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Basic payloads: Data payloads: make one, read one (2 of 5)

The basic payloads series, hands-on: data payloads: make one, read one.

The Tebako team

github.com/tamatebako
Note

Post 2 of 5 in the series Basic payloads.

○ ● ○ ○ ○

  1. Basic payloads: Run your first package

  2. Basic payloads: Data payloads: make one, read one (this post)

  3. Basic payloads: Package a Ruby application

  4. Basic payloads: Package a Rails or Sinatra application

  5. Basic payloads: Publish to your users
Note

Reference guide: Create a data payload.

The simplest payload there is: a directory of files. Fonts, schemas, dictionaries, word lists, datasets — anything versioned that applications read. No code, no compilation, one command. This post makes one and then reads it back two ways.

Data payloads a directory acme-fonts/ fonts/*.ttf __tpkg__/ manifest.yaml tfs mkimage one command one image, two ways to use it mount it press --image …:/usr/share/fonts/acme apps read the files in place read it directly tfs ls · tfs cat · tfs extract inspect and unpack on any machine

Figure 1 — A directory with a manifest becomes one image; applications mount it at a path, or you read it directly with the tfs commands.

Make the payload

Give the directory a manifest and press it into an image:

$ mkdir -p acme-fonts/fonts acme-fonts/__tpkg__
$ cp ~/Downloads/acme-*.ttf acme-fonts/fonts/
$ cat > acme-fonts/__tpkg__/manifest.yaml <<EOF
schema_version: 1
kind: data
name: acme-fonts
version: 2.1.0
provides:
  paths:
    - /fonts
EOF
$ tfs mkimage acme-fonts/ -o acme-fonts-2.1.0.tfs

You now have one file — acme-fonts-2.1.0.tfs — that is a complete, versioned, self-describing payload.

Read it back

The tfs commands inspect and unpack any image on any machine, with nothing installed:

$ tfs info acme-fonts-2.1.0.tfs     # kind, manifest, byte counts
$ tfs ls acme-fonts-2.1.0.tfs       # list the tree
$ tfs cat acme-fonts-2.1.0.tfs /fonts/acme-bold.ttf > acme-bold.ttf
$ tfs extract acme-fonts-2.1.0.tfs -o ./unpacked/

info and ls never leave the image in place faster than a directory listing; cat pulls out one file; extract unpacks the whole tree.

Mount it into an application

The other way to consume a data payload is to mount it, so an application reads the files in place. That is a press-time decision, and it belongs to the next post’s subject.

$ tebako press -r ./myapp -e bin/myapp -o myapp \
    --image acme-fonts-2.1.0.tfs:/usr/share/fonts/acme

When that packaged app runs, /usr/share/fonts/acme is the mounted image — the same bytes, no copies on disk.

What you can do now

You can turn any directory of files into a versioned payload, inspect it, pull files out of it, and mount it into an application. The next post packages the application itself.

Note

Continue with part 3 of 5: Package a Ruby application.