plugin docs: stdin/stdout uses type:"body" inside callbacks#4
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martinrode wants to merge 2 commits into
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plugin docs: stdin/stdout uses type:"body" inside callbacks#4martinrode wants to merge 2 commits into
martinrode wants to merge 2 commits into
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June 9, 2026 12:18
…form) The "Format of manifest.yml" example showed `stdin.url: "%_input.url%"` and `stdout.url: "%_output.url%"` inside the `callbacks:` block. That syntax is correct for `extensions:` (which expose the input/output as HTTP endpoints via the on-the-fly /reader and /writer mechanisms) but not for callbacks. In the callback dispatch path the placeholder is not substituted, and fylr attempts to use the literal "%_input.url%" as the URL to GET stdin from. The resulting `parse "%_input.url%": invalid URL escape "%_i"` error is what a plugin developer building a `db_pre_save` callback hit during local testing. Update both `transition_db_pre_save` and `db_pre_save` examples to use `type: "body"` (matching the IUCN plugin's `manifest.yml` and the dot.yml cookbook). Add a hint near the start of the Callbacks section explicitly calling out the extension-vs-callback transport difference and quoting the actual error message so the next person who hits it can search for it. The `extensions:` example at the top of the file is left unchanged — that one was already correct.
The "Format of manifest.yml" callback examples referenced their script files by bare relative paths (`value: "set_comment.js"`). At runtime fylr's execserver runs the plugin process with cwd set to the per-job working directory under `tempDir` — *not* the plugin's directory — so the runtime can't find the script and fails with the language-specific "module not found" error (Node.js: `MODULE_NOT_FOUND` from `Module._load`; Python: `FileNotFoundError`; etc.). The fix is the `%_exec.pluginDir%` replacement, which already exists in `internal/server/execserver/exec.go:130` and is used in working real-world plugins (e.g. `easydb-custom-data-type-iucn/manifest.yml`: `value: "%_exec.pluginDir%/src/server/main-fylr.py"`). It was just never documented on the plugin doc page. Two changes: 1. Add `%_exec.pluginDir%` to the replacement table near the top of the page, with a one-line explanation of *why* you need it (so readers don't have to hit the runtime error first to learn the rule). 2. Update the two callback example blocks to prefix their script paths with `%_exec.pluginDir%/`, matching what an actually-working plugin looks like. The extension example at the top of the file already used absolute referencing for `%info.json%`, so the change there is just adding the prefix on the script-file `value`.
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Summary
Triggered by Andre Buhl hitting the documented form while writing his first server-side plugin against a Windows-local fylr instance.
The "Format of manifest.yml" example placed the extension-style URL form (
stdin.url: "%_input.url%"/stdout.url: "%_output.url%") inside bothcallbacks.transition_db_pre_saveandcallbacks.db_pre_saveexample blocks. That form works inextensions:because fylr exposes the input/output as on-the-fly HTTP endpoints there. In callbacks the same placeholder is not substituted — the execserver receives the literal string and fails to GET stdin from it:The two callback examples now use
type: "body", matching the IUCN plugin's manifest (easydb-custom-data-type-iucn/manifest.yml) and the fylr-internal cookbooks (resources/baseconfig/fas/cookbooks/dot.yml:14ff).Added a hint block near the top of the Callbacks section that:
The
extensions:example near the top of the file is unchanged — that one was already using the correct URL form.Test plan
callbacksYAML blocks now readtype: "body"for stdin and stdoutextensions:example was left intact🤖 Generated with Claude Code