Add Timestamp git metadata file

README.md

@@ -237,6 +237,8 @@ correct key is provided set in `git_crypt_key`.
 
 * `short_ref_format`: *Optional.* When populating `.git/short_ref` use this `printf` format. Defaults to `%s`.
 
+* `timestamp_format`: *Optional.* When populating `.git/commit_timestamp` use this options to pass to [`git log --date`](https://git-scm.com/docs/git-log#Documentation/git-log.txt---dateltformatgt). Defaults to `iso8601`.
+
 * `describe_ref_options`: *Optional.* When populating `.git/describe_ref` use this options to call [`git describe`](https://git-scm.com/docs/git-describe). Defaults to `--always --dirty --broken`.
 
 #### GPG signature verification
@@ -261,6 +263,8 @@ the case.
 
 * `.git/commit_message`: For publishing the Git commit message on successful builds.
 
+ * `.git/commit_timestamp`: For tagging builds with a timestamp.
+
 * `.git/describe_ref`: Version reference detected and checked out. Can be templated with `describe_ref_options` parameter.
  By default, it will contain the `<latest annoted git tag>-<the number of commit since the tag>-g<short_ref>` (eg. `v1.6.2-1-g13dfd7b`).
  If the repo was never tagged before, this falls back to a short commit SHA-1 ref.

assets/in

@@ -50,6 +50,7 @@ gpg_keyserver=$(jq -r '.source.gpg_keyserver // "hkp://ipv4.pool.sks-keyservers.
 disable_git_lfs=$(jq -r '(.params.disable_git_lfs // false)' < $payload)
 clean_tags=$(jq -r '(.params.clean_tags // false)' < $payload)
 short_ref_format=$(jq -r '(.params.short_ref_format // "%s")' < $payload)
+timestamp_format=$(jq -r '(.params.timestamp_format // "iso8601")' < $payload)
 describe_ref_options=$(jq -r '(.params.describe_ref_options // "--always --dirty --broken")' < $payload)
 
 # If params not defined, get it from source
@@ -197,6 +198,9 @@ echo "${return_ref}" | cut -c1-7 | awk "{ printf \"${short_ref_format}\", \$1 }"
 # for example
 git log -1 --format=format:%B > .git/commit_message
 
+# Store commit date in .git/commit_timestamp. Can be used for tagging builds
+git log -1 --format=%cd --date=${timestamp_format} > .git/commit_timestamp
+
 # Store describe_ref when available. Useful to build Docker images with
 # a custom tag, or package to publish
 echo "$(git describe ${describe_ref_options})" > .git/describe_ref

test/get.sh

@@ -718,6 +718,32 @@ it_can_get_commit_message() {
     ( echo "Commit message does not match."; return 1 )
 }
 
+it_can_get_commit_timestamps() {
+  run test_commit_timestamp_format "iso8601"
+  run test_commit_timestamp_format "iso-strict"
+  run test_commit_timestamp_format "rfc"
+  run test_commit_timestamp_format "short"
+  run test_commit_timestamp_format "raw"
+  run test_commit_timestamp_format "unix"
+}
+
+test_commit_timestamp_format() {
+  local repo=$(init_repo)
+  local commit_message='Time-is-relevant!'
+  local ref=$(make_commit $repo $commit_message)
+  local dest=$TMPDIR/destination
+
+  get_uri_with_custom_timestamp $repo $dest $1
+
+  pushd $dest
+  local expected_timestamp=$(git log -1 --date=$1 --format=format:%cd)
+  popd
+
+  test -e $dest/.git/commit_timestamp || ( echo ".git/commit_timestamp does not exist."; return 1 )
+  test "$(cat $dest/.git/commit_timestamp)" = "$expected_timestamp" || \
+    ( echo "Commit timestamp for format $1 differs from expectation."; return 1 )
+}
+
 it_decrypts_git_crypted_files() {
   local repo=$(git_crypt_fixture_repo_path)
   local dest=$TMPDIR/destination
@@ -831,6 +857,7 @@ run it_can_get_signed_commit_via_tag
 run it_can_get_committer_email
 run it_can_get_returned_ref
 run it_can_get_commit_message
+run it_can_get_commit_timestamps
 run it_decrypts_git_crypted_files
 run it_clears_tags_with_clean_tags_param
 run it_retains_tags_by_default

test/helpers.sh

@@ -874,6 +874,17 @@ get_uri_with_clean_tags() {
   }" | ${resource_dir}/in "$2" | tee /dev/stderr
 }
 
+get_uri_with_custom_timestamp() {
+  jq -n "{
+    source: {
+      uri: $(echo $1 | jq -R .),
+    },
+    params: {
+      timestamp_format: \"$3\"
+    }
+  }" | ${resource_dir}/in "$2" | tee /dev/stderr
+}
+
 put_uri() {
   jq -n "{
     source: {