ID: lower-case string that identifies the operating system, for example: ID=ubuntu, ID=centos. See os-release(5) for more information. On macOS, where os-release is not available, we emulate it by setting ID=macos.

ID_LIKE: space-separated list of operating system identifiers that are closely related to the running OS. See os-release(5) for more information. The listed values are used by the CI scripts to select the proper behavior for different platforms and OS flavors.

Examples:

• On CentOS, ID_LIKE="centos rhel fedora linux"
• On Ubuntu, ID_LIKE="ubuntu debian linux"

VERSION_ID: identifies the operating system version, excluding any release code names. See os-release(5) for more information. Examples: VERSION_ID=42, VERSION_ID=22.04.

JOB_NAME: defines the type of the current CI job. Depending on the job type, the CI scripts can perform different tasks.

Supported values:

• empty: default build task
• code-coverage: debug build with tests and code coverage analysis
• limited-build: only a single debug build with tests

CACHE_DIR: directory containing cached files from previous builds, e.g., a compiled version of ndn-cxx. If not set, /tmp is used.

DISABLE_ASAN: disable building with AddressSanitizer. This is automatically set for the code-coverage job type.