Generate a PDF in Ruby on Rails

The simplest way to generate a PDF in Ruby on Rails is to call the Docweave API from a controller or a background job with Net::HTTP or Faraday: POST your rendered view HTML to /api/v1/pdf and write the returned bytes to disk — no headless browser to install or run yourself.

From a controller, using Net::HTTP

Render the invoice view to a string with render_to_string, POST it to Docweave, then stream the PDF straight back to the browser with send_data:

# app/controllers/invoices_controller.rb
require "net/http"
require "json"

class InvoicesController < ApplicationController
  DOCWEAVE_URL = URI("https://docweave.dev/api/v1/pdf")

  def download_pdf
    invoice = Invoice.find(params[:id])

    html = render_to_string(
      template: "invoices/show",
      layout: "pdf",
      locals: { invoice: invoice }
    )

    request = Net::HTTP::Post.new(DOCWEAVE_URL)
    request["Authorization"] = "Bearer #{Rails.application.credentials.docweave_api_key}"
    request["Content-Type"] = "application/json"
    request["Accept"] = "application/pdf"
    request.body = {
      source: { type: "html", html: html },
      options: { format: "A4" },
      idempotencyKey: "invoice-#{invoice.id}"
    }.to_json

    response = Net::HTTP.start(DOCWEAVE_URL.host, DOCWEAVE_URL.port, use_ssl: true) do |http|
      http.request(request)
    end

    unless response.is_a?(Net::HTTPSuccess)
      raise "Docweave render failed: #{response.code} #{response.body}"
    end

    send_data response.body,
              filename: "invoice-#{invoice.id}.pdf",
              type: "application/pdf",
              disposition: "attachment"
  end
end

From a background job, using Faraday

For larger documents or scheduled generation, do the same render-and-post inside an ActiveJob, then write the PDF to disk (or hand it off to Active Storage):

# app/jobs/generate_invoice_pdf_job.rb
require "faraday"

class GenerateInvoicePdfJob < ApplicationJob
  queue_as :pdfs
  retry_on StandardError, wait: :polynomially_longer, attempts: 3

  def perform(invoice_id)
    invoice = Invoice.find(invoice_id)

    html = ApplicationController.render(
      template: "invoices/show",
      layout: "pdf",
      assigns: { invoice: invoice }
    )

    response = Faraday.post("https://docweave.dev/api/v1/pdf") do |req|
      req.headers["Authorization"] = "Bearer #{Rails.application.credentials.docweave_api_key}"
      req.headers["Content-Type"] = "application/json"
      req.headers["Accept"] = "application/pdf"
      req.body = {
        source: { type: "html", html: html },
        options: { format: "A4" },
        idempotencyKey: "invoice-#{invoice.id}"
      }.to_json
    end

    raise "Docweave render failed: #{response.status}" unless response.success?

    pdf_path = Rails.root.join("tmp", "pdfs", "invoice-#{invoice.id}.pdf")
    FileUtils.mkdir_p(pdf_path.dirname)
    File.binwrite(pdf_path, response.body)
  end
end

…or from a Ruby AI agent, via MCP

If your agent runs in Ruby, or your workflow calls tools over MCP from any language, the Docweave MCP server exposes a generate_pdf tool — the same underlying render, no HTTP boilerplate to write:

# From a Ruby-based AI agent, over MCP — no HTTP plumbing:
generate_pdf({
  "source" => {
    "type" => "html",
    "html" => "<h1>Invoice INV-042</h1><p>Total due: $1,280.00</p>"
  },
  "outputPath" => "/tmp/invoice-042.pdf"
})

# Any MCP client (Claude, an agent framework, a custom Ruby MCP client)
# can call this tool once the server is registered — start it with:
# npx @docweave/mcp

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