Using Logwatch to monitor the Cloudflare DDNS updater script
The Cloudflare DDNS update script's log file has been set up so that utilities like Logwatch can easily parse it. To make that happen, a LogFile Group file, Service and Script have to be created for Logwatch to generate reports. The correct (general) directory structure has been created in this git archive already. Below are the details of each file.
You can implement this setup easily by copying it into your /etc/logwatch directory and then modifying the files as necessary:
cd /etc/logwatch
cp -R /path/to/CloudflareDDNS_repo/etc/logwatch/* ./
If you need help getting logwatch installed and set-up, please check out my blog post.
IMPORTANT: Starting with version 3.0 of the
cfddnsscript, you MUST use the--fmt-syslogparameter when running thecfddnsscript. Otherwise, your log file will be in JSON format, and the supplied templates will not work.
Contents
- Using Logwatch to monitor the Cloudflare DDNS updater script
LogFile Group file
This file is located within the repo at /etc/logwatch/conf/logfiles/cfddns.conf
Log file location
Update this as needed to point to the location and name of the log file generated by the updater script. Remember, by default, the log file is created in the same directory as the script itself.
LogFile = /path/to/your/cfddns.log
...
Best practices suggest you use the --log-file flag to change this location to something like /var/log/cfddns.log,
for
example. In that case, the entry would look like:
LogFile = /var/log/cfddns.log
...
Archive location and name format
If you want Logwatch to process old (archived) log files generated by something like Logrotate, then you have to specify the location and file name format of those files. I've included the generalized compressed format of such rotated files as the default in the script. Suppose you store your log files in the recommended location (/var/log/) and are using Logrotate with compression enabled, the archive line would look like:
...
Archive = /var/log/cfddns.log.?.gz
...
This would tell Logwatch, when the archive option is set to true, that your cfddns.log files are archived as: cfddns.log.1.gz, cfddns.log.2.gz, etc. and are all located in /var/log/.
Note: This line is totally optional and only used if you set the archive option in Logwatch to true. You can comment/delete this line if you wish.
External script for timestamp processing
Since the log file uses a non-standard (according to Logwatch) method of date-stamping, a custom filter had to be created. See the relevant section of this document for more information.
The script file is called with an asterisk (*) before the filename.
...
*iso8601timestamp
...
If you change the name of this file, you will have to change this line. Remember that whatever you type here as a name is converted to all-lowercase so your filename should be all lowercase also.
Service definition file
This file is located within the repo at /etc/logwatch/conf/services/cfddns.conf
LogFile Group file definition
The service file needs to know what group of log files it is responsible for processing. This MUST match the name of your LogFile Group file:
LogFile = cfddns
...
If you change your LogFile Group filename, then update it here also without the .conf extension.
Report title
The Logwatch output file (HTML or text) is divided into sections. You can define the title to be anything that has meaning for you. I have arbitrarily chosen "CloudFlare DDNS update" but you can change it to anything you want by modifying the line:
...
Title = "CloudFlare DDNS update"
Detail level
If you want to set the detail level of this service differently from your other services (which will use the --detail switch value or the value in your logwatch.conf), then you can define that level here. By default, it appears like this in the service configuration file:
...
# Override the detail level for this service
# Remember the levels are: 0, 1-4, 5, 6+
# Detail = 0
Simply change it to the value you want enforced. For example, here I'm setting it to output level 5 regardless of whatever settings everything else is using.
# Override the detail level for this service
# Remember the levels are: 0, 1-4, 5, 6+
Detail = 5
Service script
This file is located within the repo at /etc/logwatch/scripts/services/cfddns
Logwatch calls any script with a name that matches the service name. You'll notice that I just named everything cfddns to keep things simple. You can change this to whatever you want. If you changed the service name to "cloudflare.conf", for example, you would have to rename this script file to "cloudflare" with no extension. Note: The script is a PERL file (note the shebang), but it can be written in any language.
In essence, Logwatch just spits out the log file(s) defined in the LogFile Group file as standard input (STDIN) for the script and then takes whatever is output (STDOUT) from the script to assemble into its report.
