werkator/docs/configuration.md

Werkator Configuration Reference

Werkator is configured via YAML files. Settings are merged from several sources in order — later layers override earlier ones.

Config File Locations

Layer	Path	Committed to Git	Purpose
Instance config	~/.werkator.yml	No	The repository registry and the instance-level settings; optional defaults below every repository (see below)
Project config	.werkator.yml	Yes	Shared team settings
Applied instance fragment	.git/werkator/.werkator.applied.yml	No	Instance parameters installed by init --apply
Repo installation config	.git/werkator/.werkator.yml	No	Machine- or user-specific overrides, secrets
Branch config	.werkator.yml committed on a branch	Yes	That branch's build settings and build definitions

The repo install config (.git/werkator/.werkator.yml) wins on any key present in several files; the applied fragment wins over the project config. Typically the repo install config sets git.token and git.account without committing them.

The applied instance fragment (init --apply)

werkator init --apply FILE installs a YAML fragment in this very schema as its own layer (step 23) — the file a deployment wrapper hands over instead of patching configs. The fragment is validated strictly before installing: an unknown key is refused loudly, never ignored, because a typo would otherwise install a value that silently does nothing. It is then copied verbatim (comments included) to .git/werkator/.werkator.applied.yml; re-applying replaces the file, so nothing accumulates or duplicates, and the hand-edited repo install config — which always wins — is never rewritten.

Which Werkator a file is written for

Every configuration file may declare the Werkator it was written for. Without it, a version that renames or drops a key does not fail — it silently ignores what it no longer understands, and the effect shows up as a build that does the wrong thing.

werkator:
  version:
    since: "0.9.16"   # enforced: an older Werkator refuses to read this file
    below: "2.0"      # your release marker; Werkator decides how strictly to take it

There is deliberately no version of the file format (no apiVersion): no API is involved — Werkator reads its own configuration — and only one configuration generation is ever supported. The declaration exists to make an incompatibility nameable, never to run two parsers.

since is a hard floor and covers both directions:

• a newer file on an older Werkator is refused instead of being half-understood;
• a file written before a breaking change and read after it is refused as well — Werkator knows in which version its configuration format last broke, so the message can name the change: "is written for Werkator 1.4.0, but the configuration format changed incompatibly in 2.0.0: builds: is now buildSpec:".

below is optional and names the first version this file was not released for. The bound is exclusive, so below: "2.0" means everything up to 2.0.0. On its own it only warns — a caution marker nobody maintained must never stop a CI. The refusal above comes from Werkator's own knowledge of its breaking changes, not from this value. The intended routine is the one known from IDE plugins: a new version appears, the warning shows up, you try it (on a test host, or in production with a rollback ready), and then raise below and commit that.

A file that declares nothing is read as before, with a hint in the log — a missing line must never stop a server either. werkator init writes the running version into the generated config.

How far a violation reaches depends on the file, following the same rule as everything else here: the machine and project configs abort the start (the message names the file and the rollback), while an incompatible branch config fails only the builds of that branch. A branch that was cut before a migration must never stop the server or hold up the branches that are fine.

The branch layer: a branch describes its own CI

The .werkator.yml committed on a branch is applied as a third layer on top of the two above, giving the precedence branch > repo install > project. It takes precedence for everything that describes how this branch is built: the whole builds section — its own definitions and its overrides of the definitions from the project config, with buildCommand, cleanCommand, artifactDirs, log file names, and docker.image/dockerfile/context/env and werkdock.env inside them. That is how a new configuration is tried out: change it on a branch, and no other branch's builds are affected.

The branch layer is used in both places where it matters: the watcher reads the committed config of each origin branch (via git show, only when the branch moved) to decide which of its builds are due, and the build itself resolves its settings from the worktree of the commit being built.

A branch's definitions apply to that branch alone. Their selectors are evaluated for it only, so a definition committed on one branch can never trigger builds of another — even when its branches selector names one.

