Project: Icinga (Observability and Analysis / Observability)
File: 05-service-monitoring.md

The power of Icinga 2 lies in its modularity. There are thousands of community plugins available next to the standard plugins provided by the . Start your research on and look which services are already . The guides you through the plugin setup, tests and their integration with an or CheckCommand object and host/service objects inside the or . It also adds hints on existing commands. Plugins follow the which is enriched with examples and also code examples to get you started with . All existing Icinga or Nagios plugins work with Icinga 2. Community plugins can be found for example on . The recommended way of setting up these plugins is to copy them into the `PluginDir` directory. If you have plugins with many dependencies, consider creating a custom RPM/DEB package which handles the required libraries and binaries. Configuration management tools such as Puppet, Ansible, Chef or Saltstack also help with automatically installing the plugins on different operating systems. They can also help with installing the required dependencies, e.g. Python libraries, Perl modules, etc. Good plugins provide installations and configuration instructions in their docs and/or README on GitHub. Sometimes dependencies are not listed, or your distribution differs from the one described. Try running the plugin after setup and . Prior to using the check plugin with Icinga 2 you should ensure that it is working properly by trying to run it on the console using whichever user Icinga 2 is running as: RHEL/CentOS/Fedora ```bash sudo -u icinga /usr/lib64/nagios/plugins/checkmysqlhealth --help ``` Debian/Ubuntu ```bash sudo -u nagios /usr/lib/nagios/plugins/checkmysqlhealth --help ``` Additional libraries may be required for some plugins. Please consult the plugin documentation and/or the included README file for installation instructions. Sometimes plugins contain hard-coded paths to other components. Instead of changing the plugin it might be easier to create a symbolic link to make sure it doesn't get overwritten during the next update. Sometimes there are plugins which do not exactly fit your requirements. In that case you can modify an existing plugin or just write your own. Plugins can be scripts (Shell, Python, Perl, Ruby, PHP, etc.) or compiled binaries (C, C++, Go). These scripts/binaries may require additional libraries which must be installed on every system they are executed. Tip Don't test the plugins on your master instance, instead do that on the satellites and clients which execute the checks. There are errors, now what? Typical errors are missing libraries, binaries or packages. Example for a Python plugin which uses the `tinkerforge` module to query a network service: ``` ImportError: No module named tinkerforge.ip_connection ``` Its points to installing the `tinkerforge` Python module. Example for a Perl plugin which uses SNMP: ``` Can't locate Net/SNMP.pm in @INC (you may need to install the Net::SNMP module) ``` Prior to installing the Perl module via CPAN, look for a distribution specific package, e.g. `libnet-snmp-perl` on Debian/Ubuntu or `perl-Net-SNMP` on RHEL/CentOS. If you are not using the default `PluginDir` directory, you can create a custom plugin directory and constant and reference this in the created CheckCommand objects. Create a common directory e.g. `/opt/monitoring/plugins` and install the plugin there. ```bash mkdir -p /opt/monitoring/plugins cp checksnmpint.pl /opt/monitoring/plugins chmod +x /opt/monitoring/plugins/checksnmpint.pl ``` Next create a new global constant, e.g. `CustomPluginDir` in your configuration file: ``` vim /etc/icinga2/constants.conf const PluginDir = "/usr/lib/nagios/plugins" const CustomPluginDir = "/opt/monitoring/plugins" ``` Each plugin requires a object in your configuration which can be used in the or object

