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Varnish Cache Plus

Akamai Connector

Description

The Akamai Connector for Varnish allows for the integration of data and configuration between an origin Varnish server and Akamai’s CDN network.

The latest version of the Akamai Connector is 1.0.7.

Installation

In order to install the Akamai Connector for Varnish, you first need to setup access to the connector repo. If you have not already done so, please contact support at support@varnish-software.com to get assistance with repo setup.

Ubuntu Installation

> apt-get install varnish-plus-akamai-connector

Redhat Enterprise Linux Installation

> yum install varnish-plus-akamai-connector

Configuration

The following configuration steps are required to get the Akamai Connector running within your Varnish setup.

Automatic VCL Integration

include "akamai_41_auto.vcl";

This will automatically hook Akamai request and response logic into the appropriate vcl_* subroutines. All Connector functionality is enabled and no further configuration is required.

Note: This examples assumes VCL version 4.1 (there is a vcl 4.1 line in your VCL configuration). If you are using VCL version 4.0 you need to include “akamai_auto.vcl” instead of “akamai_41_auto.vcl”.

Purge Synchronization

If you would like to synchronize purge requests on this host to the Akamai network, the following Akamai CCU API fields need to be configured within the akamai-connector.conf file:

  • purge_host
  • purge_client_token
  • purge_client_secret
  • purge_access_token

Omitting these fields or removing this configuration file will cause the Akamai purge functionality to be skipped entirely.

You can also point Varnish Cache to an alternate configuration path by setting VMOD_AKAMAI_CONFIG_FILE to the alternate path.

Example

export VMOD_AKAMAI_CONFIG_FILE=/opt/akamai/.ac.conf

Starting in version 1.0.7, the connector supports purge by cache tag and CP Code.

Advanced VCL Integration

To selectively choose which features of the Connector you wish to use, you can use the following vcl subroutines (via akamai.vcl):

  • akamai_init_sureroute
  • akamai_recv_timeout
  • akamai_recv_esi
  • akamai_recv_device_detection
  • akamai_recv_true_client_ip
  • akamai_recv_sureroute
  • akamai_purge
  • akamai_deliver_edge_control
  • akamai_deliver_esi
  • akamai_deliver_vary
  • akamai_deliver_via

Each subroutines need to be called in the appropriate sub vcl_* subroutine as specified in the 2nd part of the name. For example, akamai_deliver_edge_control needs to be called in sub vcl_deliver. If multiple subroutines have the same functionality label, as specified by the 3rd part of the name, each one needs to be invoked. For example, both akamai_recv_esi and akamai_deliver_esi need to be called to integrate ESI with Akamai.

Sureroute Example:

include "akamai.vcl";

sub vcl_init {
  call akamai_init_sureroute;
}

sub vcl_recv {
  call akamai_recv_sureroute;
}

If you have unused subroutines, you can disable Varnish Cache from reporting them as an error by adding the following startup parameter to varnishd:

-p vcc_err_unref=false

Tag Based Purging:

This example will show how to override the akamai_auto.vcl to use a different purging call to Akamai to purge by cache tags. Additionally, this will show you how to use ykey purging at the same time as Akamai purging. Akamai assigns cache tags to an object through the response header Edge-Cache-Tag

include "akamai_auto.vcl";

sub vcl_recv {
  if (req.method == "PURGE") {
    # Purge Varnish and Akamai with tags
    set req.http.ykey_purges = ykey.purge(req.http.tags);
    akamai.purge_cachetag(req.http.tags);

    return (synth(941, "Purged"));
  }
}

# Add information about ykey purge to synthetic return
sub vcl_synth {
  if (resp.status == 941) {
    set resp.http.ykey_purges = req.http.ykey_purges;
  }
  # Output from Akamai purge automatically added from
  # akamai_auto.vcl
}

sub vcl_backend_response {
  # Align ykey keys with Akamai cache tags
  ykey.add_key(beresp.http.Edge-Cache-Tag);
}

Proxy support

In order to direct all request via a proxy on can set the “proxy”-key in the VMOD_AKAMAI_CONFIG_FILE. Set the key-value to a string specifing the proxy, like this [scheme]://[user:secret]@IP|host[:port]. See libcurl documentation for more details on defining a proxy.

Tunneling is also supported and enabled by setting the “http_proxy_tunnel”-key to 1 in the VMOD_AKAMAI_CONFIG_FILE.

