start-localhost-registry: Start container if it already exists

Previously an error occurred if the container existed because container
creation tried to use a name already in use.  It's safe to "start" a
container that's already started, so this makes the program idempotent.

This also handles the case of the container existing but being stopped,
which previously wasn't handled.

Makefile

@@ -3,7 +3,7 @@ SHELL := bash -euo pipefail
 .PHONY: local-image test
 
 local-image:
-	./devel/start-localhost-registry || true
+	./devel/start-localhost-registry
 	./devel/build
 
 	# Don't pull base-builder image since it's huge and not needed for local

devel/start-localhost-registry

@@ -18,12 +18,16 @@ NAME=nextstrain-local-registry
 # Docker image that provides the registry service.
 IMAGE=registry:2
 
-docker run \
-    --detach \
-    --publish 127.0.0.1:"$PORT":"$PORT" \
-    --restart always \
-    --name "$NAME" \
-    --volume "$DATA":/var/lib/registry \
-    --user "$(id -u):$(id -g)" \
-    "$IMAGE" \
-    > /dev/null
+if docker container inspect "$NAME" &>/dev/null; then
+    docker container start "$NAME"
+else
+    docker run \
+        --detach \
+        --publish 127.0.0.1:"$PORT":"$PORT" \
+        --restart always \
+        --name "$NAME" \
+        --volume "$DATA":/var/lib/registry \
+        --user "$(id -u):$(id -g)" \
+        "$IMAGE" \
+        > /dev/null
+fi