Please check if the Icinga 2 package already provides an . If that's the case, thoroughly check the required parameters and integrate the check command into your host and service objects. Best practice is to run the plugin on the CLI with the required parameters first. Example for database size checks with . ```bash /usr/lib64/nagios/plugins/checkmysqlhealth --hostname '127.0.0.1' --username root --password icingar0xx --mode sql --name 'select sum(datalength + indexlength) / 1024 / 1024 from informationschema.tables where tableschema = '\''icinga'\'';' '--name2' 'db_size' --units 'MB' --warning 4096 --critical 8192 ``` The parameter names inside the ITL commands follow the `<command name>_<parameter name>` schema. Navigate into `Commands > External Commands` and search for `mysql_health`. Select `mysql_health` and navigate into the `Fields` tab. In order to access the parameters, the Director requires you to first define the needed custom data fields: `mysqlhealthhostname` `mysqlhealthusername` and `mysqlhealthpassword` `mysqlhealthmode` `mysqlhealthname`, `mysqlhealthname2` and `mysqlhealthunits` `mysqlhealthwarning` and `mysqlhealthcritical` Create a new host template and object where you'll generic settings like `mysqlhealthhostname` (if it differs from the host's `address` attribute) and `mysqlhealthusername` and `mysqlhealthpassword`. Create a new service template for `mysql-health` and set the `mysql_health` as check command. You can also define a default for `mysqlhealthmode`. Next, create a service apply rule or a new service set which gets assigned to matching host objects. Create or modify a host object which stores the generic database defaults and prepares details for a service apply for rule. ``` object Host "icinga2-master1.localdomain" { check_command = "hostalive" address = "..." // Database listens locally, not external vars.mysqlhealthhostname = "127.0.0.1" // Basic database size checks for Icinga DBs vars.databases["icinga"] = { mysqlhealthwarning = 4096 //MB mysqlhealthcritical = 8192 //MB } vars.databases["icingaweb2"] = { mysqlhealthwarning = 4096 //MB mysqlhealthcritical = 8192 //MB } } ``` The host object prepares the database details and thresholds already for advanced rules. It also uses conditions to fetch host specified values, or set default values. ``` apply Service "db-size-" for (db_name => config in host.vars.databases) { check_interval = 1m retry_interval = 30s checkcommand = "mysqlhealth" if (config.mysqlhealthusername) { vars.mysqlhealthusername = config.mysqlhealthusername } else { vars.mysqlhealthusername = "root" } if (config.mysqlhealthpassword) { vars.mysqlhealthpassword = config.mysqlhealthpassword } else { vars.mysqlhealthpassword = "icingar0xx" } vars.mysqlhealthmode = "sql" vars.mysqlhealthname = "select sum(datalength + indexlength) / 1024 / 1024 from informationschema.tables where tableschema = '" + db_name + "';" vars.mysqlhealthname2 = "db_size" vars.mysqlhealthunits = "MB" if (config.mysqlhealthwarning) { vars.mysqlhealthwarning = config.mysqlhealthwarning } if (config.mysqlhealthcritical) { vars.mysqlhealthcritical = config.mysqlhealthcritical } vars += config } ``` This chapter describes how to add a new CheckCommand object for a plugin. Please make sure to follow these conventions when adding a new command object definition: Use whenever possible. The `command` attribute must be an array in `[ ... ]` for shell escaping. Define a unique `prefix` for the command's specific arguments. Best practice is to follow this schema: ``` <command name>_<parameter name> ``` That way you can safely set them on host/service level and you'll always know which command they control. Use command argument default values, e.g. for thresholds. Use like `set_if` definitions. Before starting with the CheckCommand definition, please check the existing objects available inside the ITL. They follow best practices and are maintained by developers and our community. This example picks a new plugin called uploaded to Icinga Exchange in June 2019. First, the plugin and ensure that . Then run it with the `--help` parameter to see the actual parameters (docs might be outdated). ``` ./check_systemd.py --help usage:

