ksonnet is a framework for writing, sharing, and deploying Kubernetes application manifests. With its CLI, you can generate a complete application from scratch in only a few commands, or manage a complex system at scale.

Specifically, ksonnet allows you to:

• Reuse common manifest patterns (within your app or from external libraries)
• Customize manifests directly with powerful object concatenation syntax
• Deploy app manifests to multiple environments
• Diff across environments to compare two running versions of your app
• Track the entire state of your app manifests in version control

STATUS: Development is ongoing—this tool is pre-alpha.

To build from source:

% PATH=$PATH:$GOPATH/bin
% go get github.com/ksonnet/ksonnet

Requires golang >=1.7 and a functional cgo environment (C++ with libstdc++). Note that recent OSX environments require golang >=1.8.1 to avoid an immediate Killed: 9.

# Include <ksonnet.git>/lib in ksonnet/jsonnet library search path.
# Can also use explicit `-J` args everywhere.
% export KUBECFG_JPATH=/path/to/ksonnet/lib

# Show generated YAML
% ks show -o yaml -f examples/guestbook.jsonnet

# Create resources
% ks apply -f examples/guestbook.jsonnet

# Modify configuration (downgrade gb-frontend image)
% sed -i.bak '\,gcr.io/google-samples/gb-frontend,s/:v4/:v3/' examples/guestbook.jsonnet
# See differences vs server
% ks diff -f examples/guestbook.jsonnet

# Update to new config
% ks apply -f examples/guestbook.jsonnet

# Clean up after demo
% ks delete -f examples/guestbook.jsonnet

• Supports JSON, YAML or jsonnet files (by file suffix).
• Best-effort sorts objects before updating, so that dependencies are pushed to the server before objects that refer to them.
• Additional jsonnet builtin functions. See lib/kubecfg.libsonnet.

The idea is to describe as much as possible about your configuration as files in version control (eg: git).

Changes to the configuration follow a regular review, approve, merge, etc code change workflow (github pull-requests, phabricator diffs, etc). At any point, the config in version control captures the entire desired-state, so the system can be easily recreated in a QA cluster or to recover from disaster.

ksonnet relies heavily on jsonnet to describe Kubernetes resources, and is really just a thin Kubernetes-specific wrapper around jsonnet evaluation. You should read the jsonnet tutorial, and skim the functions available in the jsonnet std library.