A pinned set is always taken from the repo install/project config, because none of it describes this branch's build. Which of those two files is expected to carry a key gives the two names used throughout this documentation.

host-pinned — only the machine can know it, and it never belongs in the repository:

• secrets: the whole git section;
• the host's own addresses and ports: the whole server section.

master-pinned — it belongs in the repository, where changing it needs a review, but no single branch may decide it:

• the repository-side settings: the whole gitea, executor, and watcher sections;
• the trust gate: requirePullRequest, and the Gitea status context: statusContext;
• the container sandbox policy: docker.enabled/docker.network and werkdock.enabled/werkdock.rootfs/werkdock.binary — host-pinned as long as only the host's configuration sets them, master-pinned once the committed configuration does;
• the trigger of a follow-up build: trigger.afterSuccessOf in every definition, and the whole trigger block of a definition the host defines as a follow-up. A branch may say what its deployment does, never that — or for which branches — it happens.

The distinction is documentary. Werkator applies one rule: every pinned key is stripped from the branch layer, and the value then resolves from whichever remaining layer sets it. The names say where a key is meant to live, not how it is enforced.

This keeps a branch from reaching credentials, reporting statuses to another repository, raising the global concurrency, disabling its own build container, changing its network mode, bypassing its own pull-request gate, or deploying itself. Everything else is the branch's to decide — it can already run any command through buildCommand. The pinned settings are stripped wherever they appear, in a build definition as well as in a legacy branches entry. The deprecated branches section itself is read from the repo install/project config only, and only while nothing defines a build at all.

~/.werkator.yml — the instance configuration

One Werkator instance serves a set of repositories (ADR 0009): one service, one port, one UI, one watcher loop. The set and everything shared by it live in .werkator.yml in the home directory of the user running Werkator — one instance per OS user. The file name is deliberately the same everywhere; only the location carries the meaning: home is the instance, the repository root is the project, .git is the machine. WERKATOR_HOME overrides the directory the file is looked up in.

Without this file Werkator serves the current working directory exactly as before. With it, the registry wins over the current directory: werkator server serves the registered repositories wherever it is started.

werkator:
  version:
    since: "0.9.16"          # like every other config file

repositories:                # the registry; each entry is one served repository
  - path: ~/repos/werkator   # absolute, or relative to the home directory (~ expands)
  - path: ~/repos/werkbaum
    name: baum               # optional; default is the directory basename

server:                      # the instance's server section — port, bind address, public URL, nginx
  port: 18080
executor:
  maxConcurrent: 2           # the global cap over all repositories
watcher:
  pollInterval: 10s          # one loop, one delay

defaults:                    # optional: repository-level keys merged BELOW every repository's own layers
  git:
    account: ci-bot
    token: "…"               # secrets may then live here instead of in each repository
  gitea:
    baseUrl: https://git.example.org

Key ownership once this file exists:

• Instance-level — read from this file alone: the whole server section, executor.maxConcurrent, and watcher.pollInterval. A repository file still carrying one of them is ignored on that key, with one warning naming both files; it is never merged silently.
• Repository defaults — the defaults block, in the repository config schema: merged below each repository's project config, applied fragment, machine config, and branch layer, so a repository's own value always wins. Pinning is unchanged: home defaults and the repository's machine config are both host-side layers, and a branch still cannot reach a pinned key.
• Repository-level — everything else stays in the repository's own files: gitea.*, git.* credentials, builds, retention, the other watcher keys (pullRequestGate, newBranchMaxAge, fastForwardLocalRefs), and the sandbox policy.

Repository names are the --repo selector of werkator build, retry, and status (without it a command means the current directory when served, otherwise the first registered repository) and will become the route segment of the web UI. Two entries resolving to the same name abort the start, as does an entry that is not a git repository. A repository whose configuration this Werkator must not read (see the version declaration) is skipped with an error; the others are served.

Inspect the Effective Config

java -jar build/libs/werkator.jar config:print         # only explicitly set values
java -jar build/libs/werkator.jar config:print --full  # all values including defaults

git.token is masked as *** by default, so the output can safely be shared or pasted. Add --show-secrets to print it in clear text.

.werkator.yml

Values shown are the defaults.