[-h] [-c SECONDS] [-e UNIT | -u UNIT] [-v] [-V] [-w SECONDS] ... optional arguments: -h, --help show this help message and exit -c SECONDS, --critical SECONDS Startup time in seconds to result in critical status. -e UNIT, --exclude UNIT Exclude a systemd unit from the checks. This option can be applied multiple times. For example: -e mnt- data.mount -e task.service. -u UNIT, --unit UNIT Name of the systemd unit that is beeing tested. -v, --verbose Increase output verbosity (use up to 3 times). -V, --version show program's version number and exit -w SECONDS, --warning SECONDS Startup time in seconds to result in warning status. ``` The argument description is important, based on this you need to create the command arguments. Tip When you are using the Director, you can prepare the commands as files e.g. inside the `global-templates` zone. Then run the kickstart wizard again to import the commands as external reference. If you prefer to use the Director GUI/CLI, please apply the steps in the `Add Command` form. Start with the basic plugin call without any parameters. ``` object CheckCommand "systemd" { // Plugin name without 'check_' prefix command = [ PluginContribDir + "/check_systemd.py" ] // Use the 'PluginContribDir' constant, see the contributed ITL commands } ``` Run a config validation to see if that works, `icinga2 daemon -C` Next, analyse the plugin parameters. Plugins with a good help output show optional parameters in square brackes. This is the case for all parameters for this plugin. If there are required parameters, use the `required` key inside the argument. The `arguments` attribute is a dictionary which takes the parameters as keys. ``` arguments = { "--unit" = { ... } } ``` If there a long parameter names available, prefer them. This increases readability in both the configuration as well as the executed command line. The argument value itself is a sub dictionary which has additional keys: `value` which references the runtime macro string `description` where you copy the plugin parameter help text into `required`, `set_if`, etc. for advanced parameters, check the chapter. The runtime macro syntax is required to allow value extraction when the command is executed. Tip Inside the Director, store the new command first in order to unveil the `Arguments` tab. Best practice is to use the command name as prefix, in this specific case e.g. `systemd_unit`. ``` arguments = { "--unit" = { value = "$systemdunit$" // The service parameter would then be defined as 'vars.systemdunit = "icinga2"' description = "Name of the systemd unit that is beeing tested." } "--warning" = { value = "$systemd_warning$" description = "Startup time in seconds to result in warning status." } "--critical" = { value = "$systemd_critical$" description = "Startup time in seconds to result in critical status." } } ``` This may take a while -- validate the configuration in between up until the CheckCommand definition is done. Then test and integrate it into your monitoring configuration. Remember: Do it once and right, and never touch the CheckCommand again. Optional arguments allow different use cases and scenarios. Once you have created your really good CheckCommand, please consider sharing it with our community by creating a new PR on . Please also update the documentation for the ITL. Tip Inside the Director, you can render the configuration in the Deployment section. Extract the static configuration object and use that as a source for sending it upstream. Sometimes an existing CheckCommand inside the ITL is missing a

Or you don't need a default parameter value being set. Instead of copying the entire configuration object, you can import an object into another new object. ``` object CheckCommand "http-custom" { import "http" // Import existing http object arguments += { // Use additive assignment to add missing parameters "--key" = { value = "$http_..." // Keep the parameter name the same as with http } } // Override default parameters vars.http_address = "..." } ``` This CheckCommand can then be referenced in your host/service object definitions. Icinga 2 supports the native plugin API specification from the Monitoring Plugins project. It is defined in the guidelines. The Icinga documentation revamps the specification into our own guideline enriched with examples and best practices. The output should be as short and as detailed as possible. The most common cases include: Viewing a problem list in Icinga Web and dashboards Getting paged about a problem Receiving the alert on the CLI or forwarding it to external (ticket) systems Examples: ``` <STATUS>: <A short description what happened> OK: MySQL connection time is fine (0.0002s) WARNING: MySQL connection time is slow (0.5s > 0.1s threshold) CRITICAL: MySQL connection time is causing degraded performance (3s > 0.5s threshold) ``` Icinga supports reading multi-line output where Icinga Web only shows the first