1 files changed, 71 insertions, 0 deletions
diff --git a/acid/acid-source b/acid/acid-source
new file mode 100755
index 0000000..2d507d6
--- /dev/null
+++ b/acid/acid-source
@@ -0,0 +1,71 @@
+#!/bin/bash
+
+# acid-source <name> <url> <ref-pattern>
+#
+# Check a git source for new updates.  A local cache repository is cloned if
+# <name> doesn't exist.  If updates are found, we attempt to checkout the newest
+# version according to <ref-pattern> (see <pattern> from git-for-each-ref(1)).
+#
+# On a successful run, the new object hash is printed to stdout (or the previous
+# hash, if no update occurred).  This may be a commit hash.  However, if
+# <ref-pattern> matches an annotated tag, then the hash refers to the tag object.
+# The caller should cache this hash value upon successful deployment.
+#
+# If a new version of the file tree is checked out, this file exits with code 1,
+# otherwise a stale success exits with 0.  On any error, no hash is printed, and
+# we exit with 2.
+
+gethash() {
+    git for-each-ref \
+        --count=1 \
+        --format='%(objectname)' \
+        --sort='-creatordate' \
+        "$1" # pattern
+}
+
+cd '/services'
+
+# For <name>, limit to a-z, 0-9, -, _
+if ! echo "$1" | grep -Eq '^[-_a-z0-9]*$'; then
+    echo "Bad service name: $1" >&2
+    exit 2
+fi
+
+if ! [ -d "$1" ]; then
+    git clone "$2" "$1" >&2 || exit 2
+    touch "$1/.git/previous_hash"
+    touch "$1/.git/previous_slug"
+fi
+
+cd "$1"
+
+git remote set-url origin "$2" >&2 # pick up url changes
+git fetch --all --prune >&2 || exit 2
+
+prev=$(cat '.git/previous_hash')
+next=$(gethash "$3")
+
+if [ -z "$next" ]; then
+    echo "No refs match $3" >&2
+    exit 2
+fi
+
+echo "$next"
+
+if [ "$prev" != "$next" ]; then
+    # update file tree
+    git submodule deinit --all --force >/dev/null 2>&1
+    git reset . >/dev/null 2>&1
+    git checkout . >/dev/null 2>&1
+    git clean -xffd >/dev/null 2>&1
+
+    git checkout "$next" >/dev/null 2>&1
+    git submodule update --init --recursive >&2
+
+    echo -n "Checked out " >&2
+    git log -1 --oneline --no-abbrev-commit --no-decorate >&2
+
+    exit 1
+fi
+
+exit 0