0.3.1

compose2pod 0.3.1 — the image mount type

A focused follow-up to 0.3.0: the long-form volumes type: image mount, which
closes the last long-form volume form Podman can express but compose2pod did not
yet parse.

Feature

• type: image volume mounts. A long-form entry {type: image, source, target, read_only, image: {subpath}} compiles to podman run --mount type=image,source=<ref>,target=<path>[,subpath=<abs>], mounting an image's
  rootfs into the container. Measured against docker compose config v5.1.2 and
  Podman 6.0.1:
  • source (the image reference) is required — Podman refuses a sourceless
    image mount, so compose2pod does too (a rule-two narrowing; Docker allows it
    optional at config).
  • read_only is accepted but inert — an image mount is always read-only,
    and Podman rejects both a readonly and an rw option on it, so no ro is
    emitted (matching what Docker does with the field).
  • image: {subpath} must be an absolute path — Podman requires it for an
    image mount (a relative subpath is rejected at run time), unlike a volume
subpath, which may be relative. A ${VAR} is carved out.

Docs

• The README's supported-subset section, stale since before the 0.3.0 parity
  work, now leads with the measured parity property (compose2pod refuses every
  document docker compose config refuses, verified by the differential
  conformance harness) and reflects the full 0.3.0 subset.

Downstream

• type: image compose files that previously raised now compile. Nothing else
  changes — the short form, the other long-form types, and every existing key
  behave identically.
• With image landed, the honest subset is complete for its scope: every
  remaining refusal of a form Docker accepts is either a permanent rule-two limit
  (Podman cannot form the flag) or a genuinely niche gap (a Windows drive-letter
  volume source on a Linux-targeting tool), each measured and documented in
  architecture/supported-subset.md, planning/deferred.md, and
  planning/decisions/.

Internals

• Tests at 100% line coverage (enforced); ruff select=ALL, ty, eof-fixer
  clean; the conformance harness (real Docker CLI) and integration harness (real
  Podman) both green — the integration suite mounts an image's rootfs on real
  Podman, and the final review re-measured every emitted --mount option against
  Podman 6.0.1, catching (and closing) a relative-subpath value Podman rejects
  at run time.

0.3.0

compose2pod 0.3.0 — measured parity with Docker, and a much wider accepted subset

This release makes the subset's boundary a measured one. compose2pod now
refuses every document docker compose config refuses — verified continuously
by a differential conformance harness that runs both the real Docker CLI and the
real compose2pod pipeline over the same YAML and asserts the rule. On top of that
hard floor, the accepted subset grew substantially: quoted booleans, env_file
and volumes long-form (with --mount), the full Compose duration grammar, and
the volume mount option maps. Where compose2pod still refuses a form Docker
accepts, that refusal is now measured, documented, and — for the permanent ones —
recorded as a decision with the exact Podman limitation behind it.

The parity thesis

The governing rule (decisions/2026-07-14-docker-rejection-parity.md):
accepted(compose2pod) ⊆ accepted(docker) — compose2pod must reject every
document Docker rejects, so a file that compiles is a file Docker would run.

• Reject every document docker compose config refuses. The value grammars
  (size, number, integer, count, duration, port) now match Docker's
  own — mem_limit: "", cpus: somevalue, a unitless healthcheck duration, an
  out-of-range port, a whitespace-padded scalar, all refused where Docker refuses
  them, instead of being silently accepted and compiled into a script Docker
  itself would not run.
• Read YAML the way Docker reads it (1.2). A bare on/off/yes/no stays
  an ordinary string (not a boolean), and a bare 1e3 is the float 1000.0 —
  matching Docker's YAML-1.2 parser, so SSL: on reaches the container as
  SSL=on and an on: key no longer resolves to True.
• Match Docker's null-value policy. A bare key: (null) is refused exactly
  where Docker refuses one, and treated as "unset" exactly where Docker does.
• Close the structural-key and reference gates. Non-string mapping keys,
  malformed nested shapes, undefined named-volume/network references, and
  strict long-form schemas (build, depends_on, networks, volumes,
  secrets/configs refs) are validated to Docker's own grammar.
• A differential conformance harness (tests/conformance/, CI-only) probes
  every registry key × every hostile shape plus a hand-authored corpus, running
  Docker and compose2pod over identical YAML. A document Docker rejects that
  compose2pod accepts fails the build; the reverse (an over-rejection) is
  reported and catalogued, never hidden.

