control_plane: implement cargo neon migrate

control_plane/src/bin/neon_local.rs

@@ -13,6 +13,7 @@ use control_plane::endpoint::ComputeControlPlane;
 use control_plane::local_env::LocalEnv;
 use control_plane::pageserver::{PageServerNode, PAGESERVER_REMOTE_STORAGE_DIR};
 use control_plane::safekeeper::SafekeeperNode;
+use control_plane::tenant_migration::migrate_tenant;
 use control_plane::{broker, local_env};
 use pageserver_api::models::TimelineInfo;
 use pageserver_api::{
@@ -451,6 +452,15 @@ fn handle_tenant(tenant_match: &ArgMatches, env: &mut local_env::LocalEnv) -> an
                 .with_context(|| format!("Tenant config failed for tenant with id {tenant_id}"))?;
             println!("tenant {tenant_id} successfully configured on the pageserver");
         }
+        Some(("migrate", matches)) => {
+            let tenant_id = get_tenant_id(matches, env)?;
+            let new_pageserver = get_pageserver(env, matches)?;
+            let new_pageserver_id = new_pageserver.conf.id;
+
+            migrate_tenant(env, tenant_id, new_pageserver)?;
+            println!("tenant {tenant_id} migrated to {}", new_pageserver_id);
+        }
+
         Some((sub_name, _)) => bail!("Unexpected tenant subcommand '{}'", sub_name),
         None => bail!("no tenant subcommand provided"),
     }
@@ -885,20 +895,20 @@ fn handle_mappings(sub_match: &ArgMatches, env: &mut local_env::LocalEnv) -> Res
     }
 }
 
+fn get_pageserver(env: &local_env::LocalEnv, args: &ArgMatches) -> Result<PageServerNode> {
+    let node_id = if let Some(id_str) = args.get_one::<String>("pageserver-id") {
+        NodeId(id_str.parse().context("while parsing pageserver id")?)
+    } else {
+        DEFAULT_PAGESERVER_ID
+    };
+
+    Ok(PageServerNode::from_env(
+        env,
+        env.get_pageserver_conf(node_id)?,
+    ))
+}
+
 fn handle_pageserver(sub_match: &ArgMatches, env: &local_env::LocalEnv) -> Result<()> {
-    fn get_pageserver(env: &local_env::LocalEnv, args: &ArgMatches) -> Result<PageServerNode> {
-        let node_id = if let Some(id_str) = args.get_one::<String>("pageserver-id") {
-            NodeId(id_str.parse().context("while parsing pageserver id")?)
-        } else {
-            DEFAULT_PAGESERVER_ID
-        };
-
-        Ok(PageServerNode::from_env(
-            env,
-            env.get_pageserver_conf(node_id)?,
-        ))
-    }
-
     match sub_match.subcommand() {
         Some(("start", subcommand_args)) => {
             if let Err(e) = get_pageserver(env, subcommand_args)?
@@ -935,6 +945,20 @@ fn handle_pageserver(sub_match: &ArgMatches, env: &local_env::LocalEnv) -> Resul
             }
         }
 
+        Some(("migrate", subcommand_args)) => {
+            let pageserver = get_pageserver(env, subcommand_args)?;
+            //TODO what shutdown strategy should we use here?
+            if let Err(e) = pageserver.stop(false) {
+                eprintln!("pageserver stop failed: {}", e);
+                exit(1);
+            }
+
+            if let Err(e) = pageserver.start(&pageserver_config_overrides(subcommand_args)) {
+                eprintln!("pageserver start failed: {e}");
+                exit(1);
+            }
+        }
+
         Some(("status", subcommand_args)) => {
             match get_pageserver(env, subcommand_args)?.check_status() {
                 Ok(_) => println!("Page server is up and running"),
@@ -1327,6 +1351,10 @@ fn cli() -> Command {
             .subcommand(Command::new("config")
                 .arg(tenant_id_arg.clone())
                 .arg(Arg::new("config").short('c').num_args(1).action(ArgAction::Append).required(false)))
+            .subcommand(Command::new("migrate")
+                .about("Migrate a tenant from one pageserver to another")
+                .arg(tenant_id_arg.clone())
+                .arg(pageserver_id_arg.clone()))
         )
         .subcommand(
             Command::new("pageserver")

control_plane/src/lib.rs

@@ -14,3 +14,4 @@ pub mod local_env;
 pub mod pageserver;
 pub mod postgresql_conf;
 pub mod safekeeper;
+pub mod tenant_migration;

