Added MADR for decision making following

Also added first adr for comparing Skopeo and Crane

docs/decisions/0000-use-markdown-any-decision-records.md

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+# Use Markdown Any Decision Records
+
+## Context and Problem Statement
+
+We want to record any decisions made in this project independent whether decisions concern the architecture ("architectural decision record"), the code, or other fields.
+Which format and structure should these records follow?
+
+## Considered Options
+
+* [MADR](https://adr.github.io/madr/) 3.0.0 – The Markdown Any Decision Records
+* [Michael Nygard's template](http://thinkrelevance.com/blog/2011/11/15/documenting-architecture-decisions) – The first incarnation of the term "ADR"
+* [Sustainable Architectural Decisions](https://www.infoq.com/articles/sustainable-architectural-design-decisions) – The Y-Statements
+* Other templates listed at <https://github.com/joelparkerhenderson/architecture_decision_record>
+* Formless – No conventions for file format and structure
+
+## Decision Outcome
+
+Chosen option: "MADR 3.0.0", because
+
+* Implicit assumptions should be made explicit.
+  Design documentation is important to enable people understanding the decisions later on.
+  See also [A rational design process: How and why to fake it](https://doi.org/10.1109/TSE.1986.6312940).
+* MADR allows for structured capturing of any decision.
+* The MADR format is lean and fits our development style.
+* The MADR structure is comprehensible and facilitates usage & maintenance.
+* The MADR project is vivid.

docs/decisions/0001-skopeo-vs-crane.md.md

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+# Skopeo vs Crane
+
+## Context and Problem Statement
+
+We want to decide wether to use Skopeo or Crane to replicate images from a remote source registry to a local destination registry.
+
+## Considered Options
+
+* [Skopeo](https://github.com/containers/skopeo)
+* [Crane](https://github.com/google/go-containerregistry/tree/main/cmd/crane)
+
+## Decision Outcome
+
+Chosen option: "Crane", because according to our use cases _(listed in the table below)_, Crane works for all of them :
+
+| Use Case | Skopeo | Crane |
+|---|---|---|
+| **Programmable, can be used as an SDK** | No (CLI only or via wrapping) | Yes (CLI + library) |
+| **Configuration can be done via API** | No | Yes |
+| **Move OCI Artifacts** | Yes (copy + delete) | Yes (copy + delete) |
+| **Remapping Artifacts (programmatically)** _( = modify or move image)_ | No | Yes |
+| **Image Consistency Verification** (was it really pulled correctly, is it present) | Yes (inspect manifest and compare hashes) | Yes (validate well-formed image + compare digest of image) |
+| **Memory and CPU consumption on low end devices, Disk consumption** | "Very lightweight CPU usage" / 37.1MB | "Lightweight CPU usage" / 34.7MB |
+| **Dealing with Low bandwidth networks, resume, etc.** | Can report transfer rate and progress per blob, can use `--retry`/`--retry-times` flags, evidence of people using it with [intermittent networking issues](https://github.com/containers/common/issues/654) | No resumable push -> works with single PATCH request, as per [this issue](https://github.com/google/go-containerregistry/issues/1448), can use `.withRetry`, support for [very slow speeds via buffering](https://github.com/google/go-containerregistry/issues/920) / [here](https://github.com/google/go-containerregistry/pull/923) |

docs/decisions/README.md

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+# Decisions
+
+This directory contains decision records for Harbor Satellite.
+
+For new ADRs, please use [adr-template.md](adr-template.md) or [0000-use-markdown-any-decision-records.md](0000-use-markdown-any-decision-records.md) as basis.
+More information on MADR is available at <https://adr.github.io/madr/>.
+General information about architectural decision records is available at <https://adr.github.io/>.

docs/decisions/adr-template.md

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+---
+# These are optional elements. Feel free to remove any of them.
+status: {proposed | rejected | accepted | deprecated | … | superseded by [ADR-0005](0005-example.md)}
+date: {YYYY-MM-DD when the decision was last updated}
+deciders: {list everyone involved in the decision}
+consulted: {list everyone whose opinions are sought (typically subject-matter experts); and with whom there is a two-way communication}
+informed: {list everyone who is kept up-to-date on progress; and with whom there is a one-way communication}
+---
+# {short title of solved problem and solution}
+
+## Context and Problem Statement
+
+{Describe the context and problem statement, e.g., in free form using two to three sentences or in the form of an illustrative story.
+ You may want to articulate the problem in form of a question and add links to collaboration boards or issue management systems.}
+
+<!-- This is an optional element. Feel free to remove. -->
+## Decision Drivers
+
+* {decision driver 1, e.g., a force, facing concern, …}
+* {decision driver 2, e.g., a force, facing concern, …}
+* … <!-- numbers of drivers can vary -->
+
+## Considered Options
+
+* {title of option 1}
+* {title of option 2}
+* {title of option 3}
+* … <!-- numbers of options can vary -->
+
+## Decision Outcome
+
+Chosen option: "{title of option 1}", because
+{justification. e.g., only option, which meets k.o. criterion decision driver | which resolves force {force} | … | comes out best (see below)}.
+
+<!-- This is an optional element. Feel free to remove. -->
+### Consequences
+
+* Good, because {positive consequence, e.g., improvement of one or more desired qualities, …}
+* Bad, because {negative consequence, e.g., compromising one or more desired qualities, …}
+* … <!-- numbers of consequences can vary -->
+
+<!-- This is an optional element. Feel free to remove. -->
+## Validation
+
+{describe how the implementation of/compliance with the ADR is validated. E.g., by a review or an ArchUnit test}
+
+<!-- This is an optional element. Feel free to remove. -->
+## Pros and Cons of the Options
+
+### {title of option 1}
+
+<!-- This is an optional element. Feel free to remove. -->
+{example | description | pointer to more information | …}
+
+* Good, because {argument a}
+* Good, because {argument b}
+<!-- use "neutral" if the given argument weights neither for good nor bad -->
+* Neutral, because {argument c}
+* Bad, because {argument d}
+* … <!-- numbers of pros and cons can vary -->
+
+### {title of other option}
+
+{example | description | pointer to more information | …}
+
+* Good, because {argument a}
+* Good, because {argument b}
+* Neutral, because {argument c}
+* Bad, because {argument d}
+* …
+
+<!-- This is an optional element. Feel free to remove. -->
+## More Information
+
+{You might want to provide additional evidence/confidence for the decision outcome here and/or
+ document the team agreement on the decision and/or
+ define when this decision when and how the decision should be realized and if/when it should be re-visited and/or
+ how the decision is validated.
+ Links to other decisions and resources might here appear as well.}