monitor.uptime-bars

export function uptimeBars(checks: readonly Check[], now: number, days: number, maxGapSeconds: number): readonly DayBar[]

export type BarState = "operational" | "degraded" | "outage" | "no-data";

/** One UTC day of a status page's uptime history. */
export interface DayBar {
  readonly date: string;
  /** null when nothing that day is known */
  readonly uptimeBasisPoints: number | null;
  readonly upSeconds: number;
  readonly degradedSeconds: number;
  readonly downSeconds: number;
  readonly unknownSeconds: number;
  /** outage if any down second, else degraded if any degraded, else operational; no-data when nothing is known */
  readonly state: BarState;
}

import { uptimeBars } from "#fune/monitor.uptime-bars@^1";

import { type Check } from "./monitor_check_status.ts";  ← from monitor.check-status ^1.0.0 · built alongside by fune
import { uptime } from "./monitor_uptime.ts";  ← from monitor.uptime ^1.0.0 · built alongside by fune
import { unixToIso } from "./time_unix_to_iso.ts";  ← from time.unix-to-iso ^1.0.0 · built alongside by fune
import { type BarState, type DayBar } from "./monitor_uptime_bars_types.ts";

const DAY = 86400;

/**
 * The last `days` UTC days ending with today, oldest first, each measured by
 * monitor.uptime. Today's bar ends at `now`, so it never shows the rest of
 * today as unknown.
 */
export function uptimeBars(checks: readonly Check[], now: number, days: number, maxGapSeconds: number): readonly DayBar[] {
  if (!Number.isSafeInteger(now)) throw new RangeError("now must be whole seconds");
  if (!Number.isSafeInteger(days) || days < 1 || days > 366) throw new RangeError(`days must be 1 to 366, received ${days}`);
  // Floored, not truncated: before 1970 today starts on the earlier midnight.
  const todayStart = now - (((now % DAY) + DAY) % DAY);
  const bars: DayBar[] = [];
  for (let i = days - 1; i >= 0; i--) {
    const start = todayStart - i * DAY;
    const end = i === 0 ? now : start + DAY;
    const r = uptime(checks, start, end, maxGapSeconds);
    let state: BarState;
    if (r.uptimeBasisPoints === null) state = "no-data";
    else if (r.downSeconds > 0) state = "outage";
    else if (r.degradedSeconds > 0) state = "degraded";
    else state = "operational";
    bars.push({
      date: unixToIso(start).slice(0, 10),
      uptimeBasisPoints: r.uptimeBasisPoints,
      upSeconds: r.upSeconds,
      degradedSeconds: r.degradedSeconds,
      downSeconds: r.downSeconds,
      unknownSeconds: r.unknownSeconds,
      state,
    });
  }
  return bars;
}

Install

fune build

With that line in your source, in a TypeScript project (language typescript in fune.project), fune build resolves it and its 3 dependencies, pins them in fune.lock, downloads only the TypeScript package of each, and builds the code above into your project’s .fune/build, one readable file per capability with a header linking back here. Or pin a range in fune.project and build in one step:

fune add monitor.uptime-bars

The manifest, vectors and README with only the TypeScript implementation. Install it without the registry with fune add ./monitor.uptime-bars-1.0.0-typescript.fune, or fetch it from a terminal with fune pull monitor.uptime-bars@1.0.0:typescript.

The whole function, every language, is one file too: monitor.uptime-bars-1.0.0.fune, 17,393 bytes, sha256 acd1ac7feb44a8df71bcace52d4de9ffefbaaa76498627388340399962540227. It installs into a project of any language.

// fune: before monitor.uptime-bars

// fune: after monitor.uptime-bars

// fune: replace monitor.check-status in monitor.uptime-bars
// fune: replace monitor.uptime in monitor.uptime-bars
// fune: replace time.unix-to-iso in monitor.uptime-bars

// fune: step monitor.uptime-bars after <n|label>

More from the author

## Days

- Days are UTC calendar days, `date` is `YYYY-MM-DD`. Status pages that show local days shift `now` first. - The last bar is today, and it ends at `now`, not midnight, so the part of today that has not happened yet is not reported as unknown. At exactly midnight today's bar is empty (`no-data`). - Midnight is found by flooring, so a `now` before 1970 still lands on the right day (`-1` is 1969-12-31). - Checks after `now` are ignored. - `days` is 1 to 366; 90 is the usual status page.

## State

In order: `no-data` when nothing that day is known; `outage` if any second was down; `degraded` if any second was degraded; otherwise `operational`. Unknown time alone does not change the colour of a day that has some known time: a monitor gap is not an outage. The worst moment decides, the way status pages colour their bars; the uptime figure says how bad the day was.

## Errors

- `now must be whole seconds` - `days must be 1 to 366, received X` - Everything `monitor.uptime` refuses: `maxGapSeconds must be a whole number of at least 1`, `checks must be in strictly ascending time order`, `unknown check status: X`.

Files