# The Werkator this file is written for (see the section above).
werkator:
  version:
    since: "0.9.18"   # enforced: older Werkator refuses this file
    below: "2.0"      # optional release marker; warns, does not block

server:
  # Public base URL of this Werkator installation — used for all links posted to Gitea.
  publicBaseUrl: https://ci.example.org/
  # HTTP port of the `server` subcommand (default 18080, like legacy)
  port: 18080
  # bind address of the `server` subcommand; loopback only, because the UI and the API
  # are unauthenticated — set 0.0.0.0 only deliberately (see the note below)
  bindAddress: 127.0.0.1
  # optional Impressum (legal disclosure) link in the web UI footer; empty hides the link
  impressumUrl: ""
  # Resource limits of the systemd user unit generated by `init --systemd`; empty = directive omitted.
  # Needed where the service shares a memory slice, e.g. Hostsharing Managed Webspaces, where a
  # runaway Gradle build would starve everything else in the package.
  systemd:
    memoryMax: ""   # e.g. 1G — written as `MemoryMax=` into the unit
    tasksMax: ""    # e.g. 512 — written as `TasksMax=` into the unit
  # Opt-in managed nginx+certbot Docker container for HTTPS, for hosts without
  # a usable reverse proxy (ADR 0005; see notes below and deployment.md).
  nginx:
    # manage an nginx Docker container with Let's Encrypt certificates
    enabled: false
    # public DNS name served by nginx and used for the certificate; required when enabled
    serverName: ""
    # host port published as nginx port 80 (ACME challenge + HTTPS redirect)
    httpPort: 8080
    # host port published as nginx port 443
    httpsPort: 8443
    # host nginx proxies to; empty = serverName (the container cannot reach localhost)
    upstreamHost: ""
    # name of the managed container; empty = werkator-nginx-<repo-name>
    containerName: ""
    # directory for nginx config, certificates, and logs;
    # empty = $XDG_STATE_HOME (or ~/.local/state) plus /werkator/nginx/<repo-key>
    stateDir: ""
    # e-mail for the Let's Encrypt account; empty registers without one
    letsencryptEmail: ""

# Gitea integration for fetching commits and posting build statuses.
gitea:
  baseUrl: https://git.example.org   # base URL of the Gitea instance
  owner: my-org                      # repository owner (user or organisation) for Gitea API (e.g. status checks)
  repo: my-repo                      # repository name
  statusContext: werkator            # label shown on Gitea commit status checks (default: werkator)

# Build execution settings, enforced for all builds regardless of their trigger
# (watcher, UI restart, CLI build/retry).
executor:
  # How many builds may run at the same time.
  # At most one build per branch runs regardless; each branch builds in its own
  # git worktree under .git/werkator/worktrees/, never in the primary checkout.
  # Changing this value requires a restart.
  maxConcurrent: 1

# Named build definitions (jobs, see notes below); every key names a build.
builds:
  # "default" is the base every other definition inherits its settings from — never its
  # trigger — and, with a trigger of its own, the build of every branch it selects.
  # Without this entry an implicit default build (onPush over all branches) applies;
  # writing it replaces that implicit one, so a default without a trigger is a settings
  # base and nothing else.
  default:
    # When this build runs and for which branches — the only part a definition does NOT
    # inherit from builds.default; everything below the block does.
    trigger:
      onPush: true              # build every new commit of the selected branches
      # branches: ["*", "!master"]   # names or globs; a "!" pattern excludes; default: all
      # atTimes: ["01:00"]           # daily UTC times HH:MM ("??:05" = every hour at :05)
      # activeWithin: 24h            # only branches with commits in the last 24h
      # afterSuccessOf: test         # run after every green run of that build, at its commit (pinned)
    # run before each build
    cleanCommand: rm -rf build
    # shell command for each build
    buildCommand: ./gradlew --console=plain --no-daemon test
    # directories copied as build artifacts; each is archived at its own
    # workspace-relative path, except build/reports, which archives as reports/
    # and is browsed by the artifact page's report index
    artifactDirs:
      - build/reports
      - build/doc
    stdoutLog: build.stdout.log   # filename for captured stdout
    stderrLog: build.stderr.log   # filename for captured stderr
    # Build a selected branch only while its head commit matches a pull-request head on
    # origin (refs/pull/*/head — read via plain git, no API token needed; see notes below).
    # Pinned: a branch cannot set this in its own committed config.
    requirePullRequest: false
    # Gitea check this build reports as; empty uses gitea.statusContext. Two builds of one
    # commit under the same context overwrite each other. Pinned like requirePullRequest.
    statusContext: ""
    # Optional Docker build runtime; when enabled, the clean and build commands
    # run inside a container instead of natively (see notes below).
    docker:
      # run clean/build commands in a Docker container (pinned)
      enabled: false
      # image for the build container; required when enabled
      image: ""
      # Dockerfile to (re)build the image from when it is missing or stale; empty pulls the image as-is
      dockerfile: ""
      # Docker build context used with dockerfile
      context: "."
      # Docker network mode for the build container; empty = Docker default (pinned)
      network: ""
      # additional environment variables set inside the build container
      env: {}

