5

I'm trying to parse and rewrite the output of the "resolvectl statistics" command in the hope of producing a munin plugin to monitor resolvectl processing. The output looks like this:

Transactions
                       Current Transactions:     0
                         Total Transactions: 65277

Cache
                         Current Cache Size:    13
                                 Cache Hits: 20422
                               Cache Misses: 70974

Failure Transactions
                             Total Timeouts:    32
         Total Timeouts (Stale Data Served):     0
                    Total Failure Responses:  5203
Total Failure Responses (Stale Data Served):     0

DNSSEC Verdicts
                                     Secure:     0
                                   Insecure:     0
                                      Bogus:     0
                              Indeterminate:     0

I need to rewrite this output to produce something that looks like this:

current-transactions.value 0
total-transactions.value 65277
cache-size.value 13
cache-hits.value 20422
cache-misses.value 70974
total-timeouts.value 32
total-timeouts-stale.value 0
total-failures.value 5203
total-failures-stale.value 0
dnssec-secure.value 0
dnssec-insecure.value 0
dnssec-bogus.value 0
dnssec-indeterminate.value 0

I've been able to isolate the values using this awk script:

$ sudo resolvectl statistics|awk -F ":" {'print $2'}|awk NF
     0
 65227
    13
 20422
 70974
    32
     0
  5203
     0
     0
     0
     0
     0

How can I alter the awk output to add to labels described above?

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3
  • 2
    Does your resolvectl support a --json output format? if so, it might be more robust to use that (ex. something like sudo resolvectl --json=short statistics | mlr --ijson --flatsep '-' --oxtab cat) Commented Sep 8, 2024 at 23:02
  • While I agree with the answer below, the quick and dirty solution in awk is something like awk '/Current Transactions/{print "current-transactions.value " $NF; /Total transactions/{print "total-transactions.value " $NF};/etc.etc/{}' file Commented Sep 9, 2024 at 4:11
  • Thanks for all of the suggestions! I just figured out that the root privileges required for "resolvectl statistics" means that I can't run the command directly from a munin plugin, which is run as user "munin". On to that problem... Commented Sep 9, 2024 at 12:59

3 Answers 3

Reset to default
5

Assumptions/understandings:

  • there is no single rule that can be implemented to determine the text of all labels
  • all of the strings (associated with values) are unique; for sake of discussion I'll refer to these strings as 'measurements'

General approach:

  • pre-build an array of measurement strings and their associated labels
  • split input lines on :
  • if there are 2 fields (NF==2) then ...
  • remove leading white space from both fields
  • use the first field ($1) to look up the associated label in our array
  • print the desired label and value to stdout

To simulate OP's resolvectl output:

$ cat resolve.out
Transactions
                       Current Transactions:     0
                         Total Transactions: 65277

Cache
                         Current Cache Size:    13
                                 Cache Hits: 20422
                               Cache Misses: 70974

Failure Transactions
                             Total Timeouts:    32
         Total Timeouts (Stale Data Served):     0
                    Total Failure Responses:  5203
Total Failure Responses (Stale Data Served):     0

DNSSEC Verdicts
                                     Secure:     0
                                   Insecure:     0
                                      Bogus:     0
                              Indeterminate:     0

One awk approach:

$ cat resolve.awk
BEGIN { FS = ":"
        labels["Current Transactions"] = "current-transactions"
        labels["Total Transactions"]   = "total-transactions"
        labels["Current Cache Size"]   = "cache_size"
        labels["Cache Hits"]           = "cache_hits"
        labels["Cache Misses"]         = "cache-misses" 

        # I will leave it up to OP to fill in the rest of the array
      }

NF==2 { sub(/^[[:space:]]+/,"",$1)          # strip leading white space from 1st field
        sub(/^[[:space:]]+/,"",$2)          # strip leading white space from 2nd field
        print labels[$1] ".value", $2       # use $1 to look up label from array and generate desired output
      }

Taking for a test drive:

$ cat resolve.out | awk -f resolve.awk
current-transactions.value 0
total-transactions.value 65277
cache_size.value 13
cache_hits.value 20422
cache-misses.value 70974

NOTES:

  • OP will replace cat resolve.out | with sudo resolvectl statistics |
  • output is truncated to just the first 5 lines since I've only populated the first 5 entries in the labels[] array
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Using any awk:

$ cat tst.awk
{ $0 = tolower($0); sub(/:/,"") }
/[^0-9]$/         { type = $1; next }
type == "cache"   { sub(/current /, "") }
type == "failure" { sub(/ response/, "") }
NF == 2           { $0 = type " " $0 }
/stale/           { $2 = $2 "-stale" }
NF { print $1 "-" $2 ".value", $NF }


$ awk -f tst.awk file
current-transactions.value 0
total-transactions.value 65277
cache-size.value 13
cache-hits.value 20422
cache-misses.value 70974
total-timeouts.value 32
total-timeouts-stale.value 0
total-failures.value 5203
total-failures-stale.value 0
dnssec-secure.value 0
dnssec-insecure.value 0
dnssec-bogus.value 0
dnssec-indeterminate.value 0
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3

I'd use perl:

perl -lne '
  if (/(\S.*):\s*(\d+)/) {
    ($_, $value) = (lc($1), $2);
    y/ /-/;
    s/\(stale-data-served\)/stale/;
    s/current-(?=cache-size)//;
    s/-response//;
    s/^/dnssec-/ if $section =~ /DNSSEC/;
    print "$_.value $value";
  } else {$section = $_ if /\S/}'
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