conditional labels

[axinojolais]

Hi,

Is it possible to have "conditional" labels ? For example, consider the following patterns :

FOO foo
BAR bar
FOOBAR %{FOO:foo}%{BAR:bar}?

If I match on %{FOOBAR} in my metrics, I can use {{.foo}} in the labels, because it will always be present. However, as soon as I want to use {{.bar}}, I run into problems because a line can match only %{FOO} and not %{BAR}, so sometimes bar isn't in the template context, so grok_exporter becomes unhappy : Warning : Skipping log line: foobar: unexpected result when calling onig_name_to_group_numbers()

I tried to work around it by using {{if .bar}}{{.bar}}{{end}} to no avail.

How could I achieve what I want there ? Is there a way to check that a template variable exists without making grok_exporter bail on onig_name_to_group_numbers() ?

Thanks

[fstab]

This is a bug, I will fix it in the next release and make {{.bar}} an empty string in that case. As a workaround, you can use this:

FOO foo
BAR bar
OPTIONAL_BAR %{BAR}?
FOOBAR %{FOO:foo}%{OPTIONAL_BAR:bar}

[Nitro-N]

ERRORDATE %{YEAR}/%{MONTHNUM}/%{MONTHDAY} %{TIME}
METHOD (OPTIONS|GET|HEAD|POST|PUT|DELETE|TRACE|CONNECT)
REQUEST_START %{METHOD:method} %{DATA:path} HTTP/%{DATA:http_version}
ADDITIONAL_INFO client: %{URIHOST:client}|server: %{URIHOST:server}|request: "%{REQUEST_START:request}"|upstream: "%{URI:upstream}"|host: "%{URIHOST:host}"|referrer: "%{URI:referrer}"
NGINX_ERROR ^%{ERRORDATE:time_local} \[%{LOGLEVEL:level}\] %{INT:process_id}#%{INT:thread_id}: \*(%{INT:connection_id})? %{DATA:errormessage}(, %{ADDITIONAL_INFO})*$

Please include this or the same case into tests. Labels in ADDITIONAL_INFO match are optional.

[fstab]

@Nitro-N sorry for the late reply. I pushed a test for the FOOBAR example above. Could you provide an example log line for the NGINX_ERROR pattern? Then I will add it to the test cases.

[Nitro-N]

@fstab

2018/05/29 15:33:58 [error] 50#50: *5338007 no live upstreams while connecting to upstream, client: 5.128.43.14, server: example.com, request: "GET /backend/api/event/events?_limit=0&startTime=2018-05-29T04:00:00%2B07:00 HTTP/2.0", upstream: "http://example.com/backend/api/event/events?_limit=0&startTime=2018-05-29T04:00:00%2B07:00", host: "example.com", referrer: "https://example.com/platform"
2018/05/29 15:35:33 [error] 50#50: *5340036 upstream prematurely closed connection while sending to client, client: 188.162.213.93, server: example.com, request: "GET /backend/api/ HTTP/2.0", upstream: "http://172.19.0.8:80/backend/api", host: "example.com", referrer: "https://example.com/event"
2018/05/29 18:54:03 [crit] 50#50: *5411664 SSL_do_handshake() failed (SSL: error:1417D18C:SSL routines:tls_process_client_hello:version too low) while SSL handshaking, client: 208.93.213.176, server: 0.0.0.0:443

[fstab]

Thanks for the examples. I pushed a test, it should work now.

[fstab]

Released v0.2.5 including the fix for this issue.