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Send NGINX Logs

Table of Contents

NGINX is one of the most popular web servers today. In a world driven by the web and connected APIs, its logs are a great candidate for surfacing a birds’ eye view of activity in your service.

Explore the Honeytail NGINX Example App and read the blog post with user tips on sending NGINX logs to Honeycomb.

Setup 

Capturing web logs for Honeycomb requires:

1. installing our agent, honeytail
2. configuring it to parse your NGINX logs correctly
3. launching honeytail

Install the Agent 

Download and install the latest honeytail by running:

wget -q https://honeycomb.io/download/honeytail/v1.10.0/honeytail_1.10.0_amd64.deb

echo '3db441215f97eaed068aa0531c986cf5405957e3e8e26b22c16b571091caf917  honeytail_1.10.0_amd64.deb' | sha256sum -c

sudo dpkg -i honeytail_1.10.0_amd64.deb

wget -q https://honeycomb.io/download/honeytail/v1.10.0/honeytail_1.10.0_arm64.deb

echo '4220756e5a941cde6a484cb4cfde184eb189aaf29170df301a874eb143e960ed  honeytail_1.10.0_arm64.deb' | sha256sum -c

sudo dpkg -i honeytail_1.10.0_arm64.deb

wget -q https://honeycomb.io/download/honeytail/v1.10.0/honeytail-1.10.0-1.x86_64.rpm

echo 'b23215a9301b20b2e2262a0823c9e761e8b57e1a62fd5cec35f697fce41fa863  honeytail-1.10.0-1.x86_64.rpm' | sha256sum -c

sudo rpm -i honeytail-1.10.0-1.x86_64.rpm

wget -q -O honeytail https://honeycomb.io/download/honeytail/v1.10.0/honeytail-linux-amd64

echo 'c9cc7dd1aa2b12afeb30b089061870f3407d2df0119e7c2807fec648b603e2d5  honeytail' | shasum -a 256 -c

chmod 755 ./honeytail

wget -q -O honeytail https://honeycomb.io/download/honeytail/v1.10.0/honeytail-linux-arm64

echo '1dd37227788548c4ed44592554e3c90e374c4d796c444dde9f372db8618bc7fa  honeytail' | shasum -a 256 -c

chmod 755 ./honeytail

wget -q -O honeytail https://honeycomb.io/download/honeytail/v1.10.0/honeytail-darwin-amd64

echo '9a3da0f48fe21b1e610ac6b63130dfb8118a9a0ec16abae13350edba02d85e4d  honeytail' | shasum -a 256 -c

chmod 755 ./honeytail

git clone https://github.com/honeycombio/honeytail

cd honeytail; go install

You should modify the config file and uncomment and set:

• ParserName to nginx
• WriteKey to your API key, available from the account page
• LogFiles to the path for the log file you want to ingest. For NGINX, this is typically /var/log/nginx/access.log.
• Dataset to the name of the dataset you wish to create with this log file.

Honeytail also supports configuration with YAML.

Identify Log Locations + Formats 

Make sure to run through Optional Configuration below before running honeytail, in order to get the richest metadata out of your web traffic and into your logs.

In addition to the standard configuration captured in /etc/honeytail/honeytail.conf, you will want to set the two options in the Nginx Parser Options section:

• ConfigFile: the path to your NGINX config file: whichever part of it contains the definition for the log format
• LogFormatName: the name of the log format used to produce the NGINX access log file

For example, if your nginx config file is at /etc/nginx/nginx.conf and has the following snippet:

log_format my_favorite_format '$remote_addr - $remote_user [$time_local] "$request" $status $bytes_sent';
access_log /var/log/nginx/access.log my_favorite_format;

… then ConfigFile should be set to /etc/nginx/nginx.conf and your LogFormatName value should be set to my_favorite_format.

Or configure honeytail to read the nginx logs using command line parameters:

honeytail \
    --parser=nginx \
    --dataset=examples.honeytail-nginx \
    --writekey=$HONEYCOMB_WRITE_KEY \
    --nginx.conf=/etc/nginx/nginx.conf \
    --nginx.format=my_favorite_format \
    --file=/var/log/nginx/access.log

Launch the Agent 

Start up a honeytail process using upstart or systemd or by launching the process by hand.

sudo initctl start honeytail

sudo systemctl start honeytail

honeytail -c /etc/honeytail/honeytail.conf

Backfilling Archived Logs 

In addition to getting current logs flowing, you can backfill old logs into Honeycomb to kickstart your dataset. By running honeytail from the command line, you can import old logs separate from tailing your current logs. Adding the --backfill flag to honeytail adjusts a number of settings to make it appropriate for backfilling old data, such as stopping when it gets to the end of the log file instead of the default behavior of waiting for new content (like tail).