  # Every further job inherits the settings above and brings its own trigger.
  # The nightly rebuild runs the full check instead of the quick on-commit one and is
  # recorded separately as master@pitest:
  pitest:
    trigger:
      atTimes: ["01:00"]
      branches: ["master", "release/*"]
      activeWithin: 24h
    buildCommand: ./gradlew -PfullPitTest --console=plain --no-daemon piTestFull
    artifactDirs: [build/reports, build/libs]
    statusContext: werkator/pitest

# Build artifact storage and retention.
artifacts:
  # Root directory for stored build artifacts.
  # Empty means the platform default: $XDG_STATE_HOME (or ~/.local/state) plus /werkator/artifacts/<repo-key>,
  # where <repo-key> is the sanitized absolute repository path.
  # A leading ~/ expands to the home directory; a relative path is resolved against the repository.
  rootDir: ""
  # number of builds to keep per branch
  retentionPerBranch: 3
  # Additionally drop builds older than this age; suffixes s (seconds), m (minutes), h (hours), d (days).
  # Empty means no age limit.
  # Combines with retentionPerBranch: a build is kept only while it satisfies both limits.
  # A branch's newest build is never age-pruned, so dormant branches keep their last status.
  retentionMaxAge: ""
  # Keep each branch's latest green (successful) build even beyond retentionPerBranch and retentionMaxAge.
  # This backs the permanent artifact URLs /branches/<branch-key>/... — they always serve
  # the latest green build of a branch and stay valid while newer builds fail.
  # The kept build is still dropped once its branch is deleted from origin.
  keepLatestGreen: true

# Controls the branch-polling loop.
watcher:
  # delay between poll cycles; suffixes s (seconds), m (minutes), h (hours), d (days)
  pollInterval: 10s
  # max commit age for new origin branches to be pulled automatically
  newBranchMaxAge: 5d
  # Honor the builds.<name>.requirePullRequest gates (see notes below).
  # Set false for a plain git origin without pull-request refs (no Gitea/GitHub);
  # gated branches then build on new commits like any other branch.
  pullRequestGate: true
  # At the end of each poll cycle, fast-forward the primary checkout's local branch refs
  # to their origin counterparts (see notes below). Fast-forward only — a diverged or
  # ahead local branch is never touched. Set false to leave refs/heads/* alone entirely.
  fastForwardLocalRefs: true

Notes on server.bindAddress

The default is 127.0.0.1. Neither the web UI nor the JSON API authenticates read access — which is intended, so build states and artifacts can be linked from anywhere — so Werkator is meant to sit behind the host's reverse proxy rather than on a public interface. Set 0.0.0.0 only deliberately — for the managed nginx container (which reaches Werkator over the Docker bridge, not over loopback), or when the proxy runs on another host. Installations created before v0.9.9 have bindAddress: 0.0.0.0 written into their .werkator.yml and keep it; the new default only applies where the key is absent or init writes a fresh file.

Notes on server.nginx

With nginx.enabled, the server subcommand also starts a managed nginx Docker container that serves Werkator over HTTPS (ADR 0005). This is meant for hosts that provide Docker but no usable reverse proxy (e.g. Hostsharing managed containers); otherwise prefer the reverse-proxy setup in deployment.md. Certificates are obtained and renewed via Let's Encrypt (certbot Docker container, webroot mode), so serverName must be a public DNS name pointing at the host and httpPort must be reachable from the internet as port 80 (or via a port forward). When server.publicBaseUrl is empty and serverName is set, it defaults to https://<serverName>/. All nginx/certificate failures are non-fatal warnings; the plain HTTP server keeps running without the proxy. The container is labelled org.hoennig.werkator; stale nginx containers of the repository are removed before each start, and the container is removed on shutdown. server.port must differ from httpPort and httpsPort.

Notes on builds.<name>.requirePullRequest

The gate applies to all watcher-triggered builds (push-triggered and scheduled auto builds). A manual werkator build <branch> always builds, regardless of this setting.

