= NGINX-to-Prometheus log file exporter :tip-caption: :bulb: :note-caption: :information_source: :important-caption: :heavy_exclamation_mark: :caution-caption: :fire: :warning-caption: :warning: :toc: :toc-placement!: :toc-title:
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Helper tool that continuously reads an NGINX log file (or any kind of similar log file) and exports metrics to https://prometheus.io/[Prometheus].
[discrete] == Contents
toc::[]
== Usage
You can either use a simple configuration, using command-line flags, or create a configuration file with a more advanced configuration.
Use the command-line:
Use the configuration file:
There are multiple ways to install this exporter.
=== Docker
Docker images for this exporter are available at the quay.io and pkg.github.com registries:
quay.io/martinhelmich/prometheus-nginxlog-exporter:v1docker.pkg.github.com/martin-helmich/prometheus-nginxlog-exporter/exporter:v1Have a look at the https://github.com/martin-helmich/prometheus-nginxlog-exporter/releases[releases page]
to see the available versions and how to pull their images. In general, I would
recommend using the v1 tag instead of latest.
Run the exporter as follows (adjust paths like /path/to/logs and
/path/to/config to your own needs):
Command-line flags and arguments can simply be appended to the docker run command, for example to use a
configuration file:
=== DEB and RPM packages
Each https://github.com/martin-helmich/prometheus-nginxlog-exporter/releases[release] from 1.5.1 or newer provides both DEB and RPM packages.
$ wget https://github.com/martin-helmich/prometheus-nginxlog-exporter/releases/download/v1.6.0/prometheus-nginxlog-exporter_1.6.0_linux_amd64.deb
$ apt install prometheus-nginxlog-exporter_1.6.0_linux_amd64.deb
The package come with a dependency on systemd and configure the exporter to be running automatically:
$ systemctl status prometheus-nginxlog-exporter
$ # systemctl disable prometheus-nginxlog-exporter
$ # systemctl enable prometheus-nginxlog-exporter
The packages drop a configuration file to /etc/prometheus-nginxlog-exporter.hcl
which you can adjust to your own needs.
If you do not want to use one of the pre-built packages, you can download the
binary itself and manually configure systemd to start it. You can find an
example unit file for this service
https://github.com/martin-helmich/prometheus-nginxlog-exporter/blob/master/res/package/prometheus-nginxlog-exporter.service[in this repository].
Simply copy the unit file to /etc/systemd/system:
$ wget -O /etc/systemd/system/prometheus-nginxlog-exporter.service https://raw.githubusercontent.com/martin-helmich/prometheus-nginxlog-exporter/master/res/package/prometheus-nginxlog-exporter.service
$ systemctl enable prometheus-nginxlog-exporter
$ systemctl start prometheus-nginxlog-exporter
The shipped unit file expects the binary to be located in
/usr/sbin/prometheus-nginxlog-exporter (if you sideload the exporter without
using your package manager, you might want to put it to /usr/local, instead)
and the configuration file in /etc/prometheus-nginxlog-exporter.hcl. Adjust
to your own needs.
If you run a logfile-generating service (be it NGINX, or anything that generates similar access log files) in Kubernetes, you can run the exporter as a sidecar along your "main" container within the same pod.
The following example shows you how to deploy the exporter as a sidecar, accepting logs from the main container via syslog:
In this example, the configuration file is passed via the exporter-config
ConfigMap. This might look like follows:
apiVersion: v1 kind: ConfigMap metadata: name: exporter-config data: config.hcl: | listen { port = 4040 }
namespace "nginx" {
source = {
syslog {
listen_address = "udp://127.0.0.1:5531"
format = "rfc3164"
}
}
format = "$remote_addr - $remote_user [$time_local] \"$request\" $status $body_bytes_sent \"$http_referer\" \"$http_user_agent\" \"$http_x_forwarded_for\""
labels {
app = "default"
}
}
The config file instructs the exporter to accept log input via syslog. To
forward logs to the exporter, just instruct your main container to send its
access logs via syslog to 127.0.0.1:5531 (which works, since the main
container and the sidecar share their network namespace).
