An example stow managed developer environment

What

A basic example of using GNU Stow to manage a small collection of mostly source packages released as a Vagrant base box.

Why

Some possible reasons to an approach like this include:

an interest in building dependencies from source for speed, safety, or out of necessity
an interest in bundling dependencies into multiple formats such as a "container image"
an interest in img or buildah
you like Packer and Vagrant
you're not quite ready for Nix

Example packages

Example package implementations ~~are~~ will be included for:

Possibe extensions

Packaged GNU build chain

technical computing needs "exotic" compilers

Foundation for private package layering with Vagrant

Using ssh agent forwarding makes it easy to access private source repositories when creating an environment using a base box which could contain open source or otherwise publically available source code.

Remote build caching

Download cached builds from a remote endpoint is fairly simple with a tool like curl:

work_dir=$(mktemp -d)
cache_url=${YOUR_CACHE_URL_AVAILABLE_TO_VM}

if [[ $(curl -s -f -I "${cache_url}/${STOW_BUILD_CTX_CACHED_BUILD_ID}") ]]; then
  pushd ${work_dir}
    ### Download cached bits
    echo "cached build ${STOW_BUILD_CTX_CACHED_BUILD_ID} exists. Downloading cached build and source..."
    curl "${cache_url}/${STOW_BUILD_CTX_CACHED_BUILD_ID}" > ${STOW_BUILD_CTX_CACHED_BUILD_ID}
    curl "${cache_url}/${STOW_BUILD_CTX_CACHED_SRC_ID}" > ${STOW_BUILD_CTX_CACHED_SRC_ID}
 popd

It's not hard to imagine augmenting that simple curl invocation with authorization headers, or replacing curl with a CLI to access S3 or GCS with some reasonable scheme for authentication.

GPG checksum validation

Those concerend about supply chain security, might try using GPG to verify artifact integrity.

Given:

${STOW_BUILD_CTX_CACHED_BUILD_CHECKSUM}
${STOW_BUILD_CTX_CACHED_SRC_CHECKSUM}
${STOW_BUILD_CTX_CACHED_BUILD_CHECKSUM_SIGNATURE}
${STOW_BUILD_CTX_CACHED_SRC_CHECKSUM_SIGNATURE}

where:

${STOW_BUILD_CTX_CACHED_BUILD_CHECKSUM} is a file produced by sha256sum ${STOW_BUILD_CTX_CACHED_BUILD_ID} or similar
${STOW_BUILD_CTX_CACHED_BUILD_CHECKSUM_SIGNATURE} the result of signing ${STOW_BUILD_CTX_CACHED_BUILD_CHECKSUM} with gpg or similar
${STOW_BUILD_CTX_CACHED_SRC_CHECKSUM} is the source analog of ${STOW_BUILD_CTX_CACHED_BUILD_CHECKSUM}
${STOW_BUILD_CTX_CACHED_SRC_CHECKSUM_SIGNATURE} is the source analog of ${STOW_BUILD_CTX_CACHED_BUILD_CHECKSUM_SIGNATURE}

the signature of the signed archive can be transmitted and verified

### Verify GPG signatures
echo "Verifying GPG signatures for cached build and source..."
gpg --output ${STOW_BUILD_CTX_CACHED_BUILD_CHECKSUM} --decrypt ${STOW_BUILD_CTX_CACHED_BUILD_CHECKSUM_SIGNATURE}
gpg --output ${STOW_BUILD_CTX_CACHED_SRC_CHECKSUM} --decrypt ${STOW_BUILD_CTX_CACHED_SRC_CHECKSUM_SIGNATURE}

### Verify SHA256 checksums
echo "Verifying cached build and source checksums..."
sha256sum -C ${STOW_BUILD_CTX_CACHED_BUILD_CHECKSUM}
sha256sum -c ${STOW_BUILD_CTX_CACHED_SRC_CHECKSUM}

If gpg has been configued to trust the expected signing key of the artifacts it's possible to have a slightly stronger GPG check

set -x

### Verify GPG signatures
echo "Verifying GPG signatures for cached build and source..."
gpg --output ${STOW_BUILD_CTX_CACHED_BUILD_CHECKSUM} --decrypt ${STOW_BUILD_CTX_CACHED_BUILD_CHECKSUM_SIGNATURE} |& grep -v "WARNING" 
gpg --output ${STOW_BUILD_CTX_CACHED_SRC_CHECKSUM} --decrypt ${STOW_BUILD_CTX_CACHED_SRC_CHECKSUM_SIGNATURE} |& grep -v "WARNING"

which will produce an error on any warnings from gpg such as the signing key of the artifact being of unknown trust. Reasonable people disagree as to the utility of using GPG for this task.

calebamiles/example-stow-environment