Docker: python has no installation candidate - docker

I am trying to create a docker image from my docker file which has the following content:
FROM ubuntu:latest
WORKDIR /app
ADD . /app
RUN apt-get update && apt-get install python -y
CMD python /app/main.py
LABEL color=red
which fails with the following error:
apt-get update && apt-get install python -y returned a non-zero code: 100
So please help me in solving this error

Docker is just Linux. When some apt-get install acme fails, you just need to try the exact command and or research the missing dependencies.
To replicate your error I ran: docker run -it ubuntu:latest and inside, I ran your apt-get update && apt-get install python -y. I got the error:
So, I tried with apt-get install python3 -y and it worked. Finally your Dockerfile should be:
FROM ubuntu:latest
WORKDIR /app
ADD . /app
RUN apt-get update && apt-get install python3 -y
CMD python3 /app/main.py
LABEL color=red
Older Python
If your code needs old python version, you should not use FROM ubuntu:latest because in the lastest version of ubuntu, only python3 is allowed.
Anyway if you need python2, you must research a lot on internet to get the exact steps to install python2 or use some ready to use docker images:
https://hub.docker.com/layers/python/library/python/2.7.18-slim-stretch/images/sha256-a0b3c65a15ba08138460de9fd2267b8dec30ed98407a0edac0adc0ccbe809cad?context=explore
how do i setup only python 2.7 in docker container?
https://github.com/Docker-Hub-frolvlad/docker-alpine-python2

Related

Packages wont install in docker

I am trying to install tesseract-ocr to docker from a Dockerfile. When I build the Dockerfile everything looks normal and i get no errors but when I run the container tesseract is not installed.
If I access the container using sudo docker exec -t -i <container_id> /bin/bash and manually install tesseract using apt-get install -y tesseract-ocr-all it installs and works perfectly. Why doesn't it work when I try to install it during the build process?
My Dockerfile looks like this:
FROM ubuntu:20.04
ARG DEBIAN_FRONTEND=noninteractive
RUN apt-get update \
&& apt-get install -y tesseract-ocr-all
RUN tesseract --version
FROM python:3.7
WORKDIR ocr
COPY requirements.txt .
RUN pip3 install --no-cache-dir -r requirements.txt
COPY . .
Thanks!
It looks like you are leveraging Docker multi-stage builds without realizing it.
When you put FROM python:3.7, you essentially throw away everything you have done above that, since you start a new stage.
The easiest solution I can see is to move
RUN apt-get update \
&& apt-get install -y tesseract-ocr-all
RUN tesseract --version
into the FROM python:3.7 stage, and remove the FROM ubuntu:20.04 stage.
You need to switch your user, since you likely don't have permission to run those commands. Something like this should work:
USER root
RUN apt-get update \
&& apt-get install -y tesseract-ocr-all
USER <switch back to previous user>
You'll need to figure out what the default user is to switch back, which you can probably find in the Ubuntu docs or using whoami.

Cannot install php, apache and postgres on ubuntu base image in dockerfile

I started studying docker recently and wanted to install php, apache and postgres in a ubuntu base image. But cannot run it after build.
Here is my Dockerfile
FROM ubuntu:16.04
RUN apt-get update
RUN apt-get -qq -y install curl
RUN apt-get -y install apache2
RUN apt-get -y install php7.0
RUN apt-get -y install libapache2-mod-php7.0
RUN apt-get -y install php7.0-mysql
RUN apt-get -y install php7.0-pgsql
RUN apt-get -y install php7.0-gd
RUN apt-get -y install php-pear
RUN apt-get -y install php7.0-curl
COPY . /var/www/html
EXPOSE 80
Can you please help me?
Thanks.
there are several issues here. First of all, I have the impression that you're mixing up docker and virtual machines. For this I suggest to go and read what are the differences.
Concerning your question, the problem is that the base image (ubuntu:16.04) has CMD bash (or something similar, I really didn't check) and therefore php is not considered.
In order to start apache, you should append the following:
CMD . /etc/apache2/envvars && /usr/sbin/apache2ctl -DFOREGROUND
Anyway, I'd suggest you give a check to the php official image.