Feature — a wider accepted subset

• Quoted booleans on every boolean field. read_only: "yes", tty: "true",
  init: "on", and the same on build, network/volume definitions, and
  depends_on — the YAML-1.1 boolean spellings Docker casts a string field
  through — are now accepted, via one shared values.is_bool_like/as_bool
  seam, coercing before emit so a quoted "false" never leaks a set flag.
• env_file long-form. env_file: [{path, required, format}] is accepted;
  required: false is honored with a run-time [ -f path ] guard so an absent
  optional file is skipped, format: raw is accepted, and path resolves as
  before.
• volumes long-form (--mount). The mapping entry
  {type, source, target, read_only, consistency} for type in
  bind/volume/tmpfs compiles to podman run --mount, and the nested option
  maps — bind: {propagation, selinux}, volume: {subpath},
  tmpfs: {size, mode} — map to the corresponding --mount options (selinux
z/Z → relabel=shared/private).
• The full Compose duration grammar for healthcheck interval. Compound and
  larger units — 1h, 1h30m, 1d, 1w, 1.5d, -1h — are accepted (the
  interval paces the polling loop; Podman never sees it), overflow- and
  whitespace-safe.
• Podman-version guard. Generated scripts warn at run time when Podman is
  below the version with the /etc/hosts pod-wide fix, so a silent name-
  resolution failure surfaces as an explicit warning.

Fix

• --add-host scoped to the target's dependency closure — a host entry for a
  service outside the run set no longer lands on the pod-create line.
• Two hard-rule false greens, caught by the differential harness's own
  adversarial review and closed: a trailing newline slipping past a $-anchored
  value grammar (now \Z, reachable via a YAML block scalar), and a padded /
  negative / float value on the tmpfs mount sub-schema (Docker validates it as
  unsigned; Podman's crun rejects a float mode).

Internals

• Registry unification. environment and tmpfs moved into the
  SERVICE_KEYS registry (one validate + emit + merge spec per key); the compose
  reader (the YAML-1.2 SafeLoader and format dispatch) was extracted into
  read.py with its own test surface. volumes was deliberately left
  hand-rolled — recorded as a decision (its emit needs project_dir, its
  references are document-level).
• A decisions log now records the rulings that shape the boundary — the
  docker-rejection-parity rule, the list-of-str (sysctls/volumes: ["a"])
  legitimate refusals, the volumes-stays-hand-rolled call, and the
  measured-negative-numerics finding — each with the exact Docker/Podman behavior
  and a revisit trigger, so none is re-litigated.
• Tests at 100% line coverage (enforced); ruff select=ALL, ty, eof-fixer
  clean; the CI-only integration harness (real Podman) and conformance harness
  (real Docker CLI) both green.

Why

0.2.0 rounded out the common compose keys. This release answers a sharper
question — which documents does compose2pod's "yes" actually mean? — with a
measured answer: exactly the ones Docker would run, minus a small, catalogued set
of forms Podman genuinely cannot express. The differential harness makes that a
property the build enforces, not a claim in the README, and it repeatedly caught
false greens that unit tests (which assert on generated text) could not.

Downstream

• Stricter where Docker is strict. A document that previously compiled but
  that docker compose config rejects — a native number on a duration field, a
  malformed size, a null where Docker refuses one, a bare on/yes you relied on
  being a boolean — now raises UnsupportedComposeError. This is the point: the
  script you get is one Docker would run.
• Wider where Podman can express it. Quoted booleans, env_file/volumes
  long-form, and compound durations mean fewer documents need pre-editing.
• The honest boundary. Three forms Docker accepts stay refused, each measured
  and documented: the image mount type and a Windows drive-letter source
  (planning/deferred.md, genuine parser gaps), and sysctls/volumes: ["a"]
  (decisions/, permanent — Podman cannot form the flag).

