sqlxをインストールするとfailed to run custom build command for `openssl-sys`となる

# はじめに

自分で用意した`Alpine`のコンテナ環境でRustのために`sqlx`をインストールするところでエラーが発生したのでまとめます

# 問題

以下のDockerfileを作成してbuildしたところエラーがでました

```Dockerfile:Dockerfile
FROM rust:alpine3.17

RUN apk update && apk add git alpine-sdk make
RUN rustup component add rls rust-analysis rustfmt clippy
RUN cargo install sqlx-cli

WORKDIR /app/my-todo
```

以下のエラーがでます

```
   Compiling block-buffer v0.10.3
error: failed to run custom build command for `openssl-sys v0.9.80`

Caused by:
  process didn't exit successfully: `/tmp/cargo-installDTFxxB/release/build/openssl-sys-177cbc75fe0cef49/build-script-main` (exit status: 101)
  --- stdout
  cargo:rustc-cfg=const_fn
  cargo:rustc-cfg=openssl
  cargo:rerun-if-env-changed=X86_64_UNKNOWN_LINUX_MUSL_OPENSSL_LIB_DIR
  X86_64_UNKNOWN_LINUX_MUSL_OPENSSL_LIB_DIR unset
  cargo:rerun-if-env-changed=OPENSSL_LIB_DIR
  OPENSSL_LIB_DIR unset
  cargo:rerun-if-env-changed=X86_64_UNKNOWN_LINUX_MUSL_OPENSSL_INCLUDE_DIR
  X86_64_UNKNOWN_LINUX_MUSL_OPENSSL_INCLUDE_DIR unset
  cargo:rerun-if-env-changed=OPENSSL_INCLUDE_DIR
  OPENSSL_INCLUDE_DIR unset
  cargo:rerun-if-env-changed=X86_64_UNKNOWN_LINUX_MUSL_OPENSSL_DIR
  X86_64_UNKNOWN_LINUX_MUSL_OPENSSL_DIR unset
  cargo:rerun-if-env-changed=OPENSSL_DIR
  OPENSSL_DIR unset
  cargo:rerun-if-env-changed=OPENSSL_NO_PKG_CONFIG
  cargo:rerun-if-env-changed=PKG_CONFIG_x86_64-unknown-linux-musl
  cargo:rerun-if-env-changed=PKG_CONFIG_x86_64_unknown_linux_musl
  cargo:rerun-if-env-changed=HOST_PKG_CONFIG
  cargo:rerun-if-env-changed=PKG_CONFIG
  cargo:rerun-if-env-changed=OPENSSL_STATIC
  cargo:rerun-if-env-changed=OPENSSL_DYNAMIC
  cargo:rerun-if-env-changed=PKG_CONFIG_ALL_STATIC
  cargo:rerun-if-env-changed=PKG_CONFIG_ALL_DYNAMIC
  cargo:rerun-if-env-changed=PKG_CONFIG_PATH_x86_64-unknown-linux-musl
  cargo:rerun-if-env-changed=PKG_CONFIG_PATH_x86_64_unknown_linux_musl
  cargo:rerun-if-env-changed=HOST_PKG_CONFIG_PATH
  cargo:rerun-if-env-changed=PKG_CONFIG_PATH
  cargo:rerun-if-env-changed=PKG_CONFIG_LIBDIR_x86_64-unknown-linux-musl
  cargo:rerun-if-env-changed=PKG_CONFIG_LIBDIR_x86_64_unknown_linux_musl
  cargo:rerun-if-env-changed=HOST_PKG_CONFIG_LIBDIR
  cargo:rerun-if-env-changed=PKG_CONFIG_LIBDIR
  cargo:rerun-if-env-changed=PKG_CONFIG_SYSROOT_DIR_x86_64-unknown-linux-musl
  cargo:rerun-if-env-changed=PKG_CONFIG_SYSROOT_DIR_x86_64_unknown_linux_musl
  cargo:rerun-if-env-changed=HOST_PKG_CONFIG_SYSROOT_DIR
  cargo:rerun-if-env-changed=PKG_CONFIG_SYSROOT_DIR
  run pkg_config fail: "`\"pkg-config\" \"--libs\" \"--cflags\" \"openssl\"` did not exit successfully: exit status: 1\nerror: could not find system library 'openssl' required by the 'openssl-sys' crate\n\n--- stderr\nPackage openssl was not found in the pkg-config search path.\nPerhaps you should add the directory containing `openssl.pc'\nto the PKG_CONFIG_PATH environment variable\nPackage 'openssl', required by 'virtual:world', not found\n"

  --- stderr
  thread 'main' panicked at '

  Could not find directory of OpenSSL installation, and this `-sys` crate cannot
  proceed without this knowledge. If OpenSSL is installed and this crate had
  trouble finding it,  you can set the `OPENSSL_DIR` environment variable for the
  compilation process.

  Make sure you also have the development packages of openssl installed.
  For example, `libssl-dev` on Ubuntu or `openssl-devel` on Fedora.

  If you're in a situation where you think the directory *should* be found
  automatically, please open a bug at https://github.com/sfackler/rust-openssl
  and include information about your system as well as this message.

  $HOST = x86_64-unknown-linux-musl
  $TARGET = x86_64-unknown-linux-musl
  openssl-sys = 0.9.80

  ', /usr/local/cargo/registry/src/github.com-1ecc6299db9ec823/openssl-sys-0.9.80/build/find_normal.rs:191:5
  note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace
warning: build failed, waiting for other jobs to finish...
error: failed to compile `sqlx-cli v0.6.2`, intermediate artifacts can be found at `/tmp/cargo-installDTFxxB`
```

# 解決方法

`open-ssl`に関係するライブラリを追加することで解決しました

```Dockerfile:Dockerfile
RUN apk add libffi-dev openssl-dev pkgconfig
```

# おわりに

これ系のエラーはよく発生します
ただPythonやっていたときよりはだいぶ楽だなとは思いました

# 参考

https://qiita.com/yoshrc/items/8464f3b5eb346cc91d7b

https://techoverflow.net/2022/01/17/how-to-install-pkg-config-on-alpine-linux/