Detection works without a Gitea API token: the watcher lists refs/pull/*/head on origin via git ls-remote and builds a branch only when its head commit equals one of those pull-request head commits. This ls-remote call is made at most once per poll cycle, and only when a branch requiring a pull request is otherwise due.

Because matching is by commit id, a closed pull request whose head ref still equals the branch head also counts. Distinguishing open from closed pull requests would require the Gitea API.

To build pull-request branches only, gate the default build and give the permanent branches a build of their own:

builds:
  default:
    trigger:
      onPush: true
      branches: ["*", "!main"]
    requirePullRequest: true
  main:
    trigger:
      onPush: true
      branches: ["main"]
    requirePullRequest: false

Without that second definition, direct pushes and merges to main would never build — merge commits do not match any pull-request head. The !main exclusion keeps the default build off it, so a push is built once instead of by both definitions.

A plain git origin (no Gitea/GitHub) serves no refs/pull/*/head at all, so gated branches would never build there. For such origins, disable all gates globally with watcher.pullRequestGate: false — typically in the machine-specific .git/werkator/.werkator.yml, so the committed configuration keeps the gates for forge-backed environments.

Notes on builds (build definitions)

Every key of the builds section names a build definition (a job) over the branches — ADR 0007. A build definition has a trigger block — when it runs and for which branches — and the settings that say what it does. The split is structural because trigger is the one part never inherited from builds.default. Writing any of its keys outside the block is refused with a message naming the definition: ignoring them would leave the build without a trigger, and a job that silently stops running is worse than a configuration that refuses to load.

Triggers: onPush: true builds every new commit of the selected branches; atTimes: ["HH:MM", …] rebuilds their heads once per day and slot (UTC). A slot may also be written as ??:MM — that minute of every hour, expanded to its 24 slots, so the build runs hourly. Only the latest due slot of a day triggers, so slots missed while the server was down are skipped instead of piling up, and a slot whose pool is still building is retried on the next poll cycle until it succeeds. A definition may combine them; one with none of the three triggers (onPush, atTimes, afterSuccessOf) never runs automatically — which is how builds.default is written when it is meant as a settings base only. Werkator logs a warning once when no definition has a trigger at all, because such an instance never builds anything on its own.

Follow-up builds

afterSuccessOf: <name> makes a definition a follow-up of another one, its predecessor: it runs on the predecessor's branch at the predecessor's commit whenever a run of the predecessor ends green. This is how a deployment is configured: a deployment is a build that follows a green build, and it gets everything a build has — its own row in History with log and duration, its own Gitea check under its own statusContext, restart, cancel, artifacts, and the per-branch serialization.

Every green run counts, whatever started it — the push watcher, an atTimes slot, a UI restart, werkator retry, or the startup recovery — and a repeated green run of the same commit triggers the follow-up again. The follow-up builds the commit that was tested, not the branch's current origin head. A failed, cancelled, or interrupted run triggers nothing. The follow-up runs in the branch's worktree, after its predecessor, in the branch's sandbox or container — so a deployment tool like the Docker CLI is provided the way a compiler is. It inherits builds.default like every definition, so a deployment that wants the predecessor's output has to set cleanCommand: "" itself; a deployment command should rather be self-contained and rebuild what it ships, because a restart of the follow-up alone runs without its predecessor. The pull-request gate is not consulted for a follow-up: the predecessor passed it for the same commit, and the follow-up's branches selector is its own gate.

The trigger of a follow-up is pinned: a branch's committed config can neither add afterSuccessOf to a definition nor change the trigger block of a definition the host defines as a follow-up, so a branch cannot deploy itself. What the deployment does comes with the repository, like every build command; where and when it happens, and with which credentials, is the host's. The host's part lives in .git/werkator/.werkator.yml; credentials reach the sandbox like any build setting, through werkdock.env/docker.env, and a file such as an SSH key through the werkdock sandbox's persistent toolchain home, .git/werkator/buildenv/home/ on the host, which the sandbox mounts as /root.