Detail levels
The script supports four (4) detail levels as follows:
-
Level 0: Summary output only
-
This will display a simple aggregate of status message categories over the reporting period:
- Entries successfully updated
- Entries already up to date
- Hosts failed to update
- Undefined hosts (i.e. requested to update but record doesn’t exist)
- Total warning messages
- Total errors
-
This is the recommended reporting level. It does not take up much space and is quick to read. If you see successful updates and/or up-to-date numbers match what you expect and no errors logged, then you can assume things are working properly. If the numbers aren’t right or you see errors/warnings, then you can investigate the situation by consulting the actual logs or increasing the detail level in logwatch.
-
For example, let’s suppose you are running an update every 15 minutes. Doing the math...
(update_{success}) + (update_{up-to-date}) = (24h \times 60min)/15min = 96Therefore, you expect to see ‘Entries successfully updated’ and ‘Entries already up to date’ total 96. If that’s the case and no errors or warnings are logged, things are ok. Pretty easy, right? That’s why this is the recommended filter setting.
-
-
Levels 1-4: Critical messages
- This uses the data which is summarized by Level 0 but outputs the actual messages in the log file. For example, you will see the actual text of the errors logged instead of just a total number of errors. This level of reporting is useful when initially monitoring the script's operation since you can see the text of any generated errors.
- Levels 1, 2, 3 & 4 are identical, so pick your favourite number.
-
Level 5: Verbose output
- Like the previous level, this outputs the actual messages found in the log file. However, it also includes CF-ERR tags and tally count messages. This can help you pinpoint why the Cloudflare API is rejecting your requests by letting you see things like authentication errors or malformed addresses, etc.
- Honestly, this is not much more information than L1-L4 and is often a better choice while debugging any issues since you get the Cloudflare API messages.
- This level of output is much more verbose than the summary report. It also takes much more time and patience to review, so it is only recommended when you’re dealing with issues.
- This is not recommended for day-to-day or routine reports.
-
Levels 6+: Complete log file dump
- Any number greater than 5 passed as a detail level will trigger the script to dump the entire log file out to Logwatch line-by-line. This is really only useful during debugging or dealing with serious issues where you do not have access to the actual log file.
- Use this detail level only when you need to see the entire log file and cannot otherwise access the log file.
Timestamp processing script
This file is located within the repo at /etc/logwatch/scripts/shared/iso8601timestamp
This is a modified version of the 'applyeurodate' script that comes with Logwatch. If you change
the 'stamp' variable in the cfddns script to modify the timestamp to your liking (which is totally fine!) then
you'll probably have to update this file. There are two lines you need to modify to suit your new 'stamp' variable.
This entire section is only applicable if you are an inquisitive person or if you change the hard-coded ‘stamp’ function in the script. If you did not make any changes and you like a little mystery in your life, you can safely skip this entire section.
The time format specification
'$SearchDate' is the variable used in the PERL script to do exactly what it says, search for the date stamp. I have it set up to look for the format 'year-month-dateThour:minute:secondZ', which is the ISO-8601 format.
...
$SearchDate = TimeFilter('%Y-%m-%dT%H:%M:%SZ');
...
If you changed the 'stamp' variable so it was formatted as 'month/day/year hour:minute' (ex: '09/27/2018 18:38') then you'd update the $SearchDate variable as follows:
...
$SearchDate = TimeFilter('%m/%d/%Y %H:%M');
...
The search REGEX
The PERL script uses a 'regular expression' (REGEX) to search within the log file for '$SearchDate'. For the default date stamp, this specification looks like:
...
if ($ThisLine =~ m/^$SearchDate /o) {
...
The REGEX appears between 'm/' and '/o'. In this case, it searches for '$SearchDate' appearing at the beginning (^) of the line. If you want to search anywhere in the line instead of the beginning, remove the caret (^):
...
if ($ThisLine =~ m/$SearchDate /o) {
...
or maybe you changed the date stamp to appear in square brackets at the start of the line:
...
if ($ThisLine =~ m/^\[$SearchDate\] /o) {
...
Testing
Run logwatch --help and note the options. You can test just this service locally on your screen with the following command (assuming you kept default names for everything):
# Summary output, entire duration of the log file
logwatch --service cfddns --output stdout --format text --range all --detail 0
# Minimal detail, yesterday only
logwatch --service cfddns --output stdout --format text --range yesterday --detail 1
# Verbose output, today only
logwatch --service cfddns --output stdout --format text --range today --detail 5
Final thoughts
That's it! I'm a horrible PERL programmer, so if anyone can optimize/improve the script file used for Logwatch, then please do it! Otherwise, I hope this made sense and helped you integrate the updater script with Logwatch for easy monitoring :-)