Files
neon/compute_tools
Alex Chi Z 0b330e1310 upgrade neon extension on startup (#7029)
## Problem

Fix https://github.com/neondatabase/neon/issues/7003. Fix
https://github.com/neondatabase/neon/issues/6982. Currently, neon
extension is only upgraded when new compute spec gets applied, for
example, when creating a new role or creating a new database. This also
resolves `neon.lfc_stat` not found warnings in prod.

## Summary of changes

This pull request adds the logic to spawn a background thread to upgrade
the neon extension version if the compute is a primary. If for whatever
reason the upgrade fails, it reports an error to the console and does
not impact compute node state.

This change can be further applied to 3rd-party extension upgrades. We
can silently upgrade the version of 3rd party extensions in the
background in the future.

Questions:

* Does alter extension takes some kind of lock that will block user
requests?
* Does `ALTER EXTENSION` writes to the database if nothing needs to be
upgraded? (may impact storage size).

Otherwise it's safe to land this pull request.

Signed-off-by: Alex Chi Z <chi@neon.tech>
2024-03-06 12:20:44 -05:00
..
2023-10-18 16:42:22 +03:00

Compute node tools

Postgres wrapper (compute_ctl) is intended to be run as a Docker entrypoint or as a systemd ExecStart option. It will handle all the Neon specifics during compute node initialization:

  • compute_ctl accepts cluster (compute node) specification as a JSON file.
  • Every start is a fresh start, so the data directory is removed and initialized again on each run.
  • Next it will put configuration files into the PGDATA directory.
  • Sync safekeepers and get commit LSN.
  • Get basebackup from pageserver using the returned on the previous step LSN.
  • Try to start postgres and wait until it is ready to accept connections.
  • Check and alter/drop/create roles and databases.
  • Hang waiting on the postmaster process to exit.

Also compute_ctl spawns two separate service threads:

  • compute-monitor checks the last Postgres activity timestamp and saves it into the shared ComputeNode;
  • http-endpoint runs a Hyper HTTP API server, which serves readiness and the last activity requests.

If AUTOSCALING environment variable is set, compute_ctl will start the vm-monitor located in [neon/libs/vm_monitor]. For VM compute nodes, vm-monitor communicates with the VM autoscaling system. It coordinates downscaling and requests immediate upscaling under resource pressure.

Usage example:

compute_ctl -D /var/db/postgres/compute \
            -C 'postgresql://cloud_admin@localhost/postgres' \
            -S /var/db/postgres/specs/current.json \
            -b /usr/local/bin/postgres

Tests

Cargo formatter:

cargo fmt

Run tests:

cargo test

Clippy linter:

cargo clippy --all --all-targets -- -Dwarnings -Drust-2018-idioms

Cross-platform compilation

Imaging that you are on macOS (x86) and you want a Linux GNU (x86_64-unknown-linux-gnu platform in rust terminology) executable.

Using docker

You can use a throw-away Docker container (rustlang/rust image) for doing that:

docker run --rm \
    -v $(pwd):/compute_tools \
    -w /compute_tools \
    -t rustlang/rust:nightly cargo build --release --target=x86_64-unknown-linux-gnu

or one-line:

docker run --rm -v $(pwd):/compute_tools -w /compute_tools -t rust:latest cargo build --release --target=x86_64-unknown-linux-gnu

Using rust native cross-compilation

Another way is to add x86_64-unknown-linux-gnu target on your host system:

rustup target add x86_64-unknown-linux-gnu

Install macOS cross-compiler toolchain:

brew tap SergioBenitez/osxct
brew install x86_64-unknown-linux-gnu

And finally run cargo build:

CARGO_TARGET_X86_64_UNKNOWN_LINUX_GNU_LINKER=x86_64-unknown-linux-gnu-gcc cargo build --target=x86_64-unknown-linux-gnu --release