Initial Commit

README.md

 # bash-http-monitoring
-HTTP(s) monitoring webpage via shell script
+
+HTTP(s) monitoring webpage via shell script. 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.
+
+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.
+
+Author: [Remy van Elst][6]
+
+## Screenshots 
+
+All checks are okay:
+
+![all is well image][1]
+
+A check has failed:
+
+![failed checks][2]
+
+Here is how it looks with many hosts (also note how fast it executes, 6 seconds):
+
+![many hosts][4]
+
+This is what the early version looked like:
+
+![beta][3]
+
+I had this script running at home for at least a year in that form, 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.
+
+
+## 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`).
+
+Clone the git repository:
+
+	git clone https://github.com/RaymiiOrg/bash-http-monitoring.git
+	cd bash-http-monitoring
+
+Edit the `srvmon.sh` 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[gist.github.com]=302
+
+The first part between the square brackets must match the `urls[]` part.
+
+Execute the script and send the output to a file in your webservers documentroot:
+
+	bash srvmon.sh > /var/www/index.html
+
+View that file in a web browser.
+
+### 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.sh > /var/www/index.html.tmp && /bin/mv /var/www/index.html.tmp /var/www/index.html
+
+If the check fails for whatever reason, the "old" page will not be overridden.
+
+[1]: okay.png
+[2]: fail.png
+[3]: firstVersion.png
+[4]: many.png
+[5]: https://acme.com/software/micro_httpd/
+[6]: https://raymii.org
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srvmon.sh

