Class: Skylight::NativeExtFetcher

Inherits:
Object
  • Object
show all
Includes:
FileUtils
Defined in:
lib/skylight/native_ext_fetcher.rb

Overview

Utility class for fetching the native extension from a URL

Defined Under Namespace

Classes: FetchError

Constant Summary collapse

BASE_URL = 
"https://s3.amazonaws.com/skylight-agent-packages/skylight-native".freeze
MAX_REDIRECTS = 
5
MAX_RETRIES = 
3

Class Method Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(source:, target:, version:, checksum:, arch:, logger:, required: false, platform: nil) ⇒ NativeExtFetcher

Returns a new instance of NativeExtFetcher.

Parameters:

  • source (String) —

    the base url to download from

  • target (String) —

    file to download as

  • version (String) —

    version to download

  • checksum (String) —

    checksum of the archive

  • arch (String) —

    platform architecture, e.g. ‘linux-x86_64`

  • required (Boolean) (defaults to: false) —

    whether the download is required to be successful

  • platform (defaults to: nil)
  • log (Logger) 


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# File 'lib/skylight/native_ext_fetcher.rb', line 39

def initialize(source:, target:, version:, checksum:, arch:, logger:, required: false, platform: nil)
  raise "source required" unless source
  raise "target required" unless target
  raise "checksum required" unless checksum
  raise "arch required" unless arch

  @source = source
  @target = target
  @version = version
  @checksum = checksum
  @required = required
  @platform = platform
  @arch = arch
  @logger = logger
end

Class Method Details

.fetch(**args) ⇒ Object

Creates a new fetcher and fetches

Parameters:

  • opts (Hash) 


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# File 'lib/skylight/native_ext_fetcher.rb', line 25

def self.fetch(**args)
  args[:source] ||= BASE_URL
  args[:logger] ||= Logger.new($stdout)
  new(**args).fetch
end

Instance Method Details

#basename ⇒ Object 



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# File 'lib/skylight/native_ext_fetcher.rb', line 210

def basename
  "skylight_#{@arch}.tar.gz"
end

#deconstruct_uri(uri) ⇒ Array<String>

Split the uri string into its component parts

Parameters:

Returns:

  • (Array<String>) —

    the host, port, scheme, and request_uri



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# File 'lib/skylight/native_ext_fetcher.rb', line 225

def deconstruct_uri(uri)
  uri = URI(uri)
  [uri.host, uri.port, uri.scheme == "https", uri.request_uri]
end

#error(msg, err = nil) ⇒ void

This method returns an undefined value.

Log an ‘error` to the `logger`

Parameters:

  • msg (String)
  • e (Exception) —

    the exception associated with the error



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# File 'lib/skylight/native_ext_fetcher.rb', line 254

def error(msg, err = nil)
  msg = "[SKYLIGHT] #{msg}"
  msg << "\n#{err.backtrace.join("\n")}" if err
  @logger.error msg
end

#fetch ⇒ String

Fetch the native extension, verify, inflate, and save (if applicable)

Returns:

  • (String) —

    the inflated archive



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# File 'lib/skylight/native_ext_fetcher.rb', line 58

def fetch
  log "fetching native ext; curr-platform=#{@platform}; " \
        "requested-arch=#{@arch}; version=#{@version}"

  tar_gz = "#{@target}/#{basename}"

  unless (sha2 = fetch_native_ext(source_uri, tar_gz, MAX_RETRIES, MAX_REDIRECTS))
    maybe_raise "could not fetch native extension"
    return
  end

  unless verify_checksum(sha2)
    maybe_raise "could not verify checksum"
    return
  end

  Dir.chdir File.dirname(tar_gz) do
    cmd = "tar xzvf #{tar_gz}"
    out, _status = Open3.capture2e(cmd)
    log cmd
    log out
  end

  true
ensure
  rm_f tar_gz if tar_gz
end

#fetch_native_ext(uri, out, attempts, redirects) ⇒ Object 



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# File 'lib/skylight/native_ext_fetcher.rb', line 86

def fetch_native_ext(uri, out, attempts, redirects)
  redirects.times do
    # Ensure the location is available
    mkdir_p File.dirname(out)
    rm_f out

    remaining_attempts = attempts

    log "attempting to fetch from remote; uri=#{uri}"

    begin
      host, port, use_ssl, path = deconstruct_uri(uri)

