RaspberryPiにpyenvを導入

# 背景

Amazon IoTを検証するため、使用予定のPython版SDKをRaspberryPiで使用するとエラーを吐いた。

```
pi@raspberrypi:~/iot $ ./start.sh 

Downloading AWS IoT Root CA certificate from Symantec...
  % Total    % Received % Xferd  Average Speed   Time    Time     Time  Current
                                 Dload  Upload   Total   Spent    Left  Speed
100  1758  100  1758    0     0  12381      0 --:--:-- --:--:-- --:--:-- 12468

Installing AWS SDK...
Cloning into 'aws-iot-device-sdk-python'...
remote: Counting objects: 116, done.
remote: Compressing objects: 100% (19/19), done.
remote: Total 116 (delta 3), reused 15 (delta 3), pack-reused 92
Receiving objects: 100% (116/116), 117.74 KiB | 0 bytes/s, done.
Resolving deltas: 100% (35/35), done.
Checking connectivity... done.
~/iot/aws-iot-device-sdk-python ~/iot
running install
running build
running build_py
creating build
creating build/lib.linux-armv7l-2.7
creating build/lib.linux-armv7l-2.7/AWSIoTPythonSDK
copying AWSIoTPythonSDK/MQTTLib.py -> build/lib.linux-armv7l-2.7/AWSIoTPythonSDK
copying AWSIoTPythonSDK/__init__.py -> build/lib.linux-armv7l-2.7/AWSIoTPythonSDK
creating build/lib.linux-armv7l-2.7/AWSIoTPythonSDK/core
copying AWSIoTPythonSDK/core/__init__.py -> build/lib.linux-armv7l-2.7/AWSIoTPythonSDK/core
creating build/lib.linux-armv7l-2.7/AWSIoTPythonSDK/exception
copying AWSIoTPythonSDK/exception/operationTimeoutException.py -> build/lib.linux-armv7l-2.7/AWSIoTPythonSDK/exception
copying AWSIoTPythonSDK/exception/AWSIoTExceptions.py -> build/lib.linux-armv7l-2.7/AWSIoTPythonSDK/exception
copying AWSIoTPythonSDK/exception/operationError.py -> build/lib.linux-armv7l-2.7/AWSIoTPythonSDK/exception
copying AWSIoTPythonSDK/exception/__init__.py -> build/lib.linux-armv7l-2.7/AWSIoTPythonSDK/exception
creating build/lib.linux-armv7l-2.7/AWSIoTPythonSDK/core/shadow
copying AWSIoTPythonSDK/core/shadow/shadowManager.py -> build/lib.linux-armv7l-2.7/AWSIoTPythonSDK/core/shadow
copying AWSIoTPythonSDK/core/shadow/deviceShadow.py -> build/lib.linux-armv7l-2.7/AWSIoTPythonSDK/core/shadow
copying AWSIoTPythonSDK/core/shadow/__init__.py -> build/lib.linux-armv7l-2.7/AWSIoTPythonSDK/core/shadow
creating build/lib.linux-armv7l-2.7/AWSIoTPythonSDK/core/util
copying AWSIoTPythonSDK/core/util/sigV4Core.py -> build/lib.linux-armv7l-2.7/AWSIoTPythonSDK/core/util
copying AWSIoTPythonSDK/core/util/offlinePublishQueue.py -> build/lib.linux-armv7l-2.7/AWSIoTPythonSDK/core/util
copying AWSIoTPythonSDK/core/util/__init__.py -> build/lib.linux-armv7l-2.7/AWSIoTPythonSDK/core/util
copying AWSIoTPythonSDK/core/util/progressiveBackoffCore.py -> build/lib.linux-armv7l-2.7/AWSIoTPythonSDK/core/util
creating build/lib.linux-armv7l-2.7/AWSIoTPythonSDK/core/protocol
copying AWSIoTPythonSDK/core/protocol/__init__.py -> build/lib.linux-armv7l-2.7/AWSIoTPythonSDK/core/protocol
copying AWSIoTPythonSDK/core/protocol/mqttCore.py -> build/lib.linux-armv7l-2.7/AWSIoTPythonSDK/core/protocol
creating build/lib.linux-armv7l-2.7/AWSIoTPythonSDK/core/protocol/paho
copying AWSIoTPythonSDK/core/protocol/paho/client.py -> build/lib.linux-armv7l-2.7/AWSIoTPythonSDK/core/protocol/paho
copying AWSIoTPythonSDK/core/protocol/paho/__init__.py -> build/lib.linux-armv7l-2.7/AWSIoTPythonSDK/core/protocol/paho
creating build/lib.linux-armv7l-2.7/AWSIoTPythonSDK/core/protocol/paho/securedWebsocket
copying AWSIoTPythonSDK/core/protocol/paho/securedWebsocket/securedWebsocketCore.py -> build/lib.linux-armv7l-2.7/AWSIoTPythonSDK/core/protocol/paho/securedWebsocket
copying AWSIoTPythonSDK/core/protocol/paho/securedWebsocket/__init__.py -> build/lib.linux-armv7l-2.7/AWSIoTPythonSDK/core/protocol/paho/securedWebsocket
running install_lib
creating /usr/local/lib/python2.7/dist-packages/AWSIoTPythonSDK
error: could not create '/usr/local/lib/python2.7/dist-packages/AWSIoTPythonSDK': Permission denied
pi@raspberrypi:~/iot $ sudo ./start.sh                                                                                                                                                                                                    

Running pub/sub sample application...
Traceback (most recent call last):
  File "aws-iot-device-sdk-python/samples/basicPubSub/basicPubSub.py", line 18, in <module>
    from AWSIoTPythonSDK.MQTTLib import AWSIoTMQTTClient
ImportError: No module named AWSIoTPythonSDK.MQTTLib
```

AWSIoTPythonSDKが無いみたいなので、
下記コマンドを実行したが、pipが入ってないエラーが。

```
$ sudo pip install AWSIoTPythonSDK
```

そもそもpythonのバージョンが古い。

```
$ python -V
2.7.9
```

# pyenvをインストール

必要なパッケージをインストール。

```
$ sudo apt-get install -y git openssl libssl-dev libbz2-dev libreadline-dev libsqlite3-dev
```

pyenvをclone。

```
$ git clone git://github.com/yyuu/pyenv.git ~/.pyenv
```

クローンし終わったら`.bash_profile`に設定を追加する。

```
$ sudo vi ~/.bash_profile

# 以下の内容を追記
export PYENV_ROOT="$HOME/.pyenv"
export PATH="$PYENV_ROOT/bin:$PATH"
eval "$(pyenv init -)"
```

設定を反映。

```
$ sudo source ~/.bash_profile
```

インストール可能なPythonパッケージを確認。

```
$ pyenv install --list
.
.
.
3.0.1
3.1
3.1.1
.
.
.
```

# pyenvでPythonの3.6.2をインストール

`Python3.6.2`をインストールして、バージョンを切り替える

```
$ pyenv install 3.6.2
$ pyenv global 3.6.2
```

# pipのインストール

```
$ curl -O https://bootstrap.pypa.io/get-pip.py
$ python get-pip.py
```

# pipを使用し、AWSIoTPythonSDKをインストール

```
$ pip install AWSIoTPythonSDK
```

# AWSIoTのへの接続

```
$ pi@raspberrypi:~/iot $ ./start.sh 
```

無事成功した。