Unable to locate package python

I'm trying to run the below Dockerfile contents on ubuntu image.
FROM ubuntu
RUN apt-get update
RUN apt-get install -y python
RUN apt-get install -y python-pip
RUN pip install flask
COPY app.py /opt/app.py
ENTRYPOINT FLASK_APP=/opt/app.py flask run --host=0.0.0.0
But i'm getting the below error at layer 3.
Step 1/7 : FROM ubuntu
---> 549b9b86cb8d
Step 2/7 : RUN apt-get update
---> Using cache
---> 78d87d6d9188
Step 3/7 : RUN apt-get install -y python
---> Running in a256128fde51
Reading package lists...
Building dependency tree...
Reading state information...
E: Unable to locate package python
Athough while I run the below command individually
sudo apt-get install -y python
It's successfully getting installed.
Can anyone please help me out.
Note: I'm working behind organization proxy.
Step 2/7 : RUN apt-get update
---> Using cache
You should run apt-get update and apt-get install in the same RUN instruction as follows
RUN apt-get update && apt-get install -y python
Each instruction in a Dockerfile will create separate layer in the image and the layers are cached. So the apt-get update might just use cache and not even run. This has happened in your case as well. You can see the line ---> Using cache in your logs. You can use docker build --no-cache to make docker rebuild all the layers without using cache.
You can instead just use python:3 official image as base image to run your python apps.
In the python installation tutorial there is a package name python3.x for Debian.
I think this is your case. I tested it in the Docker and this is right configuration
looks like
From ubuntu:20.04
RUN apt-get update && apt-get -y install python3.8 python3.8-dev
I feel you should rather use Python3 's image instead of using ubuntu and then installing it.
FROM python:3
RUN apt-get update && apt-get install -y python3-pip #You don't need to install pip, because it is already there in python's image
RUN pip install -r requirements.txt
COPY . /usr/src/apps #This you can change
WORKDIR /usr/src/apps/ #this as well
CMD ["python","app.py"]
Try the following, it worked for me
apt-get install python3-pip
And then for installing flask you will have to use
pip3 install flask

Docker Build Error : The command '/bin/sh -c apt-get install –y apache2' returned a non-zero code: 100

I am trying to build a Dockerfile
FROM ubuntu
RUN apt-get update
RUN apt-get install –y apache2
RUN apt-get install –y apache2-utils
RUN apt-get clean
EXPOSE 80
CMD [“apache2ctl”, “-D”, “FOREGROUND”]
when i am running this command docker build –t=”mywebserver” . I am getting below provided error in console
E: Unable to locate package –y
The command '/bin/sh -c apt-get install –y apache2' returned a non-zero code: 100
I'm not sure how, but I think you're using an en dash instead of a hyphen in front of your y.
You want -y rather than –y
If you look closely there's a subtle difference.
The Dockerfile looks fine so could be something to do with a proxy/firewall.
I would try the following:
FROM ubuntu
RUN apt-get update
Run with docker build --no-cache -t mywebserver and see if it performs the update without issues. If not then I would suggest looking at setting http/https proxy with ENV inside the dockerfile.

Ruby docker image can't install nodejs on raspberry pi

I'm trying to get a rails server setup on a raspberry pi by building a Docker image.
Image:
FROM ruby:latest
RUN apt-get update -qq && apt-get install -y build-essential libpq-dev
RUN apt-get install -y nodejs
WORKDIR /webapp
COPY Gemfile* /webapp
RUN bundle install
COPY . /webapp/
CMD ["rails", "s", "-b", "0.0.0.0"]
But I'm getting
E: Package 'nodejs' has no installation candidate
EDIT:
I have tried adding the command from the nodejs site curl -sL https://deb.nodesource.com/setup_10.x | bash - && apt-get install -y nodejs
The reason the error Package 'nodejs' has no installation candidate was showing up regardless of how you tried to add the repo to apt-get is because Skipping acquire of configured file 'main/binary-armel/Packages' as repository 'https://deb.nodesource.com/node_10.x stretch InRelease' doesn't support architecture 'armel'.
My solution was to move to an arm32v7/ruby base image and running the same commands. This will install the nodejs_4.8.2~dfsg-1_armhf.deb package which is compatible with the arm architecture.

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