I'm having trouble understanding how to create a dashboard time series plot to display a single key/value from a Loki log which is in JSON format.
eg: here is my query in the Explorer:
{job="railsdevlogs"}|json
which returns log lines such as:
{"date":"2022-01-05T21:27:21.895Z","pool":{"Pool Size":50,"Current":5,"Active":1,"Idle":4,"Dead":0,"Timeout":"5 sec"},"puma":{"Started At":"2022-01-05T20:35:26Z","Max Threads":16,"Pool Capacity":16,"Running":1,"Backlog":0,"IO Handles":15,"File Handles":2,"Socket Handles":4,"Server Log Size":46750072},"process":[{"Name":"ruby.exe","Process ID":656,"Threads":11,"Working Set":150728704,"Virtual Size":288079872},{"Name":"mysqld.exe","Process ID":4836,"Threads":3,"Working Set":360448,"Virtual Size":4445065216},{"Name":"mysqld.exe","Process ID":5808,"Threads":49,"Working Set":69906432,"Virtual Size":4924059648},{"Name":"aaaaa.exe","Process ID":14460,"Threads":18,"Working Set":49565696,"Virtual Size":5478469632},{"Name":"bbbbb.exe","Process ID":9584,"Threads":14,"Working Set":35012608,"Virtual Size":4496551936},{"Name":"ccccc.exe","Process ID":11944,"Threads":14,"Working Set":29609984,"Virtual Size":4481880064}],"gc":{"count":242,"heap_allocated_pages":1277,"heap_sorted_length":1279,"heap_allocatable_pages":9,"heap_available_slots":869213,"heap_live_slots":464541,"heap_free_slots":404672,"heap_final_slots":0,"heap_marked_slots":411311,"heap_swept_slots":457903,"heap_eden_pages":1268,"heap_tomb_pages":9,"total_allocated_pages":1278,"total_freed_pages":1,"total_allocated_objects":74364715,"total_freed_objects":73900174,"malloc_increase_bytes":640096,"malloc_increase_bytes_limit":16777216,"minor_gc_count":131,"major_gc_count":111,"remembered_wb_unprotected_objects":57031,"remembered_wb_unprotected_objects_limit":114062,"old_objects":349257,"old_objects_limit":698512,"oldmalloc_increase_bytes":640288,"oldmalloc_increase_bytes_limit":16777216},"os":{"System Name":"xxxxx","Description":"","Organization":"","Operating System":"Microsoft Windows 10 Enterprise LTSC","OS Version":"10.0.17763","OS Serial Number":"xxxxx-xxxxx-xxxxx-xxxxx","System Time":"2022-01-05T16:27:22.000-05:00","System Time Zone":-300,"Last Boot Time":"2021-12-15T23:26:38.000-05:00","System Drive":"C:","Total Physical Memory":34204393472,"Free Physical Memory":20056260608,"Total Virtual Memory":39304667136,"Free Virtual Memory":13915041792,"Number of Processes":307,"Number of Users":2,"volumes":[{"Drive":"C:\\","Type":"NTFS","Total Space":1023563264000,"Free Space":681182343168,"Block Size":4096}]},"symbol":{"size":28106},"stats_collection_time":387}
using |json will automatically create dynamic labels for all the key/values in the json log line:
gc_count = 123
os_Free_Virtual_Memory = 456789
etc.
Now I would like to plot one of these values in a grafana time series plot, but I am struggling to understand how to isolate one dynamic label and plot it.
Perhaps I'm using |json incorrectly. The documentation and examples I have read so far shows how to filter the logs using the dynamic labels, but I dont need that since I want to plot every log line.
thanks
I think this should help https://grafana.com/go/observabilitycon/2020/keynote-what-is-observability/ if you go to minute 41. There's an example which is very similar to what you're trying to achieve.
Your query should look something like:
quantile_over_time(0,99, {job="railsdevlogs"}
| json
| unwrap gc_count [1m]}
by (job)