MXS-1300: Add simple diff calculation

The `cluster diff` command prints out the difference between the source
and target MaxScale. This allows users to detect changes that have
happened on one MaxScale but not on the other.

maxctrl/lib/cluster.js

@@ -0,0 +1,123 @@
+/*
+ * Copyright (c) 2016 MariaDB Corporation Ab
+ *
+ * Use of this software is governed by the Business Source License included
+ * in the LICENSE.TXT file and at www.mariadb.com/bsl11.
+ *
+ * Change Date: 2020-01-01
+ *
+ * On the date above, in accordance with the Business Source License, use
+ * of this software will be governed by version 2 or later of the General
+ * Public License.
+ */
+require('./common.js')()
+var colors = require('colors/safe')
+
+function equalResources(oldVal, newVal) {
+    return _.isEqual(oldVal.attributes.parameters, newVal.attributes.parameters) &&
+        _.isEqual(_.get(oldVal, 'relationships.servers.data'), _.get(newVal, 'relationships.servers.data')) &&
+        _.isEqual(_.get(oldVal, 'relationships.services.data'), _.get(newVal, 'relationships.services.data')) &&
+        _.isEqual(_.get(oldVal, 'relationships.monitors.data'), _.get(newVal, 'relationships.monitors.data'))
+}
+
+function sameResource(oldVal, newVal) {
+    return oldVal.id == newVal.id
+}
+
+// Return objets that are in <a> but not in <b>
+function getDifference(a, b) {
+    return _.differenceWith(a, b, sameResource)
+}
+
+function getChangedObjects(a, b) {
+    var ours = _.intersectionWith(a, b, sameResource)
+    var theirs = _.intersectionWith(b, a, sameResource)
+    return _.differenceWith(ours, theirs, equalResources)
+}
+
+exports.command = 'cluster <command>'
+exports.desc = 'Cluster objects'
+exports.handler = function() {}
+exports.builder = function(yargs) {
+    yargs
+        .command('diff <a> <b>', 'Show differences of <a> when compared with <b>. ' +
+                 'Values must be in HOST:PORT format', {}, function(argv) {
+
+            // Sort of a hack-ish way to force only one iteration of this command
+            argv.hosts = [argv.a]
+
+            maxctrl(argv, function(host) {
+                const collections = [
+                    'servers',
+                    'monitors',
+                    'services',
+                    'users'
+                ]
+                const endpoints = [
+                    'maxscale',
+                    'maxscale/logs'
+                ]
+
+                var src = {}
+                var dest = {}
+                var promises = []
+
+                collections.forEach(function(i) {
+                    promises.push(doAsyncRequest(argv.b, i, function(res) {
+                        dest[i] = res
+                    }))
+                    promises.push(doAsyncRequest(argv.a, i, function(res) {
+                        src[i] = res
+                    }))
+                })
+
+                endpoints.forEach(function(i) {
+                    promises.push(doAsyncRequest(argv.b, i, function(res) {
+                        dest[i] = res
+                    }))
+                    promises.push(doAsyncRequest(argv.a, i, function(res) {
+                        src[i] = res
+                    }))
+                })
+
+                return Promise.all(promises)
+                    .then(function() {
+                        collections.forEach(function(i) {
+                            var newObj = getDifference(src[i].data, dest[i].data)
+                            var oldObj = getDifference(dest[i].data, src[i].data)
+                            var changed = getChangedObjects(src[i].data, dest[i].data)
+
+                            if (newObj.length) {
+                                logger.log("New:", i)
+                                logger.log(colors.green(JSON.stringify(newObj, null, 4)))
+                            }
+                            if (oldObj.length) {
+                                logger.log("Deleted:", i)
+                                logger.log(colors.red(JSON.stringify(oldObj, null, 4)))
+                            }
+                            if (changed.length) {
+                                logger.log("Changed:", i)
+                                logger.log(colors.yellow(JSON.stringify(changed, null, 4)))
+                            }
+                        })
+                        endpoints.forEach(function(i) {
+                            // Treating the resource endpoints as arrays allows
+                            // the same functions to be used to compare
+                            // individual resources and resource collections
+                            var changed = getChangedObjects([src[i].data], [dest[i].data])
+                            if (changed.length) {
+                                logger.log("Changed:", i)
+                                logger.log(colors.yellow(JSON.stringify(changed, null, 4)))
+                            }
+                        })
+                    })
+            })
+        })
+        .usage('Usage: cluster <command>')
+        .help()
+        .command('*', 'the default command', {}, function(argv) {
+            maxctrl(argv, function() {
+                return error('Unknown command. See output of `help cluster` for a list of commands.')
+            })
+        })
+}

maxctrl/lib/core.js

@@ -78,6 +78,7 @@ program
     .command(require('./alter.js'))
     .command(require('./rotate.js'))
     .command(require('./call.js'))
+    .command(require('./cluster.js'))
     .help()
     .demandCommand(1, 'At least one command is required')
     .command('*', 'the default command', {}, function(argv) {