Central hooks - 3to1go

Hooks let Central run a shell command at two points while storing an upload:

Pre command: after an upload has arrived and passed its checksum, before Central stores it. Central waits for it to finish.
Post command: after storage succeeds, or when storing a new archive fails. Earlier failures, such as a checksum mismatch, do not run the post command. Retrying a completed upload does not rerun hooks.

Use them to trigger an offsite sync, write to a log, or ping a monitoring service.

Set up

Open Custom Scripts

In Central, click Custom Scripts.

Upload a script (optional)

Under Uploaded Items, upload up to 3 files. Only .sh scripts and .txt helper files are allowed, and they must be UTF-8 text. .sh files are made executable, and Windows line endings are converted.

Set the commands

Enter a Pre Command and/or Post Command. Either:

the name of an uploaded script, such as after-upload.sh, or
any shell command, such as curl -fsS https://hc-ping.com/your-id.

Commands run with sh -c inside the Central container, from the hook scripts folder (/hook-scripts). Each command has a 5-minute timeout. Output and non-zero exit codes are written to Central’s logs; a failing hook doesn’t stop the upload.

Environment variables

Every hook gets these variables:

Variable	Value
`THREETOONEGO_APP`	`central`
`THREETOONEGO_HOOK_PHASE`	`pre` or `post`
`THREETOONEGO_HOOK_SCRIPTS_DIR`	The hook scripts folder
`THREETOONEGO_EDGE_ID`	Sending Edge’s ID
`THREETOONEGO_EDGE_INSTANCE_ID`	Sending Edge’s instance ID
`THREETOONEGO_JOB_NAME`	Backup job name
`THREETOONEGO_UPLOAD_ID`	Upload session ID
`THREETOONEGO_NAMESPACE`	Storage path, `edge_id/instance_id/job_name`
`THREETOONEGO_FILENAME`	Uploaded filename
`THREETOONEGO_FINGERPRINT`	Snapshot fingerprint
`THREETOONEGO_TIMESTAMP`	Snapshot timestamp
`THREETOONEGO_ARCHIVE_SHA256`	SHA-256 of the encrypted archive
`THREETOONEGO_ARCHIVE_SIZE_BYTES`	Archive size
`THREETOONEGO_SOURCE_ADDRESS`	IP the upload came from
`THREETOONEGO_ADVERTISED_URL`	URL the Edge advertises, if set
`THREETOONEGO_STAGED_PATH`	Where the upload is staged before storing

The post command also gets:

Variable	Value
`THREETOONEGO_STATUS`	`ok` or `error`
`THREETOONEGO_STORED_AS`	Final stored filename
`THREETOONEGO_PRUNED`	Number of old snapshots removed by retention
`THREETOONEGO_DUPLICATE`	`true` if Central already had this snapshot

Example: log each stored snapshot

after-upload.sh

#!/bin/sh
[ "$THREETOONEGO_STATUS" = "ok" ] || exit 0
echo "stored $THREETOONEGO_NAMESPACE/$THREETOONEGO_STORED_AS"

Set Post Command to after-upload.sh.

The Central image is a minimal Alpine image with sh and curl. Tools like rclone aren’t included; run those on the host or in another container that reads the same backup folder.

​Set up

​Environment variables

​Example: log each stored snapshot

Set up

Environment variables

Example: log each stored snapshot