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Balancer access logs

The Balancer access log provides information about requests received at the balancer level. Since most customers use shared load balancers, Varnish logs are only available using the log stream feature and cannot be downloaded from either the Cloud Platform interface or your servers.

For a list of the log files handled by Cloud Platform, including accessing these log files, log file retention, and their locations, see About Cloud Platform logging. You can also review information about how to streaming Varnish log entries in real time from your browser.

Note for log streaming users

Acquia’s log forwarding feature adds information to the beginning of each line that is forwarded to an external service. For more information, see File formats in forwarded log files.

Parsing the log file

The following line is a representative example of the data written into your website’s balancer access log:

127.0.0.1 - - [30/Dec/2016:18:12:20 +0000] "GET /names HTTP/1.1" 200 12750 "-"
"facebookexternalhit/1.1" http_host=www.example.com affinity="-"  upstream_addr="171.0.0.1:80" hosting_site=alphabeta request_time=1.263 forwarded_for="173.0.0.1, 172.0.0.1" upstream_status="200"
request_id="v-0000zzzz-cebb-0000-9948-0efda0c0zzzz" ssl_protocol="TLSv1.2" ssl_cipher="AES128-GCM-SHA256"

Each of the items in the balancer access log is noted in the following table, along with its description:

Position Data Description
0 127.0.0.1 The IP address of the web client accessing the balancer.
1 - The name of a remote log file, if used (- is an empty value).
2 - The username the web client was authorized under, if used (- is an empty value).
3 [30/Dec/2016:18:12:20 +0000] The date and time of the request.
4 GET The method of the request—frequently GET or POST.
5 /names The document requested, relative to the docroot of the website.
6 HTTP/1.1 The HTTP protocol used for the request.
7 200 The HTTP status code returned by the balancer—note that it may differ from the HTTP status code returned by the back end server the request was forwarded to, and production environments don’t display full information for HTTP 5xx status codes.
8 12750 Size, in bytes, of the server’s response.
9 "-" The referrer URL, if any (- is an empty value).
10 facebookexternalhit/1.1 The user-agent of the request.
11 http_host=www.example.com The requested domain name.
12 affinity="-" The back end server this request was pinned to, if any (- is an empty value).
13 upstream_addr="171.0.0.1:80" The back end server the balancer forwarded this request to.
14 hosting_site=alphabeta The internal Acquia site name this request is for.
15 request_time=1.263 Time in seconds needed to complete this request.
16 forwarded_for="173.0.0.1, 172.0.0.1"

The full set of IP addresses tracked as “requester IP,” which will contain the IP addresses of the following if they are in use by the subscription:

  • Load balancer
  • ELB (Elastic Load Balancer)
  • Content Delivery Networks or Web Application Firewalls (WAFs) such as Edge)
17 upstream_status="200" The HTTP status code returned by the back end server the request was forwarded to—note that it may differ from the HTTP status code returned by the balancer.
18 request_id="v-0000zzzz-cebb-0000-9948-0efda0c0zzzz" A unique ID attached to this request by the load balancer, which appears in several Cloud Platform log files. For more information, see Using HTTP request IDs.
19 ssl_protocol="TLSv1.2" The SSL protocol used for this request, if any.
20 ssl_cipher="AES128-GCM-SHA256" The SSL cipher used for this request, if any.