76 lines
2.2 KiB
JavaScript
76 lines
2.2 KiB
JavaScript
const { StatusCodes } = require("http-status-codes");
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const { sum, sumBy } = require("lodash");
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const db = require("../db");
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/**
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* Get status code that should be returned in the API response.
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* - OK (200) in case everything is healthy
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* - SERVICE_UNAVAILABLE (503) in case of any failures or if disabled
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*/
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function getStatusCode() {
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// check whether the portal has been manually disabled
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const disabled = getDisabled();
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if (disabled) {
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return StatusCodes.SERVICE_UNAVAILABLE;
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}
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// grab the most recent critical entry element from DB
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const entry = getMostRecentCriticalEntry();
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// in case there is no entry yet or at least one check failed in the most recent entry
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if (!entry || entry.checks.some(({ up }) => !up)) {
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return StatusCodes.SERVICE_UNAVAILABLE;
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}
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return StatusCodes.OK;
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}
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/**
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* Get the sample of most recent critical entries and
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* calculate the average response time of all of them
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*/
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function getAverageResponseTime() {
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// get most recent 10 successfull checks for the calculation
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const sample = db
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.get("critical")
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.orderBy("date", "desc")
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.filter(({ checks }) => checks.every(({ up }) => up))
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.take(10)
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.value();
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// calculate average time of response
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return Math.round(sum(sample.map(({ checks }) => sumBy(checks, "time"))) / sample.size);
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}
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/**
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* Get one, most current critical entry
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*/
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function getMostRecentCriticalEntry() {
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return db.get("critical").orderBy("date", "desc").head().value();
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}
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/**
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* Get the disabled flag state (manual portal disable)
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*/
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function getDisabled() {
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return db.get("disabled").value();
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}
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module.exports = (req, res) => {
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const statusCode = getStatusCode();
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const timeout = statusCode === StatusCodes.OK ? getAverageResponseTime() : 0;
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// We want to delay the response for the load balancer to be able to prioritize
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// servers based on the successful response time of this endpoint. Load balancer
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// will pull the server if the response is an error so there is no point in delaying
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// failures, hence 0 timeout on those.
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setTimeout(() => {
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// include some health information in the response body
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const entry = getMostRecentCriticalEntry();
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const disabled = getDisabled();
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res.status(statusCode).send({ disabled, entry });
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}, timeout);
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};
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