playground-common package giving 'Failed to build scrypt-0.5.0' error

Question

I'm trying to run my own little smart contract in the plutus-pioneer-program [fourth iteration] docker container and I'm having some problems. I've just added an extra folder alongside the other weeks. I've built this same code on other environments just fine but I got a new laptop with an M2 chip recently so my setup all broke and I figured running it in this environment would be the fastest way forward. I've narrowed the issue down to the playground-common package that my build depends on. The problem is that when I run cabal build all in my folder I get this error:

Build log (
/root/.cabal/logs/ghc-8.10.7/scrypt-0.5.0-833a2feabba78b918876049577f7c64bc2870cc56e8d7720fba2aa8ea196973a.log
):
Configuring library for scrypt-0.5.0..
cabal-3.6.2.0: Missing dependency on a foreign library:
* Missing (or bad) header file: crypto_scrypt.h
This problem can usually be solved by installing the system package that
provides this library (you may need the "-dev" version). If the library is
already installed but in a non-standard location then you can use the flags
--extra-include-dirs= and --extra-lib-dirs= to specify where it is.If the
library file does exist, it may contain errors that are caught by the C
compiler at the preprocessing stage. In this case you can re-run configure
with the verbosity flag -v3 to see the error messages.
If the header file does exist, it may contain errors that are caught by the C
compiler at the preprocessing stage. In this case you can re-run configure
with the verbosity flag -v3 to see the error messages.

cabal: Failed to build scrypt-0.5.0 (which is required by
elysium-contract-0.1.0.0). See the build log above for details.

I havent changed anything else in the project other than adding an additional folder under code. Has something changed with the playground-common package?

I also tried adding this configuration to a cabal.project.local file, but no luck:

flags: -scrypt
tests: False
benchmarks: False
optimization: 2

Using cabal version 3.4, base ^>=4.14.1.3.0 Other config:

                     , base ^>=4.14.1.3.0
                     , bytestring
                     , cardano-api
                     , containers
                     , data-default
                     , playground-common
                     , plutus-ledger-api
                     , plutus-tx-plugin
                     , plutus-tx
                     , serialise
                     , text
  default-language:    Haskell2010
  ghc-options:         -Wall -fobject-code -fno-ignore-interface-pragmas
                       -fno-omit-interface-pragmas -fno-strictness 
                       -fno-spec-constr -fno-specialise -fexpose-all-unfoldings
                       -fplugin-opt PlutusTx.Plugin:defer-errors

Answer 1

You are missing a C header file. Specifically, the part of the error message:

* Missing (or bad) header file: crypto_scrypt.h
This problem can usually be solved by installing the system package that
provides this library (you may need the "-dev" version). If the library is
already installed but in a non-standard location then you can use the flags.

On Debian based Linux systems (eg Debian, Ubuntu, Mint and probably others), you can used apt-file to find which packages provides the file:

> apt-file search crypto_scrypt.h
libnode-dev: /usr/include/nodejs/src/crypto/crypto_scrypt.h

so that installing the libnode-dev package (part of nodejs):

sudo apt install libnode-dev

will sort your problems out.

Answer 2

I have had this issue with setting up the environment on aarch64 M1 Mac, even within a Ubuntu VM on the same chip. The scrypt component fails due to its current support being limited to x86. More details can be found in this GitHub issue. https://github.com/informatikr/scrypt/issues/8

The best way around it is either a x86 machine or an x86 VM. I have setup mine as remote server. Life is easier this way

If someone did want to try to build it on a aarch64 I would recommend somehow making the build use this fork https://github.com/SupercedeTech/scrypt which is compatible