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Introduction
Knife is a command-line tool that connects a local chef-repo and the Chef Infra Server. Knife helps users to manage:
Cookbooks and recipes
Nodes
Resources that are within different cloud environments
Roles, Environments, and Data Bags
Searching for indexed data on the Chef Infra Server
About Knife Search
The knife search command searches the Chef Infra Server's database for data. Any data that the Chef Infra Server has indexed can be found using search indexes. It consists of nodes, environments, roles, data bags, and data bag contents. It is a text query that may be executed from a variety of locations, including within a recipe, using the Chef Infra Language's built-in search feature, utilizing knife's search subcommand, or using endpoints like /search or /search/INDEX in the Chef Infra Server API. The Chef Infra Server is used to run the search engine.
Syntax
This subcommand has the following syntax:
$ knife search INDEX SEARCH_QUERY
Where INDEX is one of the clients, Node, environment, or the name of a data bag, role and SEARCH_QUERY is the query syntax that will be carried out.
. For example
$ knife search '*:*' -i
And is the same search as:
$ knife search node '*:*' -i
If the Search Query does not contain any colon character, i.e. : , then the default pattern is tags: *#{@query}*
OR
addresses:*#{@query}*
OR
roles:*#{@query}*
OR
fqdn:*#{@query}*
which means the following search queries are almost the same.
A search query comprises two different parts: the search pattern and the key. A search query has the following syntax type:
key:search_pattern
where the key is a field name that is to be found in the JSON description of an indexable object present on the Chef server, and search_pattern defines what will be searched for. It is done using one of the following search patterns:
Wildcard Matching
Range Matching
exact Matching
fuzzy Matching
Both key and search_pattern are case-sensitive; the key has limited support for multiple-character wildcard matching using an asterisk ("*") (and as long as it is not the first character).
About Patterns
A search pattern is a way to search results by returning anything that matches an incomplete search query. Four search patterns can be used when searching the indexes on the Chef server: wildcard, range, exact and fuzzy.
Wildcard Matching
This search pattern is used to query for substrings that match a series of characters against incoming character strings. There are two kinds of this type of search:
A question mark is used to replace only one character.
An asterisk is used to replace any number of characters.
Range Matching
This search pattern is used to query for values within a range defined by upper and lower boundaries. A range-matching search pattern can be inclusive or exclusive of the limitations. Use curly braces ("{ }") to indicate exclusive boundaries and square brackets ("[ ]") to denote inclusive boundaries.
Exact Matching
This search pattern is used to search for a key that matches with the search query's name. If there are any spaces or quotes in the key's name, then quotes should be used. The entire query must also be included within quotes for its prevention from any command shell or maybe Ruby. The best way is to use single quotes (' ') and a search pattern with double quotes (" ") consistently with every query.
Fuzzy Matching
This search pattern is used to search based on the proximity of two strings made up of characters. An optional integer can be used to define the proximity more accurately as part of the query.
About Operators
An operator can be used to verify that specific terms are included in the results. They are omitted even when other aspects of the query match with them. Searches can use the following operators:resultsterm
OPERATOR
DESCRIPTION
AND
Use to find result when both terms exist
OR
Use to find result when either terms exist.
NOT
Use to exclude the term after NOT from the search results.
AND
To join two queries using the AND boolean operator, the following syntax is used:
$ knife search sample "id1:foo1* AND id2:foo2"
NOT
To nullify search results using the NOT boolean operator, the following syntax is used:
$ knife search sample "(NOT id:bar)"
OR
To join two queries using the OR boolean operator, the following syntax is used-
$ knife search sample "id: foo OR id:abc"
To find which of all the computers are running on the Windows platform that are linked with a role named ABC, the following syntax is used:
$ knife search node 'platform: windows AND roles:abc.'
Frequently Asked Questions
What is the use of the knife bootstrap command in Chef?
The knife bootstrap command is a way to install the chef-client on a node.
What is knife in DevOps?
Knife is a command-line tool that connects a local chef-repo and the Chef Infra Server.
What is the Node attribute in chef?
An attribute is a detail about a node. The chef-client uses attributes to understand the current state of the Node. What the Node's state was at the end of the previous chef-client run.
How do you run a chef's knife command?
chef-client — command to run on Node called convergence. Knife environment compares — all -to compare all recipes in the server across all environments. Knife environment show dev — shows environment information.
How do I download the Chef server cookbook?
In that case, use the -f option (or –force) to download the cookbook and overwrite the local directory with the version downloaded from the Chef server. Instead of downloading it under the current directory, you can specify a download directory using the -d option (or –dir option).
Conclusion
This article has extensively discussed the knife Search subcommand, its properties, and syntax.
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