rgw: replace period update --commit with function

Replace calls to 'radosgw-admin period update --commit' with an
idempotent function.

Resolves #8879

Signed-off-by: Blaine Gardner <blaine.gardner@redhat.com>

pkg/operator/ceph/object/admin.go

@@ -18,13 +18,16 @@ package object
 
 import (
 	"context"
+	"encoding/json"
 	"fmt"
 	"net/http"
 	"net/http/httputil"
 	"regexp"
+	"strings"
 
 	"github.com/ceph/go-ceph/rgw/admin"
 	"github.com/coreos/pkg/capnslog"
+	"github.com/google/go-cmp/cmp"
 	"github.com/pkg/errors"
 	cephv1 "github.com/rook/rook/pkg/apis/ceph.rook.io/v1"
 	"github.com/rook/rook/pkg/clusterd"
@@ -292,6 +295,89 @@ func isInvalidFlagError(err error) bool {
 	return exitCode == 22
 }
 
+// CommitConfigChanges commits changes to RGW configs for realm/zonegroup/zone changes idempotently.
+// Under the hood, this updates the RGW config period and commits the change if changes are detected.
+func CommitConfigChanges(c *Context) error {
+	currentPeriod, err := runAdminCommand(c, true, "period", "get")
+	if err != nil {
+		return errorOrIsNotFound(err, "failed to get the current RGW configuration period to see if it needs changed")
+	}
+
+	// this stages the current config changees and returns what the new period config will look like
+	// without committing the changes
+	stagedPeriod, err := runAdminCommand(c, true, "period", "update")
+	if err != nil {
+		return errorOrIsNotFound(err, "failed to stage the current RGW configuration period")
+	}
+
+	shouldCommit, err := periodWillChange(currentPeriod, stagedPeriod)
+	if err != nil {
+		return errors.Wrap(err, "failed to determine if the staged RGW configuration period is different from current")
+	}
+
+	if !shouldCommit {
+		nsName := fmt.Sprintf("%s/%s", c.clusterInfo.Namespace, c.Name)
+		logger.Debugf("not committing changes to RGW configuration period for CephObjectStore %q", nsName)
+		return nil
+	}
+	// don't expect json output since we don't intend to use the output from the command
+	_, err = runAdminCommand(c, false, "period", "update", "--commit")
+	if err != nil {
+		return errorOrIsNotFound(err, "failed to commit RGW configuration period changes")
+	}
+
+	return nil
+}
+
+// return true if the configuration period will change if the staged period is committed
+func periodWillChange(current, staged string) (bool, error) {
+	var currentJSON map[string]interface{}
+	var stagedJSON map[string]interface{}
+	var err error
+
+	err = json.Unmarshal([]byte(current), &currentJSON)
+	if err != nil {
+		return true, errors.Wrap(err, "failed to unmarshal current RGW configuration period")
+	}
+	err = json.Unmarshal([]byte(staged), &stagedJSON)
+	if err != nil {
+		return true, errors.Wrap(err, "failed to unmarshal staged RGW configuration period")
+	}
+
+	// There are some values in the periods that we don't care to diff because they are always
+	// different in the staged period, even when no updates are needed. Sometimes, the values are
+	// reported as different in the staging output but aren't actually changed upon commit.
+	ignorePaths := cmp.FilterPath(func(path cmp.Path) bool {
+		// path.String() outputs nothing for the crude map[string]interface{} JSON struct
+		// Example of path.GoString() output for a long path in the period JSON:
+		// root["period_map"].(map[string]interface {})["short_zone_ids"].([]interface {})[0].(map[string]interface {})["val"].(float64)
+		switch path.GoString() {
+		case `root["id"]`:
+			// "id" is always changed in the staged period, but it doesn't always update.
+			return true
+		case `root["predecessor_uuid"]`:
+			// "predecessor_uuid" is always changed in the staged period, but it doesn't always update.
+			return true
+		case `root["realm_epoch"]`:
+			// "realm_epoch" is always incremented in the staged period, but it doesn't always increment.
+			return true
+		case `root["epoch"]`:
+			// Strangely, "epoch" is not incremented in the staged period even though it is always
+			// incremented upon an actual commit. It could be argued that this behavior is a bug.
+			// Ignore this value to handle the possibility that the behavior changes in the future.
+			return true
+		default:
+			return false
+		}
+	}, cmp.Ignore())
+
+	diff := cmp.Diff(currentJSON, stagedJSON, ignorePaths)
+	diff = strings.TrimSpace(diff)
+	logger.Debugf("RGW config period diff:\n%s", diff)
+
+	return (diff != ""), nil
+}
+
 func GetAdminOPSUserCredentials(objContext *Context, spec *cephv1.ObjectStoreSpec) (string, string, error) {
 	ns := objContext.clusterInfo.Namespace