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Docker REST API

Pack assets​

Templates​

The Monitoring Connector Docker brings a host template:

  • App-Docker-Restapi-custom

The connector brings the following service templates (sorted by the host template they are attached to):

Service AliasService TemplateService Description
Node-StatusApp-Docker-Node-Status-Restapi-customCheck node status

The services listed above are created automatically when the App-Docker-Restapi-custom host template is used.

Discovery rules​

Service discovery​

Rule nameDescription
App-Docker-Restapi-ContainersDiscover Docker containers using RestAPI

More information about discovering services automatically is available on the dedicated page and in the following chapter.

Collected metrics & status​

Here is the list of services for this connector, detailing all metrics linked to each service.

Metric nameUnit
containers#container-statusN/A
containers#container.cpu.utilization.percentage%
containers#container.memory.usage.bytesB
containers#container.disk.io.read.usage.iopsiops
containers#container.disk.io.write.usage.iopsiops
containers_traffic#container.traffic.in.bitspersecondb/s
containers_traffic#container.traffic.out.bitspersecondb/s

To obtain this new metric format, include --use-new-perfdata in the EXTRAOPTIONS service macro.

Prerequisites​

API connection​

Open your favorite ssh client and configure your API to allow connections from the outside:

  • vi /lib/systemd/system/docker.service
  • Modify the line starting with ExecStart as shown below: 
ExecStart=/usr/bin/dockerd -H fd:// --containerd=/run/containerd/containerd.sock -H=tcp://0.0.0.0:2375

WARNING: This isn't safe because someone could gain root access to the host where the daemon is running. We recommend that you configure the local firewall to accept traffic only from the poller on this port.

  • Save the changes
  • Apply the changes made at the systemd level : systemctl daemon-reload
  • Restart the Docker engine: systemctl restart docker

Installing the monitoring connector​

Pack​

  1. If the platform uses an online license, you can skip the package installation instruction below as it is not required to have the connector displayed within the Configuration > Monitoring Connector Manager menu. If the platform uses an offline license, install the package on the central server with the command corresponding to the operating system's package manager:
dnf install centreon-pack-applications-docker-restapi
  1. Whatever the license type (online or offline), install the Docker connector through the Configuration > Monitoring Connector Manager menu.

Plugin​

Since Centreon 22.04, you can benefit from the 'Automatic plugin installation' feature. When this feature is enabled, you can skip the installation part below.

You still have to manually install the plugin on the poller(s) when:

  • Automatic plugin installation is turned off
  • You want to run a discovery job from a poller that doesn't monitor any resource of this kind yet

More information in the Installing the plugin section.

Use the commands below according to your operating system's package manager:

dnf install centreon-plugin-Applications-Docker-Restapi

Using the monitoring connector​

Using a host template provided by the connector​

  1. Log into Centreon and add a new host through Configuration > Hosts.
  2. Fill in the Name, Alias & IP Address/DNS fields according to your resource's settings.
  3. Apply the App-Docker-Restapi-custom template to the host. A list of macros appears. Macros allow you to define how the connector will connect to the resource, and to customize the connector's behavior.
  4. Fill in the macros you want. Some macros are mandatory.
MacroDescriptionDefault valueMandatory
DOCKERENGINEPORTPort used (default: 8080)
DOCKERENGINEEXTRAOPTIONSAny extra option you may want to add to every command (a --verbose flag for example). All options are listed here.
  1. Deploy the configuration. The host appears in the list of hosts, and on the Resources Status page. The command that is sent by the connector is displayed in the details panel of the host: it shows the values of the macros.

