AJSPEC Specification

An ajspec file provides information about the image, such as the checksum, the site where the image will be downloaded, etc. The syntax of the ajspec file is the same as used in templates.

The following table shows detailed information about ajspec parameters. The Optional column specifies whether a parameter is mandatory or not for some commands such as appjail-image(1) update and appjail-image(1) import. The Multiple column specifies whether a parameter can be specified multiple times or not.

Parameter	Optional	Multiple	Description
`<tag>.name`	Yes	No	Image name. Although it is optional it is highly recommended to have it set as it is not, the user will have to specify one when importing.
`<tag>.timestamp.<arch>`	No	No	Timestamp specifiying when the image was last updated.
`<tag>.maintainer`	Yes	Yes	In charge of maintaining the image and everything related to it.
`<tag>.comment`	Yes	No	One-line description
`<tag>.url`	Yes	No	Home page project or a website that provides more information about the image for the specific tag
`<tag>.description`	Yes	Yes	Long description.
`<tag>.sum.<arch>`	No	No	Checksum.
`<tag>.source.<arch>`	No	Yes	Sites where the image will be downloaded. If the first one fails, AppJail will try the second one and if it fails, AppJail will try the third one, and so on.
`<tag>.size.<arch>`	Yes	No	Compressed image size.
`entrypoint`	No	No	It is used by `appjail-image(1)` `update` to retrieve the ajspec when `appjail-image(1)` `import` is called and set by the latter.
`ajspec`	Yes	No	Ajspec filename used by git-like methods.
`<tag>.arch`	No	Yes	Architectures allowed by this image.
`tags`	No	Yes	Image tags.

As you can see there are some things to talk about, such as <tag> and <arch>. <tag> specifies the image tag and <arch> the image architecture. It is important to remember to add the image tag to tags and the image architecture to <tag>.arch for AppJail recognize them. See appjail-image(1) for more details.

You probably won't need to manipulate an ajspec file many times, especially if you only want to use the image, but for when you need to edit it, appjail-image(1) metadata if your best friend.

Before editing, it is worth looking at what we need to edit.

# appjail image metadata info nginx
Name            :    nginx (132)
Maintainer(s)   :
  - Francis Ford Coppola <fcoppola@example.org>
  - Quentin Tarantino <qtarantino@example.org>
Build on        :
  - amd64
Image           :    amd64
  - SHA256 = 481f09014b94433430efb2f0da52c7bdd2cc4e9b478ac9336b06710dab9d2ea5
  - SIZE = 27360
  - TIMESTAMP = Tue Jun 13 20:05:19 2023
Source          :    amd64
  - http://192.168.1.105:8080/AppJail-images/nginx/132-amd64-image.appjail
Entrypoint      :    gh+DtxdF/nginx-image
AJSPEC          :    .ajspec

This image is descriptive, but a description and perhaps other data are very important, such as the home page and a one-line description.

# appjail image metadata set -t 132 nginx comment="Robust and small WWW server"
# appjail image metadata set -t 132 nginx url="https://nginx.org/"
# cat << EOF | while IFS= read -r line; do appjail image metadata set -t 132 nginx description+="${line}"; done
NGINX is a high performance edge web server with the lowest memory footprint
and the key features to build modern and efficient web infrastructure.

NGINX functionality includes HTTP server, HTTP and mail reverse proxy, caching,
load balancing, compression, request throttling, connection multiplexing and
reuse, SSL offload and HTTP media streaming.
EOF
# appjail image metadata info nginx
Name            :    nginx (132)
Maintainer(s)   :
  - Francis Ford Coppola <fcoppola@example.org>
  - Quentin Tarantino <qtarantino@example.org>
Comment         :    Robust and small WWW server
Build on        :
  - amd64
Image           :    amd64
  - SHA256 = 481f09014b94433430efb2f0da52c7bdd2cc4e9b478ac9336b06710dab9d2ea5
  - SIZE = 27976978
  - TIMESTAMP = Tue Jun 13 20:05:19 2023
Source          :    amd64
  - http://localhost:8080/132-amd64-image.appjail
WWW             :    https://nginx.org/
Description     :
NGINX is a high performance edge web server with the lowest memory footprint
and the key features to build modern and efficient web infrastructure.

NGINX functionality includes HTTP server, HTTP and mail reverse proxy, caching,
load balancing, compression, request throttling, connection multiplexing and
reuse, SSL offload and HTTP media streaming.
Entrypoint      :    gh+DtxdF/nginx-image
AJSPEC          :    .ajspec

See also:

Images