红帽全球峰会2.4. Breakdown of definition file content
A definition file is necessary for building automation execution environments with Ansible Builder, as it specifies the content which will be included in the automation execution environment container image.
The following sections breaks down the different parts of a definition file.
2.4.1. Build args and base image
The build_arg_defaults section of the definition file is a dictionary whose keys can provide default values for arguments to Ansible Builder. See the following table for a list of values that can be used in default_build_args:
| Value | Description |
|---|---|
|
|
|
|
| Specifies the parent image for the automation execution environment, enabling a new image to be built that is based off of an already-existing image |
|
| Specifies the image used for compiling-type tasks |
The values given inside build_arg_defaults will be hard-coded into the Containerfile, so these values will persist if podman build is called manually.
If the same variable is specified in the CLI --build-arg flag, the CLI value will take higher precedence.
2.4.2. Ansible config file path
When using an ansible.cfg file to pass a token and other settings for a private account to an automation hub server, list the config file path (relative to where the definition file is located) as a string to enable it as a build argument in the initial phase of the build.
The ansible.cfg file should be formatted like the following example:
例 2.2. An ansible.cfg file
For more information on how to download a collection from automation hub, please see the related Ansible documentation page.
2.4.3. Dependencies
2.4.3.1. Galaxy
The galaxy entry points to a valid requirements file for the ansible-galaxy collection install -r … command.
The entry requirements.yml may be a relative path from the directory of the automation execution environment definition’s folder, or an absolute path.
The content of a requirements.yml file may look like the following:
例 2.3. A requirements.yml file for Galaxy
--- collections: - geerlingguy.java - kubernetes.core
---
collections:
- geerlingguy.java
- kubernetes.core2.4.3.2. Python
The python entry in the definition file points to a valid requirements file for the pip install -r … command.
The entry requirements.txt is a file that installs extra Python requirements on top of what the Collections already list as their Python dependencies. It may be listed as a relative path from the directory of the automation execution environment definition’s folder, or an absolute path. The contents of a requirements.txt file should be formatted like the following example, similar to the standard output from a pip freeze command:
例 2.4. A requirements.yml file for Python
2.4.3.3. System
The system entry in the definition points to a bindep requirements file, which will install system-level dependencies that are outside of what the collections already include as their dependencies. It may be listed as a relative path from the directory of the automation execution environment definition’s folder, or an absolute path.
To demonstrate this, the following is an example bindep.txt file that adds the libxml2 and subversion packages to a container:
例 2.5. A bindep.txt file
libxml2-devel [platform:rpm] subversion [platform:rpm]
libxml2-devel [platform:rpm]
subversion [platform:rpm]2.4.4. Additional custom build steps
The prepend and append commands may be specified in the additional_build_steps section. These will add commands to the Containerfile which will run either before or after the main build steps are executed.
The syntax for additional_build_steps must be one of the following:
a multi-line string
例 2.6. A multi-line string entry
RUN whoami RUN cat /etc/os-release
RUN whoami RUN cat /etc/os-releaseCopy to Clipboard Copied! Toggle word wrap Toggle overflow a list
例 2.7. A list entry
- RUN echo This is a post-install command! - RUN ls -la /etc
- RUN echo This is a post-install command! - RUN ls -la /etcCopy to Clipboard Copied! Toggle word wrap Toggle overflow
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