devopsbox/solsa

Solution Service Architecture

SolSA

The SolSA library for Node.js makes it possible to specify the architecture of Kubernetes applications as programs.

SolSA enables developers to configure Kubernetes-managed resources by writing JavaScript or TypeScript code instead of YAML. SolSA automatically translates the developer written code to the required lower-level YAML. SolSA integrates with IDEs such as Visual Studio Code to provide online validation, code completion, and documentation of the various resources and configuration parameters. SolSA enables the definition of architectural patterns (bundles of resources) that can be used across many applications.

Thanks to Kubernetes operators, Kubernetes applications can include not only containerized services but also managed cloud services (using for instance the IBM Cloud Operator), cloud functions (using the IBM Cloud Functions Operator), Knative services and events, etc.

While SolSA is meant to facilitate application development and deployment on the IBM Cloud and supports a few IBM-specific services out of the box, the SolSA programming model and library implementation is intended to work with any Kubernetes cluster and any cloud. No IBM Cloud account required.

SolSA is an open-source project with an Apache 2.0 license. We welcome contributions!

Motivation and Capabilities

Kubernetes is becoming the de facto standard for managing applications in the cloud. While YAML is a fine language to perform some basic configuration, we believe application developers need to reason about applications at a higher-level of abstraction using the languages and tools they are familiar with.

Developers can use SolSA to configure Kubernetes resources using JavaScript or TypeScript instead of YAML. But SolSA is not just a syntax. SolSA supports bundling together resources into reusable abstractions that expose curated configuration parameters. For instance, SolSA offers a ContainerizedService bundle that combines a Deployment and a Service, automatically bridging the two by means of auto-generated labels and selectors.

SolSA bundles can be smart and vary their content based on context. In particular, SolSA leverages Kustomize to permit targeting multiple environments, e.g., a local development cluster, a Red Hat OpenShift on IBM Cloud cluster, or an IBM Cloud Kubernetes Service cluster. SolSA automatically tailors resource bundles such as Ingress to the specifics of each targeted environment.

SolSA can synthesize all the YAML needed to deploy an application. But it does not have to do so. SolSA supports easy configuration to select which resources should be unique to an application instance and which resources should be shared across multiple instances.

SolSA facilitates the configuration of related resouces for instance a Kafka instance, a Kafka topic, and a Knative Kafka event source, by automatically reusing relevant configuration information. SolSA can not only inject configuration information from one resource into another during YAML generation but also, if necessary, during deployment using the Composable Operator. Using this operator, SolSA can for example configure a Kafka source to dynamically obtain a list of broker urls from a Kafka instance deployed at the same time.

SolSA generates pure Kubernetes YAML that can be deployed at once, i.e., with a single kubectl apply or oc apply command. SolSA does not need a server-side component.

SolSA includes an optional capability to containerize Node.js code. This facilitates the integration of components that require a little bit of glue code to interface properly, e.g., to align schemas or match protocols. This glue code can leverage Node.js frameworks such as Express or KafkaJS. SolSA builds and pushes the container image in addition to synthesizing the YAML to instantiate the image with the proper configuration.

Components

SolSA consists of:

• A solsa Node.js module that makes it possible to configure using JavaScript or TypeScript:
  • all the standard Kubernetes resources,
  • custom resources supported by a growing set of operators,
  • resource bundles that provide high-level abstractions of key architectural patterns.
• A solsa command-line interface (CLI):
  • solsa build builds container images for SolSA-defined services (if any).
  • solsa push pushes container images for SolSA-defined services (if any).
  • solsa yaml synthesizes YAML for deploying SolSA solutions on Kubernetes.

SolSA supports Node.js 8 and above, Kubernetes 1.14 and above.

Setup

Install SolSA globally:

npm install -g solsa

This will add the SolSA CLI to you PATH. Try the CLI:

solsa

Usage:
  solsa <command> [flags]

Available commands:
  build <solution.js>        build container images
  push <solution.js>         push container images to registries for current kubernetes context
  yaml <solution.js>         synthesize yaml for current kubernetes context

Global flags:
      --cluster <cluster>    use <cluster> instead of current kubernetes cluster
      --config <config>      use <config> file instead of default
  -c, --context <context>    use <context> instead of current kubernetes context

Flags for "yaml" command:
  -o, --output <file>        output base yaml and context overlays to <file>.tgz

While a global NPM install is enough to use the SolSA CLI, we recommend you also link SolSA from your home directory:

cd
npm link solsa

This will ensure that IDEs such as Visual Studio Code can locate the SolSA module and provide an optimal developer experience with code completion and hover help.

