Allow mounting /conf.d, /constants.conf, /features-enabled and /zones.*

Dockerfile

@@ -112,6 +112,14 @@ COPY --from=build-icinga2 /icinga2-bin/ /
 RUN ["install", "-o", "icinga", "-g", "icinga", "-d", "/data"]
 RUN ["bash", "-exo", "pipefail", "-c", "for d in /etc/icinga2 /var/*/icinga2; do mkdir -p $(dirname /data-init$d); mv $d /data-init$d; ln -vs /data$d $d; done"]
 
+# One shall mount /data. One can also mount /data/X.
+# But mounting /data/Y/Z will create /data/Y as root and forbid the icinga user to write there.
+# https://stackoverflow.com/questions/66362660/#comment122948160_66362660
+# Hence, we have to move /data/etc/icinga2/* two levels up, so one can mount e.g. /data/conf.d in addition to /data.
+# This also keeps everything under /data not to break any existing usage.
+# But, for a nice interface, we also create symlinks under /, so one can mount e.g. /data/conf.d as /conf.d.
+RUN ["bash", "-exo", "pipefail", "-c", "cd /data-init/etc/icinga2; for d in conf.d constants.conf features-enabled zones.*; do mv $d ../..; ln -vs ../../$d .; ln -vs /data/$d /; done"]
+
 EXPOSE 5665
 USER icinga
 CMD ["icinga2", "daemon"]

README.md

@@ -72,6 +72,13 @@ of `~icinga/.msmtprc` via the environment variable `MSMTPRC`.
 **Don't mount volumes under `/data/etc/icinga2` or `/data/var/*/icinga2`**
 unless `/data` already contains all of these directories!
 Otherwise `/data` will stay incomplete, i.e. broken.
+Instead mount any of the following directories:
+
+* `/conf.d`
+* `/constants.conf`
+* `/features-enabled`
+* `/zones.conf`
+* `/zones.d`
 
 ### Environment variables
 

entrypoint/main.go

@@ -38,13 +38,16 @@ func entrypoint() error {
 	if os.Getpid() == 1 {
 		logf(info, "Initializing /data as we're the init process (PID 1)")
 
-		for _, dir := range []string{"etc", "var/cache", "var/lib", "var/log", "var/run", "var/spool"} {
-			dest := path.Join("/data", dir, "icinga2")
+		for _, dir := range []string{
+			"etc/icinga2", "conf.d", "constants.conf", "features-enabled", "zones.conf", "zones.d",
+			"var/cache/icinga2", "var/lib/icinga2", "var/log/icinga2", "var/run/icinga2", "var/spool/icinga2",
+		} {
+			dest := path.Join("/data", dir)
 			logf(info, "Checking %#v", dest)
 
 			if _, errSt := os.Stat(dest); errSt != nil {
 				if os.IsNotExist(errSt) {
-					src := path.Join("/data-init", dir, "icinga2")
+					src := path.Join("/data-init", dir)
 					logf(info, "Copying %#v to %#v", src, dest)
 
 					if errMA := os.MkdirAll(path.Dir(dest), 0755); errMA != nil {