gnu: Add go-cloud-google-com-go-trace.

* gnu/packages/golang-web.scm (go-cloud-google-com-go-trace): New variable.
(go-cloud-google-com-go)[source] <snippet>: Remove "trace" directory.

Change-Id: Id2965aaa5107ef59d78023dc313525482a6e0e13

gnu/packages/golang-web.scm

@@ -391,6 +391,7 @@ devices.")
             ;; - cloud.google.com/go/security
             ;; - cloud.google.com/go/spanner
             ;; - cloud.google.com/go/storage
+            ;; - cloud.google.com/go/trace
             (for-each delete-file-recursively
                       (list "auth"
                             "compute/metadata"
@@ -400,7 +401,8 @@ devices.")
                             "monitoring"
                             "security"
                             "spanner"
-                            "storage"))))))
+                            "storage"
+                            "trace"))))))
     (build-system go-build-system)
     (arguments
      (list
@@ -970,6 +972,59 @@ Google Cloud Storage stores data in named objects, which are grouped into
 buckets.")
     (license license:asl2.0)))
 
+(define-public go-cloud-google-com-go-trace
+  (package
+    (name "go-cloud-google-com-go-trace")
+    (version "1.14.0")
+    (source
+     (origin
+       (method git-fetch)
+       (uri (git-reference
+              (url "https://github.com/googleapis/google-cloud-go")
+              (commit (go-version->git-ref version #:subdir "trace"))))
+       (file-name (git-file-name name version))
+       (sha256
+        (base32 "14khzbcymknsz4p40ibc8v1zsy33b33yn7fcvkfp4rkzw69wv356"))
+       (modules '((guix build utils)
+                  (ice-9 ftw)
+                  (srfi srfi-26)))
+       (snippet
+        #~(begin
+            (define (delete-all-but directory . preserve)
+              (with-directory-excursion directory
+                (let* ((pred (negate (cut member <>
+                                          (cons* "." ".." preserve))))
+                       (items (scandir "." pred)))
+                  (for-each (cut delete-file-recursively <>) items))))
+            (delete-all-but "." "trace")))))
+    (build-system go-build-system)
+    (arguments
+     (list
+      #:skip-build? #t
+      #:import-path "cloud.google.com/go/trace"
+      #:unpack-path "cloud.google.com/go"))
+    (propagated-inputs
+     (list go-github-com-googleapis-gax-go-v2
+           go-google-golang-org-api
+           go-google-golang-org-genproto
+           go-google-golang-org-genproto-googleapis-api
+           go-google-golang-org-genproto-googleapis-rpc
+           go-google-golang-org-grpc
+           go-google-golang-org-protobuf))
+    (home-page "https://cloud.google.com/go")
+    (synopsis "Go Client Library for Cloud Trace API")
+    (description
+     "This package implements the @url{https://cloud.google.com/stackdriver,
+Stackdriver} Trace API in Golang.  Stackdriver Trace is a distributed tracing
+system that collects latency data from your applications and displays it in
+the Google Cloud Platform Console.
+
+It sends application trace data to Stackdriver Trace for viewing.  Trace data
+is collected for all App Engine applications by default.  Trace data from
+other applications can be provided using this API.  This library is used to
+interact with the Trace API directly.")
+    (license license:asl2.0)))
+
 (define-public go-code-gitea-io-sdk-gitea
   (package
     (name "go-code-gitea-io-sdk-gitea")