Make new tenant/timeline IDs mandatory in create APIs. (#4304)

We used to generate the ID, if the caller didn't specify it. That's bad
practice, however, because network is never fully reliable, so it's
possible we create a new tenant but the caller doesn't know about it,
and because it doesn't know the tenant ID, it has no way of retrying or
checking if it succeeded. To discourage that, make it mandatory. The web
control plane has not relied on the auto-generation for a long time.

docker-compose/compute_wrapper/shell/compute.sh

@@ -1,6 +1,14 @@
 #!/bin/bash
 set -eux
 
+# Generate a random tenant or timeline ID
+#
+# Takes a variable name as argument. The result is stored in that variable.
+generate_id() {
+    local -n resvar=$1
+    printf -v resvar '%08x%08x%08x%08x' $SRANDOM $SRANDOM $SRANDOM $SRANDOM
+}
+
 PG_VERSION=${PG_VERSION:-14}
 
 SPEC_FILE_ORG=/var/db/postgres/specs/spec.json
@@ -13,29 +21,29 @@ done
 echo "Page server is ready."
 
 echo "Create a tenant and timeline"
+generate_id tenant_id
 PARAMS=(
      -sb 
      -X POST
      -H "Content-Type: application/json"
-     -d "{}"
+     -d "{\"new_tenant_id\": \"${tenant_id}\"}"
      http://pageserver:9898/v1/tenant/
 )
-tenant_id=$(curl "${PARAMS[@]}" | sed 's/"//g')
+result=$(curl "${PARAMS[@]}")
+echo $result | jq .
 
+generate_id timeline_id
 PARAMS=(
      -sb 
      -X POST
      -H "Content-Type: application/json"
-     -d "{\"tenant_id\":\"${tenant_id}\", \"pg_version\": ${PG_VERSION}}"
+     -d "{\"new_timeline_id\": \"${timeline_id}\", \"pg_version\": ${PG_VERSION}}"
      "http://pageserver:9898/v1/tenant/${tenant_id}/timeline/"
 )
 result=$(curl "${PARAMS[@]}")
 echo $result | jq .
 
 echo "Overwrite tenant id and timeline id in spec file"
-tenant_id=$(echo ${result} | jq -r .tenant_id)
-timeline_id=$(echo ${result} | jq -r .timeline_id)
-
 sed "s/TENANT_ID/${tenant_id}/" ${SPEC_FILE_ORG} > ${SPEC_FILE}
 sed -i "s/TIMELINE_ID/${timeline_id}/" ${SPEC_FILE}