Varnish vmod for creating a uuid
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README.rst

vmod_uuid

Varnish UUID Module

Author: Mitchell Broome, Geoff Simmons
Date: 2018-04-02
Version: trunk
Manual section:3

SYNOPSIS

import uuid;

DESCRIPTION

UUID Varnish vmod used to generate a uuid, including versions 1, 3, 4 and 5 as specified in RFC 4122. See the RFC for details about the various versions.

FUNCTIONS

uuid

Prototype
uuid()
Return value
STRING
Description
Returns a uuid version 1 (based on MAC address and the current time)
UUID
set req.http.X-Flow-ID = "cache-" + uuid.uuid();

uuid_v1

Prototype
uuid_v1()
Return value
STRING
Description
Returns a uuid version 1. The functions uuid() and uuid_v1() are aliases for one another.
Example
set req.http.X-Flow-ID = "cache-" + uuid.uuid_v1();

uuid_v3

Prototype
uuid_v3(STRING namespace, STRING name)
Return value
STRING
Description
Returns a uuid version 3, based on an MD5 hash formed from namespace and name. The namespace argument MUST be one of the following:
  • "nil" (for the "nil UUID")
  • "ns:DNS" (for the domain name system)
  • "ns:URL" (for the URL namespace)
  • "ns:OID" (for the ISO object identifier namespace)
  • "ns:X500" (for X.500 distinguished names)
  • a valid 36-character representation of a UUID, i.e. a string of the form "xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx", where all of the x's are hex digits, with appropriate restrictions on UUID formats (cf. the RFC)

If these conditions are not met, then uuid_v3() fails; it returns a null string (typically, the header specified in VCL will not be set), and an error message is emitted to the Varnish log with the tag VCL_error.

The name argument can be any string.

Example
set req.http.X-DNS-ID = uuid.uuid_v3("ns:DNS", "www.widgets.com");
set req.http.X-MyNS-ID = uuid.uuid_v3("6ba7b810-9dad-11d1-80b4-00c04fd430c8", "www.widgets.com");

uuid_v4

Prototype
uuid_v4()
Return value
STRING
Description
Returns a uuid version 4, based on random numbers.
Example
set req.http.X-Rand-ID = uuid.uuid_v4();

uuid_v5

Prototype
uuid_v5(STRING namespace, STRING name)
Return value
STRING
Description
Returns a uuid version 5, based on a SHA1 hash formed from namespace and name. The same restrictions and failure conditions regarding the namespace argument hold as for uuid_v3() above. The name argument can be any string.
Example
set req.http.X-DNS-ID = uuid.uuid_v5("ns:DNS", "www.widgets.com");
set req.http.X-MyNS-ID = uuid.uuid_v5("6ba7b810-9dad-11d1-80b4-00c04fd430c8", "www.widgets.com");

DEPENDENCIES

Libvmod-uuid requires the OSSP uuid library to generate uuids. It is available at http://www.ossp.org/pkg/lib/uuid/ or possibly as a prepackaged library (usually named uuid) from your linux distribution.

This version of the VMOD requires Varnish since version 6.0.0 or the master branch. See the project source code repository for versions compatible with a Varnish release.

INSTALLATION

See INSTALL.rst in the source repository.

HISTORY

  • Version 1.5: RPM compatible with Varnish 6.0.0
  • Version 1.4: add RPM packaging
  • Version 1.3: compatible with Varnish 5.0.0 through 5.2.
  • Verison 1.2: compatible with Varnish since 5.0.0
  • Version 1.1: requires Varnish 4.1, creates internal UUID objects only once during a client or backend context and re-uses them for subsequent calls.
  • Version 1.0: Varnish 4 version, supporting all UUID variants by Geoffrey Simmons <geoff@uplex.de>, UPLEX Nils Goroll Systemoptimierung for Otto GmbH & KG https://github.com/otto-de/libvmod-uuid
  • Version 0.1: Initial Varnish 3 version, by Mitchell Broome of Sharecare https://github.com/Sharecare/libvmod-uuid

COPYRIGHT

This document is licensed under the same license as the libvmod-uuid project. See LICENSE for details.