Using a service template provided by the connector​

  1. If you have used a host template and checked Create Services linked to the Template too, the services linked to the template have been created automatically, using the corresponding service templates. Otherwise, create manually the services you want and apply a service template to them.
  2. Fill in the macros you want (e.g. to change the thresholds for the alerts). Some macros are mandatory (see the table below).
MacroDescriptionDefault valueMandatory
CONTAINERIDExact container ID
CONTAINERNAMEExact container name (if multiple names: names separated by ':')
FILTERNAMEFilter by container name (can be a regexp)
WARNINGCONTAINERSTATUSDefine the conditions to match for the status to be WARNING. You can use the following variables: %{name}, %{state}, %{health}
CRITICALCONTAINERSTATUSDefine the conditions to match for the status to be CRITICAL. You can use the following variables: %{name}, %{state}, %{health}
WARNINGCPUWarning threshold
CRITICALCPUCritical threshold
WARNINGMEMORYWarning threshold
CRITICALMEMORYCritical threshold
WARNINGREADIOPSWarning threshold
CRITICALREADIOPSCritical threshold
WARNINGTRAFFICINWarning threshold
CRITICALTRAFFICINCritical threshold
WARNINGTRAFFICOUTWarning threshold
CRITICALTRAFFICOUTCritical threshold
WARNINGWRITEIOPSWarning threshold
CRITICALWRITEIOPSCritical threshold
EXTRAOPTIONSAny extra option you may want to add to the command (a --verbose flag for example). Toutes les options sont listées ici.--verbose
  1. Deploy the configuration. The service appears in the list of services, and on the Resources Status page. The command that is sent by the connector is displayed in the details panel of the service: it shows the values of the macros.

How to check in the CLI that the configuration is OK and what are the main options for?​

Once the plugin is installed, log into your Centreon poller's CLI using the centreon-engine user account (su - centreon-engine). Test that the connector is able to monitor a resource using a command like this one (replace the sample values by yours):

/usr/lib/centreon/plugins/centreon_docker_restapi.pl \
    --plugin=cloud::docker::restapi::plugin \
    --mode=node-status \
    --hostname='10.0.0.1' \
    --port=''   \
    --warning-node-status='' \
    --critical-node-status='%{status} !~ /ready/ || %{manager_status} !~ /reachable|-/' \
    --verbose

The expected command output is shown below:

OK: Node '10.0.0.1' Containers Running : 7, Containers Stopped : 2, Containers Paused : 0 | 'containers_running'=7;;;0; 'containers_stopped'=2;;;0; 'containers_paused'=0;;;0;
Node '10.0.0.1' Containers Running : 7, Containers Stopped : 2, Containers Paused : 0

Troubleshooting​

Please find the troubleshooting documentation for the API-based plugins in this chapter.

Available modes​

In most cases, a mode corresponds to a service template. The mode appears in the execution command for the connector. In the Centreon interface, you don't need to specify a mode explicitly: its use is implied when you apply a service template. However, you will need to specify the correct mode for the template if you want to test the execution command for the connector in your terminal.

All available modes can be displayed by adding the --list-mode parameter to the command:

/usr/lib/centreon/plugins/centreon_docker_restapi.pl \
    --plugin=cloud::docker::restapi::plugin \
    --list-mode

The plugin brings the following modes:

ModeLinked service template
container-usage [code]App-Docker-Container-Usage-Restapi-custom
list-containers [code]Used for service discovery
node-status [code]App-Docker-Node-Status-Restapi-custom
service-status [code]Not used in this Monitoring Connector

Available options​

Generic options​

All generic options are listed here:

