Improve Pan language support (#3691)

* Add a larger set of sample files for Pan

This is a fairly good cross section of Pan based on code from:
* https://github.com/quattor/template-library-examples
* https://github.com/quattor/template-library-core

* Add Pan language grammar

samples/Pan/ceph-raid.pan

@@ -0,0 +1,59 @@
+unique template site/filesystems/ceph-raid;
+
+prefix '/system/blockdevices';
+
+variable CEPH_OSD_DISKS = {
+    # SAS disks partitions
+    disks = list();
+    foreach (disk; data; value('/hardware/harddisks')) {
+        if (data['capacity'] > 1000 * GB) {
+            append(disks, disk);
+        };
+    };
+    disks;
+};
+
+'partitions' = {
+    foreach (idx; disk; CEPH_OSD_DISKS) {
+        partitions_add(
+            disk, dict(
+                format('%s1', disk), 10 * GB,
+                format('%s2', disk), 5 * GB,
+                format('%s3', disk), -1));
+        SELF[format('%s1', disk)]['offset'] = 1;
+    };
+    SELF;
+};
+
+#raid for data
+'md' = {
+    for (i = 0; i < length(CEPH_OSD_DISKS); i = i + 2) {
+        for (j = 2; j <= 3; j = j + 1) {
+            SELF[escape(format('md/%s0%s%d', CEPH_OSD_DISKS[i], CEPH_OSD_DISKS[i+1], j ))] = dict(
+                "device_list", list(format('partitions/%s%d', CEPH_OSD_DISKS[i], j), format('partitions/%s%d', CEPH_OSD_DISKS[i+1], j)),
+                "raid_level", 'RAID0',
+                "metadata", '1.2',
+            );
+        };
+    };
+    SELF;
+};
+
+# ceph OSD and journal fs
+'/system/filesystems' = {
+    # ga over software raids..
+    foreach (disk; data; value('/system/blockdevices/md')) { #check for data part/disk
+        if (match(unescape(disk), '^md/.+0.+3$')) {
+            append(merge(CEPH_FSOPTS_BASE, CEPH_DISK_OPTIONS[CEPH_FS], dict(
+                'mountpoint', format('/var/lib/ceph/osd/%s', replace('md/([a-z0A-Z]+)[0-9]*$', '$1', unescape(disk))),
+                'block_device', format('md/%s', disk),
+            )));
+        } else if (match(unescape(disk), '^md/.+0.+2$')) {
+            append(merge(CEPH_FSOPTS_DUMMY, dict(
+                'mountpoint', format('/dummy/%s', unescape(disk)),
+                'block_device', format('md/%s', disk)
+            )));
+        };
+    };
+    SELF;
+};