To build the exporter from source, simply build it with go get:
$ go get github.com/martin-helmich/prometheus-nginxlog-exporter
Alternatively, clone this repository and just run go build:
$ git clone git://github.com/martin-helmich/prometheus-nginxlog-exporter
$ cd prometheus-nginxlog-exporter
$ go build
== Collected metrics
This exporter collects the following metrics. This collector can listen on
multiple log files at once and publish metrics in different namespaces. Each
metric uses the labels method (containing the HTTP request method) and
status (containing the HTTP status code).
http_upstream_time_seconds metric
will require your access to contain the variable $upstream_response_time.Metrics are exported at the /metrics path.
These metrics are exported:
|===
| <namespace>_http_response_count_total | The total amount of processed HTTP requests/responses.
| <namespace>_http_response_size_bytes | The total amount of transferred content in bytes.
| <namespace>_http_upstream_time_seconds | A summary vector of the upstream response times in seconds. Logging these needs to be specifically enabled in NGINX using the $upstream_response_time variable in the log format.
| <namespace>_http_upstream_time_seconds_hist | Same as <namespace>_http_upstream_time_seconds, but as a histogram vector. Also requires the $upstream_response_time variable in the log format.
| <namespace>_http_response_time_seconds | A summary vector of the total response times in seconds. Logging these needs to be specifically enabled in NGINX using the $request_time variable in the log format.
| <namespace>_http_response_time_seconds_hist | Same as <namespace>_http_response_time_seconds, but as a histogram vector. Also requires the $request_time variable in the log format.
|===
Additional labels can be configured in the configuration file (see below).
<namespace> can be omitted or overridden - see <> for
more information.
== Configuration file
You can specify a configuration file to read at startup. The configuration file is expected to be either in https://github.com/hashicorp/hcl[HCL] or YAML format. Here's an example file:
listen { port = 4040 address = "10.1.2.3" metrics_endpoint = "/metrics" }
consul { enable = true address = "localhost:8500" datacenter = "dc1" scheme = "http" token = "" service { id = "nginx-exporter" name = "nginx-exporter" address = "192.168.3.1" tags = ["foo", "bar"] } }
namespace "app1" { format = "$remote_addr - $remote_user [$time_local] "$request" $status $body_bytes_sent "$http_referer" "$http_user_agent" "$http_x_forwarded_for"" source { files = [ "/var/log/nginx/app1/access.log" ] }
labels { app = "application-one" environment = "production" foo = "bar" }
histogram_buckets = [.005, .01, .025, .05, .1, .25, .5, 1, 2.5, 5, 10] }
The same file as YAML file:
listen: port: 4040 address: "10.1.2.3" metrics_endpoint: "/metrics"
consul: enable: true address: "localhost:8500" datacenter: dc1 scheme: http token: "" service: id: "nginx-exporter" name: "nginx-exporter" address = "192.168.3.1" tags: ["foo", "bar"]
namespaces:
For historic reasons, this exporter exports separate metrics for different namespaces (because the namespace is part of the metric name). However, in many (most) cases, it's more convenient to have the same metric name across different namespaces (with different log formats and names).
This can be done in two steps:
metrics_override)namespace_label)namespace "app1" { ... metrics_override = { prefix = "myprefix" } namespace_label = "vhost" ... }
prefix can be set to "", resulting metrics like http_response_count_total{...}namespace_label can be omitted - so you have full control on metric formatSome details and history on this can be found in https://github.com/martin-helmich/prometheus-nginxlog-exporter/issues/13[issue #13].
Partial case of <>:
Exported metrics will have upstream_addr and country labels.
Currently, the exporter supports reading log data from
All log sources can be configured on a per-namespace basis using the source property.
