following a log file over http

Question

For security reasons (I'm a developer) I do not have command line access to our Production servers where log files are written. I can , however access those log files over HTTP. Is there a utility in the manner of "tail -f" that can "follow" a plain text file using only HTTP?

Answer 1

You can do this if the HTTP server accepts requests to return parts of a resource. For example, if an HTTP request contains the header:

Range: bytes=-500

the response will contain the last 500 bytes of the resource. You can fetch that and then parse it into lines, etc. I don't know of any ready-made clients which will do this for you - I'd write a script to do the job.

You can use Hurl to experiment with headers (from publicly available resources).

Answer 2

I wrote a bash script for the same purpose. You can find it here https://github.com/maksim07/url-tail

Answer 3

You can use small java utility to read log file over Http using Apche HTTP Library.

HttpClient client = HttpClientBuilder.create().build();
    HttpGet request = new HttpGet(uri);
    HttpResponse response = client.execute(request);
    BufferedReader rd = new BufferedReader(new InputStreamReader(
            response.getEntity().getContent()));
    String s = "";
    while ((s = rd.readLine()) != null) {
       //Process the line
    }

Answer 4

You can use PsExec to execute command on remote computer. The tail command for windows can be found at http://tailforwin32.sourceforge.net/

If it has to be HTTP, you can write a light weight web service to achieve that easily. eg, read text within a specified file from line 0 to line 200.

Answer 5

I wrote a simple bash script to fetch URL content each 2 seconds and compare with local file output.txt then append the diff to the same file

I wanted to stream AWS amplify logs in my Jenkins pipeline

while true; do comm -13 --output-delimiter="" <(cat output.txt) <(curl -s "$URL") >> output.txt; sleep 2; done

don't forget to create empty file output.txt file first

: > output.txt

view the stream :

tail -f output.txt

UPDATE:

I found better solution using wget here:

while true; do wget -ca -o /dev/null -O output.txt "$URL"; sleep 2; done

https://superuser.com/a/514078/603774