1 # Script Debugger <a id="script-debugger"></a>
3 You can run the Icinga 2 daemon with the `-X` (`--script-debugger`)
4 parameter to enable the script debugger:
10 When an exception occurs or the [debugger](17-language-reference.md#breakpoints)
11 keyword is encountered in a user script, Icinga 2 launches a console that
12 allows the user to debug the script.
14 You can also attach the script debugger to the [configuration validation](11-cli-commands.md#config-validation):
17 # icinga2 daemon -C -X
20 Here is a list of common errors which can be diagnosed with the script debugger:
22 * Configuration errors e.g. [apply rules](03-monitoring-basics.md#using-apply)
23 * Errors in user-defined [functions](17-language-reference.md#functions)
25 ## Debugging Configuration Errors <a id="script-debugger-config-errors"></a>
27 The following example illustrates the problem of a service [apply rule](03-monitoring-basics.md#using-apply-for)
28 which expects a dictionary value for `config`, but the host custom attribute only
29 provides a string value:
32 object Host "script-debugger-host" {
33 check_command = "icinga"
35 vars.http_vhosts["example.org"] = "192.168.1.100" // a string value
38 apply Service for (http_vhost => config in host.vars.http_vhosts) {
39 import "generic-service"
41 vars += config // expects a dictionary
43 check_command = "http"
47 The error message on config validation will warn about the wrong value type,
48 but does not provide any context which objects are affected.
50 Enable the script debugger and run the config validation:
53 # icinga2 daemon -C -X
55 Breakpoint encountered in /etc/icinga2/conf.d/services.conf: 59:67-65:1
56 Exception: Error: Error while evaluating expression: Cannot convert value of type 'String' to an object.
58 /etc/icinga2/conf.d/services.conf(62): check_command = "http"
59 /etc/icinga2/conf.d/services.conf(63):
60 /etc/icinga2/conf.d/services.conf(64): vars += config
62 /etc/icinga2/conf.d/services.conf(65): }
63 /etc/icinga2/conf.d/services.conf(66):
64 You can inspect expressions (such as variables) by entering them at the prompt.
65 To leave the debugger and continue the program use "$continue".
69 You can print the variables `vars` and `config` to get an idea about
80 The `vars` attribute has to be a dictionary. Trying to set this attribute to a string caused
81 the error in our configuration example.
83 In order to determine the name of the host where the value of the `config` variable came from
84 you can inspect attributes of the service object:
88 "script-debugger-host-01"
93 Additionally you can view the service object attributes by printing the value of `this`.
95 ## Using Breakpoints <a id="script-debugger-breakpoints"></a>
97 In order to halt execution in a script you can use the `debugger` keyword:
100 object Host "script-debugger-host-02" {
101 check_command = "dummy"
105 var text = "Hello from " + macro("$name$")
112 Icinga 2 will spawn a debugger console every time the function is executed:
117 Breakpoint encountered in /etc/icinga2/tests/script-debugger.conf: 7:5-7:12
118 You can inspect expressions (such as variables) by entering them at the prompt.
119 To leave the debugger and continue the program use "$continue".
121 "Hello from script-debugger-host-02"
125 ## Debugging API Filters <a id="script-debugger-api-filters"></a>
127 Queries against the [Icinga 2 REST API](12-icinga2-api.md#icinga2-api) can use
128 filters, just like available in `assign where` expressions. If these filters cause
129 an internal error, they return an empty result to the caller.
131 In order to analyse these server-side errors, you can use the script debugger.
133 The following example tries filter for all host objects where the custom attribute
134 `os` is set. There are various possibilities to check that, one of them would be
135 `host.vars.os != ""`. Another idea is to use the [contains](18-library-reference.md#dictionary-contains) method on the custom
136 attribute dictionary like this: `host.vars.contains("os")`.
139 $ curl -k -s -u root:icinga -H 'Accept: application/json' -H 'X-HTTP-Method-Override: GET' \
140 -X POST 'https://localhost:5665/v1/objects/services' \
141 -d '{ "filter": "host.vars.contains(\"os\")", "attrs": [ "__name" ], "joins": [ "host.name", "host.vars" ], "pretty": true }'
144 This will fail on all hosts which don't have any custom attribute specified.
149 Breakpoint encountered.
150 Exception: Error: Argument is not a callable object.
151 Location: in <API query>: 1:0-1:23
152 You can inspect expressions (such as variables) by entering them at the prompt.
153 To leave the debugger and continue the program use "$continue".
164 By definition, a type method can only be invoked on an actual object.
166 In order to stay safe, add more checks to the API filter:
168 - `host.vars && host.vars.contains("os")` or
169 - `host.vars && typeof(host.vars) == Dictionary && host.vars.contains("os")`
174 $ curl -k -s -u root:icinga -H 'Accept: application/json' -H 'X-HTTP-Method-Override: GET' \
175 -X POST 'https://localhost:5665/v1/objects/services' \
176 -d '{ "filter": "host.vars && typeof(host.vars) == Dictionary && host.vars.contains(\"os\")", "attrs": [ "__name" ], "joins": [ "host.name", "host.vars" ], "pretty": true }'