Create an initial timeline on CLI tenant creation (#1689)

Resolves #1655

neon_local/src/main.rs

@@ -540,6 +540,29 @@ fn handle_tenant(tenant_match: &ArgMatches, env: &mut local_env::LocalEnv) -> an
                 "tenant {} successfully created on the pageserver",
                 new_tenant_id
             );
+
+            // Create an initial timeline for the new tenant
+            let new_timeline_id = parse_timeline_id(create_match)?;
+            let timeline = pageserver
+                .timeline_create(new_tenant_id, new_timeline_id, None, None)?
+                .context(format!(
+                    "Failed to create initial timeline for tenant {new_tenant_id}"
+                ))?;
+            let new_timeline_id = timeline.timeline_id;
+            let last_record_lsn = timeline
+                .local
+                .context(format!("Failed to get last record LSN: no local timeline info for timeline {new_timeline_id}"))?
+                .last_record_lsn;
+
+            env.register_branch_mapping(
+                DEFAULT_BRANCH_NAME.to_string(),
+                new_tenant_id,
+                new_timeline_id,
+            )?;
+
+            println!(
+                "Created an initial timeline '{new_timeline_id}' at Lsn {last_record_lsn} for tenant: {new_tenant_id}",
+            );
         }
         Some(("config", create_match)) => {
             let tenant_id = get_tenant_id(create_match, env)?;

test_runner/batch_others/test_ancestor_branch.py

@@ -35,7 +35,6 @@ def test_ancestor_branch(zenith_env_builder: ZenithEnvBuilder):
         with psconn.cursor(cursor_factory=psycopg2.extras.DictCursor) as pscur:
             pscur.execute("failpoints flush-frozen=sleep(10000)")
 
-    env.zenith_cli.create_timeline(f'main', tenant_id=tenant)
     pg_branch0 = env.postgres.create_start('main', tenant_id=tenant)
     branch0_cur = pg_branch0.connect().cursor()
     branch0_cur.execute("SHOW zenith.zenith_timeline")

test_runner/batch_others/test_zenith_cli.py

@@ -1,7 +1,7 @@
 import uuid
 import requests
 
-from fixtures.zenith_fixtures import ZenithEnv, ZenithEnvBuilder, ZenithPageserverHttpClient
+from fixtures.zenith_fixtures import DEFAULT_BRANCH_NAME, ZenithEnv, ZenithEnvBuilder, ZenithPageserverHttpClient
 from typing import cast
 
 
@@ -83,6 +83,16 @@ def test_cli_tenant_list(zenith_simple_env: ZenithEnv):
     assert tenant2.hex in tenants
 
 
+def test_cli_tenant_create(zenith_simple_env: ZenithEnv):
+    env = zenith_simple_env
+    tenant_id = env.zenith_cli.create_tenant()
+    timelines = env.zenith_cli.list_timelines(tenant_id)
+
+    # an initial timeline should be created upon tenant creation
+    assert len(timelines) == 1
+    assert timelines[0][0] == DEFAULT_BRANCH_NAME
+
+
 def test_cli_ipv4_listeners(zenith_env_builder: ZenithEnvBuilder):
     # Start with single sk
     zenith_env_builder.num_safekeepers = 1