Host and service views

We distinguish between global views and those that require a context. Global views can always be called-up directly. An example of a global view is the list of all current service problems. A context view — the Status of Host …​ view for example — namely needs to specify by name the host whose status is to be displayed. Such views can only be called-up in situations relevant to a particular host.

The global view is most easily accessed via the monitor menu.

Alternatively, you can use the Overview and Views sidebar elements. In the overview each number is clickable and takes you to a global view that individually lists the hosts or services counted in each case.

All global views are accessible in the Views element — grouped according to theme. In addition you will find a few entries that aren’t actually Views — such as for example, the Dashboards, which are sorted under the Overview theme. Dashboards can however contain views.

From a global view, with a further step you can access the details for a particular host or service. The names of hosts and services and the individual cells in other columns are clickable …

… and bring you to a more detailed (context-dependent) view.

At the top left of every view there are six symbols with which you can influence the display, and trigger actions:

Checkmk shows time stamps as relative values in all of the views of states if these are less than 24 hours in the past or future — e.g., 16 hours. You can switch this in the menu via Display > Modify display options and choose between displaying only absolute, only relative or both values, or also the Unix timestamp. You can also specify the date format in this dialog.

The tabular views can be sorted by clicking on a column’s heading. A column has three states that can be selected through a loop of multiple clicks:

Views are initially sorted ‘naturally’ according to how the view is defined. In service lists the sorting is alphabetic by service name — with the exception of Check_MK services which are always at the top. The Check_MK service is responsible for managing the monitoring agent. There are also the Check_MK Discovery and Check_MK HW/SW Inventory services. In order to sort such a list by the current state of the services a click on STATE will suffice.

Sorting by the Perf-O-Meter column sometimes produces surprising results. This is due to the graphic display of the values being partly a percentaged summarisation of the actual values. The sorting is however performed according to absolute values, and is always based on the first metric produced by a service.

Data displayed in a view can be exported a number of formats:

In a larger monitoring environment displaying all views is no longer practical. When you are monitoring 50,000 services and select the All Services view, not only will the display require a very long time — it will also not be very useful.

In such situations, in order to protect the user from long waiting times and to avoid crippling the system with absurd quantities of data, views are limited to 1000 entries in their display. Exceeding this limit produces the following warning:

As you can see, the records being displayed are not necessarily the first 1000 corresponding to the selected sorting method! There is a technical reason for this: namely that the limit is applied to the data source in the connected site’s monitoring cores. This is very important, because if we accumulate one million data records from your environment spread around the world, then 99.9% of the data will be deleted immediately. The sorting takes place from the end of the list, thus it happens after the limit. The data from all instances must, after all, be sorted together.

If you really want to see more than one thousand records, then you can reach the next level by clicking on Repeat query and allow more results. Here the limit is 5,000 records. If this limit has again been exceeded, with unlimited you can continue. Insofar this is a potentially risky action, you will require Administrator rights. You have been warned!

You can define both levels under Global Settings > User Interface:

Checkmk allows you to customise its standard views, and even to create new ones that you can incorporate into reports and dashboards. Thus you can define numerous different aspects for every view:

The edit mode for views can be accessed in two ways:

The views supplied as standard are a part of the software and as such cannot be changed, however Checkmk does recognise the concept of cloning. When a view is first customised (regardless if by using or via the list) a copy of that view is created automatically. This copy is added to your user profile.

This copy can then be customised as desired. The original view is retained but is greyed-out — overlaid by your new version in effect. You can return to the standard view later by simply deleting your clone (achieved in the table of views, as you might expect, with ).

This concept has one further advantage: namely, that you can define whether the view should be changed for all users or just for yourself. This is specified in the view’s General Properties with the Make this view available for all users checkbox. Not surprisingly, you can only select this checkbox if you have administrator permissions (or more correctly, this function has its own permission — Publish views). Additionally, single views can be locked in the role definitions.

What happens when a view has been customised and published by several users? Each user then has their own variant of the view. Which view will be visible for which user(s)? This can be determined with the following rules:

How can you create a real copy of a view, so that when done you can have both the supplied and your own views? This is defined by using Unique ID in the General Properties. Simply give your view a new name, so that it will no longer be identified as a clone of the supplied view, rather it will begin its own independent life.

This ID is the decisive keyword for opening views in the URL. The schema is very simple. Here for example is how the global view with its ID allhosts is opened:

/mysite/check_mk/view.py?view_name=allhosts

The concepts of cloning, customising and visibility can be found at many other locations in Checkmk, namely in:

How and if a view will be shown in the sidebar’s Views element, is defined under General Properties by the following characteristics:

The next block — View Properties — defines a view’s general appearance:

The Number of Columns option sets the default for the number of columns shown in the view, the Automatic page reload the default for the refresh counter. Both values can be modified by the user in the view itself via Display > Modify display options.

