Fail peadm::util::retrieve_and_upload on PCP

The `peadm::util::retrieve_and_upload` plan downloads a
PE installer tarball and then uploads it to a set of
hosts that need it (Primary and Database nodes).

When the PCP transport is in use, this upload is done
via the `bolt_shim::upload` task, which essentially
reads the file into memory, encodes it, and then
ships it over Orchestrator as a task argument.

This method of file transfer is utterly inadequate
for shipping files as large as the PE installer
which is over half of a gigabyte in size. Use
of "bolt_shim::upload" will cause either a
Linux kernel OOM, an Orchestrator OOM, or
slam into the `max-message-size` allowed by
the Orchestrator.

This commit updates `peadm::util::retrieve_and_upload`
to fail with a descriptive error message if any
of the target nodes is using the PCP transport.

Author: Sharpie

plans/util/retrieve_and_upload.pp

@@ -5,6 +5,28 @@
   String[1]  $local_path,
   String[1]  $upload_path,
 ) {
+  $nodes.peadm::fail_on_transport('pcp', @(HEREDOC/n))
+    \nThe "pcp" transport is not available for uploading PE installers as
+    the ".tar.gz" file is too large to send over the PE Orchestrator
+    as an argument to the "bolt_shim::upload" task.
+
+    To upgrade PE XL database nodes via PCP, use "download_mode = direct".
+    If Puppet download servers are not reachable over the internet,
+    upload the ".tar.gz" to an internal fileserver and use the
+    "pe_installer_source" parameter to retrieve it.
+
+    For information on configuring plan parameters, see:
+
+        https://forge.puppet.com/modules/puppetlabs/peadm/plans
+
+    Or, use the "ssh" transport for database nodes so that the
+    installer can be transferred via SCP.
+
+    For information on configuring transports, see:
+
+        https://www.puppet.com/docs/bolt/latest/bolt_transports_reference.html
+    |-HEREDOC
+
   $exists = without_default_logging() || {
     run_command("test -e '${local_path}'", 'local://localhost',
       _catch_errors => true,

spec/plans/util/retrieve_and_upload_spec.rb

@@ -41,4 +41,17 @@
 
     expect(run_plan('peadm::util::retrieve_and_upload', 'nodes' => 'primary', 'source' => '/tmp/source', 'upload_path' => '/tmp/upload', 'local_path' => '/tmp/download')).to be_ok
   end
+
+  it 'fails when nodes are configured to use the pcp transport' do
+    result = run_plan('peadm::util::retrieve_and_upload',
+                      {'nodes'       => ['pcp://node.example'],
+                       'source'      => '/tmp/source',
+                       'upload_path' => '/tmp/upload',
+                       'local_path'  => '/tmp/download'})
+
+
+    expect(result).not_to be_ok
+    expect(result.value.kind).to eq('unexpected-transport')
+    expect(result.value.msg).to match(%r{The "pcp" transport is not available for uploading PE installers})
+  end
 end