Kubernetes Cluster Setup

Minimal install

We assume that you have already configured kubectl or oc to be able to access each Kubernetes cluster you will be using with SolSA.

We assume that you have already installed kustomize and it is in your PATH. If not, please install it per Kustomize's install instructions and adjust your PATH to include it.

Proper configuration of kubectl/oc and kustomize is sufficient to enable you to use SolSA to generate YAML for all core Kubernetes resource types.

Optional install: Operators

If you intend to use SolSA to define solutions that include advanced features such as configuring cloud services or Knative resources, you will need to install the necessary Operators. On each cluster, do the following:

1. Install the Composable Operator from https://github.com/IBM/composable.

2. Install the IBM Cloud Operator from https://github.com/IBM/cloud-operators.

3. Install the IBM Event Streams Topic Operator from https://github.com/IBM/event-streams-topic.

4. Install the IBM Cloud Functions Operator from https://github.com/IBM/cloud-functions-operator.

Optional install: Knative

If you intend to use SolSA to define solutions that include Knative resources, you will need a cluster with Knative installed. For example, if you are using a cluster provisioned via the IBM Cloud Kubernetes Service, follow the instructions at https://knative.dev/docs/install/knative-with-iks.

SolSA Local Configuration File

You can optionally create a .solsa.yaml file in your home directory that describes each Kubernetes context for which you want SolSA to generate a specialized Kustomize overlay. Just like kubectl, solsa supports both cluster-level and context-level specification.

The configuration information in sosla.yaml enables cluster-specific and/or context-specific generation of Ingress resources and container image rewrites such as switching default registries or image tags.

Please refer to the full documentation of .solsa.yaml for full details, including ingress specifications for a variety of kinds of Kubernetes clusters. Shown below is a basic .solsa.yaml file that enables sosla to target the Kubernetes v1.14 cluster included in Docker Desktop v2.1.

clusters:
- name: 'docker-desktop'
  ingress:
    nodePort: true

We will assume this configuration file in the following example.

A First Example

A sample SolSA solution is provided in helloWorld.js.

const solsa = require('solsa')
const bundle = new solsa.Bundle()
module.exports = bundle

bundle.helloWorld = new solsa.ContainerizedService({ name: 'hello-world', image: 'docker.io/ibmcom/kn-helloworld', port: 8080 })
bundle.ingress = new bundle.helloWorld.Ingress()

It consists of a single containerized service and an ingress for this service.

This solution can be deployed to the current Kubernetes context using the solsa CLI and either kubectl or oc as follows.

solsa yaml helloWorld.js | kubectl apply -f -

Always replace kubectl with oc for an OpenShift cluster.

The YAML synthesized by SolSA for this example depends on the SolSA configuration file used. If no configuration file is used, the ingress definition is ignored and the CLI outputs a warning message.

Assuming the configuration file provided in the previous section, the YAML synthesized when targeting cluster docker-desktop is helloWorld.yaml. In this configuration, SolSA synthesizes Service objects with type NodePort for all the exposed service. Moreover, port numbers are assigned dynamically. We can obtain the port number for the deployed hello-world service using command:

kubectl get service hello-world -o jsonpath={.spec.ports[0].nodePort}

31509

Assuming 1.2.3.4 is the public IP of one of the worker node of the targeted Kubernetes cluster, we can then query the deployed containerized service using curl:

curl 1.2.3.4:31509

Hello World!

To undeploy the solution, use the command:

solsa yaml helloWorld.js | kubectl delete -f -

More Examples

The solsa-examples repository contains other examples of cloud-native applications, services, and architectural patterns defined using SolSA.

Building SolSA-defined Services

In order to build and deploy solutions that include SolSA-defined services, run:

solsa build mySolution.js
solsa push mySolution.js
solsa yaml mySolution.js | kubectl apply -f -

The build command builds images for the SolSA-defined services. The push command tags and pushes these images according to the SolSA configuration for the current Kubernetes context.

Development

To contribute to the development of SolSA, you will need to clone this repository, install, build, and link SolSA:

git clone https://github.com/IBM/solsa.git
cd solsa
npm install
npm run build
npm link