0.2.0

compose2pod 0.2.0 — most of the common compose subset, and a real-podman test harness

This release rounds out the per-container and pod-level keys most compose
files actually use — extends, secrets/configs, resource limits,
ulimits, and pod-wide dns/sysctls/extra_hosts — and adds a CI-only
integration harness that runs generated scripts against real Podman. That
harness caught a real bug on its first run, fixed in this same release: see
Fix, below.

Fix

• --add-host moved from podman run to podman pod create. Current
  Podman rejects --add-host on a container joining a pod ("network cannot
  be configured when it is shared with a pod") — so any generated script for
  a pod with more than one named service failed at run time. All
  --add-host emission (service-name/hostname/container_name/network
  aliases, and extra_hosts) now lands on the single podman pod create
  line instead, alongside dns/sysctls. extra_hosts is consequently now
  genuinely pod-wide (previously per-service); a host name landing on two
  different addresses — across services' extra_hosts, or against an
  alias's fixed 127.0.0.1 — is refused (UnsupportedComposeError) rather
  than resolved by guessing, matching the existing sysctls conflict rule.
• validate()/emit_script() reject malformed input cleanly instead of
  crashing. A malformed depends_on, healthcheck, hostname/
  container_name, tmpfs, or per-service networks shape now raises
  UnsupportedComposeError at the validation/emit boundary instead of an
  uncaught AttributeError/ValueError deeper in the pipeline.
• emit_script validates the pod name itself, not only the CLI — an
  adversarial EmitOptions.pod (quotes, spaces, $(...)) now raises
  cleanly instead of producing a malformed shell trap.

Feature

• extends. Same-file Compose extends: {service: <name>} is resolved
  before validation (transitive, cycle-checked, per-key merge — concat for
  list keys like cap_add/volumes, local-wins merge for environment/
  labels/healthcheck, override for scalars and command/entrypoint).
  Cross-file extends: {file: ...} stays refused, keeping the
  single-document input model.
• secrets and configs. Top-level secrets:/configs: (file:,
  environment:, and — configs only — inline content: sources) compile to
  podman secret create, mounted via --secret at /run/secrets/<name>
  (secrets) or the container root /<name> (configs, absolute target:
  only). external: true is refused; a secret and same-named config don't
  collide (distinct store names).
• Resource limits. Both the legacy scalar keys (mem_limit, cpus,
  pids_limit, cpu_shares, cpuset, shm_size, oom_score_adj,
  oom_kill_disable, ...) and the modern deploy.resources.limits/
  .reservations block map onto --memory/--cpus/--pids-limit/
  --memory-reservation. A legacy key and its deploy.resources counterpart
  targeting the same flag is refused rather than picking an undefined
  precedence.
• ulimits. A mapping of limit name to a scalar (nproc: 65535) or a
  {soft, hard} pair, emitted as --ulimit.
• Pod-level dns/sysctls/extra_hosts. These apply to every
  container in the pod (one shared /etc/resolv.conf, sysctl set, and
  /etc/hosts) — dns/dns_search/dns_opt are unioned across the
  target's dependency closure; sysctls union by key, refusing a same-key
  conflict; extra_hosts merges the same way (see Fix, above). validate()
  warns whenever any service in the document declares one of these, even
  outside the target's closure.
• Core process, confinement, and metadata keys: entrypoint, user,
  working_dir, group_add, labels, read_only, init, privileged,
  cap_add, cap_drop, security_opt, platform, devices,
  annotations, pull_policy. Each is an honest, validated passthrough to
  its podman run flag.
• profiles and stop_signal/stop_grace_period are now accepted and
  ignored (with a warning) rather than rejected — compose2pod's run set is
  always --target plus its depends_on closure, and the generated script
  always force-removes the pod, so neither key changes anything it can act
  on. A target depends_on reaching a service outside its declared profile
  still runs it (the closure is authoritative — more permissive than
  Compose, never a silent drop).

Packaging

• resolve_extends is exported from compose2pod.__all__, alongside
  the existing EmitOptions, UnsupportedComposeError, emit_script,
  to_shell, and validate.

