Docker images
Docker images for useful purposes.
The purpose of this repository and its docker images is to provide a build environment for a specific Haskell project (not mentioned here). The images may or may not be useful to anyone else.
This setup is currently working around the following issues:
- A job limit of 50 minutes on travis.org.
- Lack of caching in Haskell
stackforextra-depsdependencies in astack.yamlfile.
Haskell stack doesn't globally cache extra-deps dependencies that are
declared in a stack.yaml file. Instead, these are stored in a
project-specific cache. To get around this, dummy .cabal and stack.yaml
files are provided and a dummy project is created inside the Docker images at
/opt/stack. By using identical extra-deps and libraries, a build
environment can be created at this location which a later stack build can
re-use.
To combat the 50 minute limit on jobs at travis.org, the Docker build is split into multiple images:
centos-lts-acentos-lts-bcentos-lts-ccentos-lts-b
This is straightforward, but annoying. One annoying part of this setup is keeping the version numbers of the multiple Docker images in sync. To achieve this, the M4 macro processor is used to substitute version numbers across the Dockerfiles.
It's still necessary to switch to an explicit stack project directory (ie.
/opt/stack in this case) because of this stack issue:
commercialhaskell/stack#1731