# .git/werkator/.werkator.yml — the host's part: when, for which branches, with what
builds:
  deploy:
    trigger:
      afterSuccessOf: frontend
      branches: ["main"]
    statusContext: werkator/deploy
    werkdock:
      env:
        DEPLOY_TARGET: user@host:~/doms/example.org/htdocs-ssl

# .werkator.yml — the repository's part: what
builds:
  deploy:
    cleanCommand: ""
    buildCommand: scripts/deploy-prod.sh -y "$DEPLOY_TARGET"

A follow-up whose predecessor no definition has, and a cycle of follow-ups, refuse the start with a message naming the definition — a deployment that silently never runs is the failure the flat-key refusal exists to prevent. A branch whose committed config drops or renames the predecessor only loses its follow-up, with a warning naming the branch. A one-shot werkator build runs no follow-ups — its process ends with its build — and says which ones the server would have run.

Selector: trigger.branches lists branch names or glob patterns (* matches any characters, also across /); empty selects all origin branches. A pattern prefixed with ! excludes instead, and an exclusion always wins regardless of order — ["*", "!master"] is every branch but master. That is how a branch gets a build of its own without being built by the default one as well. activeWithin (e.g. 24h) additionally keeps only branches whose origin head commit is younger than the duration — useful to run a nightly deep check over all recently active branches. Both parts combine as an intersection.

Settings: buildCommand, cleanCommand, artifactDirs, stdoutLog/stderrLog, requirePullRequest, statusContext, and docker and werkdock with all their keys. A definition carries the complete description of its build; unset keys fall back to builds.default and then to Werkator's own defaults. requirePullRequest, statusContext, docker.enabled, docker.network, werkdock.enabled, werkdock.rootfs, and werkdock.binary are pinned (master-pinned, see the branch layer): they are read from the repo install/project config even when a branch sets them in its own committed config. So is the trigger of a follow-up build. Inheritance from builds.default covers the settings only — the trigger block says when and where this build runs and is never inherited. Definitions are part of the branch layer: a branch may add its own and override those from the project config, for its own builds only. Because the inheritance is applied after all layers are merged, a build a branch invents still inherits the host's builds.default — its sandbox policy included, which is what keeps the pinning effective for a build the host has never heard of.

The implicit default build (onPush: true, all branches) preserves the behavior without any definitions; defining other builds does not disable it, builds.default.onPush: false does. The default build records under the plain branch name; every other build records under <branch>@<name> with its own row in the branches view (sorted after its branch), its own retentionPerBranch count, latest status, and permanent latest-green artifact link. The URL key is the sanitized pool name — master@pitest is served as /branches/master_pitest/…. The pools live as long as the underlying branch exists on origin. Restart, werkator retry, and the startup recovery re-run a build under its recorded definition, resolving the settings from the current configuration — the job definition is the source of truth, not the historical run. The builds still run in their branch's worktree, one build per branch at a time. The Gitea commit status is reported per commit under gitea.statusContext, so two builds of the same commit overwrite each other's check — give the second one its own statusContext (werkator/quick, say), or keep them apart with an exclusion pattern.

The concurrency limit that used to live in this section moved to executor.maxConcurrent without an alias. A leftover builds.maxConcurrent key (or any other scalar where a definition belongs) is ignored with a warning, not a startup failure — a committed config cannot always be changed right away.

The legacy branches section

Before build definitions existed, the settings lived in a per-branch branches section, with branches.default as the fallback for every branch not listed. That section is deprecated and will be removed. It is still read, but only while the merged configuration defines no build at all: as soon as one real definition exists, branches is ignored completely and a warning names it. builds.maxConcurrent is not a definition — a configuration carrying only that leftover still uses branches.

Either or, never both: a definition now carries the complete description of its build, and two half-answers would silently pull against each other. The decision is made on the merged configuration, so a machine config that defines builds switches branches off for every branch, including the branches whose committed config still has one.

branches.<name>.autoBuild (enabled + times) is the pre-ADR-0007 schedule that goes with it: it rebuilds the branch's own pool with its regular command and logs a deprecation warning. autoBuild.times entries carrying their own buildCommand/name (a short-lived v0.9.13 syntax) are no longer supported — use a build definition.

To migrate, move branches.default to builds.default, add onPush: true, and turn every other branch entry into a definition with a branches selector of its own.