Why

Prior releases built the core single-pod model and its interpolation
semantics; this one rounds out the compose keys real-world compose files
actually use, so fewer documents need pre-editing before they run.
Discovering the --add-host regression only on a real Podman run — not from
any of the 363 existing unit tests, all of which assert on generated
script text — is exactly why the integration harness (see Internals) was
worth building: some regressions are only visible to the runtime it targets.

Downstream

• Compose files using extra_hosts for a service-specific override: it
  is now pod-wide. A host name your extra_hosts maps to one address must
  not conflict with another service's mapping, or with an alias's fixed
  127.0.0.1 — compose2pod now refuses rather than silently picking one.
• Any pod that previously failed with network cannot be configured when it is shared with a pod now works without changes to your compose file.
• API consumers: compose2pod.resolve_extends(compose) is now
  available for flattening extends outside the CLI pipeline.

Internals

• 363 tests at 100% line coverage (enforced); ruff select=ALL, ty, and
  eof-fixer clean.
• A new CI-only integration harness (tests/integration/, 10 scenarios)
  renders real compose documents and runs the generated script against real
  Podman on ubuntu-latest, asserting on exit code and output — it caught
  the --add-host regression above on its first run. Kept out of the
  100%-coverage gate and the fast suite via a location-based marker.
• compose2pod/keys.py's SERVICE_KEYS registry unifies what was
  previously three hand-synced tables (validation, emission, and the
  supported-key set) into one (validate, emit) pair per key.

0.1.8

compose2pod 0.1.8 — interpolation moves to run time

This release reverses 0.1.7: Compose ${VAR} interpolation now happens when
the generated script runs, not when compose2pod generates it. compose2pod
emits a script that runs later — typically in CI, where the real secrets and
config live — so resolving against compose2pod's own environment at generation
time baked any variable that was unset then to an empty string. References are
now emitted as live POSIX-shell fragments that the runtime shell expands.

Change

• ${VAR} is interpolated at script-run time, not generation time.
  to_shell() (new compose2pod/shell.py) re-encodes every compose-derived
  value (environment, image, command, volumes, tmpfs, env_file,
  healthcheck test) into a double-quoted shell fragment whose variable
  references stay live, so the generated script's own shell resolves them
  against its runtime environment. All the 0.1.7 forms still work — $VAR,
  ${VAR}, ${VAR:-default}, ${VAR-default}, ${VAR:?msg}, ${VAR?msg},
  ${VAR:+alt}, ${VAR+alt}, $$ — mapping onto identical POSIX sh
  parameter expansion. A bare $VAR/${VAR} is emitted as ${VAR-} so an
  unset variable expands to empty under the script's set -eu instead of
  aborting; ${VAR:?msg} now fails the script at run time (not at generation).
  Command substitution and other shell metacharacters in literal text are
  escaped, so nothing but a variable reference is ever live. The CLI prints one
  informational note listing the variables the script references at run time.

Fix

• environment null value is host passthrough. A null mapping value
  (KEY:) now emits a bare -e KEY — passing KEY through from the host,
  identical to the list form - KEY — instead of the literal -e KEY=None.
• Malformed braced references are rejected. A braced reference whose text
  after the name is not a valid operator (e.g. ${FOO!bar}) now raises a clear
  UnsupportedComposeError instead of silently dropping the trailing text.

Packaging

• Public API: the generation-time interpolate function is removed;
  to_shell is exported in its place. to_shell(value) returns a
  runtime-expandable shell fragment, not a resolved value.

Why

The 0.1.7 model resolved ${VAR} against os.environ at generation time. For
compose2pod's actual use — generate a script now, run it later in CI — that was
the wrong moment: the variables are supposed to be unset at generation and set
at run time, so 0.1.7 baked them to empty and emitted a spurious "variable not
set" warning. Deferring to the runtime shell resolves them where they exist.

Downstream

• Compose files: set ${VAR} values in the runtime environment of the
  generated script (e.g. your CI job), not in the environment that runs
  compose2pod. An unset bare ${VAR} now expands to empty at run time; write
  ${VAR:?message} where you want a missing variable to fail the run.
• API consumers: compose2pod.interpolate is gone. Use
  compose2pod.to_shell(value), which emits a runtime-expandable shell fragment
  rather than resolving the value in-process.

