Serialization

The e2b lexicon writes each Template as a Dockerfile named after the template, so several can share a directory, and indexes them with the command that builds each one.

Building

e2b.<name>.Dockerfile starts FROM the template’s fromImage. Each env entry becomes an ENV line and each run step a RUN line, in order, with WORKDIR between them when workdir is set:

FROM node:22-bookworm
ENV CI="1"
RUN apt-get update && apt-get install -y --no-install-recommends jq && rm -rf /var/lib/apt/lists/*

The primary output is a JSON index of the templates, keyed by the name each was exported as. build is the e2b template create command line for the template. It names the Dockerfile and passes --cmd, --ready-cmd, --cpu-count and --memory-mb only when the declaration sets them:

{
  "templates": {
    "steward": {
      "name": "chant-steward",
      "dockerfile": "e2b.chant-steward.Dockerfile",
      "build": "e2b template create chant-steward --dockerfile e2b.chant-steward.Dockerfile --cpu-count 2 --memory-mb 2048",
      "cpuCount": 2,
      "memoryMB": 2048
    }
  }
}

A project that declares no template gets { "templates": {} }.

Applying

chant does not build templates. Run each template’s build command in the output directory, once, and again when the declaration changes. A profile’s template then names the template, and the next steward made from that profile starts from it. A steward that already exists keeps the sandbox it has; delete it to have the next run make a new one.