# Store Apache Logs into MongoDB

This article explains how to use [Fluentd](http://fluentd.org/)'s MongoDB Output plugin ([out\_mongo](https://docs.fluentd.org/0.12/articles/broken-reference)) to aggregate semi-structured logs in real-time.

## Background

[Fluentd](http://fluentd.org/) is an advanced open-source log collector originally developed at [Treasure Data, Inc](http://www.treasuredata.com/). Because Fluentd handles logs as semi-structured data streams, the ideal database should have strong support for semi-structured data. There are several candidates that meet this criterion, but we believe [MongoDB](http://www.mongodb.org/) is the market leader.

MongoDB is an open-source, document-oriented database developed at [10gen, Inc](http://www.10gen.com/). It is schema-free and uses a JSON-like format to manage semi-structured data.

This article will show you how to use [Fluentd](http://fluentd.org/) to import Apache logs into MongoDB.

## Mechanism

The figure below shows how things will work.

![](https://3804023877-files.gitbook.io/~/files/v0/b/gitbook-legacy-files/o/assets%2F-LR7OsqPORtP86IQxs6E%2F-Lenu6JN-LAXfVTKmMPz%2F-LenuEFix8KK9dBfU0St%2Fapache-to-mongodb.png?generation=1557796551795547\&alt=media)

Fluentd does 3 things:

1. It continuously "tails" the access log file.
2. It parses the incoming log entries into meaningful fields (such as

   `ip`, `path`, etc.) and buffers them.
3. It writes the buffered data to MongoDB periodically.

## Install

For simplicity, this article will describe how to set up an one-node configuration. Please install the following software on the same node.

* [Fluentd](http://fluentd.org/)
* [MongoDB Output Plugin](https://docs.fluentd.org/0.12/articles/broken-reference)
* [MongoDB](http://www.mongodb.org/)
* Apache (with the Combined Log Format)

The MongoDB Output plugin is included in the latest version of Fluentd's deb/rpm package. If you want to use Ruby Gems to install the plugin, please use `gem install fluent-plugin-mongo`.

* [Debian Package](https://docs.fluentd.org/0.12/articles/install-by-deb)
* [RPM Package](https://docs.fluentd.org/0.12/articles/install-by-rpm)
* [Ruby gem](https://docs.fluentd.org/0.12/articles/install-by-gem)

For MongoDB, please refer to the following downloads page.

* [MongoDB Downloads](http://www.mongodb.org/downloads)

## Configuration

Let's start configuring Fluentd. If you used the deb/rpm package, Fluentd's config file is located at /etc/td-agent/td-agent.conf. Otherwise, it is located at /etc/fluentd/fluentd.conf.

### Tail Input

For the input source, we will set up Fluentd to track the recent Apache logs (typically found at /var/log/apache2/access\_log) The Fluentd configuration file should look like this:

```
<source>
  @type tail
  format apache2
  path /var/log/apache2/access_log
  pos_file /var/log/td-agent/apache2.access_log.pos
  tag mongo.apache.access
</source>
```

Please make sure that your Apache outputs are in the default \\'combined\\' format. \`format apache2\` cannot parse custom log formats. Please see the [in\_tail](https://docs.fluentd.org/0.12/articles/broken-reference) article for more information.

Let's go through the configuration line by line.

1. `type tail`: The tail Input plugin continuously tracks the log file.

   This handy plugin is included in Fluentd's core.
2. `format apache2`: Uses Fluentd's built-in Apache log parser.
3. `path /var/log/apache2/access_log`: The location of the Apache log.

   This may be different for your particular system.
4. `tag mongo.apache.access`: `mongo.apache.access` is used as the tag

   to route the messages within Fluentd.

That's it! You should now be able to output a JSON-formatted data stream for Fluentd to process.

### MongoDB Output

The output destination will be MongoDB. The output configuration should look like this:

```
<match mongo.**>
  # plugin type
  @type mongo

  # mongodb db + collection
  database apache
  collection access

  # mongodb host + port
  host localhost
  port 27017

  # interval
  flush_interval 10s

  # make sure to include the time key
  include_time_key true
</match>
```

The match section specifies the regexp used to look for matching tags. If a matching tag is found in a log, then the config inside `<match>...</match>` is used (i.e. the log is routed according to the config inside). In this example, the `mongo.apache.access` tag (generated by `tail`) is always used.

The `**` in `mongo.**` matches zero or more period-delimited tag parts (e.g. mongo/mongo.a/mongo.a.b).

**flush\_interval** specifies how often the data is written to MongoDB. The other options specify MongoDB's host, port, db, and collection.

For additional configuration parameters, please see the [MongoDB Output plugin](https://docs.fluentd.org/0.12/articles/broken-reference) article. If you are using ReplicaSet, please see the [MongoDB ReplicaSet Output plugin](https://docs.fluentd.org/0.12/articles/broken-reference) article.

## Test

To test the configuration, just ping the Apache server. This example uses the `ab` (Apache Bench) program.

```
$ ab -n 100 -c 10 http://localhost/
```

Then, access MongoDB and see the stored data.

```
$ mongo
> use apache
> db["access"].findOne();
{ "_id" : ObjectId("4ed1ed3a340765ce73000001"), "host" : "127.0.0.1", "user" : "-", "method" : "GET", "path" : "/", "code" : "200", "size" : "44", "time" : ISODate("2011-11-27T07:56:27Z") }
{ "_id" : ObjectId("4ed1ed3a340765ce73000002"), "host" : "127.0.0.1", "user" : "-", "method" : "GET", "path" : "/", "code" : "200", "size" : "44", "time" : ISODate("2011-11-27T07:56:34Z") }
{ "_id" : ObjectId("4ed1ed3a340765ce73000003"), "host" : "127.0.0.1", "user" : "-", "method" : "GET", "path" : "/", "code" : "200", "size" : "44", "time" : ISODate("2011-11-27T07:56:34Z") }
```

## Conclusion

Fluentd + MongoDB makes real-time log collection simple, easy, and robust.

## Learn More

* [Fluentd Architecture](https://www.fluentd.org/architecture)
* [Fluentd Get Started](https://docs.fluentd.org/0.12/articles/broken-reference)
* [MongoDB Output Plugin](https://docs.fluentd.org/0.12/articles/broken-reference)
* [MongoDB ReplicaSet Output Plugin](https://docs.fluentd.org/0.12/articles/broken-reference)

If this article is incorrect or outdated, or omits critical information, please [let us know](https://github.com/fluent/fluentd-docs-gitbook/issues?state=open). [Fluentd](http://www.fluentd.org/) is a open source project under [Cloud Native Computing Foundation (CNCF)](https://cncf.io/). All components are available under the Apache 2 License.