feat: pin spanner docker (#2236)

* create grepable pin with context for spanner

* try to update and pin both spanner versions

Author: taddes

.github/workflows/main-workflow.yml

@@ -836,7 +836,8 @@ jobs:
 
     services:
       spanner-emulator:
-        image: gcr.io/cloud-spanner-emulator/emulator:1.4.0
+        # SPANNER_EMULATOR_VER (unit tests) — keep in sync with docker/docker-compose.spanner.yaml
+        image: gcr.io/cloud-spanner-emulator/emulator:1.5.52
         ports:
           - 9010:9010
           - 9020:9020

docker/docker-compose.spanner.yaml

@@ -1,13 +1,7 @@
 services:
   sync-db:
-    # Getting sporadic errors in spanner.
-    # These errors are "INTERNAL: ZETASQL_RET_CHECK failure"
-    # in the `backend/query/query_engine.cc` file for spanner.
-    # These result in a 500 error, which causes the test to fail.
-    # I believe come from the SQL parser, but am not sure. I am
-    # unable to produce these errors locally, and am using the cited
-    # version.
-    image: gcr.io/cloud-spanner-emulator/emulator:1.5.13
+    # SPANNER_EMULATOR_VER (e2e/integration tests) — keep in sync with .github/workflows/main-workflow.yml
+    image: gcr.io/cloud-spanner-emulator/emulator:1.5.52
     ports:
       - "9010:9010"
       - "9020:9020"

docs/src/introduction.md

@@ -355,6 +355,13 @@ Note, that unlike MySQL, there is no automatic migrations facility. Currently, t
 
 Google supports an in-memory Spanner emulator, which can run on your local machine for development purposes. You can install the emulator via the gcloud CLI or Docker by following the instructions [here](https://cloud.google.com/spanner/docs/emulator#installing_and_running_the_emulator). Once the emulator is running, you'll need to create a new instance and a new database.
 
+**Updating the emulator version:** The emulator version is pinned in two places, each marked with `SPANNER_EMULATOR_VER`:
+
+- `docker/docker-compose.spanner.yaml` — used for e2e/integration tests
+- `.github/workflows/main-workflow.yml` — used for CI unit tests
+
+Both should always be set to the same version. When upgrading, update both and verify no regressions appear in CI.
+
 ##### Quick Setup Using prepare-spanner.sh
 
 The easiest way to set up a Spanner emulator database is to use the `prepare-spanner.sh` script: