title: I try to build an AWS CodeBuild, but failed
body: <p><a href="https://github.com/chenjianAgain/codestar_web.git" rel="nofollow noreferrer">https://github.com/chenjianAgain/codestar_web.git</a></p>
  
  <p>I setup a codebuild in AWS console. But when I started to perform a build, I met up with some errors. 
  It seems that there is something wrong with the installation of AWS cli.
  I wonder why awscli can't be installed properly. (pip install --upgrade awscli)</p>
  
  <p>Can anybody be kind to help? Many thanks.</p>
  
  <pre><code>version: 0.2
  
  phases:
    install:
      commands:
        # Install dependencies needed for running tests
        - npm install
  
        # Upgrade AWS CLI to the latest version
        - pip install --upgrade awscli
    pre_build:
      commands:
        # Discover and run unit tests in the 'tests' directory
        - npm test
    post_build:
      commands:
        # Remove existing node_modules to clear dev dependencies
        - rm -r node_modules
  
        # Install runtime dependencies
        - npm install --production
  artifacts:
    type: zip
    files:
      - template.yml
      - README.md
      - package.json
      - app.js
      - appspec.yml
      - scripts/*
      - node_modules/**/*
      - public/**/*
  
  [Container] 2019/01/31 08:07:25 Waiting for agent ping
  [Container] 2019/01/31 08:07:26 Waiting for DOWNLOAD_SOURCE
  [Container] 2019/01/31 08:07:26 Phase is DOWNLOAD_SOURCE
  [Container] 2019/01/31 08:07:26 CODEBUILD_SRC_DIR=/codebuild/output/src414370097/src/github.com/chenjianAgain/codestar_web
  [Container] 2019/01/31 08:07:26 YAML location is /codebuild/output/src414370097/src/github.com/chenjianAgain/codestar_web/buildspec.yml
  [Container] 2019/01/31 08:07:26 Processing environment variables
  [Container] 2019/01/31 08:07:26 Moving to directory /codebuild/output/src414370097/src/github.com/chenjianAgain/codestar_web
  [Container] 2019/01/31 08:07:26 Registering with agent
  [Container] 2019/01/31 08:07:26 Phases found in YAML: 3
  [Container] 2019/01/31 08:07:26  INSTALL: 2 commands
  [Container] 2019/01/31 08:07:26  PRE_BUILD: 1 commands
  [Container] 2019/01/31 08:07:26  POST_BUILD: 2 commands
  [Container] 2019/01/31 08:07:26 Phase complete: DOWNLOAD_SOURCE Success: true
  [Container] 2019/01/31 08:07:26 Phase context status code:  Message: 
  [Container] 2019/01/31 08:07:26 Entering phase INSTALL
  [Container] 2019/01/31 08:07:26 Running command npm install
  npm WARN deprecated formatio@1.1.1: This package is unmaintained. Use @sinonjs/formatio instead
  npm WARN deprecated samsam@1.1.2: This package has been deprecated in favour of @sinonjs/samsam
  npm WARN deprecated samsam@1.1.3: This package has been deprecated in favour of @sinonjs/samsam
  npm notice created a lockfile as package-lock.json. You should commit this file.
  added 79 packages from 478 contributors and audited 96 packages in 2.83s
  found 4 vulnerabilities (2 low, 2 moderate)
    run `npm audit fix` to fix them, or `npm audit` for details
  
  [Container] 2019/01/31 08:07:33 Running command pip install --upgrade awscli
  /codebuild/output/tmp/script.sh: 4: /codebuild/output/tmp/script.sh: pip: not found
  
  [Container] 2019/01/31 08:07:33 Command did not exit successfully pip install --upgrade awscli exit status 127
  [Container] 2019/01/31 08:07:33 Phase complete: INSTALL Success: false
  [Container] 2019/01/31 08:07:33 Phase context status code: COMMAND_EXECUTION_ERROR Message: Error while executing command: pip install --upgrade awscli. Reason: exit status 127
  </code></pre>