Slack

Holtdroid doesn’t talk to Slack itself. holtdroid-slack-sync is a separate, stateless job that polls channels and writes every .apk it finds, with a .meta.json sidecar, into a folder or S3 prefix that the api lists as a read-only source.

It picks up APKs:

• attached to channel messages;
• in thread replies;
• inside forwarded messages.

Optionally it announces new builds the same way as the other sync jobs: one message per pass through shoutrrr (Slack, Telegram, Discord, Matrix, ntfy, email, webhooks, …). The message lists each build’s name, version, package and size, a link to the Slack message, and two launch links:

• Quick launch starts a device right away with the user’s last provider and location;
• Launch opens the launch dialog.

1. Create the Slack app

The quickest way is to create it from the manifest:

1. Open https://api.slack.com/apps → Create New App → From a manifest, and pick the workspace.
2. Paste the manifest below, then click Create → Install to Workspace.
3. Copy the Bot User OAuth Token (xoxb-…) from OAuth & Permissions.

slack-app-manifest.yaml

display_information:
  name: Holtdroid
  description: Copies APKs posted here into Holtdroid and announces them with launch links.
  background_color: "#8a5a3c"
features:
  bot_user:
    display_name: Holtdroid
    always_online: false
oauth_config:
  scopes:
    bot:
      - channels:history
      - groups:history
      - files:read
      - users:read
      - chat:write
settings:
  org_deploy_enabled: false
  socket_mode_enabled: false
  token_rotation_enabled: false

Scope	Needed for
channels:history, groups:history	reading public / private channels
files:read	downloading the APKs
users:read	uploader names (optional; without it you see user IDs)
chat:write	announcements into Slack (optional)

Manifests can’t set the app icon, so upload it under Basic Information if you want one, e.g. assets/holtdroid-icon.png.

Then invite the bot to every channel: /invite @Holtdroid. Channels are configured by ID, e.g. C0123ABCD: open the channel details and find the ID at the bottom of About.

2. Deploy the job

The chart is in the sync repository (deploy/helm/holtdroid-sync, and oci://ghcr.io/holtdroid/charts/holtdroid-sync for tagged releases); job picks the Slack sync:

job: slack
existingSecret: holtdroid-slack-sync # SLACK_BOT_TOKEN, S3_ACCESS_KEY, S3_SECRET_KEY, NOTIFY_URL
config:
  slack:
    token: env:SLACK_BOT_TOKEN
    channels: [C0123ABCD]
  target:
    type: s3
    s3:
      endpoint: https://s3.example.com
      region: us-east-1
      bucket: holtdroid
      prefix: slack
      accessKey: env:S3_ACCESS_KEY
      secretKey: env:S3_SECRET_KEY
  notify: # optional: announce new builds
    urls: [env:NOTIFY_URL] # e.g. slack://xoxb:<bot token without xoxb->@C0123ABCD
    portalURL: https://holtdroid.example.com
    source: slack

To announce into the channel itself, reuse the bot token in the shoutrrr URL. Builds whose message is older than notify.maxAge (24 hours by default) aren’t announced, so the first pass over lookback stays quiet.

Every key can also come from HOLTDROID_SLACK_SYNC_* environment variables, e.g. HOLTDROID_SLACK_SYNC_SLACK__CHANNELS=C1,C2. The full reference is in the job’s docs.

3. Add the source to Holtdroid

Point a read-only source at the same place. Its name has to match notify.source, or the launch links open the wrong source:

sources:
  - name: slack
    type: s3
    readOnly: true
    s3:
      endpoint: https://s3.example.com
      region: us-east-1
      bucket: holtdroid
      prefix: slack
      accessKey: env:S3_ACCESS_KEY
      secretKey: env:S3_SECRET_KEY

What ends up in the source

{channel ID}/{file ID}/{file name}.apk
{channel ID}/{file ID}/{file name}.apk.meta.json

Sidecar field	Value
changelog	the message text; for a forward, the forwarder’s comment and then the original message
note, link	permalink of the message in the channel
uploadedBy	display name of whoever posted it (bots: the bot’s name; forwards: the original author)
uploadedAt	message time (forwards: the original message’s time)
title	the Slack file title, if it differs from the file name
origin	slack

It also writes {file name}.apk.icon.png, the launcher icon re-rendered at 256 px, when one can be extracted.

How it polls

Each pass reads the history of the last lookback (7 days by default) and lists the source. Only files the source doesn’t have yet get downloaded, so a restart loses nothing and does no extra work. A thread is fetched again only when it has a new reply. Edits to a top-level message rewrite its sidecar; the APK isn’t downloaded again.

Polling has these limits:

• replies to threads whose parent is older than lookback are missed;
• edits to thread replies that are already synced show up only after the thread gets another reply.