Monitor Conditions (#5048)

db/knex_migrations/2024-08-24-0000-conditions.js

@@ -0,0 +1,12 @@
+exports.up = function (knex) {
+    return knex.schema
+        .alterTable("monitor", function (table) {
+            table.text("conditions").notNullable().defaultTo("[]");
+        });
+};
+
+exports.down = function (knex) {
+    return knex.schema.alterTable("monitor", function (table) {
+        table.dropColumn("conditions");
+    });
+};

server/client.js

@@ -213,6 +213,32 @@ async function sendRemoteBrowserList(socket) {
     return list;
 }
 
+/**
+ * Send list of monitor types to client
+ * @param {Socket} socket Socket.io socket instance
+ * @returns {Promise<void>}
+ */
+async function sendMonitorTypeList(socket) {
+    const result = Object.entries(UptimeKumaServer.monitorTypeList).map(([ key, type ]) => {
+        return [ key, {
+            supportsConditions: type.supportsConditions,
+            conditionVariables: type.conditionVariables.map(v => {
+                return {
+                    id: v.id,
+                    operators: v.operators.map(o => {
+                        return {
+                            id: o.id,
+                            caption: o.caption,
+                        };
+                    }),
+                };
+            }),
+        }];
+    });
+
+    io.to(socket.userID).emit("monitorTypeList", Object.fromEntries(result));
+}
+
 module.exports = {
     sendNotificationList,
     sendImportantHeartbeatList,
@@ -222,4 +248,5 @@ module.exports = {
     sendInfo,
     sendDockerHostList,
     sendRemoteBrowserList,
+    sendMonitorTypeList,
 };

server/model/monitor.js

@@ -164,6 +164,7 @@ class Monitor extends BeanModel {
             snmpOid: this.snmpOid,
             jsonPathOperator: this.jsonPathOperator,
             snmpVersion: this.snmpVersion,
+            conditions: JSON.parse(this.conditions),
         };
 
         if (includeSensitiveData) {

server/monitor-conditions/evaluator.js

@@ -0,0 +1,71 @@
+const { ConditionExpressionGroup, ConditionExpression, LOGICAL } = require("./expression");
+const { operatorMap } = require("./operators");
+
+/**
+ * @param {ConditionExpression} expression Expression to evaluate
+ * @param {object} context Context to evaluate against; These are values for variables in the expression
+ * @returns {boolean} Whether the expression evaluates true or false
+ * @throws {Error}
+ */
+function evaluateExpression(expression, context) {
+    /**
+     * @type {import("./operators").ConditionOperator|null}
+     */
+    const operator = operatorMap.get(expression.operator) || null;
+    if (operator === null) {
+        throw new Error("Unexpected expression operator ID '" + expression.operator + "'. Expected one of [" + operatorMap.keys().join(",") + "]");
+    }
+
+    if (!Object.prototype.hasOwnProperty.call(context, expression.variable)) {
+        throw new Error("Variable missing in context: " + expression.variable);
+    }
+
+    return operator.test(context[expression.variable], expression.value);
+}
+
+/**
+ * @param {ConditionExpressionGroup} group Group of expressions to evaluate
+ * @param {object} context Context to evaluate against; These are values for variables in the expression
+ * @returns {boolean} Whether the group evaluates true or false
+ * @throws {Error}
+ */
+function evaluateExpressionGroup(group, context) {
+    if (!group.children.length) {
+        throw new Error("ConditionExpressionGroup must contain at least one child.");
+    }
+
+    let result = null;
+
+    for (const child of group.children) {
+        let childResult;
+
+        if (child instanceof ConditionExpression) {
+            childResult = evaluateExpression(child, context);
+        } else if (child instanceof ConditionExpressionGroup) {
+            childResult = evaluateExpressionGroup(child, context);
+        } else {
+            throw new Error("Invalid child type in ConditionExpressionGroup. Expected ConditionExpression or ConditionExpressionGroup");
+        }
+
+        if (result === null) {
+            result = childResult; // Initialize result with the first child's result
+        } else if (child.andOr === LOGICAL.OR) {
+            result = result || childResult;
+        } else if (child.andOr === LOGICAL.AND) {
+            result = result && childResult;
+        } else {
+            throw new Error("Invalid logical operator in child of ConditionExpressionGroup. Expected 'and' or 'or'. Got '" + group.andOr + "'");
+        }
+    }
+
+    if (result === null) {
+        throw new Error("ConditionExpressionGroup did not result in a boolean.");
+    }
+
+    return result;
+}
+
+module.exports = {
+    evaluateExpression,
+    evaluateExpressionGroup,
+};

