projectriff-archive/streaming-http-adapter-buildpack

Streaming HTTP Adapter Buildpack

This buildpack contributes the riff streaming http adapter, so that subsequent buildpacks in a buildpack group (in particular, a riff function buildpack such as the java function buildpack or the node function buildpack) can benefit from first class request/reply http support, without having to implement it.

For further details on the Streaming HTTP adapter, refer to the http-streaming-adapter project.

Usage

To use this buildback, add it in a buildpack group, before a function buildpack that wants to benefit from http support. For example, to enhance the java function buildpack, go from this definition:

[[groups]]
  # java functions
  buildpacks = [
    { id = "org.cloudfoundry.openjdk",              version = 'latest', optional = true },
    { id = "org.cloudfoundry.buildsystem",          version = 'latest', optional = true },
    { id = "io.projectriff.java",                   version = 'latest' },
  ]

to this:

[[groups]]
  # java functions
  buildpacks = [
    { id = "org.cloudfoundry.openjdk",              version = 'latest', optional = true },
    { id = "org.cloudfoundry.buildsystem",          version = 'latest', optional = true },
    { id = "io.projectriff.streaming-http-adapter", version = 'latest', optional = true },
    { id = "io.projectriff.java",                   version = 'latest' },
  ]

In the detect phase of the interested buildpack, you can make sure that the streaming adapter is available and e.g. fail the build like so:

if _, ok := d.BuildPlan[adapter.ProxyAvailable] ; !ok {
    return false, errors.New("missing the http streaming adapter buildpack")
}

To request that this buildpack contributes the adapter, add the http-proxy key (use const Dependency from the adapter package of this repo) to the buildplan:

p := detect.BuildPlan[adapter.Dependency]
if p.Metadata == nil {
    p.Metadata = buildplan.Metadata{}
}
return buildplan.BuildPlan{/*other keys + */ adapter.Dependency: p}

In the build phase of the interested buildpack, rewrite process definitions by passing the launch metadata to the Adapt() function:

return r.layers.WriteApplicationMetadata(adapter.Adapt(layers.Metadata{
    Processes: layers.Processes{
        layers.Process{Type: "function", Command: command},
        layers.Process{Type: "web", Command: command},
    },
}))