Conda-forge.github.io: Cannot install python=3.7 on Linux (libgcc-ng missing?)

[alanhdu]

When I try to create a new environment using python 3.7, I get the following error:

$ conda create -n test python=3.7
Collecting package metadata: done
Solving environment: failed

PackagesNotFoundError: The following packages are not available from current channels:

  - python=3.7 -> libgcc-ng[version='>=7.3.0']
  - python=3.7 -> libstdcxx-ng[version='>=7.3.0']
  - python=3.7 -> openssl[version='>=1.1.1a,<1.1.2a']
  - python=3.7 -> sqlite[version='>=3.26.0,<4.0a0']
  - python=3.7 -> tk[version='>=8.6.9,<8.7.0a0']
  - python=3.7 -> xz[version='>=5.2.4,<5.3.0a0']

Current channels:

  - https://conda.anaconda.org/conda-canary/linux-64
  - https://conda.anaconda.org/conda-canary/noarch
  - https://conda.anaconda.org/conda-forge/linux-64
  - https://conda.anaconda.org/conda-forge/noarch

To search for alternate channels that may provide the conda package you're
looking for, navigate to

    https://anaconda.org

and use the search bar at the top of the page.

Manually digging into this, it looks like libgcc-ng and libstdcxx-ng are both missing from the repodata.json file. When I run conda create -n test sqlite, this installs sqlite 3.22.0, which seems to be the lates tversion of sqlite on conda-forge without an explicit dependency on libgcc-ng, so it looks like a missing libgcc-ng might be the problem?

I am running Ubuntu 18.04 on conda 4.6.10.

[alanhdu]

To add more context, whatever went wrong must have happened recently, because I've been installing Python 3.7 packages successfully for quite some time now (weeks/months maybe?).

I've also tried clearing my conda cache (conda clean -pity) to no success.

[ocefpaf]

I'm assuming you don't have the default channel in your .condarc.conda-forge used to vendorize defaults compilers but thanks to conda >=4.6 we no longer have to do that, which was a bad idea to start with, you can have stable and safer environments by activating strict and having the default channel:

channel_priority: strict
channels:
  - conda-forge
  - defaults

[alanhdu]

Ah... thanks so much! TIL about channel_priority: strict...

[ocefpaf]

Ah... thanks so much! TIL about channel_priority: strict...

Sorry about the breakage. We had a bad workaround and we fixed in a way that caused this breakage, but the right was not available for conda <4.6.

PS: in conda 4.7 the strict channel will probably be enabled by default.

[xylar]

@ocefpaf, I think this needs to make its way into the documentation or be more prominent if it's already there. This also came up on gitter and I think it caught a lot of us by surprise.

[ocefpaf]

@ocefpaf, I think this needs to make its way into the documentation or be more prominent if it's already there. This also came up on gitter and I think it caught a lot of us by surprise.

Indeed. We are discussing better ways to communicate this now but for this case I need to put some docs on strict and maybe create a blog post.

[dazza-codes]

$ conda --version
conda 4.6.14
$ ...
EnvironmentSectionNotValid: The following section on '/home/joe/src/project/environment.yml' is invalid and will be ignored:
 - channel_priority

# environment.yml
channel_priority: strict

[xylar]

@darrenleeweber, I don't think it works in an environment.yml, just in a .condarc (whether in your home directory or local).

[ocefpaf]

@darrenleeweber, I don't think it works in an environment.yml, just in a .condarc (whether in your home directory or local).

It does not but this would be a nice feature to have. Pinging @jjhelmus and @msarahan who are considering this.

[jjhelmus]

It does not but this would be a nice feature to have

I agree completely. I opened conda/conda#8675 to request this feature.