Under Basic Layout there are various styles for displaying the data in tables. Most views use table — a normal table that can be sorted by columns — or Single data set — which has the legend on the left and which is mostly used for single data sets. You can however also use single data set for views with more than one object. The All Hosts view looks something like this when altered to Single data set:

The Columns box defines which columns you wish to see. The number of columns possible selection depends on the selected data source. The most columns are found in services, naturally, as all information for the particular service is available. The list can be quite long here, and if you are uncertain which column is the right one, there is only one thing to do — try it out:

Depending on the column selected, there may be specific options for this. With the column Hosts: Hostname, for example, it is possible to color the hostname according to its status using the Coloring option.

The Link field offers a selection of all views. If a view is selected here, then the column’s respective cell is clickable and takes the user to the chosen view. This really only makes sense if the targetted view has a context. The best example is the All Hosts view. The Hostname column is clickable here and takes the user to this host’s Services of host. Alternatively, dashboards can be specified here — which obviously do not require a context.

Under Tooltip, on the other hand, you will find a list of all columns. Thus you can show further information for the host or service when the user moves the mouse cursor over the respective cell (the IP-address in this example).

Let’s imagine that you’d like to display the information for particular services in a table of hosts. The following example illustrates this situation very well: here the current uptime, the CPU load, the memory usage and the NTP-synchronisation are shown for each host:

Here a table of hosts has been generated in which for each host the Perf-O-Meter service column for four different services is displayed. One sees that for one of the three hosts the CPU load and the Memory services do not exist and that the column is consequently empty.

This view’s configuration was achieved by adding columns of the Joined column type. Here the column for services in which Perf-O-Meter has been selected appears under Column. The Title entry defines the column’s heading. The service’s exact name must be entered (upper and lower case sensitive!) in the Of Service field:

Of course such a display is only useful when the view shows a list of similar hosts, all of which also utilise the selected services. This is also the reason why Checkmk does not provide views of this type — which columns are meaningful here depends entirely on the type of host selected. For Linux servers the information of interest is certainly completely different to that for USVs, for example.

The sorting within a view is configured in the fourth block. It’s only a matter of the predefined sorting method. Users can — as described above — determine the sorting order themselves with a click on the column heading. In the view’s configuration however you have more possibilities — you can define a multi-step sorting order, e.g. first by service-status, and for the same status by service name. The order so determined is retained as a subordinate sorting when the user resorts in a specific column.

Through grouping you can divide a table into several segments — in which each segment’s data is related in some way. The best example of this is the Service problems view, which is easily reached via the Overview snapin.

As you can see, this table is grouped with Service status (first all CRIT, then UNKNOWN, then WARN) - each with its own group header:

The grouping in a view is configured similarly to that with the columns. Simply define which column the grouping should relate to. It is usually only one, but can be more. All records with the same value for all selected columns will then be displayed in a group — and the column heading will be shown as the group title.

It is important that you also sort the records by priority according to the group’s selected characteristic! Otherwise it can be possible that the same group makes multiple appearances (which may at times be desirable). Incidentally, a resorting by column performed by a user has no effect on the grouping — in such a case only the group’s sequence is determined and the records sorted within the group. The groups themselves are unchanged.

An important aspect of views is the data selection. Which hosts or services should be displayed in a table? Checkmk uses the Filter concept for this purpose. Here are a couple of examples of host-filters:

Every filter can be defined with search terms or other criteria by a user, thus reducing the list of results to those records meeting the criteria. In this way the filters are AND-linked. The filter criteria actually used for a view are assembled from three sources:

The filters you assemble by editing in the view’s context/search filters box have two functions. Firstly, by clicking on you can decide which filter will be available to a user. Secondly, you can predefine filters using criteria, thus limiting the data to be displayed in the view (point 1 above).

When you create or edit a view by using context — instead of the filter for the relevant object only an optional entry field appears. In this an exact comparison always applies (upper and lower case sensitive). As an example we can take the host view, which displays all services of a specified host. The host’s name can be specified by adding a context to the view. You can also build a display in which the host to be displayed is effectively hard-coded directly in the view:

In this way you can call the view without context, or if desired, simply add it to the sidebar’s Views element without problem.

The Host search and Service search (and other) views supplied as standard behave in a special way in relation to the filters. When you you select one of these views, it opens with a filter formula, and then only shows hosts and services when this filter is activated.

Why is this so? Because it would simply be very impractical if you first had to go to All services, and then be forced to wait until several thousand services are displayed before you could filter the result with a search entry. This behaviour is regulated by the Show data only on search option:

The data source is what you might call a table or database view under databases. Checkmk does not use SQL-Data bases, but it is similarly-structured internally. In most cases you will be correct with All services or All hosts. There are however a few data sources that should be listed briefly here:

Here it can be decided whether your new view should have a context or if it will be a global view. The selections available to you depend on the data source. The most common context by far is ‘Host’. The image above appears after selecting the All services data source.

Checking the Show information of a single host box defines that the new view describes one specific host. You will thus have created the basis for a view that is not globally-visible, but instead visible via a link:

There are two options for the Service context type. If you select only Show information of a single service, you can build a view that displays all services with the same name on different hosts. If it should be a specific service for a single host, then check the Show information of a single host box.

Why do some cells have a coloured background? This points you to values lying outside the majority. This is actually not so meaningful for measurement data, but there are, for instance, users with a specially-constructed matrix who can tell at a glance if an incorrect contact group has been entered for certain hosts or services!