DawnBreather / envsubst

Overview

envsubst

The envsubst application is designed to replace placeholders in files with their respective environment variables. Its purpose can be particularly useful in CI/CD pipelines where environment-specific values need to be injected into configuration files or other types of resources.

Usage

The application provides various command-line options to customize its behavior:

• -p, --prefix: Placeholder prefix. Default is "{{".
• -s, --suffix: Placeholder suffix. Default is "}}".
• -m, --regex-mask: Placeholder regex mask. This defines the pattern that the content of the placeholder should match. Default is "[A-Z_0-9]*".
• -e, --env-file: Source of environment variables. If specified, the application will attempt to read and set environment variables from this file.

Example:

cicd_envsubst -p "{{" -s "}}" -m "[A-Z_0-9]*" -e "path/to/env/file" path/to/file_or_directory

This command will process path/to/file_or_directory, replacing placeholders that match the default format with corresponding environment variables. It will also read environment variables from path/to/env/file and use them for replacements.

envmake

The envmake application is designed to compile an environment (.env) file based on the placeholders found within specified files and directories. The placeholders are identified and then either replaced with their actual values from the existing environment variables, or retained as placeholders in the compiled environment file.

Usage

To execute the envmake application, use the following command structure:

envmake [destination_env_file] [path_to_file_or_directory ...]

Where

• destination_env_file: Path to the file where the compiled environment values should be saved.
• path_to_file_or_directory: Paths to files or directories that should be processed for placeholders. Multiple paths can be provided.

Example:

envmake ./output.env ./config.yaml ./settings/

This command will process the config.yaml file and all files within the settings/ directory, identifying and extracting placeholders. The resulting .env file will be saved as output.env.

set2secret

The set2secret application is designed to generate Kubernetes Secret manifests from a collection of environment variables referred to as "sets". The tool allows for the extraction of these sets, comparison to referenced files (for validation), and generation of a Kubernetes Secret manifest, which can then be applied to a Kubernetes cluster.

Usage

To execute the set2secret application, use the following command structure:

set2secret -s [variable_set_name ...] -n [k8s_secret_name] [-r path_to_reference_file ...]

Where

• -s, --set: Name(s) of the variable set(s) to extract from the environment. Multiple sets can be provided.
• -n, --secret-name: The desired name of the Kubernetes Secret.
• -r, --ref: (Optional) Paths to reference files containing placeholders to be validated against the extracted variable set.

Example:

set2secret -s SET1 SET2 -n my-k8s-secret -r ./config.yaml

This command will:

1. Extract variables from the environment based on the sets SET1 and SET2.
2. Compare the extracted variables to placeholders within config.yaml.
3. Generate a Kubernetes Secret manifest named my-k8s-secret.

setsubst

The setsubst application focuses on substituting environment variable placeholders within target files or directories based on the provided "sets". Given a set of environment variables (stored in YAML format), the application reads these variables and replaces placeholders within target files with the appropriate values from the sets.

Usage

To execute the setsubst application, use the following command structure:

setsubst -s [variable_set_name ...]

Where:

• -s, --set: Specifies the name(s) of the variable set(s) to extract from the environment.

After the set name(s), provide the paths to the target files or directories as positional arguments.

Example:

export SET1="
VARIABLE1: THIS is a value for VARIABLE1
VARIABLE2: |
  This is a value
  for VARIABLE2"

export SET2="
VARIABLE3: THIS is a value for VARIABLE3
VARIABLE4: |
  This is a value
  for VARIABLE4"

setsubst -s SET1 SET2 ./config.yaml ./templates/

This command will:

1. Extract variables from the environment based on the sets SET1 and SET2.
2. Substitute placeholders within config.yaml and all files within the templates/ directory.