line in the listings and everything in the detail view. Example for an end2end check with many smaller test cases integrated: ``` OK: Online banking works. Testcase 1: Site reached. Testcase 2: Attempted login, JS loads. Testcase 3: Login succeeded. Testcase 4: View current state works. Testcase 5: Transactions fine. ``` If the extended output shouldn't be visible in your monitoring, but only for testing, it is recommended to implement the `--verbose` plugin parameter to allow developers and users to debug further. Check for more implementation tips. Tip More debug output also helps when implementing your plugin. Best practice is to have the plugin parameter and handling implemented first, then add it anywhere you want to see more, e.g. from initial database connections to actual query results. Value | Status | Description |--|- 0 | OK | The check went fine and everything is considered working. 1 | Warning | The check is above the given warning threshold, or anything else is suspicious requiring attention before it breaks. 2 | Critical | The check exceeded the critical threshold, or something really is broken and will harm the production environment. 3 | Unknown | Invalid parameters, low level resource errors (IO device busy, no fork resources, TCP sockets, etc.) preventing the actual check. Higher level errors such as DNS resolving, TCP connection timeouts should be treated as `Critical` instead. Whenever the plugin reaches its timeout (best practice) it should also terminate with `Unknown`. Keep in mind that these are service states. Icinga automatically maps the from the returned plugin states. A plugin calculates specific values and may decide about the exit state on its own. This is done with thresholds - warning and critical values which are compared with the actual value. Upon this logic, the exit state is determined. Imagine the following value and defined thresholds: ``` ptc_value = 57.8 warning = 50 critical = 60 ``` Whenever `ptc_value` is higher than warning or critical, it should return the appropriate . The threshold evaluation order also is important: Critical thresholds are evaluated first and superseed everything

Warning thresholds are evaluated second If no threshold is matched, return the OK state Avoid using hardcoded threshold values in your plugins, always add them to the argument parser. Example for Python: ```python import argparse import signal import sys if name == 'main': parser = argparse.ArgumentParser() parser.add_argument("-w", "--warning", help="Warning threshold. Single value or range, e.g. '20:50'.") parser.add_argument("-c", "--critical", help="Critical threshold. Single vluae or range, e.g. '25:45'.") args = parser.parse_args() ``` Users might call plugins only with the critical threshold parameter, leaving out the warning parameter. Keep this in mind when evaluating the thresholds, always check if the parameters have been defined before. ```python if args.critical: if ptc_value > args.critical: print("CRITICAL - ...") sys.exit(2) # Critical if args.warning: if ptc_value > args.warning: print("WARNING - ...") sys.exit(1) # Warning print("OK - ...") sys.exit(0) # OK ``` The above is a simplified example for printing the and using the as exit code. Before diving into the implementation, learn more about required and more best practices below. Threshold ranges can be used to specify an alert window, e.g. whenever a calculated value is between a lower and higher critical threshold. The schema for threshold ranges looks as follows. The `@` character in square brackets is optional. ``` [@]start:end ``` There are a few requirements for ranges: `start <= end`. Add a check in your code and let the user know about problematic values. ``` 10:20 # OK 30:10 # Error ``` `start:` can be omitted if its value is 0. This is the default handling for single threshold values too. ``` 10 # Every value > 10 and < 0, outside of 0..10 ``` If `end` is omitted, assume end is infinity. ``` 10: # < 10, outside of 10.. ``` In order to specify negative infinity, use the `~` character. ``` ~:10 # > 10, outside of -..10 ``` Raise alert if value is outside of the defined range. ``` 10:20 # < 10 or > 20, outside of 10..20 ``` Start with `@` to raise an alert if the value is inside* the defined range, inclusive start/end values. ``` @10:20 # >= 10 and <= 20, inside of 