server/monitor-conditions/expression.js

@@ -0,0 +1,111 @@
+/**
+ * @readonly
+ * @enum {string}
+ */
+const LOGICAL = {
+    AND: "and",
+    OR: "or",
+};
+
+/**
+ * Recursively processes an array of raw condition objects and populates the given parent group with
+ * corresponding ConditionExpression or ConditionExpressionGroup instances.
+ * @param {Array} conditions Array of raw condition objects, where each object represents either a group or an expression.
+ * @param {ConditionExpressionGroup} parentGroup The parent group to which the instantiated ConditionExpression or ConditionExpressionGroup objects will be added.
+ * @returns {void}
+ */
+function processMonitorConditions(conditions, parentGroup) {
+    conditions.forEach(condition => {
+        const andOr = condition.andOr === LOGICAL.OR ? LOGICAL.OR : LOGICAL.AND;
+
+        if (condition.type === "group") {
+            const group = new ConditionExpressionGroup([], andOr);
+
+            // Recursively process the group's children
+            processMonitorConditions(condition.children, group);
+
+            parentGroup.children.push(group);
+        } else if (condition.type === "expression") {
+            const expression = new ConditionExpression(condition.variable, condition.operator, condition.value, andOr);
+            parentGroup.children.push(expression);
+        }
+    });
+}
+
+class ConditionExpressionGroup {
+    /**
+     * @type {ConditionExpressionGroup[]|ConditionExpression[]} Groups and/or expressions to test
+     */
+    children = [];
+
+    /**
+     * @type {LOGICAL} Connects group result with previous group/expression results
+     */
+    andOr;
+
+    /**
+     * @param {ConditionExpressionGroup[]|ConditionExpression[]} children Groups and/or expressions to test
+     * @param {LOGICAL} andOr Connects group result with previous group/expression results
+     */
+    constructor(children = [], andOr = LOGICAL.AND) {
+        this.children = children;
+        this.andOr = andOr;
+    }
+
+    /**
+     * @param {Monitor} monitor Monitor instance
+     * @returns {ConditionExpressionGroup|null} A ConditionExpressionGroup with the Monitor's conditions
+     */
+    static fromMonitor(monitor) {
+        const conditions = JSON.parse(monitor.conditions);
+        if (conditions.length === 0) {
+            return null;
+        }
+
+        const root = new ConditionExpressionGroup();
+        processMonitorConditions(conditions, root);
+
+        return root;
+    }
+}
+
+class ConditionExpression {
+    /**
+     * @type {string} ID of variable
+     */
+    variable;
+
+    /**
+     * @type {string} ID of operator
+     */
+    operator;
+
+    /**
+     * @type {string} Value to test with the operator
+     */
+    value;
+
+    /**
+     * @type {LOGICAL} Connects expression result with previous group/expression results
+     */
+    andOr;
+
+    /**
+     * @param {string} variable ID of variable to test against
+     * @param {string} operator ID of operator to test the variable with
+     * @param {string} value Value to test with the operator
+     * @param {LOGICAL} andOr Connects expression result with previous group/expression results
+     */
+    constructor(variable, operator, value, andOr = LOGICAL.AND) {
+        this.variable = variable;
+        this.operator = operator;
+        this.value = value;
+        this.andOr = andOr;
+    }
+}
+
+module.exports = {
+    LOGICAL,
+    ConditionExpressionGroup,
+    ConditionExpression,
+};