      File.open out, "w" do |f|
        res, extra = http_get(host, port, use_ssl, path, f)

        case res
        when :success
          log "successfully downloaded native ext; out=#{out}"
          return extra
        when :redirect
          log "fetching native ext; uri=#{uri}; redirected=#{res}"
          uri = extra

          next
        end
      end
    rescue StandardError => e
      remaining_attempts -= 1

      error "failed to fetch native extension; uri=#{uri}; msg=#{e.message}; " \
              "remaining-attempts=#{remaining_attempts}",
            e

      if remaining_attempts > 0
        sleep 2
        retry
      end

      return
    end
  end

  log "exceeded max redirects"
  nil
end

#http_get(host, port, use_ssl, path, out) ⇒ Object

Get with ‘Net::HTTP`

If ‘ENV` is set, it will be used as a proxy for this request.

Parameters:

  • host (String) —

    host for ‘Net::HTTP` request

  • port (String, Integer) —

    port for ‘Net::HTTP` request

  • use_ssl (Boolean) —

    whether SSL should be used for this request

  • path (String) —

    the path to request

  • out (IO) 


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# File 'lib/skylight/native_ext_fetcher.rb', line 142

def http_get(host, port, use_ssl, path, out)
  if (http_proxy = Util::Proxy.detect_url(ENV))
    log "connecting with proxy: #{http_proxy}"
    uri = URI.parse(http_proxy)
    p_host = uri.host
    p_port = uri.port
    p_user, p_pass = uri.userinfo.split(/:/) if uri.userinfo
  end

  opts = { use_ssl: use_ssl }

  if use_ssl
    # Create a cert store that doesn't enable CRL checking.
    # OpenSSL 3.x may enable CRL checking by default, which fails when
    # the CRL distribution point is unreachable.
    begin
      cert_store = OpenSSL::X509::Store.new
      cert_store.set_default_paths
      ca_file = Util::SSL.ca_cert_file_or_default
      cert_store.add_file(ca_file) if ca_file && File.exist?(ca_file)
      opts[:cert_store] = cert_store
    rescue OpenSSL::X509::StoreError => e
      log "failed to configure cert store: #{e.message}, using defaults"
    end
    opts[:verify_mode] = OpenSSL::SSL::VERIFY_PEER
  end

  Net::HTTP.start(host, port, p_host, p_port, p_user, p_pass, **opts) do |http|
    http.request_get path do |resp|
      case resp
      when Net::HTTPSuccess
        digest = Digest::SHA2.new

        resp.read_body do |chunk|
          digest << chunk
          out.write chunk
        end

        return :success, digest.hexdigest
      when Net::HTTPRedirection
        unless (location = resp["location"])
          raise "received redirect but no location"
        end

        return :redirect, location
      else
        raise "received HTTP status code #{resp.code}"
      end
    end
  end
end

#log(msg) ⇒ void

This method returns an undefined value.

Log an ‘info` to the `logger`

Parameters:



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# File 'lib/skylight/native_ext_fetcher.rb', line 244

def log(msg)
  msg = "[SKYLIGHT] #{msg}"
  @logger.info msg
end

#maybe_raise(err) ⇒ void

This method returns an undefined value.

Log an error and raise if ‘required` is `true`

Parameters:



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# File 'lib/skylight/native_ext_fetcher.rb', line 234

def maybe_raise(err)
  error err

  raise err if @required
end

#source_uri ⇒ Object

The url that will be fetched

Returns:

  • String



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# File 'lib/skylight/native_ext_fetcher.rb', line 217

def source_uri
  "#{@source}/#{@version}/#{basename}"
end

#verify_checksum(actual) ⇒ Boolean

Verify the checksum of the archive

Parameters:

Returns:

  • (Boolean) —

    whether the checksum matches



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# File 'lib/skylight/native_ext_fetcher.rb', line 198

def verify_checksum(actual)
  unless @checksum == actual
    log "checksum mismatch; expected=#{@checksum}; actual=#{actual}"
    return false
  end

  true
rescue Exception => e
  error "failed to read skylight agent archive; e=#{e.message}"
  false
end