Prometheus Alertmanager MCP Server

Implementation Reference

• src/index.ts:357-386 (handler)

  The handler function that executes the get-alert-groups tool. It constructs query parameters based on input options (active, silenced, inhibited), fetches alert groups from the Alertmanager API endpoint `/api/v2/alerts/groups`, formats the response as JSON text, and handles errors appropriately.

  async ({ active = true, silenced = false, inhibited = false }) => {
    try {
      // Build query parameters
      const params = new URLSearchParams();
      if (!active) params.append("active", "false");
      if (silenced) params.append("silenced", "true");
      if (inhibited) params.append("inhibited", "true");
      
      // Fetch alert groups
      const queryString = params.toString();
      const path = `alerts/groups${queryString ? '?' + queryString : ''}`;
      const groups = await fetchFromAlertmanager(path);
      
      return {
        content: [{
          type: "text",
          text: JSON.stringify(groups, null, 2)
        }]
      };
    } catch (error: unknown) {
      const errorMessage = error instanceof Error ? error.message : String(error);
      return {
        content: [{
          type: "text",
          text: `Error fetching alert groups: ${errorMessage}`
        }],
        isError: true
      };
    }
  }

• src/index.ts:352-356 (schema)

  Zod schema defining the input parameters for the get-alert-groups tool: optional booleans for filtering active, silenced, and inhibited alerts.

  {
    active: z.boolean().optional().describe("Include active alerts (default: true)"),
    silenced: z.boolean().optional().describe("Include silenced alerts"),
    inhibited: z.boolean().optional().describe("Include inhibited alerts"),
  },

• src/index.ts:350-387 (registration)

  The registration of the get-alert-groups tool using McpServer's tool() method, specifying the name, input schema, and handler function.

  server.tool(
    "get-alert-groups",
    {
      active: z.boolean().optional().describe("Include active alerts (default: true)"),
      silenced: z.boolean().optional().describe("Include silenced alerts"),
      inhibited: z.boolean().optional().describe("Include inhibited alerts"),
    },
    async ({ active = true, silenced = false, inhibited = false }) => {
      try {
        // Build query parameters
        const params = new URLSearchParams();
        if (!active) params.append("active", "false");
        if (silenced) params.append("silenced", "true");
        if (inhibited) params.append("inhibited", "true");
        
        // Fetch alert groups
        const queryString = params.toString();
        const path = `alerts/groups${queryString ? '?' + queryString : ''}`;
        const groups = await fetchFromAlertmanager(path);
        
        return {
          content: [{
            type: "text",
            text: JSON.stringify(groups, null, 2)
          }]
        };
      } catch (error: unknown) {
        const errorMessage = error instanceof Error ? error.message : String(error);
        return {
          content: [{
            type: "text",
            text: `Error fetching alert groups: ${errorMessage}`
          }],
          isError: true
        };
      }
    }
  );

• src/index.ts:16-41 (helper)

  Shared helper function used by get-alert-groups (and other tools) to make HTTP requests to the Alertmanager API with timeout handling, error management, and JSON response parsing.

  async function fetchFromAlertmanager(path: string, options: RequestInit = {}): Promise<any> {
    const baseUrl = process.env.ALERTMANAGER_URL || DEFAULT_ALERTMANAGER_URL;
    const url = `${baseUrl}/api/v2/${path}`;
    
    try {
      const controller = new AbortController();
      const timeoutId = setTimeout(() => controller.abort(), DEFAULT_TIMEOUT);
      
      const response = await fetch(url, {
        ...options,
        signal: controller.signal
      });
      
      clearTimeout(timeoutId);
      
      if (!response.ok) {
        throw new Error(`Alertmanager API error: ${response.status} ${response.statusText}`);
      }
      
      return await response.json();
    } catch (error: unknown) {
      const errorMessage = error instanceof Error ? error.message : String(error);
      console.error(`Error fetching from Alertmanager: ${errorMessage}`);
      throw error;
    }
  }