Internals

• architecture/supported-subset.md rewritten to describe run-time expansion,
  the ${VAR-}/$$/${VAR:?} semantics, env_file interpolation, the
  reference note, null-value passthrough, and malformed-reference rejection.
• 123 tests at 100% line coverage (enforced); ruff select=ALL, ty, and
  eof-fixer clean. test_shell.py executes emitted fragments under real
  sh -euc to prove run-time expansion, the ${VAR:?} abort, and
  command-substitution inertness.

0.1.7

compose2pod 0.1.7 — variable interpolation

A patch release resolving Compose-spec ${VAR} variable interpolation
against the process environment. Previously, a compose file using ${VAR}
reached the container as the literal placeholder text — shlex.quote
correctly single-quoted the value for safe script embedding, which also
meant the shell never expanded it, so nothing in the pipeline ever
substituted the real value. Compose files that lean on host/CI environment
values now convert and run correctly, matching docker compose.

Fix

• ${VAR}-style interpolation is resolved. Every string leaf of the
  compose document is checked against os.environ before validation: $VAR,
  ${VAR}, ${VAR:-default}, ${VAR-default}, ${VAR:?msg}, ${VAR?msg},
  ${VAR:+alt}, ${VAR+alt}, and $$ (literal $) are all supported. An
  unset $VAR/${VAR} with no default resolves to an empty string and
  prints a warning rather than failing; ${VAR:?msg}/${VAR?msg} raises a
  clear error instead of silently defaulting.

Downstream

No action needed — additive and backward compatible. A document with no
$-prefixed values is unaffected; one that already relied on the previous
literal pass-through (unlikely, since it's not useful behavior) would now see
the resolved value instead.

Internals

• architecture/supported-subset.md documents the supported interpolation
  forms and the explicit non-goal: no .env file loading, only the caller's
  existing environment is consulted.
• 123 tests at 100% line coverage (enforced); ruff select=ALL, ty, and
  eof-fixer clean.

0.1.6

compose2pod 0.1.6 — accept the service tmpfs key

A patch release that stops rejecting valid compose documents which set a
service tmpfs. The validator was over-strict: a service carrying tmpfs: —
a string or list of <path>[:<options>] entries, e.g. /tmp:mode=1777 —
raised unsupported key 'tmpfs'. Such documents now convert.

Fix

• The service tmpfs key is accepted. validate() no longer rejects a
  service that sets tmpfs:. Each entry is emitted verbatim as podman run --tmpfs <value> — Compose's short syntax maps directly onto podman's own
  --tmpfs CONTAINER-DIR[:OPTIONS] flag, so no translation is needed. No
  format validation; a malformed option string surfaces as a podman error at
  run time.

Downstream

No action needed — additive and backward compatible. Documents that previously
failed with unsupported key 'tmpfs' now emit a pod script; nothing that
converted before changes.

Internals

• architecture/supported-subset.md documents tmpfs in the Service keys
  matrix.
• 98 tests at 100% line coverage (enforced); ruff select=ALL, ty, and
  eof-fixer clean.

0.1.5

compose2pod 0.1.5 — named volumes

A patch release accepting Compose named volumes, previously a hard error.
Compose files that declare a top-level volumes: block or reference a named
volume in a service (e.g. pgdata:/var/lib/postgresql/data for database data
persistence) now convert without editing the compose file.

Fix

• Named volumes are accepted. A service volume whose source is a bare
  identifier rather than a host path (a Compose named volume) is emitted
  verbatim as -v <name>:<target>. Podman creates the volume implicitly on
  first reference — the same behavior as plain podman run -v — so no
  explicit podman volume create step is needed. The volume persists on the
  host after the pod is removed, identical to docker compose down without
  -v.
• Top-level volumes: is accepted (ignored). Mirrors the existing
  top-level networks treatment: the block's driver/driver_opts and
  external settings are never read, since implicit creation with default
  options is what podman does regardless. A non-default driver or an
  external: true volume that should pre-exist has no special handling.

