A simple watcher, provides real-time alerts for data in elasticsearch as a replacement for X-Pack
MIT License
Package esalert a simple framework for real-time alerts on data in Elasticsearch.
# esalert.yml
- name: alert_foo
# other alert parameters
- name: alert_bar
# other alert parameters
OR
# esalert.d/foo.yml
- name: alert_foo
# other alert parameters
- name: alert_foo2
# other alert parameters
and
# esalert.d/bar.yml
- name: alert_bar
# other alert parameters
- name: alert_bar2
# other alert parameters
A single alert has the following fields in its document (all are required):
- name: something_unique
interval: "*/5 * * * * *"
search_index: # see the search subsection
search_type: # see the search subsection
search: # see the search subsection
process: # see the process subsection
This is an arbitrary string to identify the alert. It must be unique amongst all of the defined alerts.
A jobber-style interval string describing when the search should be run and have the process run on the results.
The search which should be performed against elasticsearch. The results are simply held onto for the process step, nothing else is done with them at this point.
search_index: filebeat-{{.Format "2006.01.02"}}
search_type: logs
# conveniently, json is valid yaml
search: {
"query": {
"query_string": {
"query":"severity:fatal"
}
}
}
search_index
, search_type
and search
) can have go templating applied.Once the search is performed the results are kept in the context, which is then passed into this step. The process lua script then checks these results against whatever conditions are desired, and may optionally return a list of actions to take. See the alert context section for all available fields in ctx.
process:
lua_file: ./foo-process.yml
OR
process:
lua_inline: |
if ctx.HitCount > 10 then
return {
{
type = "log",
message = "got " .. ctx.HitCount .. " hits",
}
}
end
-- To indicate no actions, you can return an empty table, nil, or simply
-- don't return at all
return {}
The table returned by process is a list of actions which should be taken. Each action has a type and subsequent fields based on that type.
Simply logs an INFO message to the console. Useful if you're testing an alert and don't want to set up any real actions yet.
{
type = "log",
message = "Performing action for alert " .. ctx.Name,
}
Create and execute an http command. A warning is logged if anything except a 2xx response code is returned.
{
type = "http",
method = "POST", -- optional, defaults to GET
url = "http://example.com/some/endpoint?ARG1=foo",
headers = { -- optional
"X-FOO" = "something",
},
body = "some body for " .. ctx.Name, -- optional
}
Triggers an event in slack. The --slack-key param must be set in the runtime configuration in order to use this action type.
{
type = "slack",
text = "some text"
}
Through its lifecycle each alert has a context object attached to it. The results from the search step are included in it, as well as other data. Here is a description of the available data in the context, as well as how to use it.
NOTE THAT THE CONTEXT IS READ-ONLY IN ALL CASES
{
Name string // The alert's name
StartedTS uint64 // The timestamp the alert started at
// The following are filled in by the search step
TookMS uint64 // Time search took to complete, in milliseconds
HitCount uint64 // The total number of documents matched
HitMaxScore float64 // The maximum score of all the documents matched
// Array of actual documents matched. Keep in mind that unless you manually
// define a limit in your search query this will be capped at 10 by
// elasticsearch. Usually HitCount is the important data point anyway
Hits []{
Index string // The index the hit came from
Type string // The type the document is
ID string // The unique id of the document
Score float64 // The document's score relative to the query
Source object // The actual document
}
// If an aggregation was defined in the search query, the results will be
// set here
Aggregations object
}
Within lua scripts the context is made available as a global variable called ctx
. Fields on it are directly addressable using the above names, for example ctx.HitCount
and ctx.Hits[1].ID
.
In some areas go templates, provided by the template/text package, are used to add some dynamic capabilities to otherwise static configuration fields. In these places the context is made available as the root object. For example, {{.HitCount}}.
In addition to the fields defined above, the root template object also has some methods on it which may be helpful for working with dates. All methods defined on go's time.Time object are available. For example, to format a string into the filebeat index for the current day:
filebeat-{{.Format "2006.01.02"}}
And to do the same, but for yesterday:
filebeat-{{(.AddDate 0 0 -1).Format "2006.01.02"}}