f2c21447ce
I've moved it to the API handler in the 589cf1ed2 to do not delay
compute start. Yet, we now skip full configuration and catalog updates
in the most hot path -- waking up suspended compute, and only do it at:
- first start
- start with applying new configuration
- start for availability check
so it doesn't really matter anymore.
The problem with creating the table and test record in the API handler
is that someone can fill up timeline till the logical limit. Then it's
suspended and availability check is scheduled, so it fails.
If table + test row are created at the very beginning, we reserve a 8 KB
page for future checks, which theoretically will last almost forever.
For example, my ~1y old branch still has 8 KB sized test table:
```sql
cloud_admin@postgres=# select pg_relation_size('health_check');
pg_relation_size
------------------
8192
(1 row)
```
---------
Co-authored-by: Anastasia Lubennikova <anastasia@neon.tech>
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_ctlaccepts 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
PGDATAdirectory. - Sync safekeepers and get commit LSN.
- Get
basebackupfrom pageserver using the returned on the previous step LSN. - Try to start
postgresand wait until it is ready to accept connections. - Check and alter/drop/create roles and databases.
- Hang waiting on the
postmasterprocess to exit.
Also compute_ctl spawns two separate service threads:
compute-monitorchecks the last Postgres activity timestamp and saves it into the sharedComputeNode;http-endpointruns 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