canary-log-viewer/canary-log-viewer.ts

import readline from "readline";
import fs from "fs";
import yargs from "yargs";
import packageJson from "./package.json";

import * as Rx from "rxjs";

import { hideBin } from "yargs/helpers";
import { map, pluck, takeUntil, filter, window, mergeAll, buffer } from "rxjs/operators";


const args = yargs(hideBin(process.argv))
    .scriptName(Object.keys(packageJson.bin)[0])
    .usage(`Usage:
  $0 logfile`)
    .option("files", {
        boolean: true,
        describe: "Extract and save the embedded files from the log file"
    })
    .argv;

const argsParam0 = args._[0]?.toString();

type LogLine = {
    log: string;
    stream: string;
    time: string;
};

const rl = readline.createInterface({
    input: fs.createReadStream(argsParam0)
});

const readlineObservable = Rx.fromEvent<string>(rl, "line")
    .pipe(
        takeUntil(Rx.fromEvent(rl, "close"))
    );

const fileWindowStartObservable = readlineObservable
    .pipe(
        filter(rawLine => rawLine.includes("Dumping image"))
    );

const fileWindowStopObservable = readlineObservable
    .pipe(
        filter(rawLine => rawLine.includes("\\u003c\\u003c\\u003c\\u003c"))
    );

const logObservable = readlineObservable
    .pipe(
        window(Rx.merge(fileWindowStartObservable, fileWindowStopObservable)),
        filter((_, i) => i % 2 === (args.files ? 1 : 0)), //keep every second observable for the files stream
        mergeAll(),
        filter(rawLine => !rawLine.includes("\\u003c\\u003c\\u003c\\u003c")),
        map<string, LogLine>(line => JSON.parse(line)),
        pluck("log"),
        map(log => log.replace(/\n$/, ""))
    );

if (args.files) {
    logObservable
        .pipe(
            buffer(fileWindowStopObservable),
            map(fileLines => ({ name: fileLines.shift()?.substring(10), content: fileLines.join() }))
        )
        .subscribe({
            next: file => {
                const filename = `${argsParam0}.${file.name}`;
                fs.writeFile(filename, Buffer.from(file.content, "base64"), () => {
                    console.log(`File ${filename} is saved.`)
                });
            },
            error: console.error,
            complete: () => rl.close()
        });
} else {
    logObservable.subscribe({
        next: console.log,
        error: console.error,
        complete: () => rl.close()
    });
}