10..20 ``` Best practice is to either implement single threshold values, or fully support ranges. This requires parsing the input parameter values, therefore look for existing libraries already providing this functionality. implements a simple parser to avoid dependencies. Performance data metrics must be appended to the plugin output with a preceding `|` character. The schema is as follows: ``` <output> | 'label'=value[UOM];[warn];[crit];[min];[max] ``` The label should be encapsulated with single quotes. Avoid spaces or special characters such as `%` in there, this could lead to problems with metric receivers such as Graphite. Labels must not include `'` and `=` characters. Keep the label length as short and unique as possible. Example: ``` 'load1'=4.7 ``` Values must respect the C/POSIX locale and not implement e.g. German locale for floating point numbers with `,`. Icinga sets `LC_NUMERIC=C` to enforce this locale on plugin execution. ``` 'rta'=12.445000ms 'pl'=0% ``` The UoMs are written as-is into the (IDO, API). I.e. 12.445000ms remain 12.445000ms. In contrast, the (Graphite, InfluxDB, etc.) get perfdata (including warn, crit, min, max) normalized by Icinga. E.g. 12.445000ms become 0.012445 seconds. Some plugins change the UoM for different sizing, e.g. returning the disk usage in MB and later GB for the same performance data label. This is to ensure that graphs always look the same. gets both the as-is and the normalized perfdata. What metric backends get... |

from which perfdata UoMs (case-insensitive if possible) -| bytes (B) | B, KB, MB, ..., YB, KiB, MiB, ..., YiB bits (b) | b, kb, mb, ..., yb, kib, mib, ..., yib packets | packets seconds (s) | ns, us, ms, s, m, h, d percent | % amperes (A) | nA, uA, mA, A, kA, MA, GA, ..., YA ohms (O) | nO, uO, mO, O, kO, MO, GO, ..., YO volts (V) | nV, uV, mV, V, kV, MV, GV, ..., YV watts (W) | nW, uW, mW, W, kW, MW, GW, ..., YW ampere seconds (As) | nAs, uAs, mAs, As, kAs, MAs, GAs, ..., YAs ampere seconds | nAm, uAm, mAm, Am (ampere minutes), kAm, MAm, GAm, ..., YAm ampere seconds | nAh, uAh, mAh, Ah (ampere hours), kAh, MAh, GAh, ..., YAh watt hours | nWs, uWs, mWs, Ws (watt seconds), kWs, MWs, GWs, ..., YWs watt hours | nWm, uWm, mWm, Wm (watt minutes), kWm, MWm, GWm, ..., YWm watt hours (Wh) | nWh, uWh, mWh, Wh, kWh, MWh, GWh, ..., YWh lumens | lm decibel-milliwatts | dBm grams (g) | ng, ug, mg, g, kg, t degrees Celsius | C degrees Fahrenheit | F degrees Kelvin | K liters (l) | ml, l, hl The UoM "c" represents a continuous counter (e.g. interface traffic counters). Unknown UoMs are discarted (as if none was given). A value without any UoM may be an integer or floating point number for any type (processes, users, etc.). Next to the performance data value, warn, crit, min, max can optionally be provided. They must be separated with the semi-colon `;` character. They share the same UOM with the performance data value. ``` $ check_ping -4 -H icinga.com -c '200,15%' -w '100,5%' PING OK - Packet loss = 0%, RTA = 12.44 ms|rta=12.445000ms;100.000000;200.000000;0.000000 pl=0%;5;15;0 ``` Multiple performance data values must be joined with a space character. The below example is from the plugin. ``` load1=4.680;1.000;2.000;0; load5=0.000;5.000;10.000;0; load15=0.000;10.000;20.000;0; ``` Icinga has a safety mechanism where it kills processes running for too long. The timeout can be specified in or on the host/service object. Best practice is to control the timeout in the plugin itself and provide a clear message followed by the Unknown state. Example in Python taken from : ```python import argparse import signal import sys def handle_sigalrm(signum, frame, timeout=None): output('Plugin timed out after %d seconds' % timeout, 3) if name == 'main': parser = argparse.ArgumentParser() parser.add_argument("-t", "--timeout", help="Timeout in seconds (default 10s)", type=int, default=10) args = parser.parse_args() signal.signal(signal.SIGALRM, partial(handle_sigalrm, timeout=args.timeout)) signal.alarm(args.timeout) ``` Plugins should provide a version via `-V` or `--version` parameter which is bumped on releases. This allows to identify problems with too old or new versions on the community support channels. Example in Python taken from : ```python import argparse import signal import sys version = '0.9.1' if name == 'main': parser = argparse.ArgumentParser() parser.addargument('-V', '--version', action='version', version='%(prog)s v' + sys.modules[name].version_) ``` Plugins should provide a verbose mode with `-v` or `--verbose` in order to show more detailed log messages. This helps to debug and analyse the flow and execution steps inside the plugin. Ensure to add the parameter prior to implementing the check logic into the plugin. Example in Python taken from : ```python import argparse import signal import sys if name == 'main': parser = argparse.ArgumentParser() parser.addargument('-v', '--verbose', action='storetrue') if args.verbose: print("Verbose debug output") ``` Sometimes an existing plugin does not satisfy your

You can either kindly contact the original author about plans to add changes and/or create a patch. If you just want to format the output and state of an existing plugin it might also be helpful to write a wrapper script. This script could pass all configured parameters, call the plugin script, parse its output/exit code and return your specified output/exit code. On the other hand plugins for specific services and hardware might not yet exist. Tip Watch this presentation from Icinga Camp Berlin to learn more about . Common best practices: Choose the programming language wisely Scripting languages (Bash, Python, Perl, Ruby, PHP, etc.) are easier to write and setup but their check execution might take longer (invoking the script interpreter as overhead, etc.). Plugins written in C/C++, Go, etc. improve check execution time but may generate an overhead with installation and packaging. Use a modern VCS such as Git for developing the plugin, e.g. share your plugin on GitHub and let it sync to . Look into existing plugins endorsed by community members.* Implementation hints: Add parameters with key-value pairs to your plugin. They should allow long names (e.g. `--host localhost`) and also short parameters (e.g. `-H localhost`) `-h|--help` should print the version and all details about parameters and runtime invocation. Note: Python's ArgParse class provides this OOTB. `--version` should print the plugin . Add a functionality for detailed on-demand logging. Respect the exit codes required by the . Always add to your plugin output. Allow to specify as parameters. Example skeleton: ``` if (<timeout_reached>) then print "UNKNOWN - Timeout (...) reached | 'time'=30.0 endif <execute and fetch data> if (<thresholdcriticalcondition>) then print "CRITICAL - ... | 'time'=0.1 'myperfdatavalue'=5.0 exit(2) else if (<thresholdwarningcondition>) then print "WARNING - ... | 'time'=0.1 'myperfdatavalue'=3.0 exit(1) else print "OK - ... | 'time'=0.2 'myperfdatavalue'=1.0 endif ``` There are various plugin libraries available which will help with plugin execution and output formatting too, for example . Note Ensure to test your plugin properly with special cases before putting it into production! Once you've finished your plugin please upload/sync it to . Thanks in advance! The following examples should help you to start implementing your own ideas. There is a variety of plugins available. This collection is not complete -- if you have any updates, please send a documentation patch upstream. Please visit our which may provide an answer to your use case already. If not, do not hesitate to create a new topic. If the remote service is available (via a network protocol and port), and if a check plugin is also available, you don't necessarily need a local client. Instead, choose a plugin and configure its parameters and thresholds. The following examples are included in the : , , , , , , , package management: , , etc. performance: , !!! important is the recommended way to monitor Windows via Icinga 2. Even if the plugins it ships out-of-the-box don't already cover your needs, you can . Other (legacy) solutions include: (in combination with the Icinga 2 client and either or check commands) (disk, load, memory, network, performance counters, ping, procs, service, swap, updates, uptime, users vbs and Powershell scripts MySQL/MariaDB: , , PostgreSQL: Oracle: MSSQL: DB2: MongoDB: Elasticsearch: Redis: (interface, storage, load, memory, process) , , Tip: If you are encountering timeouts using the VMware Perl SDK, check . Ubuntu 16.04 LTS can have troubles with random entropy in Perl asked . In that case, may help. , , ,