feat: Add util for waiting for container startup; use in dbcopyall8 (#1198)

`make dev.dbcopyall8` doesn't work unless the mysql containers have been
started and are ready to run. This is not the only place we need to wait
for a functional check on a container, so in this commit I've gone ahead
and started a utility for doing so.

This first pass only supports MySQL, but we should at least add Mongo as
well, as that's also needed in one of the provisioning scripts.

I've moved the _db_copy8_targets from being an order-only prerequisite
to being a recursive make call. I'm not sure why the order-only syntax
was in use here, but in any case I needed to add in a script call
before those targets were called, so it's likely moot.

Also:

- Drop unneeded `bash -c` wrappers from db copy docker exec calls

Author: timmc-edx

Makefile

@@ -461,11 +461,14 @@ dev.dbshell:
 
 DB_NAMES_LIST = credentials discovery ecommerce notes registrar xqueue edxapp edxapp_csmh dashboard analytics-api reports reports_v1
 _db_copy8_targets = $(addprefix dev.dbcopy8.,$(DB_NAMES_LIST))
-dev.dbcopyall8: | $(_db_copy8_targets) ## Copy data from old mysql 5.7 containers into new mysql8 dbs
+dev.dbcopyall8: ## Copy data from old mysql 5.7 containers into new mysql8 dbs
+	$(MAKE) dev.up.mysql57+mysql80
+	./wait-ready.sh mysql57 mysql80
+	$(MAKE) $(_db_copy8_targets)
 
 dev.dbcopy8.%: ## Copy data from old mysql 5.7 container into a new 8 db
-	docker compose exec mysql57 bash -c "mysqldump $*" > .dev/$*.sql
-	docker compose exec -T mysql80 bash -c "mysql $*" < .dev/$*.sql
+	docker compose exec mysql57 mysqldump "$*" > .dev/$*.sql
+	docker compose exec -T mysql80 mysql "$*" < .dev/$*.sql
 	rm .dev/$*.sql
 
 dev.dbshell.%: ## Run a SQL shell on the given database.

provision.sh

@@ -130,40 +130,22 @@ fi
 
 # Ensure the MySQL5 server is online and usable
 echo "${GREEN}Waiting for MySQL 5.7.${NC}"
-until docker compose exec -T mysql57 bash -e -c "mysql -uroot -se \"SELECT EXISTS(SELECT 1 FROM mysql.user WHERE user = 'root')\"" &> /dev/null
-do
-  printf "."
-  sleep 1
-done
+./wait-ready.sh mysql57
 
 # Ensure the MySQL8 server is online and usable
 echo "${GREEN}Waiting for MySQL 8.0.${NC}"
-until docker compose exec -T mysql80 bash -e -c "mysql -uroot -se \"SELECT EXISTS(SELECT 1 FROM mysql.user WHERE user = 'root')\"" &> /dev/null
-do
-  printf "."
-  sleep 1
-done
+./wait-ready.sh mysql80
 
 # In the event of a fresh MySQL container, wait a few seconds for the server to restart
 # See https://github.com/docker-library/mysql/issues/245 for why this is necessary.
 sleep 10
 
 echo "${GREEN}Waiting for MySQL 5.7 to restart.${NC}"
-until docker compose exec -T mysql57 bash -e -c "mysql -uroot -se \"SELECT EXISTS(SELECT 1 FROM mysql.user WHERE user = 'root')\"" &> /dev/null
-do
-  printf "."
-  sleep 1
-done
-
+./wait-ready.sh mysql57
 echo -e "${GREEN}MySQL5 ready.${NC}"
 
 echo "${GREEN}Waiting for MySQL 8.0 to restart.${NC}"
-until docker compose exec -T mysql80 bash -e -c "mysql -uroot -se \"SELECT EXISTS(SELECT 1 FROM mysql.user WHERE user = 'root')\"" &> /dev/null
-do
-  printf "."
-  sleep 1
-done
-
+./wait-ready.sh mysql80
 echo -e "${GREEN}MySQL8 ready.${NC}"
 
 # Ensure that the MySQL databases and users are created for all IDAs.

wait-ready.sh

@@ -0,0 +1,40 @@
+#!/bin/bash
+# Wait for the listed services to become ready.
+#
+# This does not start the containers; that should be performed separately
+# via `make dev.up` in order to allow for parallel startup.
+
+set -eu -o pipefail
+
+function print_usage {
+    echo "Usage: $0 service1 service2 ..."
+}
+
+if [[ $# == 0 ]]; then
+    print_usage
+    exit 0
+fi
+
+function wait_db {
+    container_name="$1"
+    mysql_probe="SELECT EXISTS(SELECT 1 FROM mysql.user WHERE user = 'root')"
+    until docker compose exec -T "$container_name" mysql -uroot -se "$mysql_probe" &> /dev/null; do
+        printf "." >&2
+        sleep 1
+    done
+    echo >&2 "$container_name is ready"
+}
+
+
+for service_name in "$@"; do
+    case "$service_name" in
+        mysql*)
+            wait_db "$service_name"
+            ;;
+        # TODO: Add other services...
+        *)
+            echo >&2 "Unknown service: $service_name"
+            exit 1
+            ;;
+    esac
+done