One template with parallel builders or sequential packer builds: which for a latency-sensitive CI runner?
The trade-off Packer (HCL2 templates, assuming a recent 1.10+ release) runs every build block in one template concurrently by default, with -parallel-builds available to cap or serialize them. The alternative is splitting images into separate templates and invoking packer build one at a time in the pipeline. The constraint is a single shared build host with