How to get rid of cryptography build error?

I am trying to build a dockerfile but the problem is when it trying to build specifically cryptography is not building.

MY Dockerfile

FROM python:3.7-alpine ENV PYTHONUNBUFFERED 1 RUN apk update \ # psycopg2 dependencies && apk add --virtual build-deps gcc python3-dev musl-dev\ && apk add postgresql-dev \ && apk add build-base \ # Pillow dependencies && apk add jpeg-dev zlib-dev freetype-dev lcms2-dev openjpeg-dev tiff-dev tk-dev tcl-dev \ # CFFI dependencies && apk add libffi-dev py-cffi \ # Translations dependencies && apk add gettext \ # && apk add postgresql-client \ # cairo && apk add cairo cairo-dev pango-dev gdk-pixbuf-dev poppler-utils # fonts for weasyprint RUN mkdir ~/.fonts COPY ./fonts/* /root/.fonts/ # secret key (should be in docker-secrets, or we need to run minikube locally RUN mkdir /etc/secrets COPY secret.readme proxy_rsa_key* /etc/secrets/ # Requirements are installed here to ensure they will be cached. COPY ./requirements /requirements RUN pip install -r /requirements/local.txt COPY ./compose/local/django/entrypoint /entrypoint RUN sed -i 's/\r//' /entrypoint RUN chmod +x /entrypoint COPY ./compose/local/django/start /start RUN sed -i 's/\r//' /start RUN chmod +x /start COPY ./compose/local/django/celery/worker/start /start-celeryworker RUN sed -i 's/\r//' /start-celeryworker RUN chmod +x /start-celeryworker COPY ./compose/local/django/celery/beat/start /start-celerybeat RUN sed -i 's/\r//' /start-celerybeat RUN chmod +x /start-celerybeat COPY ./compose/local/django/celery/flower/start /start-flower RUN sed -i 's/\r//' /start-flower RUN chmod +x /start-flower WORKDIR /app ENTRYPOINT ["/entrypoint"] 

when I try to build my dockerfile it shows:

Building wheel for cryptography (PEP 517): finished with status 'error' ERROR: Command errored out with exit status 1: error: Can not find Rust compiler ---------------------------------------- ERROR: Failed building wheel for cryptography 

I tried to solve but i couldn't. I am newbie in docker.Please help how to get rid of this problem.

6 Answers

cryptography < 3.5:

You can skip the rust installation and other related dependencies by adding the line below before apk add commands:

ENV CRYPTOGRAPHY_DONT_BUILD_RUST=1 

cryptography >= 3.5: Thanks @riptusk331

After this version rust will be required. Either install a specific version <3.5 or follow cryptography installation instructions. It is stated in the attached link that they are very aggressively explained in the docs.

Since the error is...

error: Can not find Rust compiler 

...the solution is to install the rust compiler. You'll also need cargo, the Rust package manager, and it looks like your Dockerfile is missing openssl-dev.

The following builds successfully for me:

FROM python:3.7-alpine ENV PYTHONUNBUFFERED 1 RUN apk add --update \ build-base \ cairo \ cairo-dev \ cargo \ freetype-dev \ gcc \ gdk-pixbuf-dev \ gettext \ jpeg-dev \ lcms2-dev \ libffi-dev \ musl-dev \ openjpeg-dev \ openssl-dev \ pango-dev \ poppler-utils \ postgresql-client \ postgresql-dev \ py-cffi \ python3-dev \ rust \ tcl-dev \ tiff-dev \ tk-dev \ zlib-dev RUN pip install cryptography 

Note that the above apk add ... command line is largely the same as what you've got; I've just simplified the multiple apk add ... statements into a single apk add execution.

pip install -U pip is what all I had to do

Some people might come here (Like I did) looking for a fix just for Python, not necessarily Alpine.

Several options are available, mentioned in the github issue. (only pick one of these)

1. You can install rust, as another answer mentioned
2. You can downgrade your cryptography version to 3.4.x
3. You can upgrade to pip version 19.1.1 or higher, which installs precompiled packages

I faced the same issue and in order to resolve it I tried out the following:

1. Answer provided by @larsks. RUN apk add cargo openssl-dev helped. But this resulted in a huge image size for me (>1GB). Best practice is to always target the bare-minimum with a small image size. This way, we don't expose ourselves to any external vulnerabilities.

2. Answer provided by Sabri Özgür, ENV CRYPTOGRAPHY_DONT_BUILD_RUST=1. This worked great!

3. Based on the comment added by @riptusk331 for the earlier answer, simply ignoring the Rust build may only work for now, as Cryptography 3.5+ will start requiring Rust.

My solution just to be safe was;

... ENV CRYPTOGRAPHY_DONT_BUILD_RUST=1 ... RUN pip install cryptography==3.4.6 ... 

This way, I managed to keep the image size at a considerably lower value while getting the build to pass.

Editing pyvenv.cfg by adding in my .env:

CRYPTOGRAPHY_DONT_BUILD_RUST=1 

then doing pip install cryptography, solved my issue.