## Building (parts of) yugabyte locally

Yugabyte is best built inside of a docker container for the correct runtime environment mimicking the one
the actual release is built with itself.

I found a suitable build environment by looking at the yb's CI scripts: https://github.com/yugabyte/yugabyte-db/blob/master/.github/workflows/build.yml.

### Steps

Check out the source code.

Make sure build was clean (not initialized in local environment), otherwise move or delete `build` dir

From inside the source directory, start a build shell like this:

```sh
docker run --rm -ti -v "$PWD":/opt/yb-build/yugabyte-db yugabyteci/yb_build_infra_centos7:v2021-03-26T05_02_29
```

Go to the build directory:

```sh
cd /opt/yb-build/yugabyte-db
```


In the shell, run 

```sh
./yb_build.sh release --download-thirdparty --ninja --cmake-only
```

to setup the build.

Then you can use `ninja` commands to build submodules of yb:

```sh
cd /opt/yb-build/yugabyte-db/build/release-gcc-dynamic-ninja
ninja yb_util

# or

ninja rocksdb
```

The built artifacts can be found in the `bin` and `lib` directories. If you built only a submodule you can hot patch it on the server by just copying the `.so` file for a
submodule that you just built. (As an additional check, compare the sizes of the original and the new `.so` file).

### Finding ninja targets

The mapping between source directories and target modules might not be obvious. To get at least a list of supported output
modules you can use `ninja -t targets`. To test whether you got the right module you can add an error to a source file to see
if the target build fails (i.e. contains the source file in question).

### Building a full release

You can use

```sh
./yb_build.sh release --download-thirdparty --ninja
```

to build the full release but that will take a long time (took ~30min for me).