Creating CodeQL query suites

Note: This article was migrated from the CodeQL documentation website in January 2023.

About creating CodeQL query suites

CodeQL query suites provide a way of selecting queries, based on their filename, location on disk, or metadata properties. Create query suites for the queries that you want to frequently use in your CodeQL analyses.

Query suites allow you to pass multiple queries to CodeQL without having to specify the path to each query file individually. Query suite definitions are stored in YAML files with the extension .qls. A suite definition is a sequence of instructions, where each instruction is a YAML mapping with (usually) a single key. The instructions are executed in the order they appear in the query suite definition. After all the instructions in the suite definition have been executed, the result is a set of selected queries.

Locating queries to add to a query suite

When creating a query suite, you first need to specify the locations of the queries that you want to select. You can define the location of one or more queries using:

A query instruction—tells CodeQL to look for one or more specified .ql files:
```
- query: <path-to-query>
```
The argument must be one or more file paths, relative to the CodeQL pack containing the suite definition.
A queries instruction—tells CodeQL to recursively scan a directory for .ql files:
```
- queries: <path-to-subdirectory>
```
The path of the directory must be relative to the root of the CodeQL pack that contains the suite definition file. To find the queries relative to a different CodeQL pack, add a from field:
```
- queries: <path-to-subdirectory>
  from: <ql-pack-name>
  version: ^x.y.z
```
The version field is optional and specifies a range of compatible versions of this CodeQL pack. If you don’t specify a version, then the most recent version of the pack is used.
A qlpack instruction—tells CodeQL to resolve queries in the default suite of the named CodeQL pack:
```
- qlpack: <qlpack-name>
  version: ^x.y.z
```
The default suite of a query pack includes a recommended set of queries inside of that query pack. Not all query packs have a default suite. If the given query pack does not define a default suite, the qlpack instruction will resolve to all of the queries within the pack.

The version field is optional and specifies a range of compatible versions of this CodeQL pack. If you don’t specify a version, then the most recent version of the pack is used.

Note: When pathnames appear in query suite definitions, they must always be given with a forward slash, /, as a directory separator. This ensures that query suite definitions work on all operating systems.

You must add at least one query, queries, or qlpack instruction to your suite definition, otherwise no queries will be selected. If the suite contains no further instructions, all the queries found from the list of files, in the given directory, or in the named CodeQL pack are selected. If there are further filtering instructions, only queries that match the constraints imposed by those instructions will be selected.

Filtering the queries in a query suite

After you have defined the initial set of queries to add to your suite by specifying query, queries, or qlpack instructions, you can add include and exclude instructions. These instructions define selection criteria based on specific properties:

When you execute an include instruction on a set of queries, any queries that match your conditions are retained in the selection, and queries that don’t match are removed.
When you execute an exclude instructions on a set of queries, any queries that match your conditions are removed from the selection, and queries that don’t match are retained.

The order of your filter instructions is important. The first filter instruction that appears after the locating instructions determines whether the queries are included or excluded by default. If the first filter is an include, the initially located queries will only be part of the suite if they match an explicit include filter. If the first filter is an exclude, the initially located queries are part of the suite unless they are explicitly excluded.

Subsequent instructions are executed in order and the instructions that appear later in the file take precedence over the earlier instructions. So, include instructions can be overridden by a later exclude instructions that match the same query. Similarly, excludes can be overridden by a later include.

For both instructions, the argument is a constraint block—that is, a YAML map representing the constraints. Each constraint is a map entry, where the key is typically a query metadata property. The value can be:

A single string.
A /-enclosed regular expression.
A list containing strings, regular expressions, or both.

To match a constraint, a metadata value must match one of the strings or regular expressions. When there is more than one metadata key, each key must be matched. The standard metadata keys available to match on are: description, id, kind, name, tags, precision, and problem.severity. For more information about query metadata properties, see “Metadata for CodeQL queries.”

In addition to metadata tags, the keys in the constraint block can also be:

query filename—matches on the last path component of the query file name.
query path—matches on the path to the query file relative to its enclosing CodeQL pack.
tags contain—one of the given match strings must match one of the space-separated components of the value of the @tags metadata property.
tags contain all—each of the given match strings must match one of the components of the @tags metadata property.

