防止pip安装某些依赖项 [英] Prevent pip from installing some dependencies

问题描述

我们正在为Python中的Alexa技能开发 AWS Lambda 函数，并使用pip将ask-sdk软件包安装到我们的dist/目录中:

We're developing an AWS Lambda function for Alexa skill in Python and using pip to install the ask-sdk package to our dist/ directory:

pip install -t dist/ ask-sdk

-t dist/的麻烦在于，因为pip希望在其中具有所有依赖项，即使它们在系统范围内安装也是如此.

The trouble is with the -t dist/ because pip wants to have all the dependencies there, even if they are installed system-wide.

现在，ask-sdk对boto3有依赖性，该依赖性引入了许多其他软件包.但是， AWS Lambda 运行时环境提供了boto3，并且无需将其及其依赖项与我们的代码打包在一起.我确实在系统中安装了boto3并且import boto3可以工作，所以我认为pip应该很高兴，但是由于-t dist/，它总是会安装它.

Now, ask-sdk has a dependency on boto3 which pulls in a whole lot of other packages. However the AWS Lambda runtime environment provides boto3 and there is no need to package that and its dependencies with our code. I do have boto3 installed in the system and import boto3 works, so I thought pip should be happy, but because of -t dist/ it always installs it.

我可以以某种方式仅安装ask-sdk及其系统中不存在的依赖项吗，例如ask-sdk-core，但不是已经安装的那些?

Can I somehow install just ask-sdk and its dependencies that don't exist in the system, e.g. ask-sdk-core, but not those that are already installed?

一种方法是列出所有模块并使用pip --no-deps，但这意味着要不断手动跟踪依赖项，我们希望避免这种情况.

One way is to list all the modules and use pip --no-deps but that means a constantly keeping track of the dependencies manually, we would like to avoid that.

我想以某种方式告诉pip:如果该软件包已经安装，即使没有安装在-t dist/中，也请不要将副本放在dist/中.

Somehow I would like to tell pip: if the package is already installed, even if not in -t dist/ don't put a copy in dist/.

有可能吗?

谢谢！

推荐答案

尽管您不能告诉pip安装除boto3所需的所有依赖项之外的所有依赖项"，但是您可以通过计算<pip freeze输出中的c6>和ask-sdk(使用Python 3.6.6测试):

Although you can't tell pip to "install all dependencies except those required by boto3", you can generate the needed requirements.txt by computing the difference between boto3 and ask-sdk from pip freeze output (tested with Python 3.6.6):

# get boto3 requirements
pip install boto3 -t py_lib.boto3
PYTHONPATH=py_lib.boto3 pip freeze > requirements-boto3.txt

# get ask-sdk requirements
pip install ask-sdk -t py_lib.ask-sdk
PYTHONPATH=py_lib.ask-sdk pip freeze > requirements-ask-sdk.txt

# compute their difference
grep -v -x -f requirements-boto3.txt requirements-ask-sdk.txt > requirements-final.txt

# patch to add one missing dep from boto3
# aws don't have this for some reason
grep urllib3 requirements-boto3.txt >> requirements-final.txt

requirements-final.txt包含以下内容:

ask-sdk==1.5.0
ask-sdk-core==1.5.0
ask-sdk-dynamodb-persistence-adapter==1.5.0
ask-sdk-model==1.6.2
ask-sdk-runtime==1.5.0
certifi==2018.11.29
chardet==3.0.4
idna==2.8
requests==2.21.0
urllib3==1.24.1

要将最后一组依赖项安装到文件夹:

To install the final set of dependencies to a folder:

pip install --no-deps -r requirements-final.txt -t py_lib

通过跳过boto3依赖项，您可以从python依赖项中保存大约45M的数据. ask-sdk依赖项仅约为7.5M(压缩后为2.1M)，如果需要，您可以使用内置的lambda代码编辑器.

By skipping the boto3 dependencies, you can save about 45M of data from your python dependencies. The ask-sdk dependencies are only about 7.5M (2.1M compressed), allow you to use the build-in lambda code editor if you need to.

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