Notes on watcher.fastForwardLocalRefs

Builds run in worktrees that share the primary checkout's .git, so a build tool can read refs/heads/* there. Werkator itself never needs those refs to be current — it builds the commit refs/remotes/origin/<branch> points at — but build tools do. A common case is a check that refuses to run when the local main branch differs from its origin counterpart; without this key it would fail on every build once origin moved on, because nothing would ever advance the local ref.

The fast-forward runs at the end of the poll cycle, after the due branches were enqueued. That order is required, not cosmetic: a local ref lagging behind origin is exactly how the watcher recognizes new commits, so a ref kept in sync earlier — by this key, a cron job, or a mirroring fetch refspec (+refs/heads/*:refs/heads/*) — would silently stop the branch from ever being built.

Only fast-forwards are applied, as a compare-and-swap against the commit just read. A local branch that diverged from origin or is ahead of it stays untouched, so local work in the primary checkout is never lost. The branch checked out in the primary checkout is advanced with git merge --ff-only, which refuses to overwrite conflicting uncommitted changes; a refusal is logged and the cycle continues.

Notes on builds.<name>.docker

With docker.enabled, Werkator shells out to the docker CLI; the docker command must be on the PATH. When dockerfile is set, the image is (re)built whenever the Dockerfile content, its path, or the context path changed. Staleness is tracked via the image label org.werkator.build-inputs-sha256. A Gradle cache volume werkator-gradle-<repo-key> is created per repository and mounted as GRADLE_USER_HOME. The build worktree is bind-mounted into the container; after each command the ownership of build/ and .gradle/ is repaired to the host user. Git works inside the container: the primary repository's .git is mounted read-only (so build steps can run read-only git commands like git log or git describe), with .git/werkator/ masked by an empty tmpfs so the build can never read the machine config (git.token) or the control token. Note that the rest of .git — including .git/config — is visible to builds; Werkator never stores credentials there, and neither should you. The Docker socket is mounted into the container and DOCKER_HOST/TESTCONTAINERS_* variables are set, so Testcontainers-based builds work inside the container. All Werkator containers carry org.hoennig.werkator labels; stale build containers of the repository are removed before the first Docker build after a restart.

Notes on builds.<name>.werkdock

With werkdock.enabled, Werkator runs the build in a bubblewrap sandbox instead of native execution. This is the third runtime, for hosts without root and without a Docker daemon (e.g. Hostsharing managed webspaces); see docs/plan/17-bwrap-build-runtime.md and ADR 0008. Since step 21 session C the sandbox is executed by the werkdock CLI (werkdock.binary, default: resolved via PATH) — Werkator no longer invokes bwrap itself; bwrap must be installed for werkdock. The section was called bwrap and its binary key bwrap.werkdock until v1.2.0; both are still read, with a warning naming the file, so an installation can be migrated at its next configuration edit rather than at the next update. werkdock doctor checks the host's capability (it replaced the retired tools/werkator-build-prerequisites.sh in step 23).

werkdock.rootfs names the prepared root filesystem archive — a Debian-base rootfs with the build tools (JDK, git, locales, project-specific tooling) built elsewhere, since debootstrap is unavailable on the target. It is a local path or an http(s) URL; a URL is downloaded once into .git/werkator/buildenv/. Build the archive with tools/build-bwrap-rootfs.sh on any machine with Docker. The archive is loaded once per source as the werkdock image werkator-buildenv-<hash> into werkdock's store ($WERKDOCK_HOME, default ~/.werkdock) — shared by every repository of this OS user; the hash derives from the source string, so a changed rootfs loads a fresh image and stale ones can be removed from the store. Per-repo Gradle caches persist in .git/werkator/buildenv/home, bound as /root. werkdock.env adds environment variables inside the sandbox; the environment is otherwise cleared (docker semantics) — the server's environment does not leak in. Files created inside the sandbox are owned by the host user, because uid 0 maps back to the unprivileged webspace user.

docker and werkdock are mutually exclusive per branch: enabling both is rejected at start, not silently picked. Git works inside the sandbox exactly as inside the Docker container: the primary .git is mounted read-only with .git/werkator/ masked, so builds can run read-only git commands but never reach the machine config or the control token.

.git/werkator/.werkator.yml (not committed)

# Machine- or user-specific overrides and secrets. Keys here win over .werkator.yml.
git:
  account: my-user              # technical username for git HTTPS authentication
  token: glpat-xxxxxxxxxxxxxxxxxxxx # Gitea API token — never commit this