Dependencies

Plugins can depend on other binaries, which are then downloaded by Botkube along with a given plugin. This is supported for both executor and source plugins.

Define dependencies for plugin index generation

As a part of the Metadata method, define the Dependencies property. The key is the name of the dependency, and the value is a structure with links to binaries for each platform.

info

For downloading plugins and theirs dependencies, Botkube uses go-getter library. It supports multiple URL formats (such as HTTP, Git repositories or S3), and is able to unpack archives and extract binaries from them. For more details, see the documentation on the go-getter GitHub repository.

const (
	kubectlVersion   = "v1.28.1"
)

// Metadata returns details about kubectl plugin.
func (e *Executor) Metadata(context.Context) (api.MetadataOutput, error) {
	return api.MetadataOutput{
		// ...
		Dependencies: map[string]api.Dependency{
			"kubectl": {
				URLs: map[string]string{
					"windows/amd64": fmt.Sprintf("https://dl.k8s.io/release/%s/bin/windows/amd64/kubectl.exe", kubectlVersion),
					"darwin/amd64":  fmt.Sprintf("https://dl.k8s.io/release/%s/bin/darwin/amd64/kubectl", kubectlVersion),
					"darwin/arm64":  fmt.Sprintf("https://dl.k8s.io/release/%s/bin/darwin/arm64/kubectl", kubectlVersion),
					"linux/amd64":   fmt.Sprintf("https://dl.k8s.io/release/%s/bin/linux/amd64/kubectl", kubectlVersion),
					"linux/s390x":   fmt.Sprintf("https://dl.k8s.io/release/%s/bin/linux/s390x/kubectl", kubectlVersion),
					"linux/ppc64le": fmt.Sprintf("https://dl.k8s.io/release/%s/bin/linux/ppc64le/kubectl", kubectlVersion),
					"linux/arm64":   fmt.Sprintf("https://dl.k8s.io/release/%s/bin/linux/arm64/kubectl", kubectlVersion),
					"linux/386":     fmt.Sprintf("https://dl.k8s.io/release/%s/bin/linux/386/kubectl", kubectlVersion),
				}
			},
		},
	}, nil
}

Such a definition will result in the following dependencies section in the plugin index:

entries:
  - name: kubectl
    # ...
    urls:
      - url: "..." # URL for darwin/amd64 binary
        # ...
        platform:
          os: darwin
          architecture: amd64
        dependencies:
          kubectl:
            url: https://dl.k8s.io/release/v1.28.1/bin/darwin/amd64/kubectl
      - url: "..." # URL for darwin/arm64 binary
        # ...
        dependencies:
          kubectl:
            url: https://dl.k8s.io/release/v1.28.1/bin/darwin/arm64/kubectl
      - url: "..." # URL for linux/amd64 binary
        # ...
        platform:
          os: linux
          architecture: amd64
        dependencies:
          kubectl:
            url: https://dl.k8s.io/release/v1.28.1/bin/linux/amd64/kubectl
      - url: "..." # URL for linux/arm64 binary
        # ...
        platform:
          os: linux
          architecture: arm64
        dependencies:
          kubectl:
            url: https://dl.k8s.io/release/v1.28.1/bin/linux/arm64/kubectl

Read how to use the plugin index in the Repository document.

Using dependencies

During Botkube startup, Botkube plugin manager fetches the plugin binaries along with all dependencies. Each dependency binary is named exactly as specified in the plugin index. The dependency is fetched to a directory specified in the PLUGIN_DEPENDENCY_DIR environment variable passed to the plugin.

To make it easier, there's a helper function plugin.ExecuteCommand in the github.com/kubeshop/botkube/pkg/plugin package, which does all of the above. For example, the kubectl plugin uses the following code:

// set additional env variables
envs := map[string]string{
	"KUBECONFIG": kubeConfigPath,
}

// runCmd is e.g. "kubectl get pods --all-namespaces"
// plugin.ExecuteCommand will replace kubectl with full path to the kubectl binary dependency
out, err := plugin.ExecuteCommand(ctx, runCmd, plugin.ExecuteCommandEnvs(envs))

Example

To get familiar with the full example, see the kubectl plugin in the Botkube repository. The Kubectl plugin depends on the official kubectl CLI binary, which is defined as a part of the Metadata method.