Akamai Configuration

The Akamai Connector requires no additional changes to your Akamai configuration and is designed to operate with your current Akamai environment as-is.

For best results, ensure that your Akamai configuration classifies requests as cacheable by default and excludes those requests that are not cacheable.

The Connector, using VCL, can correctly define the cacheability status and appropriate TTLs. However, the early classification will ensure that the Akamai Intelligent Platform will use SureRoute and Tiered Distribution for non cacheable and cacheable content respectfully.

To utilize Device Characteristics in Varnish you will need to enable the behavior for Device Characteristics on your Configuration.

Validating Installation

Run the following curl command:

curl -I http://[host]/akamai/testobject.html \
     -H "Via: akamai.net(ghost) (AkamaiGHost)"

Substitute [host] with the name or IP address of the Varnish server running the Akamai Connector. You should see the following response:

HTTP/1.1 200 OK
Content-Length: 20480
Date: Thu, 09 Mar 2017 23:19:41 GMT
X-Varnish: 2
Edge-Control: max-age=130
Cache-Control: post-check=120
Via: 1.1 varnish-v4, Akamai Connector/[version]
X-varnish-hits: 0
Accept-Ranges: bytes
Connection: keep-alive

In particular, verify you have a successful 200 response code or that the Via header states Akamai Connector.

Feature Overview

The Akamai Connector for Varnish offers the following functionality.

Object TTL and Grace

The Varnish Cache internal value of beresp.ttl, beresp.grace, and beresp.uncacheable will be synchronized with the Akamai CDN on each request. These values will supersede the Cache-Control header.

In your Luna Property Configuration for Akamai, set your caching behavior to honor origin cache control and expires.

Purge Synchronization

When a purge request is handled by Varnish Cache, the Connector will synchronize the invalidation request against the Akamai CDN. The Connector will use the value of req.url and req.http.Host for invalidation.

The akamai-connector.conf needs to have all of the purge_* fields filled in, otherwise purge synchronization is skipped on this host.

If purge synchronization is configured, Varnish Cache will relay the Akamai CCU API response as its purge response.

CCU API credentials need to be generated via the Luna Control Center.

True Client IP

The Varnish Cache value of req.http.True-Client-IP will always contain the True Client IP of the requestor.

In Luna, make sure the header used is True-Client-IP.

SureRoute

The Connector will respond to requests for /akamai/testobject.html with a native SureRoute response.

The response size is configured via sureroute_resp_bytes in akamai-connector.conf.

In Luna, make sure the SureRoute test object path is /akamai/testobject.html.

ESI

ESI processing in Varnish Cache is deferred to Akamai when requests originate from the Akamai CDN.

In Luna, make sure the ESI processor is enabled.

Device Characterization

Each characteristic in the X-Akamai-Device-Characteristics field will be put into its own header. The header name is X-ADC-[characteristic] where [characteristic] is the characteristic name. For example, the value of is_mobile will be put into the X-ADC-is_mobile header.

Connection Keep-Alive

Connections between Akamai CDN and Varnish Cache will be held open for 301 seconds.

API

The connector supports Akamai calls to purge by cache tag and CP Code.

These functions require the akamai-connector.conf to be configured with the appropriate Akamai CCU API values for purge_host, purge_client_token, purge_client_secret, and purge_access_token. The connector will automatically sign the request using the configured Akamai credentials in akamai-connector.conf.

If akamai-connector.conf is not configured, these calls do nothing.

is_esi

BOOL is_esi()

Returns true if the object to be delivered was scanned during fetch for ESI instructions (beresp.do_esi was set). Only valid when called from sub vcl_deliver. Returns false if called from any other VCL function.

This is useful in situations where you have layered caches, and for some set of the incoming requests Varnish is not the edge layer where the ESI processing should be executed. To help the next layer know whether the data should be scanned for ESI instructions or not, this vmod can be used to set a response header.

Arguments: None

Type: Function

Returns: Bool

set_session_timeout_idle

VOID set_session_timeout_idle(DURATION timeout)

Set the session idle timeout. The timeout will be set for the current session only, and will silently fail if the session is not available in the current VCL sub.

Note: This function will only have effect if the target Varnish version has built in support for per session idle timeouts.

Example

sub vcl_recv {
  if(...) {
    akamai.set_session_timeout_idle(300s);
  }
}

Arguments:

  • timeout accepts type DURATION

Type: Function

Returns: None

duration2real

REAL duration2real(DURATION, REAL)

Convert a VCL DURATION to a VCL REAL.

