This is a text-only version of the following page on https://raymii.org: --- Title : Bash HTTP monitoring dashboard Author : Remy van Elst Date : 27-12-2020 Last update : 11-01-2021 URL : https://raymii.org/s/software/Bash_HTTP_Monitoring_Dashboard.html Format : Markdown/HTML --- This is a shell script that creates a webpage with the status of HTTP(s) sites. Parallel checking, thus very fast, only dependencies are curl and bash (version 4 or above). For all of you who want a simple script with a nice webpage to check a few websites. Perfect for a wall mounted monitoring display and a Raspberry Pi. Installation and configuration is easy to do inside the script. It scales well, both on the checking side as the information display page (dense on purpose). Failed checks appear right on top for you to act on. I had this script running at home for at least a year. When I showed it to a friend he liked it, asked me to make it public, but before I did that I polished it up a bit. There is a screenshot of that early version on this page. > Screenshot when all checks are green: ![all is well image][1]

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You can set an expected status code and a max timeout per check, so if you consider your site up when it returns a 302 (redirect) or 401 (unauthorized) the script consider that okay. If the status code is not what is configured or there is a timeout or another error, the script considers the check failed. If a check fails, the script will check that specific one again after 5 seconds to prevent flapping. **[Source code here][8] on github.** What this does not have: - Notifications - History There however is the option to set a `callback_url`, whenever a check fails the script will send the status to that URL, allowing you to set up your own history logging or alerting. ### Changelog * 27-12-2020: Initial release * 30-12-2020: Added `cgi-bin`/`docker` support * 11-01-2021: Added callback URL for failed checks ### Installation & Configuration Make sure you have curl installed (`apt install curl`). If you need a very simple webserver, try [micro-httpd, by ACME][5]. (`apt install micro-httpd`). The scripts outputs HTML directly, so setup involves a cronjob that writes that output to a file. You can view that file locally in a web browser, or place it on a webserver. The cronjob setup is for a webserver. Clone the git repository: git clone https://github.com/RaymiiOrg/bash-http-monitoring.git cd bash-http-monitoring Edit the `srvmon` script and add your sites. A few examples are provided. This is the syntax: urls[gists]="https://gist.github.com" urls[lobsters]="https://lobste.rs" urls[raymii.org]="https://raymii.org" urls[example]="http://example.org:3000/this/is/a/test" The first part between the square brackets is the name, the second part between the quotes is the URL you want to monitor. It can be just a domain, an IP or an actual URL, including port and such. If you want to override the default status code for a check, this is the syntax: statuscode[gists]=302 The first part between the square brackets must match the `urls[]` part. Further global configuration options include: maxConcurrentCurls=12 # How many curl checks to run at the same time defaultTimeOut=10 # Max timeout of a check in seconds flapRetry=5 # After how many seconds should we re-check any failed checks? (To prevent flapping) title="Status Dashboard" # Title of the webpage cgi=false # Enable or disable CGI header callbackURL="" # leave empty to disable, otherwise see readme Execute the script and send the output to a file in your webservers documentroot: bash srvmon > /var/www/index.html View that file in a web browser. #### CGI header (Docker) * Update 30-12-2020: This was contributed by [rabbit-of-caerbannog][9] Some HTTP servers, like Apache, support CGI scripts. To make it brief, these are scripts which are handed a HTTP request to reply to. The main advantage of using the script as a CGI script, is that the page is generated on demand and as such, provides a live-view on each page load. If the page is public, this method should be avoided, as it can be easily abused. If you want to set up CGI mode, you need to copy the script to your server CGI directory. You can use `docker` to try this out. Like so: docker run -d -p 9090:80 -v $PWD/srvmon:/usr/local/apache2/cgi-bin/srvmon hypoport/httpd-cgi #### Callback URL This script does not provide other means of alerting or history. If you do want that, you must do a bit of work yourself. The script supports a `callback url`, whenever a check failed, it will do a POST request to a configurable URL with the status and error. This allows you to setup logging, history, graphs or otherwise alerting yourself. No examples are provided as of yet but feel free to open a merge request. The JSON sent is in the following format: { "url": "The configured URL, URL encoded", "name": "The configured name" "expected_status": "The configured expected status code", // as a string "actual_status": "The actual status code", // as a string "error": "descriptive error text (from curl mostly)" } Each failed check results in its own request. No bundling is done. You can use HTTPbin to test locally. HTTPbin is a so called `echo` server, anything that is sent to it is returned for debugging purposes. Set this in the config: callbackURL="http://127.0.0.1:8888/post/" Run httpbin in a local docker: docker run -p 8888:80 kennethreitz/httpbin Configure some failed checks, either a non matching status code or a non-existing domain: Example json data: { "url": "https%3A%2F%2Fgist.github.com", "name": "gist.github.com", "expected_status": "309", "actual_status": "302", "error": "Status code does not match expected code" } Another example: { "url": "https%3A%2F%2Fwww.buiekjhkjhkhkhkjhnradar.nl", "name": "www.buienradar.nl", "expected_status": "200", "actual_status": "000", "error": "curl: (6) Could not resolve host: www.buiekjhkjhkhkhkjhnradar.nl" } #### Cronjob setup If you want to set up a cronjob, send the output to a temp file and when finished, move that temp file over the "actual" file. Otherwise you might end up with an incomplete page when the checks are running. Like so: * * * * * /bin/bash /opt/srvmon/srvmon > /var/www/index.html.tmp && /bin/mv /var/www/index.html.tmp /var/www/index.html Change the folders/paths to your setup. If the check fails for whatever reason, the "old" page will not be overridden. ### Screenshots All checks are okay: ![all is well image][1] A check has failed. All failed checks appear on top: ![failed checks][2] Here is how it looks with many hosts (also note how fast it executes, 5 seconds): ![many hosts][4] This is what the early version looked like: ![beta][3] [1]: /s/inc/img/okay.png [2]: /s/inc/img/fail.png [3]: /s/inc/img/firstVersion.png [4]: /s/inc/img/many.png [5]: https://acme.com/software/micro_httpd/ [8]: https://github.com/RaymiiOrg/bash-http-monitoring [9]: https://github.com/RaymiiOrg/bash-http-monitoring/pull/2 --- License: All the text on this website is free as in freedom unless stated otherwise. This means you can use it in any way you want, you can copy it, change it the way you like and republish it, as long as you release the (modified) content under the same license to give others the same freedoms you've got and place my name and a link to this site with the article as source. This site uses Google Analytics for statistics and Google Adwords for advertisements. You are tracked and Google knows everything about you. Use an adblocker like ublock-origin if you don't want it. All the code on this website is licensed under the GNU GPL v3 license unless already licensed under a license which does not allows this form of licensing or if another license is stated on that page / in that software: This program is free software: you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation, either version 3 of the License, or (at your option) any later version. This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details. You should have received a copy of the GNU General Public License along with this program. If not, see . Just to be clear, the information on this website is for meant for educational purposes and you use it at your own risk. I do not take responsibility if you screw something up. Use common sense, do not 'rm -rf /' as root for example. If you have any questions then do not hesitate to contact me. See https://raymii.org/s/static/About.html for details.