs_processedmetric5count

  4. echo "$line"

    5line="$metric=$count"6echo "$line"
    outputjobs_processed=5
    values this stepjobs_processed=5line
metric A metric is a named measurement emitted by a script.
counter A counter records how many things were processed.
fixed name Keeping the metric name stable lets later tools compare values over time.