Examples of filtering which queries are run

A common use case is to create a query suite that runs all queries in a CodeQL pack, except for a few specific queries that the user does not want to run. In general, we recommend filtering on the query id, which is a unique and stable identifier for each query. The following three query suite definitions are semantically identical and filter by the query id:

This filter matches all the queries in the default suite of codeql/cpp-queries, except for the two queries with the excluded identifiers:

- qlpack: codeql/cpp-queries
- exclude:
    id:
      - cpp/cleartext-transmission
      - cpp/cleartext-storage-file

In this example, a separate exclude instruction is used for each query:

- qlpack: codeql/cpp-queries
- exclude:
    id: cpp/cleartext-transmission
- exclude:
    id: cpp/cleartext-storage-file

In this example, a regular expression excludes the same two queries. It would also exclude any future queries added to the suite with identifiers that begin: cpp/cleartext-:

- qlpack: codeql/cpp-queries
- exclude:
    id:
      - /^cpp\/cleartext-.*/

To define a suite that selects all queries in the default suite of the codeql/cpp-queries CodeQL pack, and then refines them to only include security queries, use:

- qlpack: codeql/cpp-queries
- include:
    tags contain: security

To define a suite that selects all queries with @kind problem and @precision high from the my-custom-queries directory, use:

- queries: my-custom-queries
- include:
    kind: problem
    precision: very-high

Note that the following query suite definition behaves differently from the definition above. This definition selects queries that are @kind problem or are @precision very-high:

- queries: my-custom-queries
- include:
    kind: problem
- include:
    precision: very-high

To create a suite that selects all queries with @kind problem from the my-custom-queries directory except those with @problem.severity recommendation, use:

- queries: my-custom-queries
- include:
    kind: problem
- exclude:
    problem.severity: recommendation

To create a suite that selects all queries with @tag security and @problem.severity high or very-high from the codeql/cpp-queries CodeQL pack, use:

- queries: .
  from: codeql/cpp-queries
- include:
    tags contain: security
    problem.severity:
    - high
    - very-high

Note: You can use the codeql resolve queries /path/to/suite.qls command to see which queries are selected by a query suite definition. For more information, see the resolve queries reference documentation.

Reusing existing query suite definitions

Existing query suite definitions can be reused by specifying:

An import instruction—adds the queries selected by a previously defined .qls file to the current suite:
```
- import: <path-to-query-suite>
```
The path to the imported suite must be relative to the CodeQL pack containing the current suite definition. If the imported query suite is in a different QL pack you can use:
```
- import: <path-to-query-suite>
  from: <ql-pack>
  version: ^x.y.z
```
The version field is optional and specifies a range of compatible versions of this CodeQL pack. If you don’t specify a version, then the most recent version of the pack is used.

Queries added using an import instruction can be filtered using subsequent exclude instructions.
An apply instruction—adds all of the instructions from a previously defined .qls file to the current suite. The instructions in the applied .qls file are executed as if they appear in place of apply. Any include and exclude instructions from the applied suite also act on queries added by any earlier instructions:
```
- apply: <path-to-query-suite>
```
The apply instruction can also be used to apply a set of reusable conditions, saved in a .yml file, to multiple query definitions. For more information, see the examples below.

Reusability Examples

To use the same conditions in multiple query suite definitions, create a separate .yml file containing your instructions. For example, save the following in a file called reusable-instructions.yml:

- include:
    kind:
    - problem
    - path-problem
    tags contain: security
    precision:
    - high
    - very-high

Add reusable-instructions.yml to the same CodeQL pack as your current query suite. Then, in one or more query suites, use the apply instruction to apply the reusable instructions to the current suite. For example:

- queries: queries/cpp/custom
- apply: reusable-instructions.yml

This will filter the queries in queries/cpp/custom to only include those that match the reusable conditions.

You can also create a suite definition using reusable-instructions.yml on queries in a different CodeQL pack. If the .qls file is in the same CodeQL pack as the queries, you can add a from field immediately after the apply instruction:

# load queries from the default suite of my-org/my-other-custom-queries
- qlpack: my-org/my-other-custom-queries

# apply the reusable instructions from the my-org/my-custom-instructions CodeQL pack
- apply: reusable-instructions.yml
  from: my-org/my-custom-instructions
  version: ^1.2.3 # optional

A common use case for an import instruction is to apply a further filter to queries from another query suite. For example, this suite will further filter the cpp-security-and-quality suite and exclude low and medium precision queries:

- import: codeql-suites/cpp-security-and-quality.qls
  from: codeql/cpp-queries
- exclude:
    precision:
      - low
      - medium

If you want to include queries imported from another suite, the syntax is a little different:

- import: codeql-suites/cpp-security-and-quality.qls
  from: codeql/cpp-queries
- exclude: {}
- include:
    precision:
      - very-high
      - high

Notice the empty exclude instruction. This is required to ensure that the subsequent include instruction is able to filter queries from the imported suite.

Naming a query suite

You can provide a name for your query suite by specifying a description instruction:

- description: <name-of-query-suite>

This value is displayed when you run codeql resolve queries, if the suite is added to a “well-known” directory. For more information, see “Specifying well-known query suites.”

Using query suites with CodeQL

You can specify query suites on the command line for any command that accepts .qls files. For example, you can compile the queries selected by a suite definition using query compile, or use the queries in an analysis using database analyze. For more information about analyzing CodeQL databases, see “Analyzing databases with the CodeQL CLI.”