When reading from log files, all that is needed is a files property:
namespace "test" {
source {
files = ["/var/log/nginx/access.log"]
// ...
}
}
The exporter can also open and listen on a Syslog port and read logs from there. Configuration works as follows:
namespace "test" { source { syslog { listen_address = "udp://127.0.0.1:8514" <1> format = "rfc3164" <2> tags = ["nginx"] }
// ...
<1> The listen_address might be either a TCP or UDP address. UNIX sockets are not supported (yet -- pull requests are welcome)
<2> The format may be one of rfc3164, rfc5424, rfc6587 or auto. If omitted, it will default to auto.
Have a look at http://nginx.org/en/docs/syslog.html[the respective section of the NGINX documentation] on how to set up NGINX to log into syslog.
The exporter contains features that are currently experimental and may change without prior notice.
To use these features, either set the -enable-experimental flag or add a enable_experimental
option to your configuration file (on the root of the configuration file document, like
enable_experimental: true in YAML or enable_experimental = true in HCL).
Re-labeling lets you add arbitrary fields from the parsed log line as labels to your metrics.
To add a dynamic label, add a relabel statement to your configuration file:
namespace "app-1" { // ...
<1> The whitelist property is optional; if set, only the supplied values will be added as label.
All other values will be subsumed under the "other" label value. See #16 for a more detailed
discussion around the reasoning.
Dynamic relabeling also allows you to aggregate your metrics by request path (which replaces
the experimental feature originally introduced in #23). The following example splits the content of
the request variable at every space (using split) and return the second element (index 1) of the
resulting list which is the base for the regex):
namespace "app1" { // ...
relabel "request_uri" { from = "request" split = 2
match "^/users/[0-9]+" {
replacement = "/users/:id"
}
match "^/profile" {
replacement = "/profile"
}
If a match is found, the replacement replaces each occurrence of the corresponding match in the original value. Otherwise the processing continues to check the following match statements.
The YAML configuration for relabelings works similar to the HCL configuration:
namespaces:
If your regular expression contains groups, you can also use the matched values of those in the replacement value:
relabel "request_uri" { from = "request" split = 2
If Nginx is running in a docker container and is configured to log to /dev/stdout and /dev/stderr (this is the
default configuration of the official nginx image), then you can export logs using Docker's default logging driver.
To do this use a source configuration as follows:
namespace "test" { source { docker { container = "nginx_container_name" }
// ...
The host's docker socket needs to be mounted to the container. For example, if using the docker run command as follows:
== Frequently Asked Questions
I have started the exporter, but it is not exporting any application-specific metrics!
This may have several issues:
<namespace>_parse_errors_total metric, which will indicate how many log lines could not be parsed.The exporter exports the
<namespace>_http_response_count_totalmetric, but not [other metric that is mentioned in the README]!
Most metrics require certain values to be present in the access log files that are not present in the NGINX default configuration. Especially, make sure that the access log contains the http://nginx.org/en/docs/http/ngx_http_upstream_module.html#var_upstream_response_time[`$upstream_response_time`], http://nginx.org/en/docs/http/ngx_http_log_module.html#var_request_time[`$request_time`] and/or http://nginx.org/en/docs/http/ngx_http_core_module.html#variables[`$body_bytes_sent`] variables. These need to be enabled in the NGINX configuration (more precisely, the log_format setting) and then added to the format specified for the exporter.
How can I configure NGINX to export these variables?
Have a look at NGINX's https://www.nginx.com/resources/admin-guide/logging-and-monitoring/[Logging and Monitoring] guide. It contains some good examples that contain the $request_time and $upstream_response_time:
log_format upstream_time '$remote_addr - $remote_user [$time_local] '
'"$request" $status $body_bytes_sent '
'"$http_referer" "$http_user_agent"'
'rt=$request_time uct="$upstream_connect_time" uht="$upstream_header_time" urt="$upstream_response_time"';
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