Arguments: None

Type: Function

Returns: Real

obj_ttl

DURATION obj_ttl()

Return the obj.ttl. Only valid in VCL functions where obj exists. Returns 0 if called from any other VCL function.

Arguments: None

Type: Function

Returns: Duration

obj_grace

DURATION obj_grace()

Return the obj.grace. Only valid in VCL functions where obj exists. Returns 0 if called from any other VCL function.

Arguments: None

Type: Function

Returns: Duration

obj_keep

DURATION obj_keep()

Return the obj.keep. Only valid in VCL functions where obj exists. Returns 0 if called from any other VCL function.

Arguments: None

Type: Function

Returns: Duration

parse_adc_params

VOID parse_adc_params(STRING)

Parse the Akamai Device Characteristics header string. Each value gets put into its own request header with an X-ADC- prefix.

Expects the format to be param=value with semicolon separating pairs and optional spaces in between.

Example

sub vcl_recv {
  akamai.akamai.parse_adc_params("brand_name=Google;is_tablet=false; device_os=Android");
  if (req.http.X-ADC-brand_name == "Google") {
  ...
  }
}

Arguments: None

Type: Function

Returns: None

purge

VOID purge(STRING url, STRING hostname = "", BOOL delete = 0, STRING delims = "")

Send a purge request to the Akamai CCU API. This requires the akamai-connector.conf to be configured with the appropriate Akamai CCU API values for purge_host, purge_client_token, purge_client_secret, and purge_access_token. If the akamai-connector.conf is not configured, this call does nothing.

Arguments:

  • url accepts type STRING

  • hostname accepts type STRING with a default value of empty. optional

  • delete accepts type BOOL with a default value of 0 optional

  • delims accepts type STRING with a default value of empty. optional

Type: Function

Returns: None

purge_cachetag

VOID purge_cachetag(STRING tags, BOOL delete = 0, STRING delims = " ,")

Send a cache tag purge request to the Akamai CCU API. This requires the akamai-connector.conf to be configured with the appropriate Akamai CCU API values for purge_host, purge_client_token, purge_client_secret, and purge_access_token. If the akamai-connector.conf is not configured, this call does nothing.

Arguments:

  • tags accepts type STRING

  • delete accepts type BOOL with a default value of 0 optional

  • delims accepts type STRING with a default value of , optional

Type: Function

Returns: None

purge_cpcode

VOID purge_cpcode(STRING cpcodes, BOOL delete = 0, STRING delims = " ,")

Send a cpcode purge request to the Akamai CCU API. This requires the akamai-connector.conf to be configured with the appropriate Akamai CCU API values for purge_host, purge_client_token, purge_client_secret, and purge_access_token. If the akamai-connector.conf is not configured, this call does nothing.

Arguments:

  • cpcodes accepts type STRING

  • delete accepts type BOOL with a default value of 0 optional

  • delims accepts type STRING with a default value of , optional

Type: Function

Returns: None

api

VOID api(STRING method, STRING url, STRING json)

Send an Akamai CCU v3 API call.

Arguments:

  • method accepts type STRING

  • url accepts type STRING

  • json accepts type STRING

Type: Function

Returns: None

get_resp_code

INT get_resp_code()

Get the response code for the last invocation of purge(). If purge() was not called, 0 is returned.

Arguments: None

Type: Function

Returns: Int

get_resp_body

STRING get_resp_body()

Get the response body for the last invocation of purge(). If purge() was not called, an empty string is returned.

Arguments: None

Type: Function

Returns: String

get_resp_reason

STRING get_resp_reason()

Get the response reason phrase for the last invocation of purge(). If purge() was not called, an empty string is returned.

Arguments: None

Type: Function

Returns: String

NULL_OK sureroute

OBJECT NULL_OK sureroute()

Create a sureroute backend.

Arguments: None

Type: Object

Returns: Object.

.backend

BACKEND .backend()

Return the sureroute backend.

Arguments: None

Type: Method

Returns: Backend

get_useragent

STRING get_useragent()

Return the user agent string for this VMOD, a composition of the VMOD name and version.

Arguments: None

Type: Function

Returns: String

Availability

The akamai connector VMOD is available in Varnish Cache Plus version 6.0.2r1 and later.