samples: add prometheus text file collector mustach template

Because prometheus needs timestamp information add that to mustach, and
update manual page what tags are available.

Reference: https://prometheus.io/docs/instrumenting/exposition_formats/
Signed-off-by: Sami Kerola <kerolasa@iki.fi>

man/dhcpd-pools.1.in

@@ -107,10 +107,11 @@ The default format is
 \fB\-\-mustach\fR=\fITEMPLATE\fR
 Output using mustach
 .I template
-file.  Mustache tags in the template are same as json output without IP
-address information.  When the native output formats controlled with
+file.  This is useful when the native output formats controlled with
 .B \-\-format
-option do not provide what you need you should use mustach instead.
+option do not provide what you need.  See below example mustach template
+that is using all available {{tags}} to demonstrate what can be displayed
+and how.
 .IP
 @bindir@/dhcpd-pools --config @docdir@/dhcpd.conf --leases
 @docdir@/dhcpd.leases --mustach @docdir@/mustach.template
@@ -286,6 +287,9 @@ ISC dhcpd configuration file.
 .TP
 @DHCPDLEASE_FILE@
 ISC dhcpd lease file.
+.TP
+@docdir@/prometheus.template
+Prometheus text file collector mustach template.
 .SH AUTHORS
 Original design by Sami Kerola.
 .br

samples/Makemodule.am

@@ -1,4 +1,5 @@
 dist_doc_DATA = \
 	samples/dhcpd.conf \
 	samples/dhcpd.leases \
-	samples/mustach.template
+	samples/mustach.template \
+	samples/prometheus.template

samples/mustach.template

@@ -13,6 +13,8 @@ Subnets:{{#subnets}}
     backup_count: {{backup_count}}
     backup_percent: {{backup_percent}}
     status: {{status}}
+    gettimeofday: {{gettimeofday}}
+    lease_file_mtime: {{lease_file_mtime}}
 {{/subnets}}
 
 Shared-networks:{{#shared-networks}}
@@ -27,6 +29,8 @@ Shared-networks:{{#shared-networks}}
     backup_count: {{backup_count}}
     backup_percent: {{backup_percent}}
     status: {{status}}
+    gettimeofday: {{gettimeofday}}
+    lease_file_mtime: {{lease_file_mtime}}
 {{/shared-networks}}
 
 Summary:{{#summary}}
@@ -41,4 +45,6 @@ Summary:{{#summary}}
     backup_count: {{backup_count}}
     backup_percent: {{backup_percent}}
     status: {{status}}
+    gettimeofday: {{gettimeofday}}
+    lease_file_mtime: {{lease_file_mtime}}
 {{/summary}}

samples/prometheus.template

@@ -0,0 +1,30 @@
+# This mustach template can be used as Prometheus text file.
+# https://prometheus.io/
+
+# HELP dhcpd_pools_ranges The range statistics.
+# TYPE dhcpd_pools_ranges gauge
+{{#subnets}}dhcpd_pools_ranges{range="{{first_ip}}",used="1"} {{used}} {{gettimeofday}}000
+dhcpd_pools_ranges{range="{{first_ip}}",touched="1"} {{touched}} {{gettimeofday}}000
+dhcpd_pools_ranges{range="{{first_ip}}",defined="1"} {{defined}} {{gettimeofday}}000
+dhcpd_pools_ranges{range="{{first_ip}}",free="1"} {{free}} {{gettimeofday}}000
+dhcpd_pools_ranges{range="{{first_ip}}",touch_count="1"} {{touch_count}} {{gettimeofday}}000
+dhcpd_pools_ranges{range="{{first_ip}}",status="1"} {{status}} {{gettimeofday}}000
+{{/subnets}}
+# HELP dhcpd_pools_shared_nets The shared networks statistics.
+# TYPE dhcpd_pools_shared_nets gauge
+{{#shared-networks}}dhcpd_pools_shared_nets{location="{{location}}",defined="1"} {{defined}} {{gettimeofday}}000
+dhcpd_pools_shared_nets{location="{{location}}",used="1"} {{used}} {{gettimeofday}}000
+dhcpd_pools_shared_nets{location="{{location}}",touched="1"} {{touched}} {{gettimeofday}}000
+dhcpd_pools_shared_nets{location="{{location}}",free="1"} {{free}} {{gettimeofday}}000
+dhcpd_pools_shared_nets{location="{{location}}",touch_count="1"} {{touch_count}} {{gettimeofday}}000
+dhcpd_pools_shared_nets{location="{{location}}",status="1"} {{status}} {{gettimeofday}}000
+{{/shared-networks}}
+# HELP dhcpd_pools_summary Statistics of the all networks.
+# TYPE dhcpd_pools_summary gauge
+{{#summary}}dhcpd_pools_summary{location="{{location}}",defined="1"} {{defined}} {{gettimeofday}}000
+dhcpd_pools_summary{location="{{location}}",used="1"} {{used}} {{gettimeofday}}000
+dhcpd_pools_summary{location="{{location}}",touched="1"} {{touched}} {{gettimeofday}}000
+dhcpd_pools_summary{location="{{location}}",free="1"} {{free}} {{gettimeofday}}000
+dhcpd_pools_summary{location="{{location}}",touch_count="1"} {{touch_count}} {{gettimeofday}}000
+dhcpd_pools_summary{location="{{location}}",status="1"} {{status}} {{gettimeofday}}000
+{{/summary}}

