ktmpl

ktmpl is a tool for processing Kubernetes manifest templates. It is a very simple client-side implementation of the Templates + Parameterization proposal.

Synopsis

ktmpl 0.6.0
Produces a Kubernetes manifest from a parameterized template

USAGE:
    ktmpl [OPTIONS] <template>

FLAGS:
    -h, --help       Prints help information
    -V, --version    Prints version information

OPTIONS:
    -b, --base64-parameter <NAME> <VALUE>
            Same as --parameter, but for values already encoded in Base64
    -p, --parameter <NAME> <VALUE>
            Supplies a value for the named parameter
    -f, --parameter-file <PARAMETER_FILE>...
            Path to a YAML file with parameter values
    -s, --secret <NAME> <NAMESPACE>
            A secret to Base64 encode after parameter interpolation

ARGS:
    <template>    Path to the template file to be processed (use "-" to read from stdin)

Usage

Run ktmpl TEMPLATE where TEMPLATE is a path to a Kubernetes manifest template in YAML format. The included example.yml is a working example template.

To provide values for template parameters, use the --parameter, --base64-parameter or --parameter-file options.

The included example.yml and params.yml files are used in the following examples.

Using the --parameter option:

ktmpl example.yml --parameter MONGODB_PASSWORD secret

Using the --parameter-file option:

ktmpl example.yml --parameter-file params.yml

A parameter file must contain one or more YAML documents. Each document must be a YAML hash with string keys and string values, corresponding to template parameters and their values, respectively.

In parameter files, if the same parameter is defined more than once, the last defined value will be used. Parameter values supplied via the --parameter option will override any that are defined via parameter files.

Template parameters that have default values can be overridden with the same mechanisms:

ktmpl example.yml --parameter MONGODB_USER carl --parameter MONGODB_PASSWORD secret

The processed template will be output to stdout, suitable for piping into a kubectl command:

ktmpl example.yml --parameter MONGODB_PASSWORD password | kubectl create -f -

If a parameter's parameterType is base64, the value passed for that parameter via --parameter will be Base64-encoded before being inserted into the template. If the value passed via --parameter is already Base64-encoded, and hence encoding it again would be an error, use the --base64-parameter option instead:

ktmpl example.yml --base64-parameter MONGODB_PASSWORD c2VjcmV0 | kubectl create -f -

This can be handy when working with Kubernetes secrets, or anywhere else binary or opaque data is needed. Values provided via parameter files are always treated as plain strings, so the --base64-parameter option is required for values that are already Base64-encoded.

When working with Kubernetes secrets with values that contain a parameter as well as literal text, such as a config file with passwords in it, the --secret option is useful. For example, using the provided secret_example.yml template:

ktmpl secret_example.yml --parameter PASSWORD narble --secret webapp default

"webapp" is the name of the secret and "default" is the namespace of the secret. This will cause ktmpl to Base64 encode every value in the named secret's data hash after the normal parameter interpolation step. When using the --secret option, you probably don't want to use base64 as the parameterType for any parameters within the secret, since the entire value will be Base64 encoded after interpolation. If a Kubernetes secret named with the --secret option is not found in the template, ktmpl will exit with an error.

It's also possible to supply the template via stdin instead of a named file by using - as the filename:

cat example.yml | ktmpl - --parameter MONGODB_PASSWORD password | kubectl create -f -

Installing ktmpl

Homebrew

brew install ktmpl

Cargo

cargo install ktmpl

Precompiled binary

Releases

Docker

docker pull jimmycuadra/ktmpl

Building from source

1. Install the appropriate version of Rust for your system.
2. Run git clone git@github.com:jimmycuadra/ktmpl.git.
3. Inside the freshly cloned repository, run cargo install --path ..

Make sure Cargo's bin directory is added to your PATH environment variable.

Development

To package the current release for distribution, update TAG in the Makefile and then run make. Release artifacts will be written to the dist directory. Your GPG secret key will be required to sign sha256sums.txt.

Docker images for jimmycuadra/ktmpl and jimmycuadra/ktmpl:$TAG will be created, but you must push them manually. cargo publish must be run manually to release to crates.io.

Legal

ktmpl is released under the MIT license. See LICENSE for details.