Prometheus Alertmanager MCP Server

Implementation Reference

• src/index.ts:108-154 (handler)

  The handler function that executes the 'get-alerts' tool: builds query params based on inputs, fetches alerts from Alertmanager, formats them into a structured response, and handles errors.

  async ({ filter, silenced = false, inhibited = false, active = true }) => {
    try {
      // Build query parameters
      const params = new URLSearchParams();
      if (filter) params.append("filter", filter);
      if (silenced) params.append("silenced", "true");
      if (inhibited) params.append("inhibited", "true");
      if (!active) params.append("active", "false");
      
      // Fetch alerts
      const queryString = params.toString();
      const path = `alerts${queryString ? '?' + queryString : ''}`;
      const alerts = await fetchFromAlertmanager(path) as Alert[];
      
      // Format alerts
      const formattedAlerts = alerts.map((alert: Alert): FormattedAlert => ({
        fingerprint: alert.fingerprint,
        alertname: alert.labels.alertname,
        severity: alert.labels.severity || 'unknown',
        summary: alert.annotations.summary || 'No summary provided',
        description: alert.annotations.description || 'No description provided',
        startsAt: alert.startsAt,
        status: {
          state: alert.status.state,
          silenced: alert.status.silencedBy.length > 0,
          inhibited: alert.status.inhibitedBy.length > 0,
        },
        labels: alert.labels,
      }));
      
      return {
        content: [{
          type: "text",
          text: JSON.stringify(formattedAlerts, null, 2)
        }]
      };
    } catch (error: unknown) {
      const errorMessage = error instanceof Error ? error.message : String(error);
      return {
        content: [{
          type: "text",
          text: `Error fetching alerts: ${errorMessage}`
        }],
        isError: true
      };
    }
  }

• src/index.ts:102-107 (schema)

  Zod input schema defining optional parameters for filtering and including different types of alerts.

  {
    filter: z.string().optional().describe("Filtering query (e.g. alertname=~'.*CPU.*')"),
    silenced: z.boolean().optional().describe("Include silenced alerts"),
    inhibited: z.boolean().optional().describe("Include inhibited alerts"),
    active: z.boolean().optional().describe("Include active alerts (default: true)"),
  },

• src/index.ts:100-155 (registration)

  Registration of the 'get-alerts' tool on the MCP server using server.tool(), specifying name, input schema, and handler function.

  server.tool(
    "get-alerts",
    {
      filter: z.string().optional().describe("Filtering query (e.g. alertname=~'.*CPU.*')"),
      silenced: z.boolean().optional().describe("Include silenced alerts"),
      inhibited: z.boolean().optional().describe("Include inhibited alerts"),
      active: z.boolean().optional().describe("Include active alerts (default: true)"),
    },
    async ({ filter, silenced = false, inhibited = false, active = true }) => {
      try {
        // Build query parameters
        const params = new URLSearchParams();
        if (filter) params.append("filter", filter);
        if (silenced) params.append("silenced", "true");
        if (inhibited) params.append("inhibited", "true");
        if (!active) params.append("active", "false");
        
        // Fetch alerts
        const queryString = params.toString();
        const path = `alerts${queryString ? '?' + queryString : ''}`;
        const alerts = await fetchFromAlertmanager(path) as Alert[];
        
        // Format alerts
        const formattedAlerts = alerts.map((alert: Alert): FormattedAlert => ({
          fingerprint: alert.fingerprint,
          alertname: alert.labels.alertname,
          severity: alert.labels.severity || 'unknown',
          summary: alert.annotations.summary || 'No summary provided',
          description: alert.annotations.description || 'No description provided',
          startsAt: alert.startsAt,
          status: {
            state: alert.status.state,
            silenced: alert.status.silencedBy.length > 0,
            inhibited: alert.status.inhibitedBy.length > 0,
          },
          labels: alert.labels,
        }));
        
        return {
          content: [{
            type: "text",
            text: JSON.stringify(formattedAlerts, null, 2)
          }]
        };
      } catch (error: unknown) {
        const errorMessage = error instanceof Error ? error.message : String(error);
        return {
          content: [{
            type: "text",
            text: `Error fetching alerts: ${errorMessage}`
          }],
          isError: true
        };
      }
    }
  );

• src/index.ts:16-41 (helper)

  Utility function for making API requests to Alertmanager with timeout handling and error management, used by the get-alerts handler.

  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;
    }
  }