src/mustach-dhcpd-pools.c

@@ -44,6 +44,7 @@
 #include <error.h>
 #include <stdlib.h>
 #include <sys/stat.h>
+#include <sys/time.h>
 #include <unistd.h>
 
 #include "close-stream.h"
@@ -144,6 +145,20 @@ static int must_put_range(void *closure, const char *name, int escape
 		fprintf(file, "%d", e->oh.status);
 		return 0;
 	}
+	if (!strcmp(name, "gettimeofday")) {
+		struct timeval tp;
+
+		gettimeofday(&tp, NULL);
+		fprintf(file, "%ld", tp.tv_sec);
+		return 0;
+	}
+	if (!strcmp(name, "lease_file_mtime")) {
+		struct stat st;
+
+		stat(e->state->dhcpdlease_file, &st);
+		fprintf(file, "%ld", st.st_mtime);
+		return 0;
+	}
 	return 0;
 }
 
@@ -198,6 +213,20 @@ static int must_put_shnet(void *closure, const char *name, int escape
 		fprintf(file, "%d", e->oh.status);
 		return 0;
 	}
+	if (!strcmp(name, "gettimeofday")) {
+		struct timeval tp;
+
+		gettimeofday(&tp, NULL);
+		fprintf(file, "%ld", tp.tv_sec);
+		return 0;
+	}
+	if (!strcmp(name, "lease_file_mtime")) {
+		struct stat st;
+
+		stat(e->state->dhcpdlease_file, &st);
+		fprintf(file, "%ld", st.st_mtime);
+		return 0;
+	}
 	return 0;
 }
 

tests/mustach

@@ -9,11 +9,13 @@ if [ ! -d tests/outputs ]; then
 fi
 
 dhcpd-pools -c $top_srcdir/samples/dhcpd.conf -l $top_srcdir/samples/dhcpd.leases \
-	--mustach $top_srcdir/samples/mustach.template -o tests/outputs/$IAM
+	--mustach $top_srcdir/samples/mustach.template |
+	sed '/gettimeofday:/d; /lease_file_mtime:/d' >| tests/outputs/$IAM
 
 echo "--- skip ok ---" >> tests/outputs/$IAM
 dhcpd-pools -c $top_srcdir/samples/dhcpd.conf -l $top_srcdir/samples/dhcpd.leases \
-	--mustach $top_srcdir/samples/mustach.template --skip-ok --warning 44 >> tests/outputs/$IAM
+	--mustach $top_srcdir/samples/mustach.template --skip-ok --warning 44 |
+	sed '/gettimeofday:/d; /lease_file_mtime:/d' >> tests/outputs/$IAM
 
 diff -u $top_srcdir/tests/expected/$IAM tests/outputs/$IAM
 exit $?