emi 0.0.9

Eons Modular Installer

eons Modular Installer

Use the eons modular installer (EMI) to configure systems.

EMI is a package manager that uses the eons python library by executing arbitrary "actions" which are provided by the repository (per eons).
The default repository is https://infrastructure.tech.

This means emi install a_package will execute the "install" action and provide it with the arguments "a_package".

Basically, we're iterating on the tried-and-true universal install script:

Installation

pip install emi

Usage

Emi should behave as expected: you can install, update and remove packages.

Emi uses the current user's home directory to store configuration and data relating to operations (e.g. what packages at what versions have been installed where).

Because emi is built on eons, the actions you request do not have to be installed prior: anything not found in your home directory will be automatically downloaded for you.

Verbiage

Merx
Actions intended for use with emi will be labeled as "merx". This derives from latin: "emi merx" is roughly "I bought the goods", merx being goods or wares. In this case any "goods" available for "purchase" may be "bought" (i.e. downloaded; there is no exchange of currency in emi, only network bandwidth) by emi.

A merx may be invoked through its Transaction() method, which is called by its UserFunction() (per eons.UserFunctor; meaning merx() calls merx.Transaction()). Transaction() is what you'll want to override when creating your own merx.

NOTE: you'll also want to override the Merx.Rollback() method for when things go wrong.

Tomes
Packages intended for use in merx are called "tomes", i.e. semantically heavy symbols. "heavy" here alludes to the fact that tomes and what they act upon may contain multiple libraries. However, each tome, be it a library itself, a set of binaries, or even just a simple environment variable, is still referenced by emi as a single symbol (i.e. name).

A tome on the default repository will typically be a zip containing directories like "bin", "inc", "lib", etc. It is up to the package maintainer to adhere to these standards or to be consistent in their own (e.g. for use with their own merx). Each maintainer is likewise responsible for ensuring their tome's cross-platform viability and documentation.

To restate the above, emi install a_package, when using the default install script and repo through eons, will generate 2 requests:

1. merx_install will be downloaded and placed in ~/.eons/merx/install.py.
2. tome_a_package will be downloaded to ~/.eons/tmp/a_package/ and used as an arg in the install.py Merx.Transaction().

EBBS is used to build tomes; EMI is used to install them. Actions intended for use in EBBS are called "builders"; actions intended for use in EMI are called merx.

Merx, as a noun, rather than the typical verb (the same as "installation" vs "install", "removal" vs "remove", etc.) can be rationalized as a requested change. For example, the emi analogy follows that a merchant would "sell you a change" in your system, provided that you give them the knowledge of how to do that (i.e. the Tomes). This is like asking a contractor to build a new room onto your house, only the contractor would need to know the blueprint for the room ahead of time.

Arguments

Emi accepts no additional arguments. Everything beyond the merx (first arg) is made available to the merx. It is up to this merx to decide what to do with the information it is given (usually multiple args past the 2nd equate to multiple packages to install, remove, etc. but that is only convention and in now way required).

This behavior is different from EBBS and the eons Fetch() mechanics.

Because of the treatment of arguments, it is preferred to have many different merx than to have a single merx with many options. For example, apt install -y in proper emi style would be rewritten as apt auto-install or something similar.

Directories

Emi will attempt to use the best directory for the current user by first testing access to common system directories (i.e. check for admin privileges). If a tome can be written to a system directory for use by all users, it will be. Otherwise, the tome will be written to ~/.eons/. This behavior can be overwritten by specifying ..._path in the config (see below), where ... is whichever path you'd like to override (e.g. bin_path, inc_path, lib_path, etc.).

All other data, including the config file and database are stored in ~/.eons/.

WINDOWS USERS: You must set all ..._paths in your config.json or rely only on local user installations (i.e. in the ~/.eons/ folder). Automatic support for system path discovery on Windows may be added in a future release.

Merx

All merx are placed in ~/.eons/merx. These are saved indefinitely. You can also create your own merx in that directory, and they will be automatically usable by emi. The ~/.eons/merx directory is the eons.Executor.repo['store'], i.e. where the self-registering functors for emi (the merx) are kept.

Tomes

Tomes are downloaded to ~/.eons/tmp. Currently, these are saved indefinitely but that will be changed in a future release. The idea is that a merx should move the contents of the tome to the appropriate location in the filesystem and record that location in the database (see below).

Configuration

Emi uses the default config file ~/.eons/config.json. While this can be overridden, it is much preferred to leave it as is.

This configuration file is used for all eons.Executor.Fetch() calls, which means any merx that Fetch()s a value can find it in this config.

Database

Emi uses a SQLite database to keep track of all merx transaction and the locations of all tomes.

This database is stored in ~/.eons/catalog.db.

All columns which can have multiple entries will be semicolon delimited.

Tomes

A record of all tomes is kept in the tomes table:

Name	Data Type	Not NULL
id	INTEGER	true
name	VARCHAR	false
version	VARCHAR	false
installed_at	VARCHAR	false
retrieved_from	VARCHAR	false
first_retrieved_on	FLOAT	false
last_retrieved_on	FLOAT	false
additional_notes	VARCHAR	false

Transactions

Everytime emi is invoked, it will record the Transaction it executes. These data are storde in the transactions table:

Name	Data Type	Not NULL
id	INTEGER	true
when	FLOAT	false
merx	VARCHAR	false
tomes	VARCHAR	false
result	INTEGER	false

Repository

Online repository settings can be specified with:

--repo-store (default = ./eons/)
--repo-url (default = https://api.infrastructure.tech/v1/package)
--repo-username
--repo-password

Keep in mind that emi --repo-store ... merx tomes on the command line is equivalent to having "repo_store": "..." in the config.json.
Please don't store your credentials in the config.

NOTE: you do not need to supply any repo settings to download packages from the public repository. For more info on the repo integration, see the eons library