错误:在Docker中的Alpine上安装psycopg2时找不到pg_config可执行文件

Question

我正在尝试使用Postgres和Docker构建Flask应用程序.我想连接到Postgres的AWS RDS实例,但是使用Docker作为我的Flask应用程序.但是,当尝试设置psycopg2它时会遇到错误,因为它无法找到pg_config.这是错误:

Building api
Step 1/5 : FROM python:3.6.3-alpine3.6
 ---> 84c98ca3b5c5
Step 2/5 : WORKDIR /usr/src/app
 ---> Using cache
 ---> 407c158f5ee4
Step 3/5 : COPY . .
 ---> 966df18d329e
Step 4/5 : RUN pip install -r requirements.txt
 ---> Running in 284cc97aeb63
Collecting aniso8601==1.3.0 (from -r requirements.txt (line 1))
  Downloading aniso8601-1.3.0.tar.gz (57kB)
Collecting click==6.7 (from -r requirements.txt (line 2))
  Downloading click-6.7-py2.py3-none-any.whl (71kB)
Collecting Flask==0.12.2 (from -r requirements.txt (line 3))
  Downloading Flask-0.12.2-py2.py3-none-any.whl (83kB)
Collecting Flask-RESTful==0.3.6 (from -r requirements.txt (line 4))
  Downloading Flask_RESTful-0.3.6-py2.py3-none-any.whl
Collecting Flask-SQLAlchemy==2.3.2 (from -r requirements.txt (line 5))
  Downloading Flask_SQLAlchemy-2.3.2-py2.py3-none-any.whl
Collecting itsdangerous==0.24 (from -r requirements.txt (line 6))
  Downloading itsdangerous-0.24.tar.gz (46kB)
Collecting Jinja2==2.9.6 (from -r requirements.txt (line 7))
  Downloading Jinja2-2.9.6-py2.py3-none-any.whl (340kB)
Collecting MarkupSafe==1.0 (from -r requirements.txt (line 8))
  Downloading MarkupSafe-1.0.tar.gz
Collecting psycopg2==2.7.3.1 (from -r requirements.txt (line 9))
  Downloading psycopg2-2.7.3.1.tar.gz (425kB)
    Complete output from command python setup.py egg_info:
    running egg_info
    creating pip-egg-info/psycopg2.egg-info
    writing pip-egg-info/psycopg2.egg-info/PKG-INFO
    writing dependency_links to pip-egg-info/psycopg2.egg-info/dependency_links.txt
    writing top-level names to pip-egg-info/psycopg2.egg-info/top_level.txt
    writing manifest file 'pip-egg-info/psycopg2.egg-info/SOURCES.txt'
    Error: pg_config executable not found.

    Please add the directory containing pg_config to the PATH
    or specify the full executable path with the option:

        python setup.py build_ext --pg-config /path/to/pg_config build ...

    or with the pg_config option in 'setup.cfg'.

    ----------------------------------------
Command "python setup.py egg_info" failed with error code 1 in /tmp/pip-build-01lf5grh/psycopg2/
ERROR: Service 'api' failed to build: The command '/bin/sh -c pip install -r requirements.txt' returned a non-zero code: 1

这是我的Dockerfile:

FROM python:3.6.3-alpine3.6

WORKDIR /usr/src/app

COPY . .

RUN pip install -r requirements.txt

CMD ["python", "app.py"]

许多其他人似乎在本地有类似的问题,但没有一个涉及使用Docker.这似乎是一个Docker问题,因为我可以设置一个本地虚拟环境,并且设置工作正常,因为我在本地安装了Postgres,它能够找到我的本地pg_config.

似乎在容器构建/设置期间,Docker正试图pg_config在容器内查找.有没有办法pg_config在容器中安装一个,即使我不会使用Postgres的容器化实例,而是使用RDS上的实例？

欢迎任何和所有关于如何解决这个问题的建议.谢谢!

Answer 1

使用Python 3.4.8,3.5.5,3.6.5和2.7.14测试(只需用2替换3):

# You can use a specific version too, like python:3.6.5-alpine3.7
FROM python:3-alpine

WORKDIR /usr/src/app

COPY requirements.txt .

RUN \
 apk add --no-cache postgresql-libs && \
 apk add --no-cache --virtual .build-deps gcc musl-dev postgresql-dev && \
 python3 -m pip install -r requirements.txt --no-cache-dir && \
 apk --purge del .build-deps

COPY . .

CMD ["python3", "app.py"]

说明:要构建Psycopg,您需要包gcc musl-dev postgresql-dev.然后你还需要pg_config可执行文件:虽然简单安装postgresql-dev也可以工作,postgresql-libs也可以,并且占用大约12 MB的空间.

这是答案的原始版本(基于此Dockerfile),我将Python手动安装到纯Alpine图像上,因为那时Python没有为Python 3.6和Alpine 3.7提供Docker镜像.如果你想安装这样的Python 2.7,也可以apk add py2-pip(py-pip在较旧的Alpine repos中调用).

FROM alpine:3.7

WORKDIR /usr/src/app

COPY requirements.txt .

RUN \
 apk add --no-cache python3 postgresql-libs && \
 apk add --no-cache --virtual .build-deps gcc python3-dev musl-dev postgresql-dev && \
 python3 -m pip install -r requirements.txt --no-cache-dir && \
 apk --purge del .build-deps

COPY . .

CMD ["python3", "app.py"]

Answer 2

在从requirements.txtDockerfile安装依赖项之前，只需添加这些命令（psycopg2 依赖项）

# install psycopg2 dependencies
RUN apk update
RUN apk add postgresql-dev gcc python3-dev musl-dev

来源：https : //testdriven.io/blog/dockerizing-django-with-postgres-gunicorn-and-nginx/

Answer 3

我通过将以下内容添加到我的 Dockerfile 中解决了这个问题：

RUN apt-get update \
    && apt-get -y install libpq-dev gcc \
    && pip install psycopg2

这将安装 psycopg2 依赖项。

Answer 4

你可以试试：

pip install psycopg2-binary