control_plane/src/pageserver.rs

@@ -15,7 +15,9 @@ use std::{io, result};
 
 use anyhow::{bail, Context};
 use camino::Utf8PathBuf;
-use pageserver_api::models::{self, TenantInfo, TimelineInfo};
+use pageserver_api::models::{
+    self, LocationConfig, TenantInfo, TenantLocationConfigRequest, TimelineInfo,
+};
 use postgres_backend::AuthType;
 use postgres_connection::{parse_host_port, PgConnectionConfig};
 use reqwest::blocking::{Client, RequestBuilder, Response};
@@ -508,6 +510,27 @@ impl PageServerNode {
         Ok(())
     }
 
+    pub fn location_config(
+        &self,
+        tenant_id: TenantId,
+        config: LocationConfig,
+    ) -> anyhow::Result<()> {
+        let req_body = TenantLocationConfigRequest { tenant_id, config };
+
+        self.http_request(
+            Method::PUT,
+            format!(
+                "{}/tenant/{}/location_config",
+                self.http_base_url, tenant_id
+            ),
+        )?
+        .json(&req_body)
+        .send()?
+        .error_from_body()?;
+
+        Ok(())
+    }
+
     pub fn timeline_list(&self, tenant_id: &TenantId) -> anyhow::Result<Vec<TimelineInfo>> {
         let timeline_infos: Vec<TimelineInfo> = self
             .http_request(

