defmodule Hibana.Plugins.DevErrorPage do
@moduledoc """
Rich error pages for development with stack traces, request info, and code context.
## Usage
# Only in dev!
plug Hibana.Plugins.DevErrorPage
## Options
- `:enabled` - Whether the dev error page rendering is active (default: `true`)
"""
use Hibana.Plugin
import Plug.Conn
@impl true
def init(opts), do: %{enabled: Keyword.get(opts, :enabled, true)}
@impl true
def call(conn, %{enabled: true}) do
register_before_send(conn, fn conn ->
if conn.status >= 500 and not conn.halted do
render_error_page(conn)
else
conn
end
end)
end
def call(conn, _), do: conn
@doc "Render an exception as a rich HTML error page"
def render_exception(conn, kind, reason, stacktrace) do
html = build_error_html(kind, reason, stacktrace, conn)
conn
|> put_resp_content_type("text/html")
|> send_resp(500, html)
|> halt()
end
defp render_error_page(conn) do
%{conn | resp_body: build_simple_error_html(conn)}
end
defp build_error_html(kind, reason, stacktrace, conn) do
title = exception_title(kind, reason)
message = Exception.message(reason) |> html_escape()
stack_html = format_stacktrace(stacktrace)
request_html = format_request(conn)
"""
#{title}
Request
#{request_html}
Stack Trace
#{stack_html}
Hibana Dev Error Page -- This page is only shown in development.
"""
end
defp build_simple_error_html(conn) do
"""
500 Error
500 -- Internal Server Error
#{conn.method} #{conn.request_path}\nStatus: #{conn.status}
"""
end
defp exception_title(:error, %{__struct__: mod}), do: inspect(mod)
defp exception_title(kind, _), do: to_string(kind)
defp format_stacktrace(stacktrace) do
stacktrace
|> Enum.map(fn
{mod, fun, arity, location} ->
file = Keyword.get(location, :file, ~c"?") |> to_string()
line = Keyword.get(location, :line, 0)
arity_str = if is_list(arity), do: length(arity), else: arity
is_app = not String.contains?(file, "/deps/") and not String.starts_with?(file, "(")
class = if is_app, do: "app", else: "lib"
"""
#{inspect(mod)}.#{fun}/#{arity_str}
#{file}:#{line}
"""
_ ->
""
end)
|> Enum.join("\n")
end
defp format_request(conn) do
headers =
conn.req_headers
|> Enum.map(fn {k, v} -> "| #{k} | #{html_escape(v)} |
" end)
|> Enum.join()
"""
| Method | #{conn.method} |
| Path | #{conn.request_path} |
| Query | #{conn.query_string} |
| Remote IP | #{conn.remote_ip |> Tuple.to_list() |> Enum.join(".")} |
#{headers}
"""
end
defp html_escape(str) when is_binary(str) do
str
|> String.replace("&", "&")
|> String.replace("<", "<")
|> String.replace(">", ">")
|> String.replace("\"", """)
end
defp html_escape(other), do: html_escape(to_string(other))
end