Upgrading to Varnish Cache 9.1

This document only lists breaking changes that you should be aware of when upgrading from to Varnish Cache 9.1. For a complete list of changes, please refer to the change log and Changes in Varnish Cache 9.1.

IPv4 addresses in IPv6 and ACLs#

IPv4 compatible and IPv4 mapped IPv6 addresses, that is IPv6 addresses in the forms ::<IP4> and ::ffff:<IP4>, now get rewritten to IPv4 addresses.

For example, with Varnish Cache up to and including 9.0, an IPv6 peer address ::ffff:176.58.90.154 would confusingly be logged as 176.58.90.154, but would not match an ACL allowing 176.58.90.154.

This has changed now: what looks like IPv4 gets rewritten to IPv4, such that, for the example above, an ACL allowing 176.58.90.154 would match, while an ACL allowing ::ffff:176.58.90.154 would no longer match.

VCL: synthetic() removed#

The synthetic() VCL action has been removed. Since Varnish Cache 5.0.0, body data can be created by setting beresp.body in vcl_backend_error {} and by setting resp.body in vcl_synth {}, and these continue to be available as the one way to create body data, as in these examples:

• set resp.body = "string" + " more strings";
• set resp.body += " appending even " + "more strings";
• set resp.body = :blob:;
• set resp.body += :blobappend:;

These examples equally work on beresp.body in vcl_backend_error {}.

The direct replacement for synthetic(<string>); is set resp.body += <string>; in vcl_synth {} and set beresp.body += <string>; in vcl_backend_error {}.

The only difference in behavior is that synthetic(<nullstring>) would create the string (null) for <nullstring> being a NULL pointer internally, while set resp.body = <nullstring> creates the empty string "" and set resp.body += <nullstring> is a NOOP.

VCL variables changed#

Setting req.max_age = 0s now forces a cache miss with request coalescing, where it previously had no effect.

Breaking changes for VMOD authors#

The LBODY_SET and LBODY_ADD compatibility defines have been removed from vrt.h. LBODY_{SET,ADD}_{BLOB,STRING} should be used instead.

The functions VRT_synth_strands(), VRT_synth_blob(), VRT_synth_page() and VRT_Stv() have been removed from the runtime. VRT_l_resp_body() and VRT_l_beresp_body() should be used instead.

The struct VCL_conf and struct VSC_main declarations have been removed from vrt.h. struct vmod_data has moved to vmod_abi.h. Neither of these should have been used by VMODs.

The VDP API has been changed: After a non-zero return of .init(), .fini() is no longer called. This might require adjustments of .init() to add cleanup for error returns.

cache/cache_varnishd.h has been renamed to cache/cache_int.h. You should avoid using it and try to stick to the API (vrt.h and cache.h if needed).