Re: [PATCH 9/9] doc: Creation of local apt repo caching upstream Debian packages

[Claudius Heine <claudius.heine.ext@siemens.com>]

Hi,

On 10/2/18 2:19 PM, Maxim Yu. Osipov wrote:
> Signed-off-by: Alexander Smirnov <asmirnov@ilbers.de>
> Signed-off-by: Maxim Yu. Osipov <mosipov@ilbers.de>
> ---
>   doc/user_manual.md | 39 +++++++++++++++++++++++++++++++++++++++
>   1 file changed, 39 insertions(+)
> 
> diff --git a/doc/user_manual.md b/doc/user_manual.md
> index db58cf1..d69dd0d 100644
> --- a/doc/user_manual.md
> +++ b/doc/user_manual.md
> @@ -19,6 +19,8 @@ Copyright (C) 2016-2017, ilbers GmbH
>    - [Add a Custom Application](https://github.com/ilbers/isar/blob/master/doc/user_manual.md#add-a-custom-application)
>    - [Enabling Cross-compilation](https://github.com/ilbers/isar/blob/master/doc/user_manual.md#isar-cross-compilation)
>    - [Create an ISAR SDK root filesystem](https://github.com/ilbers/isar/blob/master/doc/user_manual.md#create-an-isar-sdk-root-filesystem)
> + - [Creation of local apt repo caching upstream Debian packages](https://github.com/ilbers/isar/blob/master/doc/user_manual.md#creation-repo-caching-upstream-debian)
> +
>   
>   ## Introduction
>   
> @@ -686,3 +688,40 @@ ii  crossbuild-essential-armhf           12.3                   all          Inf
>   /usr/share/doc/libhello-dev/copyright
>   ~#
>   ```
> +
> +## Creation of local apt repo caching upstream Debian packages
> +
> +### Motivation
> +
> +Cache upstream debian packages to reduce time for further downloads and to be able to work offline.
> +
> +### Solution
> +
> + - Trigger creation of local apt caching Debian packages during image generation.
> +
> +```
> +bitbake -c cache_base_repo multiconfig:qemuarm-stretch:isar-image-base
> +```
> +
> + - Set `ISAR_USE_CACHED_BASE_REPO` in `conf/local.conf`:
> +
> +```
> +# Uncomment this to enable use of cached base repository
> +#ISAR_USE_CACHED_BASE_REPO ?= "1"

No that doesn't make sense to me.

In my opinion its very important to not have such flags or commands. 
Caching and reproducible builds should be the default operation, 
upgrading or removing the cache should be an extra step.

The cache should be created and used on every image build. On the first 
build the cache is empty and on the next build its full, so it will be used.

Use apt preferences to git the cache a higher priority than the upstream 
repos to archive that.

Also if the sources.list is different when setting 
`ISAR_USE_CACHED_BASE_REPO` than the image is different from the first one.

Also please avoid those binary settings like 
`ISAR_USE_CACHED_BASE_REPO`. That just bad design because it leads to 
every tiny setting having an own variable. Use FEATURE variables with 
entries like:

`ISAR_BUILD_FEATURE = "cross-build use-cache ..."`

Yes cross-builds should have been done like this as well IMO.

Cheers,
Claudius

> +```
> + - Remove build artifacts to use only local base-apt:
> +
> +```
> +sudo rm -rf tmp/stamps/ tmp/work/ tmp/deploy/isar-apt/ tmp/deploy/images
> +
> +```
> +
> + - Trigger again generation of image (now using local caching repo):
> +
> +```
> +bitbake multiconfig:qemuarm-stretch:isar-image-base
> +```
> +
> +### Limitation
> +
> +So far the local base-apt repo is not gpg signed.
> 

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