OptionDescription
--modeDefine the mode in which you want the plugin to be executed (see--list-mode).
--dyn-modeSpecify a mode with the module's path (advanced).
--list-modeList all available modes.
--mode-versionCheck minimal version of mode. If not, unknown error.
--versionReturn the version of the plugin.
--custommodeWhen a plugin offers several ways (CLI, library, etc.) to get information the desired one must be defined with this option.
--list-custommodeList all available custom modes.
--multipleMultiple custom mode objects. This may be required by some specific modes (advanced).
--pass-managerDefine the password manager you want to use. Supported managers are: environment, file, keepass, hashicorpvault and teampass.
--verboseDisplay extended status information (long output).
--debugDisplay debug messages.
--filter-perfdataFilter perfdata that match the regexp. Example: adding --filter-perfdata='avg' will remove all metrics that do not contain 'avg' from performance data.
--filter-perfdata-advFilter perfdata based on a "if" condition using the following variables: label, value, unit, warning, critical, min, max. Variables must be written either %{variable} or %(variable). Example: adding --filter-perfdata-adv='not (%(value) == 0 and %(max) eq "")' will remove all metrics whose value equals 0 and that don't have a maximum value.
--explode-perfdata-maxCreate a new metric for each metric that comes with a maximum limit. The new metric will be named identically with a '_max' suffix). Example: it will split 'used_prct'=26.93%;0:80;0:90;0;100 into 'used_prct'=26.93%;0:80;0:90;0;100 'used_prct_max'=100%;;;;
--change-perfdata --extend-perfdataChange or extend perfdata. Syntax: --extend-perfdata=searchlabel,newlabel,target[,[newuom],[min],[m ax]] Common examples: Convert storage free perfdata into used: --change-perfdata='free,used,invert()' Convert storage free perfdata into used: --change-perfdata='used,free,invert()' Scale traffic values automatically: --change-perfdata='traffic,,scale(auto)' Scale traffic values in Mbps: --change-perfdata='traffic_in,,scale(Mbps),mbps' Change traffic values in percent: --change-perfdata='traffic_in,,percent()'
--extend-perfdata-groupAdd new aggregated metrics (min, max, average or sum) for groups of metrics defined by a regex match on the metrics' names. Syntax: --extend-perfdata-group=regex,namesofnewmetrics,calculation[,[ne wuom],[min],[max]] regex: regular expression namesofnewmetrics: how the new metrics' names are composed (can use $1, $2... for groups defined by () in regex). calculation: how the values of the new metrics should be calculated newuom (optional): unit of measure for the new metrics min (optional): lowest value the metrics can reach max (optional): highest value the metrics can reach Common examples: Sum wrong packets from all interfaces (with interface need --units-errors=absolute): --extend-perfdata-group=',packets_wrong,sum(packets_(discard |error)_(in|out))' Sum traffic by interface: --extend-perfdata-group='traffic_in_(.*),traffic_$1,sum(traf fic_(in|out)_$1)'
--change-short-output --change-long-outputModify the short/long output that is returned by the plugin. Syntax: --change-short-output=pattern~replacement~modifier Most commonly used modifiers are i (case insensitive) and g (replace all occurrences). Example: adding --change-short-output='OK~Up~gi' will replace all occurrences of 'OK', 'ok', 'Ok' or 'oK' with 'Up'
--change-exitReplace an exit code with one of your choice. Example: adding --change-exit=unknown=critical will result in a CRITICAL state instead of an UNKNOWN state.
--range-perfdataRewrite the ranges displayed in the perfdata. Accepted values: 0: nothing is changed. 1: if the lower value of the range is equal to 0, it is removed. 2: remove the thresholds from the perfdata.
--filter-uomMask the units when they don't match the given regular expression.
--opt-exitReplace the exit code in case of an execution error (i.e. wrong option provided, SSH connection refused, timeout, etc). Default: unknown.
--output-ignore-perfdataRemove all the metrics from the service. The service will still have a status and an output.
--output-ignore-labelRemove the status label ("OK:", "WARNING:", "UNKNOWN:", CRITICAL:") from the beginning of the output. Example: 'OK: Ram Total:...' will become 'Ram Total:...'
--output-xmlReturn the output in XML format (to send to an XML API).
--output-jsonReturn the output in JSON format (to send to a JSON API).
--output-openmetricsReturn the output in OpenMetrics format (to send to a tool expecting this format).
--output-fileWrite output in file (can be combined with json, xml and openmetrics options). E.g.: --output-file=/tmp/output.txt will write the output in /tmp/output.txt.
--disco-formatApplies only to modes beginning with 'list-'. Returns the list of available macros to configure a service discovery rule (formatted in XML).
--disco-showApplies only to modes beginning with 'list-'. Returns the list of discovered objects (formatted in XML) for service discovery.
--float-precisionDefine the float precision for thresholds (default: 8).
--source-encodingDefine the character encoding of the response sent by the monitored resource Default: 'UTF-8'.
--hostnameIP Addr/FQDN of the docker node (can be multiple).
--portPort used (default: 8080)
--protoSpecify https if needed (default: 'http')
--credentialsSpecify this option if you access server-status page with authentication
--usernameSpecify the username for authentication (mandatory if --credentials is specified)
--passwordSpecify the password for authentication (mandatory if --credentials is specified)
--basicSpecify this option if you access server-status page over basicauthentication and don't want a '401 UNAUTHORIZED' error to be logged on your web server. Specify this option if you access server-status page over hidden basic authentication or you'll get a '404 NOT FOUND' error. (use with --credentials)
--timeoutThreshold for HTTP timeout (default: 10)
--cert-fileSpecify certificate to send to the web server
--key-fileSpecify key to send to the web server
--cacert-fileSpecify root certificate to send to the web server
--cert-pwdSpecify certificate's password
--cert-pkcs12Specify type of certificate (PKCS12)
--api-displayPrint json api.
--api-write-displayPrint json api in a file (to be used with --api-display).
--api-read-fileRead API from file.
--reload-cache-timeTime in seconds before reloading list containers cache (default: 300)
--http-peer-addrSet the address you want to connect to. Useful if hostname is only a vhost, to avoid IP resolution.
--proxyurlProxy URL. Example: http://my.proxy:3128
--proxypacProxy pac file (can be a URL or a local file).
--insecureAccept insecure SSL connections.
--http-backendPerl library to use for HTTP transactions. Possible values are: lwp (default) and curl.
--ssl-optSet SSL Options (--ssl-opt="SSL_version => TLSv1" --ssl-opt="SSL_verify_mode => SSL_VERIFY_NONE").
--curl-optSet CURL Options (--curl-opt="CURLOPT_SSL_VERIFYPEER => 0" --curl-opt="CURLOPT_SSLVERSION => CURL_SSLVERSION_TLSv1_1" ).

