Make journal num entries configurable

Author: tierpod

cmd/sd-dbus-hooks/config.go

@@ -7,10 +7,13 @@ import (
 	"gopkg.in/yaml.v2"
 )
 
+const defaultJournalNumEntries = 20
+
 type Config struct {
 	Units             []Unit `yaml:"units"`
 	HTTP              HTTP   `yaml:"http"`
 	SubscribeInterval int    `yaml:"subscribe_interval"`
+	JournalNumEntries uint64 `yaml:"journal_num_entries"`
 }
 
 func (c *Config) getUnit(name string) (Unit, error) {
@@ -58,5 +61,10 @@ func LoadConfig(path string) (*Config, error) {
 		return nil, err
 	}
 
+	// use default value if journal_num_entries is not set
+	if c.JournalNumEntries == 0 {
+		c.JournalNumEntries = defaultJournalNumEntries
+	}
+
 	return &c, err
 }

cmd/sd-dbus-hooks/journal.go

@@ -10,8 +10,6 @@ import (
 	"github.com/coreos/go-systemd/sdjournal"
 )
 
-const journalNumEntries = 20
-
 type unitJournalHandler struct {
 	conn *dbus.Conn
 	cfg  *Config
@@ -21,7 +19,7 @@ func (h unitJournalHandler) ServeHTTP(w http.ResponseWriter, r *http.Request) {
 	name := r.URL.Path[len("/unit/journal/"):]
 
 	jcfg := sdjournal.JournalReaderConfig{
-		NumFromTail: 20,
+		NumFromTail: h.cfg.JournalNumEntries,
 		Matches: []sdjournal.Match{
 			{
 				Field: sdjournal.SD_JOURNAL_FIELD_SYSTEMD_UNIT,
@@ -37,7 +35,7 @@ func (h unitJournalHandler) ServeHTTP(w http.ResponseWriter, r *http.Request) {
 		return
 	}
 
-	log.Printf("[INFO] journal: show last %v entries for %v", journalNumEntries, name)
+	log.Printf("[INFO] journal: show last %v entries for %v", h.cfg.JournalNumEntries, name)
 	scanner := bufio.NewScanner(jr)
 	for scanner.Scan() {
 		fmt.Fprintf(w, "%v\n", scanner.Text())

config/config.dist.yaml

@@ -8,6 +8,8 @@ http:
 
 # receive all changed units every interval over dbus
 subscribe_interval: 5
+# show last N journal entries from end
+journal_num_entries: 20
 
 # units list
 units: