libcrange

A library for parsing and generating range expressions.

Description

A library for parsing and generating range expressions. libcrange for modules to add symbolic name lookup features as well as functions to retreive additional data.

##Requirements

Red Hat / Scientific / CentOS

• apr apr-devel flex pcre pcre-devel sqlite sqlite-devel libyaml libyaml-devel perl-YAML-Syck perl perl-core perl-devel perl-libs python-devel

Ubuntu / Debian

• libapr1 libapr1-dev flex libpcre3 libpcre3-dev sqlite3 libsqlite3-dev libsqlite3-0 libyaml-0-2 libyaml-dev libyaml-syck-perl perl-base libperl5.14 libperl-dev

Range Syntax

Simple ranges:

• node1,node2,node3,node4 == node1..node4 == node1..4
• node1000..1099 == node1000..99 # auto pads digits to the end of the range
• 1..100 # numeric only ranges
• foo1-2.domain.com == foo1.domain.com-foo2.domain.com # domain support
• 209.131.40.1-209.131.40.255 == 209.131.40.1-255 # IP ranges

Clusters:

A cluster is a way to store node membership into groups. Depending on your backend module how this is stored may vary. In the case of the YAML module, a cluster is defined by the membership of the CLUSTER key

• %cluster101 == nodes defined in /var/range/cluster101.yaml - Default key CLUSTER
• %cluster101:ALL or %cluster101:FOO == nodes defined in a specific key of ks301/nodes.cf
• %%all == assuming %all is a lust of clusters, the additional % will expand the list of clusters to node list that is their membership
• *node == returns the cluster(s) that node is a member of

Operatons:

• range1,range2 == union
• range1,-range2 == set difference
• range1,&range2 == intersection
• ^range1 == admins for the nodes in range1
• range1,-(range2,range3) == () can be used for grouping
• range1,&/regex/ # all nodes in range1 that match regex
• range1,-/regex/ # all nodes in range1 that do not match regex

Advanced ranges:

• foo{1,3,5} == foo1,foo3,foo5
• %cluster30{1,3} == %cluster301,%cluster303
• %cluster301-7 == nodes in clusters cluster301 to cluster307
• %all:KEYS == all defined sections in cluster all
• %{%all} == expands all clusters in %all
• %all:dc1,-({f,k}s301-7) == names for clusters in dc1 except ks301-7,fs301-7
• %all:dc1,-|ks| == clusters in dc1, except those matching ks

Functions:

libcrange modules can define certain functions to look up data about hosts or clusters The yaml module for instance implements some of the following functions.

• has(KEY;value) - looks for a cluster that has a key with some certain value
• allclusters() - returns a range of all clusters
• • and get_clusters(node) - return the first cluster a node is a member of
• clusters(node) - return all clusters a node is a member of
• has(ENVIRONMENT; production) would return any clusters with the a key called ENVIRONMENT set to production
• mem(CLUSTER; foo.example.com) => which keys under CLUSTER is foo.example.com a member of

Other functions can be added via modules that provide useful insight into your environment

• vlan(host) - return vlan for this host
• dc(host) - return datacenter for this host
• drac(host) - might do an API call on backend to central host db to look up a drac IP for a host