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.

// Metadata returns details about Helm plugin.
func (e *Executor) Metadata(context.Context) (api.MetadataOutput, error) {
    return api.MetadataOutput{
        // ...
        Dependencies: map[string]api.Dependency{
            "helm": {
                // Links source: https://github.com/helm/helm/releases/tag/v3.6.3
                // Using go-getter syntax to unwrap the underlying directory structure.
                // Read more on https://github.com/hashicorp/go-getter#subdirectories
                URLs: map[string]string{
                  "darwin/amd64":  "https://get.helm.sh/helm-v3.6.3-darwin-amd64.tar.gz//darwin-amd64",
                  "darwin/arm64":  "https://get.helm.sh/helm-v3.6.3-darwin-arm64.tar.gz//darwin-arm64",
                  "linux/amd64":   "https://get.helm.sh/helm-v3.6.3-linux-amd64.tar.gz//linux-amd64",
                  "linux/arm":     "https://get.helm.sh/helm-v3.6.3-linux-arm.tar.gz//linux-arm",
                  "linux/arm64":   "https://get.helm.sh/helm-v3.6.3-linux-arm64.tar.gz//linux-arm64",
                  "linux/386":     "https://get.helm.sh/helm-v3.6.3-linux-386.tar.gz//linux-386",
                  "linux/ppc64le": "https://get.helm.sh/helm-v3.6.3-linux-ppc64le.tar.gz//linux-ppc64le",
                  "linux/s390x":   "https://get.helm.sh/helm-v3.6.3-linux-s390x.tar.gz//linux-s390x",
                  "windows/amd64": "https://get.helm.sh/helm-v3.6.3-windows-amd64.zip//windows-amd64",
                }
            },
        },
    }, nil
}

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

- name: helm
  # ...
  urls:
    - url: "..." # URL to darwin/amd64 plugin binary
      platform:
        os: darwin
        architecture: amd64
      dependencies:
        helm:
          url: https://get.helm.sh/helm-v3.6.3-darwin-amd64.tar.gz//darwin-amd64
    - url: "..." # URL to darwin/amd64 plugin binary
      platform:
        os: darwin
        architecture: arm64
      dependencies:
        helm:
          url: https://get.helm.sh/helm-v3.6.3-darwin-arm64.tar.gz//darwin-arm64
    - url: "..." # URL to linux/amd64 plugin binary
      platform:
        os: linux
        architecture: amd64
      dependencies:
        helm:
          url: https://get.helm.sh/helm-v3.6.3-linux-amd64.tar.gz//linux-amd64
    - url: "..." # URL to linux/arm64 plugin binary
      platform:
        os: linux
        architecture: arm64
      dependencies:
        helm:
          url: https://get.helm.sh/helm-v3.6.3-linux-arm64.tar.gz//linux-arm64

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.

For example, in case of Helm executor, to run the Helm binary fetched by Botkube plugin manager, the plugin uses the following code:

    commandName := "helm" // name of the binary specified in Dependencies
    // Check if PLUGIN_DEPENDENCY_DIR environment variable is set; if not, Go will try to lookup for `helm` binary
    depDir, found := os.LookupEnv("PLUGIN_DEPENDENCY_DIR")
    if found {
        // Use exactly the binary from the $PLUGIN_DEPENDENCY_DIR directory
        commandName = fmt.Sprintf("%s/%s", depDir, commandName)
    }

    // Execute the command and return output
    cmd := exec.CommandContext(ctx, commandName, args...)
    out, err := cmd.CombinedOutput()

Example

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