51f3128657
This adds test coverage for 'compute_ctl', as it is now used by all the python tests. There are a few differences in how 'compute_ctl' is called in the tests, compared to the real web console: - In the tests, the postgresql.conf file is included as one large string in the spec file, and it is written out as it is to the data directory. I added a new field for that to the spec file. The real web console, however, sets all the necessary settings in the 'settings' field, and 'compute_ctl' creates the postgresql.conf from those settings. - In the tests, the information needed to connect to the storage, i.e. tenant_id, timeline_id, connection strings to pageserver and safekeepers, are now passed as new fields in the spec file. The real web console includes them as the GUCs in the 'settings' field. (Both of these are different from what the test control plane used to do: It used to write the GUCs directly in the postgresql.conf file). The plan is to change the control plane to use the new method, and remove the old method, but for now, support both.
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 the vm-informant binary is present at /bin/vm-informant, it will also be started. For VM
compute nodes, vm-informant communicates with the VM autoscaling system. It coordinates
downscaling and (eventually) will request 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