CentOS7にpython3.10系を入れた場合のSSLエラー(pip is configured with locations that require TLS/SSL, however the ssl module in Python is not available.)

前提

• docker(CentOS7)を作成
• 上記にPython3.10.5をインストール
• pipで別途用意したrequirements.txtのライブラリをインストールしようとしていた

問題点

• "pip install -r requirements.txt"を実行しようとしたら、SSLエラーが発生した

エラー内容

WARNING: pip is configured with locations that require TLS/SSL, however the ssl module in Python is not available.
WARNING: Retrying (Retry(total=4, connect=None, read=None, redirect=None, status=None)) after connection broken by 'SSLError("Can't connect to HTTPS URL because the SSL module is not available.")': /simple/asgiref/
WARNING: Retrying (Retry(total=3, connect=None, read=None, redirect=None, status=None)) after connection broken by 'SSLError("Can't connect to HTTPS URL because the SSL module is not available.")': /simple/asgiref/
WARNING: Retrying (Retry(total=2, connect=None, read=None, redirect=None, status=None)) after connection broken by 'SSLError("Can't connect to HTTPS URL because the SSL module is not available.")': /simple/asgiref/
WARNING: Retrying (Retry(total=1, connect=None, read=None, redirect=None, status=None)) after connection broken by 'SSLError("Can't connect to HTTPS URL because the SSL module is not available.")': /simple/asgiref/
WARNING: Retrying (Retry(total=0, connect=None, read=None, redirect=None, status=None)) after connection broken by 'SSLError("Can't connect to HTTPS URL because the SSL module is not available.")': /simple/asgiref/
Could not fetch URL https://pypi.org/simple/asgiref/: There was a problem confirming the ssl certificate: HTTPSConnectionPool(host='pypi.org', port=443): Max retries exceeded with url: /simple/asgiref/ (Caused by SSLError("Can't connect to HTTPS URL because the SSL module is not available.")) - skipping
ERROR: Could not find a version that satisfies the requirement asgiref==3.5.2 (from versions: none)
ERROR: No matching distribution found for asgiref==3.5.2
WARNING: pip is configured with locations that require TLS/SSL, however the ssl module in Python is not available.
Could not fetch URL https://pypi.org/simple/pip/: There was a problem confirming the ssl certificate: HTTPSConnectionPool(host='pypi.org', port=443): Max retries exceeded with url: /simple/pip/ (Caused by SSLError("Can't connect to HTTPS URL because the SSL module is not available.")) - skipping

やらないといけなかったこと

• そもそもPython3.10系はopen-sslのv1.1.1以上が必須になっていた
• CentOS7にはopen-sslの1.1.1が入っていないので、自分でインストールしてあげる必要がある
• 以下のコマンドを実行すればOK

yum install epel-release
yum install openssl11 openssl11-devel

export CFLAGS=$(pkg-config --cflags openssl11)
export LDFLAGS=$(pkg-config --libs openssl11)

./configure
make
sudo make install

結論

公式ドキュメントをちゃんと読まないとだめですね。。。