control_plane/src/tenant_migration.rs

@@ -0,0 +1,202 @@
+//!
+//! Functionality for migrating tenants across pageservers: unlike most of neon_local, this code
+//! isn't scoped to a particular physical service, as it needs to update compute endpoints to
+//! point to the new pageserver.
+//!
+use crate::local_env::LocalEnv;
+use crate::{
+    attachment_service::AttachmentService, endpoint::ComputeControlPlane,
+    pageserver::PageServerNode,
+};
+use pageserver_api::models::{
+    LocationConfig, LocationConfigMode, LocationConfigSecondary, TenantConfig,
+};
+use std::collections::HashMap;
+use std::time::Duration;
+use utils::{
+    generation::Generation,
+    id::{TenantId, TimelineId},
+    lsn::Lsn,
+};
+
+/// Given an attached pageserver, retrieve the LSN for all timelines
+fn get_lsns(
+    tenant_id: TenantId,
+    pageserver: &PageServerNode,
+) -> anyhow::Result<HashMap<TimelineId, Lsn>> {
+    let timelines = pageserver.timeline_list(&tenant_id)?;
+    Ok(timelines
+        .into_iter()
+        .map(|t| (t.timeline_id, t.last_record_lsn))
+        .collect())
+}
+
+/// Wait for the timeline LSNs on `pageserver` to catch up with or overtake
+/// `baseline`.
+fn await_lsn(
+    tenant_id: TenantId,
+    pageserver: &PageServerNode,
+    baseline: HashMap<TimelineId, Lsn>,
+) -> anyhow::Result<()> {
+    loop {
+        let latest = match get_lsns(tenant_id, pageserver) {
+            Ok(l) => l,
+            Err(e) => {
+                println!(
+                    "🕑 Can't get LSNs on pageserver {} yet, waiting ({e})",
+                    pageserver.conf.id
+                );
+                std::thread::sleep(Duration::from_millis(500));
+                continue;
+            }
+        };
+
+        let mut any_behind: bool = false;
+        for (timeline_id, baseline_lsn) in &baseline {
+            match latest.get(timeline_id) {
+                Some(latest_lsn) => {
+                    println!("🕑 LSN origin {baseline_lsn} vs destination {latest_lsn}");
+                    if latest_lsn < baseline_lsn {
+                        any_behind = true;
+                    }
+                }
+                None => {
+                    // Expected timeline isn't yet visible on migration destination.
+                    // (IRL we would have to account for timeline deletion, but this
+                    //  is just test helper)
+                    any_behind = true;
+                }
+            }
+        }
+
+        if !any_behind {
+            println!("✅ LSN caught up.  Proceeding...");
+            break;
+        } else {
+            std::thread::sleep(Duration::from_millis(500));
+        }
+    }
+
+    Ok(())
+}
+
+/// This function spans multiple services, to demonstrate live migration of a tenant
+/// between pageservers:
+///  - Coordinate attach/secondary/detach on pageservers
+///  - call into attachment_service for generations
+///  - reconfigure compute endpoints to point to new attached pageserver
+pub fn migrate_tenant(
+    env: &LocalEnv,
+    tenant_id: TenantId,
+    dest_ps: PageServerNode,
+) -> anyhow::Result<()> {
+    // Get a new generation
+    let attachment_service = AttachmentService::from_env(env);
+
+    let previous = attachment_service.inspect(tenant_id)?;
+    let mut baseline_lsns = None;
+    if let Some((generation, origin_ps_id)) = &previous {
+        let origin_ps = PageServerNode::from_env(env, env.get_pageserver_conf(*origin_ps_id)?);
+
+        if origin_ps_id == &dest_ps.conf.id {
+            println!("🔁 Already attached to {origin_ps_id}, freshening...");
+            let gen = attachment_service.attach_hook(tenant_id, dest_ps.conf.id)?;
+            let dest_conf = LocationConfig {
+                mode: LocationConfigMode::AttachedSingle,
+                generation: gen.map(Generation::new),
+                secondary_conf: None,
+                tenant_conf: TenantConfig::default(),
+            };
+            dest_ps.location_config(tenant_id, dest_conf)?;
+            println!("✅ Migration complete");
+            return Ok(());
+        }
+
+        println!("🔁 Switching origin pageserver {origin_ps_id} to stale mode");
+
+        let stale_conf = LocationConfig {
+            mode: LocationConfigMode::AttachedStale,
+            generation: Some(Generation::new(*generation)),
+            secondary_conf: None,
+            tenant_conf: TenantConfig::default(),
+        };
+        origin_ps.location_config(tenant_id, stale_conf)?;
+
+        baseline_lsns = Some(get_lsns(tenant_id, &origin_ps)?);
+    }
+
+    let gen = attachment_service.attach_hook(tenant_id, dest_ps.conf.id)?;
+    let dest_conf = LocationConfig {
+        mode: LocationConfigMode::AttachedMulti,
+        generation: gen.map(Generation::new),
+        secondary_conf: None,
+        tenant_conf: TenantConfig::default(),
+    };
+
+    println!("🔁 Attaching to pageserver {}", dest_ps.conf.id);
+    dest_ps.location_config(tenant_id, dest_conf)?;
+
+    if let Some(baseline) = baseline_lsns {
+        println!("🕑 Waiting for LSN to catch up...");
+        await_lsn(tenant_id, &dest_ps, baseline)?;
+    }
+
+    let cplane = ComputeControlPlane::load(env.clone())?;
+    for (endpoint_name, endpoint) in &cplane.endpoints {
+        if endpoint.tenant_id == tenant_id {
+            println!(
+                "🔁 Reconfiguring endpoint {} to use pageserver {}",
+                endpoint_name, dest_ps.conf.id
+            );
+            endpoint.reconfigure(Some(dest_ps.conf.id))?;
+        }
+    }
+
+    for other_ps_conf in &env.pageservers {
+        if other_ps_conf.id == dest_ps.conf.id {
+            continue;
+        }
+
+        let other_ps = PageServerNode::from_env(env, other_ps_conf);
+        let other_ps_tenants = other_ps.tenant_list()?;
+
+        // Check if this tenant is attached
+        let found = other_ps_tenants
+            .into_iter()
+            .map(|t| t.id)
+            .any(|i| i == tenant_id);
+        if !found {
+            continue;
+        }
+
+        // Downgrade to a secondary location
+        let secondary_conf = LocationConfig {
+            mode: LocationConfigMode::Secondary,
+            generation: None,
+            secondary_conf: Some(LocationConfigSecondary { warm: true }),
+            tenant_conf: TenantConfig::default(),
+        };
+
+        println!(
+            "💤 Switching to secondary mode on pageserver {}",
+            other_ps.conf.id
+        );
+        other_ps.location_config(tenant_id, secondary_conf)?;
+    }
+
+    println!(
+        "🔁 Switching to AttachedSingle mode on pageserver {}",
+        dest_ps.conf.id
+    );
+    let dest_conf = LocationConfig {
+        mode: LocationConfigMode::AttachedSingle,
+        generation: gen.map(Generation::new),
+        secondary_conf: None,
+        tenant_conf: TenantConfig::default(),
+    };
+    dest_ps.location_config(tenant_id, dest_conf)?;
+
+    println!("✅ Migration complete");
+
+    Ok(())
+}