acid: Improve git error handling

Exit early from the cyche-source script on key git errors, where
previously we would mindlessly continue on to execute a bunch of broken
commands.  Errors at this stage should be caught to prevent an attempt
to build and deploy the code (even --force 'd builds).

Signed-off-by: Malfurious <m@lfurio.us>

1 files changed, 11 insertions, 9 deletions

diff --git a/acid/cyche-source b/acid/cyche-source
index dd290ac..e53ef6f 100755
--- a/acid/cyche-source
+++ b/acid/cyche-source
@@ -6,12 +6,14 @@
 # <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)).
 #
-# The new (or current, if no update occurred) object hash is printed to stdout.
-# This may be a commit hash.  However, if <ref-pattern> matches an annotated tag,
-# then the hash names the tag object.  The caller should cache this hash value
-# upon successful deployment.
+# 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 the file tree is updated, this file exits non-zero.
+# 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 \
@@ -24,7 +26,7 @@ gethash() {
 cd '/services'
 
 if ! [ -d "$1" ]; then
-    git clone "$2" "$1" >&2
+    git clone "$2" "$1" >&2 || exit 2
     touch "$1/.git/previous_hash"
     touch "$1/.git/previous_slug"
 fi
@@ -32,14 +34,14 @@ fi
 cd "$1"
 
 git remote set-url origin "$2" >&2 # pick up url changes
-git fetch --all --prune >&2
+git fetch --all --prune >&2 || exit 2
 
 prev=$(cat '.git/previous_hash')
 next=$(gethash "$3")
 
 if [ -z "$next" ]; then
-    # no matching refs
-    next="$prev"
+    echo "No refs match $3" >&2
+    exit 2
 fi
 
 echo "$next"