+#!/bin/bash
+# author: Remy van Elst - https://raymii.org
+# license: gnu gpl v3
+
+# Start of configuration.
+
+#array names must not contain spaces, only a-ZA-Z.
+declare -A urls # do not remove this line
+urls[dilbert.com]="https://dilbert.com"
+urls[gist.github.com]="https://gist.github.com"
+urls[github.com]="https://github.com"
+urls[lobste.rs]="https://lobste.rs"
+urls[raymii.org]="https://raymii.org"
+urls[treesforlife.org.uk]="https://treesforlife.org.uk"
+urls[tweakers.net]="https://tweakers.net"
+urls[www.buienradar.nl]="https://www.buienradar.nl"
+urls[www.google.com]="https://www.google.com"
+urls[www.smbc-comics.com]="https://www.smbc-comics.com"
+urls[xkcd.com]="https://xkcd.com"
+
+# The default status code. Can be overriden per URL lower in the script.
+defaultExpectedStatusCode=200
+
+# Expected code for url, key must match urls[]. Only for URL's you consider UP, but for example require authentication
+declare -A statuscode # do not remove this line
+statuscode[gist.github.com]=302
+
+# How many curl checks to run at the same time
+maxConcurrentCurls=12
+
+# Start of script. Do not edit below
+
+
+# We're writing the status code to a file, reading that later on. Why? 
+# Because an array cannot be filled via a subprocess (curl ... &).
+set -e
+shopt -s nullglob
+
+# This function allows the script to execute all the curl calls in paralell. 
+# Otherwise, if one would timeout or take long, the rest after that would be
+# slower.
+doRequest() {
+  name="${1}"
+  url="${2}"
+  checkStartTimeMs=$(date +%s%3N) # epoch in microseconds, but stripped so it's milliseconds
+  statuscode=$(curl --max-time 10 --silent --show-error --insecure --output /dev/null --write-out "%{http_code}" "$url" 2>${tempfolder}/FAIL/${name}.error)
+  checkEndTimeMs=$(date +%s%3N)
+  timeCheckTook=$((checkEndTimeMs-checkStartTimeMs))
+  
+  if [[ ! -z ${statuscode[${name}]} ]]; then
+    defaultExpectedStatusCode=${statuscode[${name}]}
+  fi 
+
+  if [[ ${defaultExpectedStatusCode} -eq ${statuscode} ]]; then
+    echo ${timeCheckTook} > ${tempfolder}/OK/${name}.duration
+  else
+    echo ${statuscode} > ${tempfolder}/FAIL/${name}.status
+  fi
+}
+
+writeOkayChecks() {
+  echo "</div></div>"
+  echo "<div class=row><div class=col>"
+  echo "<h2>Checks</h2>"
+  pushd "${tempfolder}/OK" 2>&1 >/dev/null
+  okFiles=(*.duration)
+  okCount=${#okFiles[@]}
+  if [[ okCount -gt 0 ]]; then
+    for filename in "${okFiles[@]}"; do
+      if [[ -r $filename ]]; then
+        value="$(cat $filename)"
+        filenameWithoutExt=${filename%.*}
+        echo -n '<a href="#" class="btn btn-success disabled" tabindex="-1" role="button" aria-disabled="true" style="margin-top: 10px; padding: 10px;">'
+        echo -n "${filenameWithoutExt}"
+        echo -n "<font color=LightGray> ("
+        echo -n ${value}
+        echo -n " ms)</font>"
+        echo -n "</a> &nbsp;"
+      fi
+    done
+  fi
+  popd 2>&1 >/dev/null
+}
+
+writeFailedChecks() {
+  pushd "${tempfolder}/FAIL" 2>&1 >/dev/null
+  failFiles=(*.status)
+  failCount=${#failFiles[@]}
+  if [[ failCount -gt 0 ]]; then
+    echo '<div class="alert alert-danger" role="alert">'
+    echo "Errors occured! ${failCount} check(s) have failed."
+    echo "</div>"
+    echo '<table class="table">'
+    echo '<thead><tr>'
+    echo '<th>Name</th>'
+    echo '<th>HTTP Status/Expected</th>'
+    echo '<th>Error</th>'
+    echo '</tr></thead><tbody>'
+    for filename in "${failFiles[@]}"; do
+      if [[ -r $filename ]]; then
+        filenameWithoutExt=${filename%.*}
+        error="$(cat ${filenameWithoutExt}.error)"
+        status="$(cat ${filename})"
+        echo -n "<tr class='table-danger'><td>"
+        echo -n "${filenameWithoutExt}"
+        echo -n "</td><td>"
+        echo -n "${status} / "
+        if [[ -z ${statuscode[${filenameWithoutExt}]} ]]; then
+          echo -n "200"
+        else
+          echo -n "${statuscode[${filenameWithoutExt}]}"
+        fi
+        echo -n "</td><td>"
+        echo -n "${error}"
+        echo "</td></tr>"
+      fi
+    done
+    echo "</tbody></table>"
+  else 
+    echo '<div class="alert alert-success" role="alert">'
+    echo "All is well, all services are up."
+    echo "</div>"
+  fi
+  popd 2>&1 >/dev/null
+}
+
+cleanupFailedCheckFiles() {
+  pushd "${tempfolder}/FAIL" 2>&1 >/dev/null
+  errorFiles=(*.error)
+  errorCount=${#errorFiles[@]}
+  for filename in "${errorFiles[@]}"; do
+    if [[ -r $filename ]]; then
+      rm "${filename}"
+    fi
+  done
+
+  statusFiles=(*.status)
+  statusCount=${#statusFiles[@]}
+  for filename in "${statusFiles[@]}"; do
+    if [[ -r $filename ]]; then
+      rm "${filename}"
+    fi
+  done
+  popd 2>&1 >/dev/null
+  rmdir "${tempfolder}/FAIL"
+}
+
+cleanupOKCheckFiles() {
+  pushd "${tempfolder}/OK" 2>&1 >/dev/null
+  okFiles=(*.duration)
+  okCount=${#okFiles[@]}
+  for filename in "${okFiles[@]}"; do
+    if [[ -r $filename ]]; then
+      rm "${filename}"
+    fi
+  done
+  popd 2>&1 >/dev/null
+  rmdir "${tempfolder}/OK"
+}
+
+# Total script duration timer
+start=$(date +%s%3N)
+
+tmpdir=$(mktemp -d)
+tempfolder=${tmpdir:-/tmp/statusmon/}
+
+# try to create folders, if it fails, stop the script.
+mkdir -p "${tempfolder}/OK" || exit 1
+mkdir -p "${tempfolder}/FAIL" || exit 1
+
+pushd "${tempfolder}" 2>&1 >/dev/null
+
+# Do the checks parallel
+for key in "${!urls[@]}"
+do
+  value=${urls[$key]}
+  if [[ "$(jobs | wc -l)" -ge ${maxConcurrentCurls} ]] ; then # run 12 curl commands at max parallel
+      wait -n
+  fi
+  doRequest "$key" "$value" &
+done
+wait 
+
+# Header
+
+echo '<!doctype html><html lang="en"><head><meta charset="utf-8"><meta name="viewport" content="width=device-width, initial-scale=1, shrink-to-fit=no">'
+echo '<link rel="stylesheet" href="https://cdn.jsdelivr.net/npm/bootstrap@4.5.3/dist/css/bootstrap.min.css" integrity="sha384-TX8t27EcRE3e/ihU7zmQxVncDAy5uIKz4rEkgIXeMed4M0jlfIDPvg6uqKI2xXr2" crossorigin="anonymous">'
+
+echo "<title>Monitoring</title>"
+echo "</head><body>"
+echo "<div class=container><div class=row><div class=col>"
+echo "<h1>Monitoring</h1>"
+echo "</div></div>"
+echo "<div class=row><div class=col>"
+
+# Failed checks, if any, go on top
+writeFailedChecks;
+
+# Okay checks go below the failed checks
+writeOkayChecks
+
+# Cleanup the status files
+cleanupFailedCheckFiles
+cleanupOKCheckFiles
+
+# Footer
+
+echo "</div></div>"
+echo "<div class=row><div class=col>"
+echo "<h2>Info</h2>"
+echo "<p>Last check: "
+date
+
+# stop the total timer
+end=$(date +%s%3N)
+runtime=$((end-start))
+echo "<br>Total duration: ${runtime} ms"
+
+echo "<br>Monitoring script by <a href='https://raymii.org/'>Remy van Elst</a>. License: GNU AGPLv3. "
+echo "<a href='https://github.com/raymiiorg/bash-http-monitoring'>Source code</a>"
+echo "</p>"
+echo "</div></div></div>"
+echo "</body></html>"
+
+popd 2>&1 >/dev/null
+
+rmdir "${tempfolder}"
\ No newline at end of file