Downstream

No action needed — additive and backward compatible. Documents that previously
failed with unsupported top-level keys: ['volumes'] or "named volume ... is
not supported" now emit a pod script; nothing that converted before changes.

Internals

• architecture/supported-subset.md documents the bind-mount vs named-volume
  disambiguation (source starts with .// vs bare identifier) and the
  default-driver-only limitation.
• 95 tests at 100% line coverage (enforced); ruff select=ALL, ty, and
  eof-fixer clean.

0.1.4

compose2pod 0.1.4 — accept the service container_name key

A patch release that stops rejecting valid compose documents which set a
service container_name. The validator was over-strict: a service carrying
container_name: — used to give a service a stable name that other services
connect to — raised unsupported key 'container_name'. Such documents now
convert.

Fix

• The service container_name key is accepted. validate() no longer
  rejects a service that sets container_name:, and the name is made
  resolvable to 127.0.0.1 inside the pod, exactly like hostname and network
  aliases already are: it joins the --add-host set so other services reach it
  by that name. The actual podman container keeps its internal
  {pod}-{service} name (used for podman cp, healthcheck polling, and
  diagnostics) — only name resolution is affected, matching the pod's
  shared network namespace.

Downstream

No action needed — additive and backward compatible. Documents that previously
failed with unsupported key 'container_name' now emit a pod script; nothing
that converted before changes.

Internals

• architecture/supported-subset.md merges the hostname/container_name
  note explaining both are shared-namespace-resolvable but never change the
  real --name.
• 92 tests at 100% line coverage (enforced); ruff select=ALL, ty, and
  eof-fixer clean.

0.1.3

compose2pod 0.1.3 — anonymous volumes no longer crash

A patch release fixing a crash on Compose files that use anonymous volumes. A
short-form volume that is a single container path with no source:target (e.g.
- /var/cache/models) passed validation but then crashed the emitter with
ValueError: not enough values to unpack. Such files now convert.

Fix

• Anonymous volumes are emitted as -v <path>. A colon-less volume entry
  is a Compose anonymous volume; it is now rendered verbatim as podman run -v <path> (podman creates an anonymous volume at that container path) instead of
  crashing run_flags. No host-path translation is applied — the entry names a
  container path, not a host source.
• Malformed colon-less volumes are rejected loudly. A colon-less entry that
  is not absolute (e.g. ./cache) is invalid Compose and now raises a clear
  unsupported-style error instead of silently emitting a broken -v ./cache,
  keeping compose2pod's "refuse loudly, never emit a silently broken script"
  contract.

Downstream

No action needed — additive and backward compatible. Compose files that
previously crashed with ValueError: not enough values to unpack on an
anonymous volume now emit a pod script; nothing that converted before changes.

Internals

• architecture/supported-subset.md documents anonymous volumes in the Volumes
  matrix (absolute accepted and emitted as -v <path>; non-absolute raises).
• 89 tests at 100% line coverage (enforced); ruff select=ALL, ty, and
  eof-fixer clean.

0.1.2

compose2pod 0.1.2 — accept the service hostname key

A patch release that stops rejecting valid compose documents which set a
service hostname. The validator was over-strict: a service carrying
hostname: — used to give a service a stable name that other services connect
to — raised unsupported key 'hostname'. Such documents now convert.

Fix

• The service hostname key is accepted. validate() no longer rejects a
  service that sets hostname:, and the hostname is made resolvable to
  127.0.0.1 inside the pod, exactly like a network alias: it joins the
  --add-host set so other services reach the service by that name. Because all
  services share one network namespace (and the pod's UTS namespace), only name
  resolution is meaningful — no per-container --hostname is emitted.

Downstream

No action needed — additive and backward compatible. Documents that previously
failed with unsupported key 'hostname' now emit a pod script; nothing that
converted before changes.

Internals

• architecture/supported-subset.md adds hostname to the supported
  service-key matrix with the shared-namespace resolution rationale.
• 86 tests at 100% line coverage (enforced); ruff select=ALL, ty, and
  eof-fixer clean.