The specific locations on your system may vary from ours, but once you fill in your system’s values instead of our examples, you can backfill using this command:

honeytail --writekey=YOUR_API_KEY --dataset="nginx API logs" --parser=nginx \
  --file=/var/log/nginx/access.16.log \
  --nginx.conf=/etc/nginx/nginx.conf \
  --nginx.format=api_fmt \
  --backfill

This command can be used at any point to backfill from archived log files. You can read more about our agent honeytail or its backfill behavior here.

Troubleshooting 

Check out honeytail Troubleshooting for debugging tips.

Optional Configuration 

Nginx logs can be an incredibly powerful, high-level view of your system—especially so if they are configured correctly and enriched with custom, application-specific information about each request. Below are two simple ways to pack those logs with more useful metadata.

Missing Default Options 

Nginx comes with some fairly powerful optional log fields that are not included by default. This is the log_format we recommend for any configuration file (note the extra quotes around some fields):

log_format combined '$remote_addr - $remote_user [$time_local] $host '
    '"$request" $status $bytes_sent $body_bytes_sent $request_time '
    '"$http_referer" "$http_user_agent" $request_length "$http_authorization" '
    '"$http_x_forwarded_proto" "$http_x_forwarded_for" $server_name';
access_log /var/log/nginx/access.log combined;

You may already have an access_log line, but by defining a log_format (combined, in the example above) and specifying the format name (--nginx.format=combined), you will be able to take advantage of all of these additional fields. Make sure that all fields that start $http_ are quoted in your log_format:

• $bytes_sent: the size of the response sent back to the client, including headers
• $host: the requested Host header, identifying how your server was addressed
• $http_authorization: authorization headers, for associating logs with individual users (must be quoted)
• $http_referer: the referring site, if the client followed a link to your site (must be quoted)
• $http_user_agent: the User-Agent header, useful in identifying your clients (must be quoted)
• $http_x_forwarded_for: the origin IP address, if running behind a load balancer (must be quoted)
• $http_x_forwarded_proto: the origin protocol, if terminating TLS in front of nginx (must be quoted)
• $remote_addr: the IP address of the host making the connection to nginx
• $remote_user: the user name supplied when/if using basic authentication
• $request_id: an nginx-generated unique ID to every request (only available in nginx version 1.11 and later).
• $request_length: the length of the client’s request, including headers and body
• $request_time: the time (in ms) the server took to respond to the request
• $request: the HTTP method, request path, and protocol version
• $server_name: the hostname of the machine accepting the request
• $status: the HTTP status code returned for this request

Embedding Custom Response Headers 

Nginx can also be configured to extract custom request and response headers. Of the two, response headers are the most powerful in this case—they can carry application-specific IDs or timers back through to the nginx log. Having all of the information pertinent to a single request, available in a single log line, can be an incredibly powerful tool in diagnosing the origin of a problem in your system.

To include a specific response header in your access.log, add an $upstream_http_ variable to your log_format—the response header values will be written out and ingested by our nginx parser! Make sure to put quotes around these variables to capture any embedded spaces.

For example, an X-RateLimit-Remaining header can be output by adding $upstream_http_x_ratelimit_remaining to the log_format line. See the nginx docs for more about extracting metadata from the HTTP response or request.

As with other fields which may output strings (for example,$http_user_agent), be careful when logging strings—add an extra set of double quotes around values which might contain spaces, in order to ensure correct parsing.

A final trick: sometimes, response headers may be set for logging that should not be exposed back to the user. In this case, the proxy_hide_header directive may be used to strip out specific headers by name:

log_format combined `... "$upstream_x_internal_top_secret" ...`; # Wrap string values with double quotes
access_log /var/log/nginx/access.log combined;
location / {
  proxy_pass http://127.0.0.1:8080;        # Expose port 8080
  proxy_hide_header X-Internal-Top-Secret; # Strip from client
}

Scrubbing Personally Identifiable Information 

While we believe strongly in the value of being able to track down the precise query causing a problem, we understand the concerns of exporting log data which may contain sensitive user information.

With that in mind, we recommend using honeytail’s nginx parser, but adding a --scrub_field=sensitive_field_name flag to hash the concrete sensitive_field_name value, or --drop_field=sensitive_field_name to drop it altogether and prevent it being sent to Honeycomb’s servers.

Find more information about dropping or scrubbing sensitive field.

Parsing URL Patterns 

honeytail can break URLs up into their component parts, storing extra information in additional columns. This behavior is turned on by default for the request field on nginx datasets, but can become more useful with a little bit of guidance from you.

See honeytail’s documentation for details on configuring our agent to parse URL strings.

Open Source 

Honeytail is open source and Apache 2.0 licensed.

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