Modes options​

All available options for each service template are listed below:

OptionDescription
--memcachedMemcached server to use (only one server).
--redis-serverRedis server to use (only one server). Syntax: address[:port]
--redis-attributeSet Redis Options (--redis-attribute="cnx_timeout=5").
--redis-dbSet Redis database index.
--failback-fileFailback on a local file if Redis connection fails.
--memexpirationTime to keep data in seconds (default: 86400).
--statefile-dirDefine the cache directory (default: '/var/lib/centreon/centplugins').
--statefile-suffixDefine a suffix to customize the statefile name (default: '').
--statefile-concat-cwdIf used with the '--statefile-dir' option, the latter's value will be used as a sub-directory of the current working directory. Useful on Windows when the plugin is compiled, as the file system and permissions are different from Linux.
--statefile-formatDefine the format used to store the cache. Available formats: 'dumper', 'storable', 'json' (default).
--statefile-keyDefine the key to encrypt/decrypt the cache.
--statefile-cipherDefine the cipher algorithm to encrypt the cache (default: 'AES').
--container-idExact container ID.
--container-nameExact container name (if multiple names: names separated by ':').
--use-nameUse docker name for perfdata and display.
--add-healthGet container health status (call inspector endpoint).
--no-statsDon't get container statistics.
--filter-nameFilter by container name (can be a regexp).
--filter-countersOnly display some counters (regexp can be used). Example: --filter-counters='^container-status$'
--warning-container-statusDefine the conditions to match for the status to be WARNING. You can use the following variables: %{name}, %{state}, %{health}.
--critical-container-statusDefine the conditions to match for the status to be CRITICAL. You can use the following variables: %{name}, %{state}, %{health}.
--warning- --critical-Thresholds. Can be: 'read-iops', 'write-iops', 'traffic-in', 'traffic-out', 'cpu' (%), 'memory' (%).

All available options for a given mode can be displayed by adding the --help parameter to the command:

/usr/lib/centreon/plugins/centreon_docker_restapi.pl \
    --plugin=cloud::docker::restapi::plugin \
    --mode=container-usage \
    --help