Problem finding libpython on Ubuntu

[andreasnoack]

This has caused some problems for CIBot lately

julia> ENV["PYTHON"]="/usr/bin/python3"
"/usr/bin/python3"

(v1.0) pkg> build PyCall
  Building Conda ─→ `~/.julia/packages/Conda/m7vem/deps/build.log`
  Building PyCall → `~/.julia/packages/PyCall/rUul9/deps/build.log`
┌ Error: Error building `PyCall`:
│ ERROR: LoadError: Couldn't find libpython; check your PYTHON environment variable.
│
│ The python executable we tried was /usr/bin/python3 (= version3.6);
│ the library names we tried were ["libpython3.6m.so", "libpython3.6m", "libpython3.6", "libpython"]
│ and the library paths we tried were AbstractString["/usr/lib","/usr/lib", "/usr", "/usr/lib"]
│ Stacktrace:
│  [1] error(::String) at ./error.jl:33
│  [2] find_libpython(::String) at /home/andreasnoack/.julia/packages/PyCall/rUul9/deps/build.jl:129
│  [3] top-level scope at logging.jl:313
│  [4] top-level scope at /home/andreasnoack/.julia/packages/PyCall/rUul9/deps/build.jl:196
│  [5] include at ./boot.jl:317 [inlined]
│  [6] include_relative(::Module, ::String) at ./loading.jl:1038
│  [7] include(::Module, ::String) at ./sysimg.jl:29
│  [8] include(::String) at ./client.jl:388
│  [9] top-level scope at none:0
│ in expression starting at /home/andreasnoack/.julia/packages/PyCall/rUul9/deps/build.jl:170
└ @ Pkg.Operations /buildworker/worker/package_linux64/build/usr/share/julia/stdlib/v1.0/Pkg/src/Operations.jl:1068

[tkf]

We are trying to improve libpython discovery #556 (which is surprisingly hard). Can you run

wget https://gist.githubusercontent.com/tkf/d980eee120611604c0b9b5fef5b8dae6/raw/9f074cd233f83180676b4421212ed33c257968af/find_libpython.py
/usr/bin/python3 find_libpython.py --list-all

and paste the output (if any) here?

If it doesn't output anything, try:

/usr/bin/python3 find_libpython.py --list-all --verbose

Also, let me know the output of lsb_release -a just for record.

[andreasnoack]

This one seems able to find libpython

andreasnoack@anubis:~$ /usr/bin/python3 find_libpython.py --list-all
/usr/lib/x86_64-linux-gnu/libpython3.6m.so.1.0

No LSB modules are available.
Distributor ID: Ubuntu
Description:    Ubuntu 17.10
Release:        17.10
Codename:       artful

[tkf]

Thanks, good to know.

[rishisubramanian]

Just letting you know that I have the same issue on Ubuntu 18.10 (Development). My libpython location is the same at /usr/lib/x86_64-linux-gnu/libpython3.6m.so.1.0.
No LSB modules are available. Distributor ID: Ubuntu Description: Ubuntu Cosmic Cuttlefish (development branch) Release: 18.10 Codename: cosmic

[tkf]

If you feel brave you can try #556 with ] add PyCall#remotes/cache/pull/556/head :)

[andreasnoack]

If you feel brave you can try #556 with ] add PyCall#remotes/cache/pull/556/head :)

Great. It works.

[huckl3b3rry87]

So, the master is fixed?

I am still getting a build error using the latest tagged version

configure: error: failed to find a C++ compiler or C++ compiler g++ does not work
================================[ ERROR: Ipopt ]================================

LoadError: failed process: Process(`./configure --prefix=/home/mavs/.julia/v0.6/Ipopt/deps/usr coin_skip_warn_cxxflags=yes '--with-blas=/home/mavs/.julia/v0.6/Ipopt/deps/usr/lib/libcoinblas.a -lgfortran' --with-lapack=/home/mavs/.julia/v0.6/Ipopt/deps/usr/lib/libcoinlapack.a ''`, ProcessExited(1)) [1]
while loading /home/mavs/.julia/v0.6/Ipopt/deps/build.jl, in expression starting on line 13

================================================================================
INFO: Building PyCall
===============================[ ERROR: PyCall ]================================

LoadError: Couldn't find libpython; check your PYTHON environment variable.

The python executable we tried was python3 (= version 3.5);
the library names we tried were String["libpython3.5m.so", "libpython3.5m", "libpython3.5", "libpython"]
and the library paths we tried were String["/usr/lib", "/usr/lib", "/usr", "/usr/lib"]
while loading /home/mavs/.julia/v0.6/PyCall/deps/build.jl, in expression starting on line 265

================================================================================

================================[ BUILD ERRORS ]================================

WARNING: Ipopt and PyCall had build errors.

 - packages with build errors remain installed in /home/mavs/.julia/v0.6
 - build the package(s) and all dependencies with `Pkg.build("Ipopt", "PyCall")`
 - build a single package by running its `deps/build.jl` script

================================================================================
INFO: Package database updated
INFO: Building Conda
INFO: Building PyCall
Info: PyCall is using /usr/bin/python2.7 (Python 2.7.12) at /usr/bin/python2.7, libpython = libpython2.7
Info: /home/mavs/.julia/v0.6/PyCall/deps/deps.jl has been updated
Info: /home/mavs/.julia/v0.6/PyCall/deps/PYTHON has been updated

Or is there a fix for this?

[tkf]

No master still has the problem. #556 is not merged yet.

[stevengj]

Fixed by #556